ACUTE METHAMPHETAMINE ADMINISTRATION INCREASES TYROSINE-HYDROXYLASE MESSENGER-RNA LEVELS IN THE RAT LOCUS-COERULEUS

Tyrosine hydroxylase (TH) mRNA levels in the rat substantia nigra (SN) , ventral tegmental area (VTA) and locus coeruleus (LC) were measured by in situ hybridization histochemistry 1, 4, 6 and 24 h after a singl e injection of methamphetamine (MAP, 4 mg/kg, i.p.) or an equivalent v olume of saline. TH mRNA levels in LC were transiently increased (130% of control saline group, P < 0.05) at 1 h after MAP injection, and re turned to basal levels within 4 h. In contrast, acute MAP administrati on did not significantly affect TH mRNA levels in SN and VTA. These fi ndings are the first to demonstrate TH mRNA expression in the differen t responses of catecholaminergic neurons to acute MAP administration. (C) 1997 Elsevier Science B.V.