Correlation between cellular changes in supraoptic and paraventricular nuclei and water-drinking in neuroleptic-treated rats.

The neuroleptics haloperidol and thioridazine were injected intraperitoneally in rats for 81 days. During this time the rats' water consumption was measured. Drug-treated animals drank significantly less water for the first 40 days of the experiment only. On day 82 the rats were perfused for electron microscopy. The rat's paraventricular and supraoptic nuclei were embedded, sectioned, stained for electron microscopy and viewed for morphological change. There were significantly more darkly staining neurons in the haloperidol-treated rats than in control rats. Thioridazine-treated rats had more dark neurons but the difference was not significant. These dark cells had the appearance of highly stimulated neurons. Some appeared to be degenerating.