Striatal membrane-bound and soluble catechol-O-methyl-transferase after selective neuronal lesions in the rat.
Activities of the two forms of catechol-O-methyltransferase (COMT), viz. the soluble (S-COMT) and the membrane-bound (MB-COMT), have been studied in the rat striatum to characterize their localization in relation to the nigrostriatal dopaminergic neurons. Selective unilateral nigrostriatal dopaminergic lesions were produced by an intranigral injection of 6-hydroxydopamine (6-OHDA; 8 micrograms/site). 6-OHDA caused an extensive lesion of the dopaminergic neurons as revealed by non-detectable concentrations of dopamine in the striata of the lesioned sites. In spite of that neither S-COMT nor MB-COMT activities were altered in comparison with the intact control striata. The intrastriatal injection of kainic acid significantly increased S-COMT activity but to some extent decreased MB-COMT activity. Kainic acid did not alter the striatal concentration of dopamine. These results suggest that both S-COMT and MB-COMT reside postsynaptically the nigrostriatal dopaminergic neurons. S-COMT seems to be found mainly in striatal glial cells, whereas striatal MB-COMT might be located both in postsynaptic neuronal and extraneuronal cells.
D000818:Animals; D001665:Binding Sites; D002394:Catechol O-Methyltransferase / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology; D003342:Corpus Striatum / Q000201:enzymology* / Q000648:ultrastructure; D004298:Dopamine / Q000378:metabolism; D006892:Hydroxydopamines; D007608:Kainic Acid; D008297:Male; D009434:Neural Pathways / Q000201:enzymology; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains; D012995:Solubility; D013378:Substantia Nigra / Q000187:drug effects* / Q000378:metabolism
D006892:Hydroxydopamines; D016627:Oxidopamine; D002394:Catechol O-Methyltransferase; D007608:Kainic Acid; D004298:Dopamine