Long-term effects of amphetamine neurotoxicity on tyrosine hydroxylase mRNA and protein in aged rats. J Pharmacol Exp Ther 286

Four injections (intraperitoneal) of 3 mg/kg amphetamine (2 hr apart) produced pronounced hyperthermia and sustained de-creases in dopamine levels and tyrosine hydroxylase (TH) pro-tein levels in the striatum of 15-month-old male rats. A partial recovery of striatal dopamine levels was observed at 4 months after amphetamine. In contrast, TH mRNA and TH protein levels in the midbrain were unaffected at all time points tested up to 4 months after amphetamine treatment. The number of TH-immunopositive cells in the midbrain was also unchanged at 4 months after amphetamine, even though the number of TH-positive axons in the striatum remained dramatically decreased at this time point. Interestingly, TH-immunopositive cell bodies were observed 4 months after amphetamine in the lateral cau-date/putamen, defined anteriorly by the genu of the corpu