Effects of morphine and aging on brain calmodulin levels in mice.

Calmodulin levels were determined in brain areas (cerebellum, cortex, diencephalon, medulla + pons and striatum) of immature, mature and old mice one hour after they were injected with morphine (10 mg/kg, s.c.) and 3 days after morphine pellet (75 mg) implantation (during tolerance). Acutely, morphine caused significant (two-fold) increases in calmodulin in striatal regions from immature and old mice, and increased calmodulin after morphine administration to mature mice occurred only in the cerebellum. After tolerance to morphine had developed, calmodulin levels in all brain regions were the same as those from placebo-implanted mice.