title: GABAergic and catecholaminergic innervation of mediobasal hypothalamic beta-endorphin cells projecting to the medial preoptic area.
abstract: In the absence of cellular estrogen receptors or proven direct estrogen action in the rat, it is assumed that estrogen indirectly regulates the secretory activity of the preoptic area luteinizing hormone-releasing hormone-producing cells. We have previously shown that pro-opiomelanocortin neurons in the arcuate nucleus of the rat send axons rostrally to connect with luteinizing hormone-releasing hormone neurons of the preoptic area. An experiment combining retrograde tracing and double-immunostaining was used to test the hypothesis that rat GABAergic and/or catecholaminergic neurons can influence luteinizing hormone-releasing hormone-producing cells via mediobasal hypothalamic beta-endorphin neurons. The retrograde tracer horseradish peroxidase was injected into the medial preoptic area; two days later, arcuate nucleus Vibratome sections were double-immunostained for beta-endorphin and glutamate decarboxylase or tyrosine hydroxylase. Light and electron microscopic analysis of these triple-labeled sections demonstrated that a population of beta-endorphin-immunoreactive neurons concentrated in the ventromedial arcuate nucleus contain retrogradely transported horseradish peroxidase granules and form synaptic contacts with glutamate decarboxylase- and tyrosine hydroxylase-immunoreactive axon terminals. The present data suggest that arcuate nucleus GABA and catecholamine fibers may influence luteinizing hormone-releasing hormone-containing neurons via projective pro-opiomelanocortin cells.
mesh_terms: D000818:Animals; D001370:Axonal Transport; D005260:Female; D005968:Glutamate Decarboxylase / Q000032:analysis*; D006735:Horseradish Peroxidase; D007033:Hypothalamus, Middle / Q000166:cytology* / Q000201:enzymology / Q000648:ultrastructure; D007150:Immunohistochemistry; D016253:Microscopy, Immunoelectron; D009412:Nerve Fibers / Q000201:enzymology / Q000648:ultrastructure*; D009474:Neurons / Q000166:cytology* / Q000201:enzymology / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D014446:Tyrosine 3-Monooxygenase / Q000032:analysis*; D001615:beta-Endorphin / Q000032:analysis*
chemical_list: D001615:beta-Endorphin; D006735:Horseradish Peroxidase; D014446:Tyrosine 3-Monooxygenase; D005968:Glutamate Decarboxylase