Effect of lithium chloride on the neurosecretory system of the rat hypothalamus.

The response of the hypothalamic-pituitary neurosecretory system (HPNS) of rats to a single and repeated injection (200 mg/kg each time) of lithium chloride was studied by quantitative cytochemical analysis. The response of the HPNS was found to depend directly on the dose of lithium given and to consist of activation of synthesis and liberation of neurosecretion after a single dose of LiCl or inhibition of hormone formation in the hypothalamus and exhaustion of the reserves of neurosecretion in the neurohypophysis after a course of injections. In the recovery period (7--30 days after stopping the course of injections of LiCl) the previous state of the HPNS was gradually restored.