O papel do hormônio do crescimento na reserva ovariana em camundongos modelo de restrição calórica

Abstract

The objective of this study was to evaluate the number of primordial, primary, secondary and tertiary follicles, as well as the diameter of the nucleus, oocyte and follicle, and the levels of proteins Forkhead Box O3a (FOXO3a) Forkhead Box O3A phosphorylated (p-FOXO3a) in ovaries of Ames Dwarf mice (df/df), with deficient secretion of endogenous growth hormone (GH), receiving or not treatment with exogenous GH; and mice that over express the endogenous GH (bGH). The groups that received exogenous GH were subjected to a treatment with the hormone by subcutaneous injection, given twice a day, starting at the age of fourteen months, during six weeks. After the euthanasia ovaries were removed. Histological analysis was performed to count ovarian follicles and oocyte, nuclear and follicular diameters, and immunohistochemical analysis to evaluate the presence of proteins FOXO3a and p-FOXO3a. The groups of df/df mice had higher number of primordial, in transition and total follicles than normal mice (p<0.0001, p=0.0002 and p<0.0001, respectively). The groups that received the treatment with GH had lower numbers of primordial and total follicles (p=0.009 and p=0.018, respectively). The group of bGH mice had lower numbers of of primordial, in transition, primary and total follicles than the control group (p=0.0001, p=0.0037, p=0.0006 and p=0.0009, respectively). In the immunohistochemistry was observed that in the primordial follicles of normal groups animals the quantity of proteins FOXO3a and p-FOXO3a was lower compared to groups of df/df mice (p=0.009 and p=0.01, respectively). The groups treated with GH had lower quantity of protein FOXO3a (p=0.03) and higher quantity of FOXO3a (p=0.01), in primordial follicles, compared with their control groups. The group of bGH mice presented a higher quantity of p-FOXO3a in primary follicles compared to control group (p=0.006). df/df mice had a larger ovarian primordial follicle reserve than normal mice and the treatment with GH in adult life was able to activate reserve both normal and df/df animals. The opposite was observed in bGH, which presented a smaller ovarian reserve. In addition, the presence of the p-FOXO3a seems to be direct related to activation of primordial follicle growth and under the control of GH.