Effect of chronic lithium treatment with or without haloperidol on number and sizes of neurons in rat neocortex.

The present study used stereological methods to determine whether long-term administration of lithium, with or without haloperidol, affects the number and average volume of neocortical neurons. Twenty-five rats were divided into three groups and given no treatment, lithium, or lithium combined with haloperidol. Serum lithium levels ranged from 0.5 to 0.8 mmol/l. Haloperidol was injected intraperitoneally at a daily dose of 1 mg/kg. After 30 weeks of treatment, the animals were killed and the brains were prepared. Neocortical volume, density of neurons, total number of neurons and mean volume of neurons were estimated. As no differences were found between the groups, the present study provides no evidence for quantitative morphological changes in the cerebral cortex due to long-term 'therapeutic' levels of lithium, with or without haloperidol.