Abstract
Quantitative assessment of immunocytochemical staining for gonadotropin-releasing hormone (GnRH) was undertaken to determine the effects of an intracranial implant of melatonin on the GnRH neuronal system in the male white-footed mouse (Peromyscus leucopus). Melatonin-containing pellets stereotaxically placed in the anterior hypothalamic area (AH) caused a 60% reduction in testes weight relative to control mice with melatonin-free pellets in the AH (p less than 0.01). Subcutaneous melatonin-containing implants had little effect on reproductive state (p less than 0.8). Melatonin pellets in the AH increased significantly both the optical density (OD) for immunostaining of cell bodies in the medial preoptic area and AH (p less than 0.04), and the percentage of area covered by GnRH fibers and beads in the median eminence (p less than 0.01). The melatonin-induced increase in OD of the GnRH cell bodies was independent of the distance of the cells from the melatonin implant, and there was little apparent effect of melatonin on the size and morphology of the GnRH cell bodies, or the trajectories of their fiber pathways. These results support the hypothesis that the antigonadal action of melatonin in the brain involves suppression of the release, rather than the synthesis of GnRH. Also, this effect may not be mediated via a direct action of melatonin on GnRH neurons. The finding that the brain site and time course for melatonin's antigonadal action in male. P. leucopus is similar to that found previously in the female is evidence that melatonin may induce gonadal regression, in part, by helping to suppress the tonic secretion of gonadotropins.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.