WHAT HORMONES MAY REGULATE FOOD-INTAKE IN FISH

This is an overview of the hormones which may be involved in food inta ke control in fish, and some hypothetical pathways of their action are given based on mammalian knowledge. Most of the observed effects of t hese hormones may result from four types of mechanisms, each hormone a cting by one or several as follows: (1) hormones could have a direct e ffect on central nervous system centres, associated with food intake b ehaviour or via vagal afferent neurons; (2) an indirect effect may occ ur via the gut which slows gastrointestinal transit, thus resulting in stomach distention which activates vagal afferent neurons; (3) they c ould have an indirect effect, acting directly on intermediary metaboli sm via glucose, flee fatty acids or amino acids mobilization or storag e; (4) the last possible pathway is an indirect effect by modifying di rectly or indirectly secretions of other hormones involved in food int ake control. Some of these hormones (CCK, PYY, glucagon, adrenalin) ac t as short-term factors which regulate meal ingestion and are generall y inhibitory factors. On the other hand, other hormones (GH, TH, and l eptin) require more time to modify food intake behaviour, and appear a s stored calorie regulators However, the orientation of hormones to sh ort-term or to long-term action is not always clear as it has been not ed for insulin and glucocorticoids, and may depend on the hormonal and metabolite environment.