Changes in expression of appetite-regulating hormones in the cunner (Tautogolabrus adspersus) during short-term fasting and winter torpor

- Summer fasting decrease brain orexin, NPY, CART and CCK mRNA levels.
- Natural winter torpor decreased mRNA levels of orexin, NPY, CART and CCK.
- Gut CCK expression levels decreased during summer fasting.
- Orexin, NPY, CCK and CART may play roles in appetite regulation in cunner.

Feeding in vertebrates is controlled by a number of appetite stimulating (orexigenic, e.g. orexin and neuropeptide Y, NPY) and appetite suppressing (anorexigenic, e.g. cholecystokinin, CCK and cocaine- and amphetamine-regulated transcript, CART) hormones. Cunners (Tautogolabrus adspersus) survive the winter in shallow coastal waters by entering a torpor-like state, during which they forgo feeding. In order to better understand the mechanisms regulating appetite/fasting in these fish, quantitative real-time PCR was used to measure transcript expression levels of four appetite-regulating hormones: NPY, CART, orexin and CCK in the forebrain (hypothalamus and telencephalon) and CCK in the gut of fed, short-term summer fasted, and natural winter torpor cunners. Summer fasting induced a decrease in hypothalamic orexin levels and telencephalon NPY, CART and CCK mRNA levels. All brain hormone mRNA levels decreased during natural torpor as compared to fed summer fish. In the gut, CCK expression levels decreased during summer fasting. These results indicate that, in cunner, orexin, NPY, CART and CCK may play a role in appetite regulation and might mediate different physiological responses to short-term summer fasting and torpor-induced long-term fasting.