Effect of chronic lithium treatment on isolation-induced behavioral and biochemical effects in mice

The following effects were induced in mice by a prolonged of isolation (6-7 weeks from weaning): (1) reduction in motor activity; (2) reduction in the effect of oxotremorine on rectal temperature; (3) increase in the response to salbutamol, a beta-adrenergic stimulant. Chronic lithium treatment (2 mg/ml in the drinking water during the last 3-4 weeks of isolation) prevented these phenomena. The number and affinity of beta-adrenergic receptors in the whole mouse brain (excluding the cerebellum) was unmodified by either isolation or by lithium. It is suggested that lithium blocks isolation-induced hypersensitivity, especially of the beta-adrenergic system; this mechanism may be involved in the therapeutic action of lithium.