Immunocytochemical localization of hypothalamic luteinizing hormone-releasing hormone in male ferrets

LHRH-containing neurons within the hypothalamus were immunocytochemically identified in adult male ferrets that were either gonadally intact, castrated, or castrated and treated with testosterone. The distribution of LHRH-immunopositive neuron cell bodies was similar in the three treatment groups. The majority of these cells was located mediobasally in the retrochiasmatic area, including some within the ventrolateral aspects of the arcuate nucleus. These soma were associated with a dense basal LHRH fiber plexus which extended to the median eminence. A smaller number of cell bodies was found slightly more dorsal and lateral to the major concentration at the base and midline. Isolated LHRH perikarya were occasionally observed in dorsal areas of the hypothalamus. There were no differences in the mean total number of hypothalamic LHRH cell bodies identified in the three treatment groups. These results indicate that the documented negative feedback effects of testosterone on LH secretion in male ferrets are not the result of an alteration in the absolute number of neurons capable of synthesizing LHRH.