Maternal protein restriction before and during pregnancy leads to a gestational day-dependent response of folliculogenesis in outbred mice

Abstract

Knowledge of follicle development during pregnancy under experimental conditions could be a key factor to understanding maternal ovarian activity. Thus, this study evaluated the effects of maternal protein restriction before and during pregnancy on folliculogenesis. Swiss outbred female mice were allocated to either a control (CC; 20% protein) or treated (TT; 8% protein) group. Pregnant females were killed either on Gestational day (GD) 7.5 or GD17.5 and the ovaries were evaluated using histomorphometric and immunohistochemical methods. TT females showed higher feed and energy intakes, but lower bodyweight gain at GD17.5 (P<0.05). They also had lower number of secondary follicles at GD7.5 and a higher proportion of primordial follicles at GD17.5 (P<0.05). In addition, the areas of the secondary follicles and their granulosa layer were smaller in the TT group on GD7.5, whereas the areas of the oocyte and granulosa layer from atretic follicles were larger (P<0.05). Notwithstanding the slight increase in the insulin-like growth factor 1 (IGF1) receptor expression on GD7.5 in the TT group, there was a marked reduction in IGF1 expression detected in secondary follicles on GD17.5 (P<0.05). Collectively, these results demonstrate that protein restriction during pregnancy negatively affects follicle quality by reducing the size and activation capacity, which is more severe in late pregnancy.

Partial loss of arcuate kisspeptin neurons in female rats stimulates luteinizing hormone and decreases prolactin secretion induced by estradiol

“…Follicles were classified in primordial (intact oocyte surrounded by one layer of squamous follicular cells), primary (intact oocyte surrounded by one layer of cubic cells), preantral (intact oocyte surrounded by more than one layer of cuboidal cells), secondary (presence of a non-completed antrum), tertiary (whole developed antrum, peripheral oocyte surrounded by corona radiata and the presence of cumulus oophorus), and atretic (infiltration of macrophages and leucocytes and detachment of granulosa cells), as described previously. 27 Follicles with intact oocytes from each category were counted in all the selected semi-serial histological sections and the number of each follicle type counted was multiplied by a factor of 10 to estimate the absolute number of follicles in the entire ovary. Regressing corpora lutea, identified by its shrunken appearance and predominance of cells with eosinophilic cytoplasm, 28 were not considered in the counting because they reflected ovulations previous to the NK3-SAP treatment.…”