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.
- Cyclic AMP