Dopamine antagonist haloperidol increases carboxypeptidase E mRNA in rat neurointermediate pituitary but not in various other rat tissues.

Carboxypeptidase E (CPE) is involved with the biosynthesis of many neuropeptides, including several whose genes are regulated by haloperidol treatments. In this study, we examined whether haloperidol alters CPE mRNA levels in a variety of tissues. Rats were treated for either 1, 3, 7, 14, or 21 days with 2 mg/kg haloperidol, and then Northern blot analysis performed on RNA from neurointermediate pituitary, anterior pituitary, hypothalamus, striatum, cerebellum, and adrenal. The 14 and 21 day treatments produced a significant 90-110% elevation of CPE mRNA in neurointermediate pituitary. However, the levels of CPE mRNA in the other tissues were not significantly influenced by the haloperidol treatments. This finding indicates that CPE is not co-regulated with peptide hormone mRNAs in all tissues.