Date of Award

1997

Degree Type

Thesis

Degree Name

Bachelor of Science Honours

Faculty

Faculty of Science, Technology and Engineering

First Advisor

Arun Dharmarajan

Second Advisor

Prof Alan Bittles

Abstract

Apoptosis, a form of physiological cell death, has been found to occur during regression of the corpus luteum (Juengel etal, 1993; Dharmarajan etal, 1994). The pathways involved in this process, however, have yet to be specified. One possible mediator of corpus luteum regression is the Fas (or AP0-1 or CD95) receptor, a transmembrane protein which induces apoptosis in the cell when ligated. In order to further confirm this hypolhesis, the present study establishes and quantitates the presence and regulation of Fas receptor and Fas ligand (Fasl) in the rat corpus luteum during pregnancy and post-partum. The animals used were sexually mature (1 0-12 week old) female Wistar rats. The presence of Fas and Fasl in the rat corpus luteum at various stages of pregnancy and post-partum was investigated by immunohistochemistry using an anti-Fas monoclonal antibody and an anti-FasL polyclonal antibody. FasL was localised in corpora lutea throughout pregnancy, whilst Fas was localised at day 1 of pregnancy and at the time of luteolysis. Information on the steady state mRNA levels of Fasl was obtained using relative quantitative reverse transcription PCR (RT-PCR) analysis of RNA isolated from rat ovaries at various stages of pregnancy and post-partum. Expression of Fasl mRNA increased significantly at day 22 of pregnancy, just prior to parturition, and decreased by day 3 post-partum. The ability of an anti-rat Fas monoclonal antibody to block spontaneous apoptosis in corpora lutea placed in an in vitro culture model with serum-free medium was examined by analysis of extracted DNA using 3'-end labelling. Treatment with an anti-rat Fas monoclonal a11tibody demonstrated a reduction in the occurrence of spontaneous apoptosis. Roles for Fas receptor and Fas ligand in corpus luteum function were proposed, and the suitability of the in vitro corpus luteum culture model for future studies investigating molecular mechanisms of Fas-mediated apoptosis in the corpus luteum was discussed.

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