Dopaminergic regulation of three somatostatin mRNAs in goldfish brain

Three distinct somatostatin cDNAs characterized previously from goldfish br ain encode three preprosomatostatins (PSS), designated as PSS-I, PSS-II and PSS-III. In this study, dopaminergic regulation of PSS gene expression was examined by Northern blot analysis in the forebrain of goldfish. Intraperi toneal injection of the non-selective dopamine (DA) agonist, apomorphine, s ignificantly decreased the levels of all three PSS mRNAs, indicating an inh ibitory regulation of PSS gene expression by DA. The involvement of DA rece ptor subtypes in the regulation of PSS gene expression was examined using t he D1 receptor agonist and antagonist drugs SKF 38393 and SCH 23390, and th e D2 agonist and antagonist drugs LY 171555 and pimozide, respectively. The results provide evidence for inhibitory and/or stimulatory regulation of P SS gene expression by DA through both D1 and D2 receptors, which are depend ent on the temporal pattern of dopamine input and reproductive stage of the fish. Demonstration of involvement of both DA D1 and D2 receptors in the d opaminergic regulation of goldfish brain PSS gene expression is a novel fin ding, distinct from the observations in mammalian models. (C) 1999 Elsevier Science B.V. All rights reserved.