Neurochemistry is the study of

chemicals A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., wit ...

, including

neurotransmitter A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse. The cell receiving the signal, any main body part or target cell, may be another neuron, but could also be a gland or muscle cell. Neuro ...

s and other molecules such as psychopharmaceuticals and

neuropeptides Neuropeptides are chemical messengers made up of small chains of amino acids that are synthesized and released by neurons. Neuropeptides typically bind to G protein-coupled receptors (GPCRs) to modulate neural activity and other tissues like the ...

, that control and influence the physiology of the

nervous system In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes th ...

. This particular field within

neuroscience Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions and disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, development ...

examines how neurochemicals influence the operation of

neuron A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. N ...

synapse In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell. Synapses are essential to the transmission of nervous impulses from ...

s, and

neural network A neural network is a network or circuit of biological neurons, or, in a modern sense, an artificial neural network, composed of artificial neurons or nodes. Thus, a neural network is either a biological neural network, made up of biological ...

s. Neurochemists analyze the

biochemistry Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and ...

and

molecular biology Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physi ...

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

s in the nervous system, and their roles in such neural processes including

cortical plasticity Neuroplasticity, also known as neural plasticity, or brain plasticity, is the ability of neural networks in the brain to change through growth and reorganization. It is when the brain is rewired to function in some way that differs from how it ...

neurogenesis Neurogenesis is the process by which nervous system cells, the neurons, are produced by neural stem cells (NSCs). It occurs in all species of animals except the porifera (sponges) and placozoans. Types of NSCs include neuroepithelial cells (NECs) ...

, and neural differentiation.

History

While neurochemistry as a recognized science is relatively new, the idea behind neurochemistry has been around since the 18th century. Originally, the brain had been thought to be a separate entity apart from the peripheral nervous system. Beginning in 1856, there was a string of research that refuted that idea. The chemical makeup of the brain was nearly identical to the makeup of the peripheral nervous system. The first large leap forward in the study of neurochemistry came from

Johann Ludwig Wilhelm Thudichum Johann Ludwig Wilhelm Thudichum, also known as John Louis William Thudichum (August 27, 1829, Büdingen – September 7, 1901) was a German-born physician and biochemist. From 1847 he studied medicine at the University of Giessen, where he ...

, who is one of the pioneers in the field of "brain chemistry." He was one of the first to hypothesize that many neurological illnesses could be attributed to an imbalance of chemicals in the brain. He was also one of the first scientists to believe that through chemical means, the vast majority of neurological diseases could be treated, if not cured. Irvine Page (1901-1991) was an American psychologist that published the first major textbook focusing on neurochemistry in 1937. He had also established the first department that was solely devoted to the study of neurochemistry in 1928 at the Munich Kaiser Wilhelm Institute for Psychiatry. Back in the 1930s, neurochemistry was mostly referred to as "brain chemistry" and was mostly devoted to finding different chemical species without directly proposing their specific roles and functions in the nervous system. The first biochemical pathology test for any brain disease can be attributed to Maria Buscaino (1887-1978), a neuropsychiatrist who studied schizophrenia. She found that treating her patients' urine who had schizophrenia, extrapyramidal disorders, or amentia, with 5% silver nitrate produced a black precipitate linked with an abnormal level of amines. This became known as the "Buscaino Reaction." In the 1950s, neurochemistry became a recognized scientific research discipline. The founding of neurochemistry as a discipline traces its origins to a series of "International Neurochemical Symposia", of which the first symposium volume published in 1954 was titled ''Biochemistry of the Developing Nervous System''. These meetings led to the formation of the

International Society for Neurochemistry The International Society for Neurochemistry (ISN) is a professional society for neurochemists and neuroscientists throughout the world. History The idea of an organization like the ISN began in the mid-1950s as scientists began to devote more att ...

and the

American Society for Neurochemistry The American Society for Neurochemistry (ASN) is a professional society for neurochemists and neuroscientists from North, Central, and South America and the Caribbean, whose research concerns the role and interactions of small molecules (protein ...

. These early gatherings discussed the tentative nature of possible neurotransmitter substances such as

acetylcholine Acetylcholine (ACh) is an organic chemical that functions in the brain and body of many types of animals (including humans) as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Part ...

histamine Histamine is an organic nitrogenous compound involved in local immune responses, as well as regulating physiological functions in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Since histamine was discovered in ...

substance P Substance P (SP) is an undecapeptide (a peptide composed of a chain of 11 amino acid residues) and a member of the tachykinin neuropeptide family. It is a neuropeptide, acting as a neurotransmitter and as a neuromodulator. Substance P and its clos ...

, and

serotonin Serotonin () or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Its biological function is complex and multifaceted, modulating mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and vas ...

. By 1972, ideas were more concrete. One of the first major successes in using chemicals to alter brain function was the

L-DOPA -DOPA, also known as levodopa and -3,4-dihydroxyphenylalanine, is an amino acid that is made and used as part of the normal biology of some plants and animals, including humans. Humans, as well as a portion of the other animals that utilize -DOPA ...

experiment. In 1961, Walter Burkmayer injected L-DOPA into a patient with

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 ...

. Shortly after injection, the patient had a drastic reduction in tremors, and they were able to control their muscles in ways they hadn't been able to in a long time. The effect peaked within 2.5 hours and lasted approximately 24 hours.

Neurotransmitters and neuropeptides

The most important aspect of neurochemistry is the neurotransmitters and neuropeptides that comprise the chemical activity in the nervous system. There are many neurochemicals that are integral for proper neural functioning. The neuropeptide oxytocin, synthesized in magnocellular neurosecretory cells, plays an important role in maternal behavior and sexual reproduction, particularly before and after birth. It is a precursor protein that is processed proteolytically to activate the neuropeptide as its shorter form. It is involved in the letdown reflex when mothers breastfeed, uterine contractions, and the hypothalamic-pituitary-adrenal axis where oxytocin inhibits the release of cortisol and adrenocorticotropic hormone. Glutamate, which is the most abundant neurotransmitter, is an excitatory neurochemical, meaning that its release in the synaptic cleft causes the firing of an action potential. GABA, or Gamma-aminobutyric acid, is an inhibitory neurotransmitter. It binds to the plasma membrane in the synapses of neurons, triggering the influx of negatively charged chloride ions and the efflux of positively charged potassium ions. This exchange of ions leads to the hyperpolarization of the transmembrane potential of the neuron, which is caused by this negative change. Dopamine is a neurotransmitter with much importance in the limbic system which regulates emotional function regulation. Dopamine has many roles in the brain including cognition, sleep, mood, milk production, movement, motivation, and reward. Serotonin is a neurotransmitter that regulates mood, sleep, and other roles of the brain. It is a peripheral signal mediator and is found in the gastrointestinal tract as well as in blood. Research also suggests that serotonin may play an important role in liver regeneration.

Neurotypical neurochemistry

Neurochemistry is the study of the different types, structures, and functions of neurons and their chemical components. Chemical signaling between neurons is mediated by neurotransmitters, neuropeptides, hormones, neuromodulators, and many other types of signaling molecules. Many neurological diseases arise due to an imbalance in the brain's neurochemistry. For example, in Parkinson's Disease, there is an imbalance in the brain's level of dopamine. Medications include neurochemicals that are used to alter brain function and treat disorders of the brain. A typical neurochemist might study how the chemical components of the brain interact, neural plasticity, neural development, physical changes in the brain during disease, and changes in the brain during aging.

Neurochemistry of PTSD

One of the major areas of research within neurochemistry is looking at how

post-traumatic stress disorder Post-traumatic stress disorder (PTSD) is a mental and behavioral disorder that can develop because of exposure to a traumatic event, such as sexual assault, warfare, traffic collisions, child abuse, domestic violence, or other threats on ...

alters the brain. Neurotransmitter level fluctuations can dictate whether a

PTSD Post-traumatic stress disorder (PTSD) is a mental and behavioral disorder that can develop because of exposure to a traumatic event, such as sexual assault, warfare, traffic collisions, child abuse, domestic violence, or other threats on a ...

episode occurs and how long the episode lasts.

Dopamine Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic compound, organic chemical of the catecholamine and phenethylamine families. Dopamine const ...

has less of an effect than

norepinephrine Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as both a hormone and neurotransmitter. The name "noradrenaline" (from Latin '' ad'', ...

. Different neurochemicals can affect different parts of the brain. This allows drugs to be used for

to not have an undesired effect on other brain processes. An effective medication to help alleviate nightmares associated with

Prazosin Prazosin is an α1 blocker medication primarily used to treat high blood pressure, symptoms of an enlarged prostate, and nightmares related to post-traumatic stress disorder (PTSD). It is a less preferred treatment of high blood pressure. Other ...

References

External links