Age-related effects of MPTP on norepinephrine concentrations of various areas of rat brains.

The effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on the norepinephrine (NE) levels of 11 areas of rat brains were investigated. Male Long-Evans rats, aged 4 weeks (young group) and 21 months (old group), were injected intraperitoneally (i.p.) with MPTP (3 mg/kg) daily for 8 days. Control rats received an i.p. injection of saline. Rats were sacrificed 24 h after the last injection. NE in various brain areas were assayed by high pressure liquid chromatography with electrochemical detection. Multidose treatment of MPTP caused no alteration of levels of NE in any brain area of young rats. In contrast, a marked increase in concentration of NE was found in locus coeruleus, dorsal raphe nuclei and amygdala of old rats. These results indicate that MPTP selectively causes lesions in the noradrenergic system of rats and that the neurotoxic effects of MPTP in rats may depend on age.