Alterations of the muscarinic cholinergic (mACh) receptors in the striatum of the MPTP-induced parkinsonian model in mice: in vitro quantitative autoradiographical analysis.

The alteration of muscarinic cholinergic (mACh) receptors in the striatum of mice after administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was examined using a [3H]quinuclidinyl benzilate [( 3H]QNB) in vitro labeling macro-autoradiographic technique and mACh receptor concentration was quantitatively analyzed using a computer analysis system. Two weeks after cessation of MPTP administration, the striatal mACh receptors were significantly increased. In the subchronic phase, at 6 weeks, the striatal mACh receptors were significantly decreased but recovered to the normal level by the treatment with L-dihydroxyphenylalanine (L-DOPA) for two weeks before sacrifice. These findings indicated that the striatal mACh receptors are strongly regulated by the nigrostriatal dopaminergic function.