The ontogenesis of lithium-induced effects on suckling: inhibition and facilitation.

The ontogenesis of the effect of lithium on suckling behavior was assessed by administering lithium carbonate directly and acutely to 15-, 20-, 30-, and 35-day-old rat pups. Lithium significantly interfered with nipple attachment in 15-day-old rat pups in a dose-dependent pattern, but it facilitated attachment at some doses (40, 60, 80 mg/kg) in weanling-age rat pups. Furthermore, lithium pretreatment reversed quipazine-induced interference of attachment in weanling-age rats. These effects are similar to those previously reported with serotonergic antagonists, suggesting a similar mechanism, perhaps via the inositol phosphate second messenger system.