CENTRAL MONOAMINERGIC RESPONSES TO SALINITY AND TEMPERATURE RISES IN COMMON CARP

Juvenile common carp, Cyprinus carpio, were exposed to increased level s of salinity (1% NaCl) at 25 degrees C and 30 degrees C, Levels of th e monoamine neurotransmitters dopamine (DA) and serotonin (5-HT) and t heir metabolites dihydroxyphenylacetic acid and 5-hydroxyindoleacetic acid were determined in different brain parts, Whereas the elevated te mperature only resulted in higher levels of the metabolites, increased salinity caused increased levels of DA and 5-HT as well. Increased le vels appeared after the first day of exposure and most effects were fu rther enhanced after 1 week in 1% NaCl. Increases in DA and 5-HT level s were most pronounced in the hypothalamus, which is the major integra tive centre controlling the release of hormones, Thus, one possible ro le of these changes in neurotransmitter metabolism could be to control the release of prolactin and cortisol, two major hormones involved in the regulation of ion homeostasis in teleosts.