Blockade of dopamine transporter and tyrosine hydroxylase activity loss by [D-Ala(2), D-Leu(5)]enkephalin in methamphetamine-treated CD-1 mice.

[D-Ala(2), D-Leu(5)]enkephalin (DADLE) has been previously reported to prolong the survival of tissues both in the periphery and in the central nervous system. Here, we show that DADLE was able to block the protein as well as the functional loss of dopamine transporter (DAT) and tyrosine hydroxylase (TH) induced by methamphetamine. Male CD-1 mice received four injections of methamphetamine (10 mg/kg, i.p. ) at 2-h intervals. DADLE (4 mg/kg, i.p.) was given 30 min before each injection of methamphetamine. Western blotting and enzymatic assays showed that DADLE blocked the protein loss and functional impairment of DAT and TH induced by methamphetamine.