![Albino Rat](https://upload.wikimedia.org/wikipedia/commons/1/1d/Albino_Rat.jpg)
A laboratory rat or lab rat is a
brown rat
The brown rat (''Rattus norvegicus''), also known as the common rat, street rat, sewer rat, wharf rat, Hanover rat, Norway rat, Norwegian rat and Parisian rat, is a widespread species of common rat. One of the largest muroids, it is a brown o ...
of the subspecies ''
Rattus norvegicus domestica'' which is bred and kept for scientific research. While
less commonly used for research than mice (see
laboratory mouse
The laboratory mouse or lab mouse is a small mammal of the order Rodentia which is bred and used for scientific research or feeders for certain pets. Laboratory mice are usually of the species ''Mus musculus''. They are the most commonly used ...
), rats have served as an important
animal model
An animal model (short for animal disease model) is a living, non-human, often genetic-engineered animal used during the research and investigation of human disease, for the purpose of better understanding the disease process without the risk of ha ...
for research in
psychology
Psychology is the scientific study of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries betwe ...
and
biomedical science
Biomedical sciences are a set of sciences applying portions of natural science or formal science, or both, to develop knowledge, interventions, or technology that are of use in healthcare or public health. Such disciplines as medical microbio ...
.
Origins
![Rat Killing Dog](https://upload.wikimedia.org/wikipedia/commons/c/c9/Rat_Killing_Dog.jpg)
In 18th century Europe, wild brown rats ran rampant and this infestation fueled the industry of rat-catching.
Rat-catcher
A rat-catcher is a person who kills or captures rats as a professional form of pest control. Keeping the rat population under control was practiced in Europe to prevent the spread of diseases, most notoriously the Black Death, and to prevent d ...
s would not only make money by trapping the rodents, but also by selling them for food or, more commonly, for
rat-baiting
Rat-baiting is a blood sport
A blood sport or bloodsport is a category of sport or entertainment that involves bloodshed. Common examples of the former include combat sports such as cockfighting and dog fighting, and some forms of hunt ...
.
Rat-baiting was a popular sport, which involved filling a pit with rats and timing how long it took for a
terrier
Terrier (from Latin ''terra'', 'earth') is a type of dog originally bred to hunt vermin. A terrier is a dog of any one of many breeds or landraces of the terrier type, which are typically small, wiry, game, and fearless. Terrier breeds vary ...
to kill them all. Over time, breeding the rats for these contests may have produced variations in color, notably the
albino
Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and pink or blue eyes. Individuals with the condition are referred to as albino.
Varied use and interpretation of the term ...
and hooded varieties. The first time one of these albino mutants was brought into a laboratory for a study was in 1828 for an experiment on
fasting
Fasting is the abstention from eating and sometimes drinking. From a purely physiological context, "fasting" may refer to the metabolic status of a person who has not eaten overnight (see " Breakfast"), or to the metabolic state achieved after ...
. Over the next 30 years, rats were used for several more experiments and eventually the laboratory rat became the first animal
domesticated
Domestication is a sustained multi-generational relationship in which humans assume a significant degree of control over the reproduction and care of another group of organisms to secure a more predictable supply of resources from that group. A ...
for purely scientific reasons.
![WT and TK rat photo](https://upload.wikimedia.org/wikipedia/commons/e/e5/WT_and_TK_rat_photo.jpg)
In Japan, there was a widespread practice of keeping rats as a domesticated pet during the
Edo period
The or is the period between 1603 and 1867 in the history of Japan, when Japan was under the rule of the Tokugawa shogunate and the country's 300 regional '' daimyo''. Emerging from the chaos of the Sengoku period, the Edo period was characteriz ...
and in the 18th century guidebooks on keeping domestic rats were published by Youso Tamanokakehashi (1775) and Chingan Sodategusa (1787). Genetic analysis of 117 albino rat strains collected from all parts of the world carried out by a team led by Takashi Kuramoto at
Kyoto University
, mottoeng = Freedom of academic culture
, established =
, type = National university, Public (National)
, endowment = ¥ 316 billion (2.4 1000000000 (number), billion USD)
, faculty = 3,480 (Teaching Staff)
, administrative_staff ...
in 2012 showed that the albino rats descended from hooded rats and all the albino rats descended from a single ancestor.
As there is evidence that the hooded rat was known as the "Japanese rat" in the early 20th century, Kuramoto concluded that one or more Japanese hooded rats might have been brought to Europe or the Americas and an albino rat that emerged as a product of the breeding of these hooded rats was the common ancestor of all the albino laboratory rats in use today.
Use in research
![Cut_Rat](https://upload.wikimedia.org/wikipedia/commons/5/54/Cut_Rat.jpg)
The rat found early use in laboratory research in five areas:
W. S. Small suggested that the rate of learning could be measured by rats in a maze; a suggestion employed by
John B. Watson
John Broadus Watson (January 9, 1878 – September 25, 1958) was an American psychologist who popularized the scientific theory of behaviorism, establishing it as a psychological school.Cohn, Aaron S. 2014.Watson, John B." Pp. 1429–1430 in ''T ...
for his Ph.D. dissertation in 1903. The first rat colony in America used for nutrition research was started in January 1908 by
Elmer McCollum
Elmer Verner McCollum (March 3, 1879 – November 15, 1967) was an American biochemist known for his work on the influence of diet on health.Kruse, 1961. McCollum is also remembered for starting the first rat colony in the United States to be us ...
and then, nutritive requirements of rats were used by
Thomas Burr Osborne and
Lafayette Mendel
Lafayette Benedict Mendel (February 5, 1872 – December 9, 1935) was an American biochemist known for his work in nutrition, with longtime collaborator Thomas B. Osborne, including the study of Vitamin A, Vitamin B, lysine and tryptophan.
...
to determine the details of
protein nutrition. The
reproductive function of rats was studied at the Institute for Experimental Biology at the
University of California, Berkeley
The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant u ...
by
Herbert McLean Evans
Herbert McLean Evans (September 23, 1882 – March 6, 1971) was an American anatomist and embryologist best known for co-discovering Vitamin E.
Education
He was born in Modesto, California. In 1908, he obtained his medical degree from Johns Ho ...
and Joseph A. Long. The
genetics
Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...
of rats was studied by
William Ernest Castle
William Ernest Castle (October 25, 1867 – June 3, 1962) was an early American geneticist.
Early years
William Ernest Castle was born on a farm in Ohio and took an early interest in natural history. He graduated in 1889 from Denison University ...
at the
Bussey Institute
The Bussey Institute (1883–1936) was a respected biological institute at Harvard University. It was named for Benjamin Bussey, who, in 1835, endowed the establishment of an undergraduate school of agriculture and horticulture and donated land i ...
of
Harvard University
Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...
until it closed in 1994. Rats have long been used in
cancer research
Cancer research is research into cancer to identify causes and develop strategies for prevention, diagnosis, treatment, and cure.
Cancer research ranges from epidemiology, molecular bioscience to the performance of clinical trials to evaluate and ...
; for instance at the
Crocker Institute for Cancer Research.
![MorrisWaterMaze](https://upload.wikimedia.org/wikipedia/commons/b/bc/MorrisWaterMaze.jpg)
The historical importance of this species to scientific research is reflected by the amount of literature on it: roughly 50% more than that on
laboratory mice
The laboratory mouse or lab mouse is a small mammal of the order Rodentia which is bred and used for scientific research or feeders for certain pets. Laboratory mice are usually of the species ''Mus musculus''. They are the most commonly used ...
.
Laboratory rats are frequently subject to
dissection
Dissection (from Latin ' "to cut to pieces"; also called anatomization) is the dismembering of the body of a deceased animal or plant to study its anatomical structure. Autopsy is used in pathology and forensic medicine to determine the cause o ...
or
microdialysis
Microdialysis is a minimally-invasive sampling technique that is used for continuous measurement of free, unbound analyte concentrations in the extracellular fluid of virtually any tissue. Analytes may include endogenous molecules (e.g. neurotra ...
to study internal effects on organs and the brain, such as for
cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
or
pharmacological
Pharmacology is a branch of medicine, biology and pharmaceutical sciences concerned with drug or medication action, where a drug may be defined as any artificial, natural, or endogenous (from within the body) molecule which exerts a biochemica ...
research. Laboratory rats not sacrificed may be
euthanized
Animal euthanasia ( euthanasia from el, εὐθανασία; "good death") is the act of killing an animal or allowing it to die by withholding extreme medical measures. Reasons for euthanasia include incurable (and especially painful) conditi ...
or, in some cases, become
pets
A pet, or companion animal, is an animal kept primarily for a person's company or entertainment rather than as a working animal, livestock, or a laboratory animal. Popular pets are often considered to have attractive appearances, intelligence, ...
.
Domestic rat
The fancy rat (''Rattus norvegicus domestica'') is the domesticated form of ''Rattus norvegicus'', the brown rat, and the most common species of rat kept as a pet. The name ''fancy rat'' derives from the use of the noun '' fancy'' for a hobby, ...
s differ from wild rats in many ways: they are calmer and significantly less likely to bite, they can tolerate greater crowding, they breed earlier and produce more offspring, and their
brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a v ...
s,
liver
The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...
s,
kidney
The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...
s,
adrenal gland
The adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer cortex which ...
s, and
heart
The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide t ...
s are smaller.
Scientists have bred many strains or "lines" of rats specifically for experimentation. Most are derived from the
albino
Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and pink or blue eyes. Individuals with the condition are referred to as albino.
Varied use and interpretation of the term ...
Wistar rat, which is still widely used. Other common strains are the Sprague Dawley, Fischer 344, Holtzman albino strains, Long–Evans, and Lister black hooded rats.
Inbred strain
Inbred strains (also called inbred lines, or rarely for animals linear animals) are individuals of a particular species which are nearly identical to each other in genotype due to long inbreeding. A strain is inbred when it has undergone at least ...
s are also available, but are not as commonly used as inbred mice.
Much of the
genome of ''Rattus norvegicus'' has been
sequenced
In genetics and biochemistry, sequencing means to determine the primary structure (sometimes incorrectly called the primary sequence) of an unbranched biopolymer. Sequencing results in a symbolic linear depiction known as a sequence which suc ...
. In October 2003, researchers succeeded in
cloning
Cloning is the process of producing individual organisms with identical or virtually identical DNA, either by natural or artificial means. In nature, some organisms produce clones through asexual reproduction. In the field of biotechnology, cl ...
two laboratory rats by
nuclear transfer
Nuclear transfer is a form of cloning. The step involves removing the DNA from an oocyte (unfertilised egg), and injecting the nucleus which contains the DNA to be cloned. In rare instances, the newly constructed cell will divide normally, rep ...
. This was the first in a series of developments that have begun to make rats tractable as
genetic research subjects, although they still lag behind mice, which lend themselves better to the
embryonic stem cell
Embryonic stem cells (ESCs) are pluripotent stem cells derived from the inner cell mass of a blastocyst, an early-stage pre- implantation embryo. Human embryos reach the blastocyst stage 4–5 days post fertilization, at which time they consi ...
techniques typically used for genetic manipulation. Many investigators who wish to trace observations on
behavior
Behavior (American English) or behaviour (British English) is the range of actions and mannerisms made by individuals, organisms, systems or artificial entities in some environment. These systems can include other systems or organisms as wel ...
and
physiology
Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
to underlying
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
s regard aspects of these in rats as more relevant to humans and easier to observe than in mice, giving impetus to the development of genetic research techniques applicable to rat.
A 1972 study compared
neoplasms
A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
in Sprague Dawley rats from six different commercial suppliers and found highly significant differences in the incidences of
endocrine
The endocrine system is a messenger system comprising feedback loops of the hormones released by internal glands of an organism directly into the circulatory system, regulating distant target organs. In vertebrates, the hypothalamus is the neu ...
and
mammary
A mammary gland is an exocrine gland in humans and other mammals that produces milk to feed young offspring. Mammals get their name from the Latin word ''mamma'', "breast". The mammary glands are arranged in organs such as the breasts in primat ...
tumors. There were even significant variations in the incidences of
adrenal medulla
The adrenal medulla ( la, medulla glandulae suprarenalis) is part of the adrenal gland. It is located at the center of the gland, being surrounded by the adrenal cortex. It is the innermost part of the adrenal gland, consisting of chromaffin cel ...
tumors among rats from the same source raised in different laboratories. All but one of the
testicular
A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testost ...
tumors occurred in the rats from a single supplier. The researchers found that the incidence of tumors in Sprague Dawley rats from different commercial sources varied as much from each other as from the other strains of rats. The authors of the study "stressed the need for extreme caution in evaluation of
carcinogen
A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substan ...
icity studies conducted at different laboratories and/or on rats from different sources."
During
food rationing due to World War II, British biologists ate laboratory
rat, creamed.
Scientists have also spent time studying the
thermoregulation
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
of the rat's tail in research. The rat's tail works as a variable heat exchanger. The tails blood flow is allows for thermoregulation to take place because it is under control of sympathetic vasoconstrictor nerves.
Vasodilation
Vasodilation is the widening of blood vessels. It results from relaxation of smooth muscle cells within the vessel walls, in particular in the large veins, large arteries, and smaller arterioles. The process is the opposite of vasoconstriction, ...
occurs when the tail temperature increases, causing heat loss.
Vasoconstriction
Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation, the widening of blood vessel ...
occurs when the tail temperature decreases allowing heat to be conserved. Thermoregulation in the rat tail has been used to study metabolism.
Stocks and strains
A ''
strain
Strain may refer to:
Science and technology
* Strain (biology), variants of plants, viruses or bacteria; or an inbred animal used for experimental purposes
* Strain (chemistry), a chemical stress of a molecule
* Strain (injury), an injury to a mu ...
'', in reference to rodents, is a group in which all members are, as nearly as possible, genetically identical. In rats, this is accomplished through
inbreeding
Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and o ...
. By having this kind of population, it is possible to conduct experiments on the roles of genes, or conduct experiments that exclude variations in genetics as a factor. By contrast, populations are used when identical
genotype
The genotype of an organism is its complete set of genetic material. Genotype can also be used to refer to the alleles or variants an individual carries in a particular gene or genetic location. The number of alleles an individual can have in a ...
s are unnecessary or a population with genetic variation is required, and these rats are usually referred to as ''stocks'' rather than ''strains''.
Wistar rat
![Wistar rat](https://upload.wikimedia.org/wikipedia/commons/f/ff/Wistar_rat.jpg)
The Wistar rat is an outbred albino rat. This breed was developed at the
Wistar Institute
The Wistar Institute () is an independent, nonprofit research institution in biomedical science, with expertise in oncology, immunology, infectious disease and vaccine research. Located on the campus of the University of Pennsylvania, Wistar was ...
in 1906 for use in biological and medical research, and is notably the first rat developed to serve as a
model organism
A model organism (often shortened to model) is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workin ...
at a time when laboratories primarily used the
house mouse
The house mouse (''Mus musculus'') is a small mammal of the order Rodentia, characteristically having a pointed snout, large rounded ears, and a long and almost hairless tail. It is one of the most abundant species of the genus '' Mus''. Althoug ...
(''Mus musculus''). More than half of all laboratory rat strains are descended from the original colony established by
physiologist
Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical a ...
Henry Herbert Donaldson
Henry Herbert Donaldson (12 May 1857 – 23 January 1938) was an American pioneer of neurology. One of his most influential studies was on the effect of sensory deprivation, based on the study of Laura Bridgman's brain, on the development of the ...
, scientific administrator Milton J. Greenman, and
genetic researcher/
embryologist
Embryology (from Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, '' -logia'') is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and ...
Helen Dean King
Helen Dean King (September 27, 1869 – March 7, 1955) was an American biologist. She was involved in breeding the Wistar lab rat, a strain of rats genetically homogeneous albinos intended for use in biological and medical research.
Life and wor ...
.
The Wistar rat is currently one of the most popular rats used for laboratory research. It is characterized by its wide head, long ears, and a tail length that is always less than its body length. The Sprague Dawley rat and Long–Evans rat were developed from Wistar rats. Wistar rats are more active than others like Sprague Dawley rats. The
spontaneously hypertensive rat Spontaneously hypertensive rat (SHR) is a laboratory rat which is an animal model of essential (or primary) hypertension, used to study cardiovascular disease. It is the most studied model of hypertension measured as number of publications. The SH ...
and the Lewis rat are other well-known stocks developed from Wistar rats.
Long–Evans rat
The Long–Evans rat is an outbred rat developed by Drs. Long and Evans in 1915 by crossing several Wistar females with a wild gray male. Long-Evans rats are white with a black hood, or occasionally white with a brown hood. They are utilized as a multipurpose model organism, frequently in behavioral research, especially in alcohol research. Long-Evans consume alcohol in a much higher rate compared to other strains, thus require less time for these behavioral studies.
Sprague Dawley rat
![SpragueDawleyRat](https://upload.wikimedia.org/wikipedia/commons/d/dc/SpragueDawleyRat.jpg)
The Sprague Dawley rat is an outbred, multipurpose breed of albino rat used extensively in medical and nutritional research. Its main advantage is its calmness and ease of handling. This breed of rat was first produced by the Sprague Dawley farms (later to become the
Sprague Dawley Animal Company) in
Madison, Wisconsin
Madison is the county seat of Dane County and the capital city of the U.S. state of Wisconsin. As of the 2020 census the population was 269,840, making it the second-largest city in Wisconsin by population, after Milwaukee, and the 80th-lar ...
, in 1925. The name was originally hyphenated, although the brand styling today (Sprague Dawley, the trademark used by
Envigo
Envigo (en-VEE-go) is a privately held contract research organization and laboratory animal sourcer that provides live animals and related products and services to pharmaceutical and biotechnology industries, government, academia and other life ...
) is not. The average litter size of the Sprague Dawley rat is 11.0.
These rats typically have a longer tail in proportion to their body length than Wistar rats. They were involved in the
Séralini affair
The Séralini affair was the controversy surrounding the publication, retraction, and republication of a journal article by French molecular biologist Gilles-Éric Séralini. First published by ''Food and Chemical Toxicology '' in September 201 ...
, where the herbicide
RoundUp was claimed to increase the occurrence of tumor in these rats. However, since these rats are known to grow tumors at a high (and very variable) rate, the study was considered flawed in design and its findings unsubstantiated.
Biobreeding rat
The biobreeding rat (a.k.a. the biobreeding diabetes-prone rat or BBDP rat) is an inbred strain that spontaneously develops autoimmune
type 1 diabetes
Type 1 diabetes (T1D), formerly known as juvenile diabetes, is an autoimmune disease that originates when cells that make insulin (beta cells) are destroyed by the immune system. Insulin is a hormone required for the cells to use blood sugar for ...
. Like
NOD mice Non-obese diabetic or NOD mice, like biobreeding rats, are used as an animal model for type 1 diabetes. Diabetes develops in NOD mice as a result of insulitis, a leukocytic infiltrate of the pancreatic islets. The onset of diabetes is associated w ...
, biobreeding rats are used as an animal model for Type 1 diabetes. The strain re-capitulates many of the features of human type 1 diabetes and has contributed greatly to the research of T1DM pathogenesis.
Brattleboro rat
The Brattleboro rat is a strain that was developed by
Henry A. Schroeder
Henry Alfred Schroeder (June 18, 1906 - 1975) Doctor of Medicine, M.D., American College of Physicians, F.A.C.P was an American Physiology, physiologist and writer.
Schroeder was born in Short Hills, New Jersey and graduated from Yale College in ...
and technician Tim Vinton in
West Brattleboro
West Brattleboro is a census-designated place (CDP) in the town of Brattleboro, Vermont, United States. The population was 3,222 at the 2000 census.
Geography
According to the United States Census Bureau, the CDP has a total area of 25.9 km ...
,
Vermont
Vermont () is a state in the northeast New England region of the United States. Vermont is bordered by the states of Massachusetts to the south, New Hampshire to the east, and New York to the west, and the Canadian province of Quebec to ...
, beginning in 1961, for
Dartmouth Medical School
The Geisel School of Medicine at Dartmouth is the graduate medical school of Dartmouth College in Hanover, New Hampshire. The fourth oldest medical school in the United States, it was founded in 1797 by New England physician Nathan Smith. It is o ...
. It has a naturally occurring genetic mutation that makes specimens unable to produce the
hormone
A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required ...
vasopressin
Human vasopressin, also called antidiuretic hormone (ADH), arginine vasopressin (AVP) or argipressin, is a hormone synthesized from the AVP gene as a peptide prohormone in neurons in the hypothalamus, and is converted to AVP. It then travel ...
, which helps control kidney function. The rats were being raised for laboratory use by Dr. Henry Schroeder and technician Tim Vinton, who noticed that the litter of 17 drank and urinated excessively.
Hairless rat
Hairless laboratory rats provide researchers with valuable data regarding compromised immune systems and genetic kidney diseases. It is estimated that there are over 25 genes that cause
recessive
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...
hairlessness in laboratory rats. The more common ones are denoted as rnu (Rowett nude), fz (fuzzy), and shn (shorn).
![Nackratte_01](https://upload.wikimedia.org/wikipedia/commons/0/08/Nackratte_01.jpg)
* Rowett nude rats, first identified in 1953 in Scotland, have no
thymus
The thymus is a specialized primary lymphoid organ of the immune system. Within the thymus, thymus cell lymphocytes or ''T cells'' mature. T cells are critical to the adaptive immune system, where the body adapts to specific foreign invaders. ...
. The lack of this organ severely compromises their immune system, with infections of the respiratory tract and eyes increasing the most dramatically.
* Fuzzy rats were identified in 1976 in a Pennsylvania lab. The leading cause of death among fz/fz rats is ultimately a progressive kidney failure that begins around the age of 1 year.
* Shorn rats were bred from Sprague Dawley rats in Connecticut in 1998.
They also suffer from severe kidney problems.
Lewis rat
The Lewis rat was developed by Margaret Lewis from
Wistar stock in the early 1950s. Characteristics include albino coloring, docile behavior, and low fertility.
[
The Lewis rat suffers from several spontaneous pathologies: first, they can suffer from high incidences of neoplasms, with the rat's lifespan mainly determined by this. The most common are adenomas of the pituitary and adenomas/adenocarcinomas of the adrenal cortex in both sexes, mammary gland tumors and endometrial carcinomas in females, and C-cell adenomas/adenocarcinomas of the thyroid gland and tumors of the haemopoietic system in males. Second, Lewis rats are prone to develop a spontaneous transplantable lymphatic leukaemia. Lastly, when in advanced age, they sometimes develop spontaneous glomerular sclerosis.][
Research applications include transplantation research, induced arthritis and inflammation, experimental allergic encephalitis, and STZ-induced diabetes.]
Royal College of Surgeons rat
The Royal College of Surgeons
The Royal College of Surgeons is an ancient college (a form of corporation) established in England to regulate the activity of surgeons. Derivative organisations survive in many present and former members of the Commonwealth. These organisations a ...
rat (or RCS rat) is the first known animal with inherited retinal degeneration. Although the genetic defect was not known for many years, it was identified in the year 2000 as a mutation in the gene MERTK. This mutation results in defective retinal pigment epithelium phagocytosis of photoreceptor outer segments.
Shaking rat Kawasaki
The shaking rat Kawasaki (SRK) is an autosomal recessive
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...
mutant rat that has a short deletion in the RELN (reelin) gene. This results in the lowered expression of reelin protein, essential for proper cortex
Cortex or cortical may refer to:
Biology
* Cortex (anatomy), the outermost layer of an organ
** Cerebral cortex, the outer layer of the vertebrate cerebrum, part of which is the ''forebrain''
*** Motor cortex, the regions of the cerebral cortex i ...
lamination and cerebellum
The cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cerebel ...
development. Its phenotype is similar to the widely researched reeler
A reeler is a mouse mutant, so named because of its characteristic "reeling" gait. This is caused by the profound underdevelopment of the mouse's cerebellum, a segment of the brain responsible for locomotion. The mutation is autosomal and recess ...
mouse. Shaking rat Kawasaki was first described in 1988. This and the Lewis rat are well-known stocks developed from Wistar rats.
Zucker rat
The Zucker rat was bred to be a genetic model for research on obesity and hypertension. They are named after Lois M. Zucker and Theodore F. Zucker, pioneer researchers in the study of the genetics of obesity. There are two types of Zucker rat: a lean Zucker rat, denoted as the dominant trait (Fa/Fa) or (Fa/fa); and the characteristically obese (or fatty) Zucker rat or Zucker diabetic fatty rat (ZDF rat), which is actually a recessive trait
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...
(fa/fa) of the leptin receptor
Leptin receptor, also known as LEP-R or OB-R, is a type I cytokine receptor, a protein that in humans is encoded by the ''LEPR'' gene. LEP-R functions as a receptor for the fat cell-specific hormone leptin. LEP-R has also been designated as CD2 ...
, capable of weighing up to — more than twice the average weight.
Obese Zucker rats have high levels of lipids
Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include ...
and cholesterol
Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell mem ...
in their bloodstream, are resistant to insulin without being hyperglycemic
Hyperglycemia is a condition in which an excessive amount of glucose circulates in the blood plasma. This is generally a blood sugar level higher than 11.1 mmol/L (200 mg/dL), but symptoms may not start to become noticeable until even ...
, and gain weight from an increase in both the size
Size in general is the Magnitude (mathematics), magnitude or dimensions of a thing. More specifically, ''geometrical size'' (or ''spatial size'') can refer to linear dimensions (length, width, height, diameter, perimeter), area, or volume ...
and number
A number is a mathematical object used to count, measure, and label. The original examples are the natural numbers 1, 2, 3, 4, and so forth. Numbers can be represented in language with number words. More universally, individual numbers c ...
of fat cells
Adipocytes, also known as lipocytes and fat cells, are the cells that primarily compose adipose tissue, specialized in storing energy as fat. Adipocytes are derived from mesenchymal stem cells which give rise to adipocytes through adipogenesis. I ...
. Obesity in Zucker rats is primarily linked to their hyperphagic nature and excessive hunger; however, food intake does not fully explain the hyperlipidemia or overall body composition.
Knockout rats
A knockout rat (also spelled ''knock out'' or ''knock-out'') is a genetically engineered
Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including t ...
rat with a single gene turned off through a targeted mutation. Knockout rats can mimic human diseases, and are important tools for studying gene function and for drug discovery
In the fields of medicine, biotechnology and pharmacology, drug discovery is the process by which new candidate medications are discovered.
Historically, drugs were discovered by identifying the active ingredient from traditional remedies or by ...
and development. The production of knockout rats became technically feasible in 2008, through work financed by $120 million in funding from the National Institutes of Health
The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late ...
(NIH) via the Rat Genome Sequencing Project Consortium, and work accomplished by the members of the Knock Out Rat Consortium (KORC). Knockout rat disease models for Parkinson's disease
Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms becom ...
, Alzheimer's disease
Alzheimer's disease (AD) is a neurodegeneration, neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in short-term me ...
, hypertension
Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...
, and diabetes
Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
, using zinc-finger nuclease technology, are being commercialized by SAGE Labs.
See also
* Laboratory mouse
The laboratory mouse or lab mouse is a small mammal of the order Rodentia which is bred and used for scientific research or feeders for certain pets. Laboratory mice are usually of the species ''Mus musculus''. They are the most commonly used ...
* Animal testing on rodents
Rodents are commonly used in animal testing, particularly mice and rats, but also guinea pigs, hamsters, gerbils and others. Mice are the most commonly used vertebrate species, due to their availability, size, low cost, ease of handling, and fast ...
* Morris water maze
The Morris water navigation task, also known as the Morris water maze (not to be confused with ''Water maze (neuroscience), water maze''), is a behavioral procedure mostly used with rodents. It is widely used in behavioral neuroscience to study ...
* ''Rat Genome Database
The Rat Genome Database (RGD) is a database of rat genomics, genetics, physiology and functional data, as well as data for comparative genomics between rat, human and mouse. RGD is responsible for attaching biological information to the rat gen ...
''
References
Further reading
*
External links
"Rat Genome"
''Nature''
''Rat Genome Database''
Medical College of Wisconsin
''Index of Inbred Rat Strains''
database, Jacskson Laboratory
''Rat Model Summary''
database, Knock Out Rat Consortium (archived copy)
{{Authority control
Animal models
Articles containing video clips