ABSTRACT
Objective To investigate the contents of cAMP and cGMP in the central nervous system in morphine dependent and withdrawal rats.Methods A physical morphine dependent model in rats was established by subcutaneous injection of morphine in gradually increasing doses.The cAMP and cGMP contents in the brain regions were determined by radioimmunoassay.Results Compared with control group,morphine dependence could significantly decrease the cGMP content or profoundly increase the cAMP content and the cAMP/cGMP ratio in rat striatum,diencephalons,midbrain,pons and hippocampus,but these changes described above were not detected in cerebellum.Compared with morphine dependent group,naloxone induced withdrawal could significantly decrease the cGMP contents or increase the cAMP contents and the cAMP/cGMP ratio in striatum and hippocampus,but these changes described above were not observed in the other regions.Conclusion The changes of the cAMP and cGMP contents may be one of the important molecular mechanisms leading to morphine dependence and abstinence.