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Life sciences

Characteristic glucuronidation pattern of physiologic concentration of morphine in rat brain.


PMID 11065168

Abstract

Formation of conjugated metabolites from morphine at a very low level in brain was studied in vitro in rats. Incubation of a low concentration of 3H-morphine with brain homogenate followed by two successive high-performance liquid chromatographic analyses showed that endogenous morphine is converted by brain enzymes to its 3- and 6-glucuronides (M-3-G and M-6-G), and codeine glucuronide (Cod-G). However, the formation of morphine-6-sulfate was likely to be low if it was produced at all. All of the cerebral hemisphere, brain stem and cerebellum were capable of producing M-3-G, M-6-G and Cod-G, although there were differences in selectivity. The capacity of the brain for glucuronide formation was far less than that of the liver, but UDP-glucuronosyltransferase in brain was much more selective in forming M-6-G and Cod-G than liver enzymes.