PRESERVATION OF AUTORECEPTOR-MEDIATED INCREASES IN DOPAMINE SYNTHESISIN AGED MICE WITH EXPERIMENTALLY-INDUCED PARKINSONISM

This study examined autoreceptor (i.e. haloperidol)-mediated regulatio n of dopamine synthesis in normal aged mice and aged mice with a parti al lesion of the nigrostriatal dopamine system induced by 1-methyl-4-p henyl 1,2,3,6-tetrahydropyridine (MPTP). There were no significant dif ferences between haloperidol-induced increases in striatal dihydroxyph enylalanine (DOPA) accumulation between lesioned and unlesioned animal s. Striatal DOPA/dopamine ratios were significantly increased in lesio ned animals treated with haloperidol as compared to normal lesioned an imals treated only with haloperidol. These data suggest that striatal dopamine synthetic capacity and autoreceptor-mediated regulation of do pamine synthesis are relatively preserved in aged mice, even after a m oderate nigrostriatal lesion. Aged dopamine neurons appear to retain t he ability to increase synthesis and release of dopamine in the presen ce of an appropriate pharmacological stimulus. (C) 1997 Elsevier Scien ce Ireland Ltd.