Effects of Aging and Morphine Administration on Calmodulin and Calmodulin-Regulated Enzymes in Striata of Mice

Publisher Website
Google Scholar
Abstract
Male ICR mice, young (25 days old), mature (3 mo. old), and old (22 mo.), were injected with morphine sulfate (10 mg/kg, s.c.) or were implanted with morphine pellets (75 mg). Controls received saline injections or placebo pellets. One hour after injections and 72 h after pellet implantations, the mice were decapitated and striatal regions were removed for the following analyses: calmodulin (CaM) levels via radioimmunoassay and activities of cyclic nucleotide phosphodiesterases, adenylate and guanylate cyclases, and Ca2+,Mg2+-ATPase. Acute morphine treatment produced the following: increases in calmodulin levels in the young and old mice while having no effect on mature levels; increases in activities of guanylate cyclase of mature mice while decreasing those of the old mice; no effects on activity of adenylate cyclase; decreased activity of cAMP-phosphodiesterase in young mice only; and decreased activity of Ca2+,Mg2+-ATPase in the old mice only. The only changes found in striata from morphine-tolerant mice when compared with age-matched controls were elevations in cGMP-phosphodiesterase activities in all 3 age groups. Differences in control values of the 3 age groups were as follows: CaM levels, mature > old > young; Ca2+,Mg2+ -ATPase activity, old > mature-young. The results indicate age-induced changes in cellular regulation and biochemical responses to morphine.