Reactive changes of kisspeptin-producing hypothalamic neuroendocrine cells during hypogonadism and its replacement therapy by the kisspeptin analogue in rats

BACKGROUND: This study is devoted to the morphological substantiation of the model of male hypogonadism and to establishing the effectiveness of its replacement therapy at the level of the central link of the hypothalamic-pituitary-testicular axis using morphological methods. Information about reactive changes in neuroendocrine cells that synthesize the peptide kisspeptin, which regulates the production of gonadoliberin when modeling male and female hypogonadism, has not been described in the literature, which prevents the creation of a micro-morphological basis for the development of models of hypogonadism and the implementation of further preclinical studies of the effectiveness of its replacement therapy. The goal is to carry out a morphological analysis of kisspeptin-producing neuroendocrine cells of the hypothalamus in normal conditions, with experimental hypogonadism and after replacement therapy.

AIM: To carry out a morphological analysis of kisspeptin-producing neuroendocrine cells of the hypothalamus in normal conditions, with experimental hypogonadism and after replacement therapy.

MATERIALS AND METHODS: The objects of the study were 3 groups of adult male Wistar rats 6–8 months of age. In animals of the first and second groups, after anesthesia, total ischemia of both testicles was caused by ligating the left and right spermatic cord with the vascular bundle of the testicle for 60 minutes. Rats of the second group, a few minutes after restoration of testicular blood flow, were given replacement therapy by daily administration of a synthetic analogue of kisspeptin KS6 for 7 days. Control animals of the third group were subjected to sham surgery. After 10 days, all animals were sacrificed, their brains were removed and embedded in paraffin. Nissl-stained frontal histological sections of the most massive areas of the kisspeptin-producing nuclei of the hypothalamus-periventricular and arcuate-were examined using the Imagescope program (Electronic Analysis, Russia). The number of cell bodies of viable and dead neurons was counted (under the control of immunohistochemical identification of the caspase-3 antigen), and the area of the body, nucleus and cytoplasm of viable cells was calculated. Statistical processing of the data was carried out using the GraphPad PRISM (USA) program to determine the median, upper and lower quartiles. Differences were considered significant at p < 0.01.

RESULTS: Simulation of acute ischemia caused a significant increase in the number of dead neurons, a slight decrease in the number of viable neurons and a decrease in the area of their cytoplasm in both kisspeptin-producing nuclei. As a result of KS6 replacement therapy, most neuronal cell bodies retained their original phenotype, but the number of dead neurons was high in both experimental groups.

CONCLUSIONS: Modeling of male hypogonadism using the method of bilateral acute testicular ischemia induces death and partially reversible degenerative changes in kisspeptin-producing neuroendocrine cells of the hypothalamus. Neuropeptide KS6 has a pronounced restorative effect on kisspeptin-producing neurons of the hypothalamus, which is due to its specific activating effect on endocrine cells of all parts of the hypothalamic-pituitary-testicular axis.