Hirano bodies are intracellular aggregates of

actin Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of over ...

and actin-associated proteins first observed in

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 ...

s (nerve cells) by Asao Hirano in 1965. The eponym ‘Hirano bodies’ was not introduced until 1968, by Schochet ''et al.'', three years after Hirano first observed the proteins. Hirano bodies are found in the nerve cells of individuals afflicted with certain neurodegenerative disorders, such as

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 ...

and Creutzfeldt–Jakob disease. Hirano bodies were first described in the CA1 in patients with

amyotrophic lateral sclerosis Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or Lou Gehrig's disease, is a neurodegenerative disease that results in the progressive loss of motor neurons that control voluntary muscles. ALS is the most comm ...

and parkinsonism-dementia complex (ALS-PDC). Hirano bodies (Hb) are found mostly in the neuronal processes in the pyramidal layer in the Sommer’s sector (CA1) of the

hippocampus The hippocampus (via Latin from Greek , 'seahorse') is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, a ...

, mostly arising from age related changes in the

microfilament Microfilaments, also called actin filaments, are protein filaments in the cytoplasm of eukaryotic cells that form part of the cytoskeleton. They are primarily composed of polymers of actin, but are modified by and interact with numerous other pr ...

system. Hirano bodies are often described as rod-shaped, crystal-like, and eosinophilic (pink after staining with

haematoxylin Haematoxylin or hematoxylin (), also called natural black 1 or C.I. 75290, is a compound extracted from heartwood of the logwood tree (''Haematoxylum campechianum'') with a chemical formula of . This naturally derived dye has been used as a h ...

and eosin). They are frequently seen in hippocampal pyramidal cells. An experimental model of Hirano body formation has been reported, using a genetically altered strain of the slime mold '' Dictyostelium discoideum''. Hirano bodies have been noted as a function of age without obvious underlying neurodegeneration.

Alzheimer's disease

The Sommer’s sector (CA1) of the

has been described to be influential in the formation of new memories, as well as, containing

inclusion bodies Inclusion bodies are aggregates of specific types of protein found in neurons, a number of tissue cells including red blood cells, bacteria, viruses, and plants. Inclusion bodies of aggregations of multiple proteins are also found in muscle cells ...

that contribute to a hallmark of Alzheimer’s disease (AD), intellectual deficit. Alzheimer’s neurofibrillary tangles show a preference to form in the CA1, which is one of the major areas in which Hb’s have been observed. There are a larger number of Hb’s found in people with Alzheimer’s disease than those without the disease. Additionally many processes of Alzheimer’s

neurofibrillary tangle Neurofibrillary tangles (NFTs) are aggregates of hyperphosphorylated tau protein that are most commonly known as a primary biomarker of Alzheimer's disease. Their presence is also found in numerous other diseases known as tauopathies. Little is kn ...

s have been observed to contain Hirano bodies. Hirano bodies are described as cytoplasmic paracrystalline lattices, which are a main form of a pathological feature seen in a broad spectrum of

neurodegenerative diseases A neurodegenerative disease is caused by the progressive loss of structure or function of neurons, in the process known as neurodegeneration. Such neuronal damage may ultimately involve cell death. Neurodegenerative diseases include amyotrophic ...

, such as Alzheimer’s disease (AD). There is an upregulation of a macroautophagic pathway related to AD that can be related to an actin aggregate thought to be an intermediate in the formation of Hirano bodies. More specifically the

and actin binding proteins seen in Hirano bodies are a significant feature of an Alzheimer’s disease brain. Additionally, variations in the locational characteristics of ''β''-amyloid precursor proteins seen in Alzheimer’s disease are connected to Hirano bodies. It was observed that Hirano bodies are a specific site of a C-terminal fragment of ''β''-amyloid precursor proteins.

Notes

References

* Gajdusek, D. Carleton, Clarence J. Gibbs, Jr. and Michael Alpers. (1965) ''Slow Latent and Temperate Virus Infections.'' Bethesda:

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 ...

National Institute of Neurological Diseases and Blindness The National Institute of Neurological Disorders and Stroke (NINDS) is a part of the U.S. National Institutes of Health (NIH). It conducts and funds research on brain and nervous system disorders and has a budget of just over US$2.03 billion. The ...

OCLC 463013735
*

External links

{{Eponymous medical signs for nervous system Histopathology