Interstrain correlation between behavioural effects of lithium and effects on cortical cyclic AMP.

Six inbred mouse strains were studied to explore possible correlations between lithium effects on behaviour and on cortical cyclic AMP. The strains were fed lithium in ground food for 3 weeks before behavioural tests and ex vivo evaluation of cyclic AMP accumulation. Replicating previous reports, there was a significant inverse correlation (r = 0.73, n = 6) between spontaneous activity and noradrenaline-induced cyclic AMP, and an almost significant correlation (r = 0.67, n = 6) between spontaneous activity and adenosine-induced cyclic AMP accumulation. The effect of lithium to depress spontaneous activity correlated with its effect to inhibit adenosine-induced rises in cyclic AMP (r = 0.716, n = 6). There were significant strain differences in the behavioural responses to amphetamine. In two strains where amphetamine raised activity and lithium inhibited the amphetamine-induced rise, lithium also significantly inhibited the adenosine-induced rise in cyclic AMP. Two other strains showed amphetamine-induced rises in activity that were not inhibitable by lithium, and these strains showed no significant inhibition by lithium of adenosine-induced cyclic AMP accumulation. The remaining two strains showed no behavioural activity increase with amphetamine.