Neurotransmitter Systems of Some Brain Regions of Rats Subjected to Chronic Morphine Intoxication

The content of neurotransmitters and their metabolites was investigated in brain cortex hemispheres, thalamus and brainstem of rats subjected to chronic morphine intoxication (7-21 days). Morphine administration for 7-14 days was accompanied by changes of the catecholamine system functioning, which was the most pronounced in the thalamus and the brainstem. These changes included increased secretion of dopamine and noradrenaline, their decrease in the brain tissue, and an increased content of their metabolites. The changes in serotonin and GABA content were less pronounced and included a decrease of serotonin level and the increase of the GABA content in different periods of opiate administration.