Close Juxtapositions between Luteinizing Hormone-Releasing Hormone-Immunoreactive Neurons and Corticotropin-Releasing Factor-Immunoreactive Axons in the Human Diencephalon

Abstract

Gonadal functions are modulated by corticotropin-releasing factor (CRF) in the rat via direct suppression of LH-releasing hormone (LHRH) release. Although there is evidence of direct morphological contacts between the LHRH and CRF-immunoreactive (-IR) structures in the rat hypothalamus, little is known about the morphological base of CRF-influenced LHRH release in man. Thus, we studied the distribution of the CRF-IR and LHRH-IR systems in the human diencephalon and revealed putative CRF-LHRH juxtapositions using double label immunohistochemistry. LHRH-IR cells were present mainly in the infundibular region and the medial preoptic area. CRF-IR neuronal structures were observed in the periventricular area, paraventricular nucleus, infundibular region, and median eminence. CRF-LHRH juxtapositions were found mainly in the infundibulum and median eminence. Few juxtapositions were detected in the medial preoptic area. In these regions, black diaminobenzidine/silver-labeled CRF-IR fibers abutted fusiform brown diaminobenzidine-labeled LHRH neurons, usually forming multiple contacts. Examination of semithin sections of these close associations with the aid of oil immersion revealed no cleft between CRF-IR nerve terminals contacting LHRH-IR structures. These findings suggest that the juxtapositions between the LHRH-IR and CRF-IR neurons may be functional synapses forming the morphological substrate of the CRF-controlled LHRH secretion. Moreover, the wide distribution of CRF-IR elements suggests that CRF controls other diencephalic functions as well.

Brain response to putative pheromones in lesbian women

“…The preoptic area of the hypothalamus harbors cells releasing luteinic hormone-releasing hormone (8). These cells develop from the migrating neuroblasts of the olfactory mucosa (9) and mediate estrogen feedback. The estrogen feedback differs between males and females and also is reported to differ between homosexual men (HoM) and heterosexual men (HeM) (10).…”

Corticotropin-Releasing Hormone and Pro-Opiomelanocortin Gene Expression in Female Monkeys with Differences in Sensitivity to Stress

“…Also, CRH fibers have been shown to be juxapositioned on GnRH neurons in humans [33]. Thus, the elevation in hypothalamic CRH in SS animals may decrease GnRH production even in the absence of stress.…”

Projections to the Preoptic Area from the Paraventricular Nucleus, Arcuate Nucleus and the Bed Nucleus of the Stria Terminalis Are Unlikely to Be Involved in Stress-Induced Suppression of GnRH Secretion in Sheep

“…Alternatively, neurones located in the PVN, such as those that produce CRH and AVP and project to the median eminence, could influence GnRH secretion by acting on GnRH terminals located in the median eminence. In humans, juxtapositions have been observed between CRH fibres and GnRH terminals in the median eminence [55] and in vitro studies showed that CRH inhibited GnRH release from the rat median eminence in a dose-dependent manner [56, 57] although this was not observed with in vivo push-pull perfusion of the rat median eminence [58]. On the other hand, infusion of CRH into the POA of the rat on the day of proestrus caused a significant reduction in LH secretion [58].…”