Seasonal Expression of Gonadotropin Genes in the Pituitary and Testes of Male Plateau Zokor (Eospalax baileyi)

SIMPLE SUMMARY: The plateau zokor lives on the Qinghai-Tibet Plateau and is a local endemic subterranean rodent. As a result of climate change and human activities, the population has increased rapidly, causing damage to grassland resources. Exploring reproductive mechanisms is a central issue in the effective management of the population. However, they are difficult to catch and difficult to breed artificially. Consequently, the scientific problem of seasonal reproduction of plateau zokor remains unclear. We systematically investigated the expression of gonadotropin genes in the pituitary gland and testes of the male plateau zokor during the breeding and non-breeding seasons and identified the target cells in the testes on which the luteinizing hormone and follicle stimulating hormone act. This study aims to provide a theoretical basis for further research on the seasonal reproduction of plateau zokor and explore new ideas for the effective management of their populations. ABSTRACT: The gonadotropins, luteinizing hormone (LH) and follicle stimulating hormone (FSH), are glycoprotein hormones in the hypothalamic-pituitary-gonadal (HPG) axis and regulate mammalian reproduction. The expression of these genes in the plateau zokor (Eospalax baileyi) is poorly understood. We characterized the immunolocalization of the luteinizing hormone receptor (LHR) and follicle stimulating hormone receptor (FSHR) in the testes and evaluated the positive immunohistochemical results and the relative mRNA expression of gonadotropin genes. During the non-breeding season (September), the relative testes weight and the seminiferous tubule diameter were significantly reduced. All germ cell types were observed during the breeding season (May), whereas only spermatogonia were observed during the non-breeding season. LHR was present in the Leydig cells whereas FSHR was present in the Sertoli cells. The mean optical density was higher during the breeding season. The mRNA expression of LHβ and FSHβ was lower in the pituitary but LHR and FSHR genes expression were higher in the testes during the breeding season. These data elucidate the expression of gonadotropin genes in the HPG axis of the male plateau zokor and suggest that gonadotropins play a vital role in the regulation of seasonal breeding.