Biochemical basis for analgesic activity of morphine-6-glucuronide—I: Penetration of morphine-6-glucuronide in the brain of rats

摘要: Abstract To understand the potent analgesic action of morphine-6-glucuronide (M-6-G), which was reported previously to be a minor metabolite morphine in several mammalian species, penetration this conjugate into brain investigated using 14 C-labeled compound. A similar study also conducted with C-morphine. These studies presented evidence that, although M-6-G highly polar conjugate, it can penetrate blood barrier and react receptor without prior hydrolysis glucuronide linkage. It further suggested that lack activity produced morphine-3-glucuronide (M-3-G), major morphine, attributable its inability receptor, because penetrates as well M-6-G.