Mutual synaptic associations between neurons containing neuropeptide Y and neurons containing enkephalin in the arcuate nucleus of the rat hypothalamus.
We determined reciprocal synaptic associations between neurons containing neuropeptide Y (NPY) and neurons containing enkephalin-8 peptide (Enk-8) in the arcuate nucleus (ARC) of the rat hypothalamus by using a double-staining immunocytochemical method. Animals treated with an intraventricular administration of colchicine and animals treated with a hemicomplete cut of the medial basal hypothalamus were used. We principally labeled NPY with silver-gold particles and Enk-8 with diaminobenzidine (DAB) chromogen but in part labeled reversely the two antigens to obtain better visualization of Enk-8 cell bodies. Neurons immunoreactive for NPY were found in the mediobasal area, while those for Enk-8 were located somewhat laterally. Their fibers, however, were densely distributed throughout the ARC in a similar fashion. Electron microscopically, we found synaptic junctions between axonal terminals of Enk-8 neurons and perikarya of NPY neurons and between axonal terminals of NPY neurons and perikarya of Enk-8 neurons. In addition, we found synaptic junctions between immunoreactive Enk-8 cell bodies and processes and also between immunoreactive NPY cell bodies and processes. These interneuronal associations may contribute to the interaction of information coming in or going out from this nucleus.
Department of Pathophysiology, Norman Bethune University of Medical Sciences, Changchun, People's Republic of China.
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Li
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Hisano
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Daikoku
D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000166:cytology*; D001369:Axons / Q000502:physiology; D003078:Colchicine / Q000494:pharmacology; D004745:Enkephalins / Q000032:analysis*; D007150:Immunohistochemistry; D007365:Intercellular Junctions / Q000502:physiology / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D009474:Neurons / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure*; D009478:Neuropeptide Y / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000502:physiology / Q000648:ultrastructure*
D004745:Enkephalins; D009478:Neuropeptide Y; D003078:Colchicine