| Summary: | Thesis (M.Sc.)--Memorial University of Newfoundland, 2011. Biology Includes bibliographical references. In vertebrates, appetite regulation is a complex process involving both nervous and endocrine systems. Melanin-concentrating hormone (MCH) and gonadotropin-releasing hormone (GnRH) are two endocrine factors that have been found to regulate food intake in fish and other vertebrates. These hormones were characterized in winter flounder, Pseudopleuronectes americanus, a flatfish common in Newfoundland bottom waters. mRNAs encoding several forms of both hormones were identified and shown to be expressed in tissues previously found to be involved in appetite regulation, including the brain (telencephalon, optic tectum, and hypothalamus) and midgut. Adult fish submitted to fasting displayed higher brain expression levels of transcripts encoding MCH and its receptor, MCH-R1, suggesting that the MCH system might stimulate feeding in flounder. Conversely, both chicken- and salmon-GnRH mRNA levels were lower in fasted fish suggesting an appetite-inhibiting effect. Our results suggest that MCH and GnRH, along with their receptors, might play an important role in regulating feeding in winter flounder.
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