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Light microscopic immunocytochemical identification of leucine enkephalin

Dimka V. Hinova-Palova, Lawrence Edelstein, Boycho V. Landzhov, Minko Minkov, Lina G. Malinova, Alexandar Alexandrov, Stanislav Hristov, Adrian M. Paloff, Wladimir A. Ovtscharoff


Leucine-enkephalin is a potent and naturally-occurring opioid peptide which serves to inhibit other neurotransmitters involved with pain perception, thereby reducing its emotional and physical impact. Nevertheless, there is little data in the literature concerning leucine-enkephalin-immunoreactivity (Leu-enk-ir) in the human claustrum. The objectives of this study were to confirm the existence of leucine-enkephalin immunoreactive neurons and fibers in the human claustrum. Light microscopy was used to describe their morphology and distribution. Samples of claustrum were obtained from the brains of two females (39 and 48 years of age) and two males (27 and 42 years of age). The brains did not show any overt signs of pathology or trauma. Immunoreactivity to Leuenk was assessed via the Avidin-Biotin Complex Method. Light-microscopic analysis confirmed the presence of Leu-enk-ir neurons and fibres in all areas of the human claustrum. The cell bodies varied in shape and size, and were divided into three groups: small, medium and large. The density of immunostaining varied both within and between the cell types, with some neurons, staining more darkly or lightly than others. The large and medium sized cells most likely correspond to claustrocortical projection neurons while the small-sized cells appear to be inhibitory interneurons. It is our hope that these results will be contributed to a better understanding the functions of claustrum, in both health and disease, given its relationship with the development of autism, schizophrenia, Alzheimer disease, Parkinson disease and Huntington disease.


leucine-enkephalin; human claustrum; immunocytochemistry

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About The Authors

Dimka V. Hinova-Palova
Medical university of Sofia

Department of Anatomy and Histology

Lawrence Edelstein
Medimark corp., San Diego, CA
United States

Boycho V. Landzhov
Medical university of Sofia

Department of anatomy and histology

Minko Minkov
Medical university of Varna

Department of anatomy histology and embryology

Lina G. Malinova
Medical university of Sofia

Department of anatomy and histology

Alexandar Alexandrov
Medical university of Sofia

Department of forensic medicine and deontology

Stanislav Hristov
Medical university of Sofia

Department of forensic medicine and deontology

Adrian M. Paloff
Medical university of Varna

Department of anatomy and histology

Wladimir A. Ovtscharoff
Medical university of Sofia

Department of anatomy and hiistology

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