Effects of melatonin and gonadal androgens on cell proliferation in the pituitary of viscachas (Lagostomus maximus maximus)

GABRIELA JUDITH ROSALES; FABRICIO IVÁN BUSOLINI; FABIÁN HEBER MOHAMED; VERÓNICA PALMIRA FILIPPA

CELL PROLIFERATION

WILEY

Lugar: Londres; Año: 2016

0960-7722

Objectives: Melatonin and androgens are involved in the regulation of cell proliferation. However, the effect of these hormones on pituitary pars distalis (PD) of male viscachas is not fully understood. In the present study, we analyzed the melatonin and gonadal androgens effects on proliferating cell nuclear antigen (PCNA) expression. Materials and methods: Pituitary glands from fetus, immature, prepubertal, and adult viscachas during their reproductive cycle, after melatonin administration and after castration were used. PCNA-ir cells were detected by immunocytochemistry and morphometrically quantified by image analysis. Results: the total percentage of PCNA-ir cells varied seasonally in the adult pituitary, with maximum values during the reproductive period and minimum values during the gonadal regression period. The percentage of PCNA-ir cells increased after melatonin administration, whereas it decreased after castration. The caudal end and ventral region were the PD zones which were most affected by seasonal variations and castration. The PCNA expression was highest in fetal pituitary from midpregnancy. The number of PCNA-ir cells decreased during sexual maturity. Conclusions: Our results demonstrated the effect of gonadal androgens on cell proliferation during the reproductive period and sexual maturity of animals. Exogenous melatonin increased PD cell proliferation in adults. Thus, these hormones might be involved in different mechanisms that regulate the cell renewal of PD in this seasonally breeding rodent.