GABAergic and catecholaminergic innervation of mediobasal hypothalamic beta-endorphin cells projecting to the medial preoptic area

Neuroscience. 1992 Nov;51(2):391-9. doi: 10.1016/0306-4522(92)90323-t.


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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Axonal Transport
  • Female
  • Glutamate Decarboxylase / analysis*
  • Horseradish Peroxidase
  • Hypothalamus, Middle / cytology*
  • Hypothalamus, Middle / enzymology
  • Hypothalamus, Middle / ultrastructure
  • Immunohistochemistry
  • Microscopy, Immunoelectron
  • Nerve Fibers / enzymology
  • Nerve Fibers / ultrastructure*
  • Neurons / cytology*
  • Neurons / enzymology
  • Neurons / ultrastructure
  • Rats
  • Rats, Sprague-Dawley
  • Tyrosine 3-Monooxygenase / analysis*
  • beta-Endorphin / analysis*


  • beta-Endorphin
  • Horseradish Peroxidase
  • Tyrosine 3-Monooxygenase
  • Glutamate Decarboxylase