| Daily rhythms in physiology, such as feeding cycles and hormonal cycles, are evident in most organisms, but little is known about these cycles in fish. In this study, the mRNA expression profile of proteins involved in circadian regulation and endocrine neuropeptides involved in appetite and wakefulness were measured in the goldfish and Atlantic cod hypothalamus. My results show that fish do have circadian rhythms, that neuropeptide mRNA expressions fluctuate over the day and that these profiles are dependent on photoperiod and feeding status.;In addition, as little is known about the long-term effects of appetite-related peptides, this study examines the effects of chronic administration of peptides on daily food intake and mRNA expressions of other important appetite regulators in goldfish. My results show that long-term continuous administration of cholecystokinin (CCK) decreases food intake when infused centrally or peripherally, and that hypothalamic amylin mRNA expression decreases in response to chronic peripheral infusion of CCK. |
