Multifactorial regulation of reproduction and gonadal development in fish

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My research objective over many years has been to understand hormonal control of reproduction and growth in fish by studying brain regulation of gonadotropin and growth hormone production. We have contributed to the understanding of mechanisms by which hypothalamic gonadotropin-releasing hormone regulates pituitary luteinizing hormone, follicle stimulating hormone and growth hormone production. We have also provided novel information on paracrine regulation of testicular and ovarian function in fish by investigating the local effects of gonadal hormones in the regulation of gametogenesis (egg and sperm production) and steroidogenesis. Our recent findings suggest that gonadotropin-inhibitory hormone (GnIH) and thyroid hormones are among the key factors that influence the integrated control of reproduction and growth in fish. The proposed study will build on our past work and focus on three primary research areas conducted simultaneously in my group: (1) The role of thyroid hormones and GnIH, working in concert with brain neuro-hormones and gonadal hormones, to regulate reciprocal control of pituitary gonadotropins and growth hormone production; (2) The role of thyroid hormones and GnIH, working in concert with pituitary and gonadal hormones, to regulate ovarian and testicular development and differentiation. (3) Changes in metabolic pathways required to energetically support and sustain prolonged periods of reproduction and growth. The proposed studies in these areas will be designed to meet the following major research objectives:*** ***1. Understand the integrated control of gonadotropin and growth hormone production***2. Understand the integrated regulation of testicular and ovarian development and function during reproductive and growth phases***3. Elucidate the regulation of metabolism to sustain reproduction and growth******We will use state-of-the-art facilities and innovative experimental approaches to investigate the proposed objectives. These projects will be used as a vehicle for the training of HQP in the broad areas of comparative endocrinology, and will involve three PhD and two MSc students as well as several undergraduate students, visiting students and scientists. The proposed research will enhance our understanding of the integrated reciprocal control of reproduction and growth and associated changes in metabolism in fish, as well as providing important information on integrated regulation of testicular and ovarian development and function. The results will be relevant to all vertebrate species by providing an insight into the mechanisms by which delicate balance between reproduction and growth is regulated. Furthermore, the proposed studies will have translational potential in aquaculture and environmental toxicology by improving our ability to assess adverse impacts of environmental contaminants with hormone-like activities in the aquatic ecosystem.