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(112) REGULATION OF TESTICULAR APOPTOSIS IN GOLDFISH. Andreu-Vieyra, Claudia1, Habibi, Hamid1, 1 Department of Biological Sciences, Calgary, CA ABSTRACT- Apoptosis is a form of cell death characterized by morphological and biochemical changes such as cell shrinkage, chromatin condensation, DNA fragmentation, formation of apoptotic bodies and minimal inflammatory response. Apoptosis is believed to be involved in different physiological events, including follicular atresia. There is information on the role of GnRH as an autocrine/paracrine regulator of ovarian function, but little is known about functional significance of GnRH in testis. We have previously shown that GnRH is able to induce apoptosis in mature goldfish ovarian follicles and testes. The objective of this work was to further investigate the mechanism of GnRH-induced apoptosis in mature goldfish testis. Goldfish brain and gonads contain two types of GnRH, salmon GnRH (sGnRH) and chicken GnRH-II (cGnRH-II). Both GnRH forms were found to be expressed and stimulate apoptosis in the goldfish testis by increasing activity of caspase-3 and -8. Treatments with gonadotropins and gonadal steroids including testosterone, 11-keto testosterone and estradiol were found to decrease spontaneous and GnRH-induced DNA fragmentation in the mature testis. The pro-survival effect of gonadotropin was found to involve stimulation of gonadal steroids as well as Bcl-2 and Bcl-xl protein levels in the goldfish testis. The overall findings provide a strong support for the hypothesis that GnRH plays an important role in autocrine/paracrine regulation of testicular development in goldfish. Funded by NSERC. KEY WORDS: apoptosis, GnRH, testis, gonadotropins |
