Regulation of hen granulosa cell fate during ovarian follicular development.
|Title:||Regulation of hen granulosa cell fate during ovarian follicular development.|
|Abstract:||To determine if tumour necrosis factor alpha (TNF a ) plays a role in the regulation of follicular growth and selection, studies were performed on F1 and F5,6 granulosa cells in the presence or absence of maximally stimulatory concentrations of luteinizing hormone (LH), transforming growth factor alpha (TGF a ) or carbamylcholine chloride (Cch). Assessments of follicular growth were performed primarily using [3H]-thymidine incorporation assays, while survival was assessed using 3-(4,5-dimethylthiazol-2-yl)-3,5-diphenyl tetrazolium bromide (MTT), DNA degradation and vital staining assays. Basal [3H]-thymidine incorporation was significantly higher in F5,6 (smallest follicles in follicular hierarchy versus F1 (largest follicle in follicular hierarchy) granulosa cells while the opposite was observed for MTT metabolism. LH stimulated [3H]-thymidine incorporation in F5,6 cells, while inhibiting [3H]-thymidine incorporation in F1 cells. In contrast, (TGF a ) stimulated [3H]-thymidine incorporation in F1 cells and to a lesser extent, F5,6 cells. TNF a had no apparent effect on basal, LH- or TGF a -induced [3H]-thymidine incorporation in either F1 or F5,6 granulosa cells. In addition, while neither TNF a nor TGF a alone affected the viability of cultured granulosa cells from either developmental stage, in the presence of both factors an increase in MTT metabolism occurred in F5,6 but not F1 granulosa cells. In contrast to the TNF a -TGF a studies, interactions between TNF a and Cch were not observed irrespective of the stage of follicular development and the rate of MTT metabolism was not affected by either factor. F5,6 cell viability in vitro decreased with time in the presence of TNF a or TGF a while the combination of these intraovarian regulators significantly delayed this decrease. In contrast, only TGF a increased MTT metabolism in sparsely cultured F5,6 granulosa cells during the first 24 hours of culture, after which time no significant changes were observed. TGF a also significantly decreased the amount of DNA fragmentation, while TNF a had no significant effect in the presence or absence of the growth factor. In conclusion, the objective of this research was to study TNF a and its interactions with Cch, TGF a and LH in the regulation of granulosa cell fate, ie proliferation, differentiation and apoptosis, as well as the possible signalling mechanisms involved during follicular development. (Abstract shortened by UMI.)|
|Collection||Thèses, 1910 - 2010 // Theses, 1910 - 2010|