Changes in ribonuclease in the central nervous system of mice during morphine dependence development, withdrawal and...

Ribonuclease has been studied in the whole brain homogenate of mice after a single dose of morphine (10 mg/kg), during the development of tolerance and dependence, during the course of withdrawal and naloxone administration. The enzyme increased dose dependently following the administration of morphine. Withdrawal caused a sudden fall in the enzyme with partial recovery by the 6th day of abstinence. Naloxone injections in normal, tolerant, dependent and deprived animals caused a reduction in the enzyme level. The morphine-induced increase in enzyme activity is suggested to be in direct correlation with a reduction in protein synthesis which can be ascribed to a disturbance of the translation processes.