Intra- and extraneuronal formation of the two major noradrenaline metabolites in the cns of rats

Abstract

Abstract The two major noradrenaline metabolites in the rat brain, total 3-methoxy-4-hydroxyphenylglycol(MOPEG) and total 3,4-dihydroxy-phenylglycol (DOPEG), were measured by a new analytical procedure after intraventricular (i.v.t.) injection of [3H]noradrenaline or [3H]dopamine. I.v.t. injection of [3H]noradrenaline to rats with a 6-hydroxydopamine-induced destruction of nerve terminals in the central nervous system, resulted in an increased accumulation of 3H-MOPEG compared to 3H-DOPEG. On the contrary, reserpine induced a greater increase in 3H-DOPEG than in 3H-MOPEG accumulation when these two metabolites were formed from [3H]noradrenaline synthesized in vivo by i.v.t. injection of [3H]dopamine. These results indicate that the formation of DOPEG and MOPEG occur with some preference intra- and extraneuronally, respectively. The results, however, also show that these two formations sites should not be considered as specific.