Effect of naloxone on concentration and analgesic action of morphine in rats

The aim of the present investigation is to study the effect of Naloxone on the analgesic action and on the concentration of Morphine in the brain and serum of rats. The results showed that Naloxone could antagonize the analgesic effect of Morphine overdose on the different studied physiological functions of the nervous system of rats. It reduced voluntary activity, decreased respiratory rate and response to external stimuli with loss of pain reflexes. Naloxone alone induced hyperalgesia and increased the above mentioned parameters indicating its stimulant effect on the nervous system. In the present study, the concentration of Morphine and Naloxone in sera and brains were determined by using combined thin layer chromatography and ultraviolet spectrophotometric methods. It was found that Naloxone decreased Morphine concentrations in serum and brain tissues by more than 20%. It may be concluded that, Naloxone not only antagonises the action of Morphine overdose on the central nervous system but also it alters its kinetic and disposition