The effects of nicotine, hexamethonium and ethanol on the secretion of the antidiuretic and oxytocic hormones of the rat.

The actions of nicotine, hexamethonium, and ethanol on the hypothalamo-hypophysial system have been investigated in the rat. The antidiuretic action of nicotine was not inhibited by ethanol, nor by doses of hexamethonium which were sufficient to block both its pressor and convulsant actions. Hexamethonium itself had an antidiuretic action the mechanism of which has been investigated. Nicotine caused a release of oxytocin into the blood which was not blocked by ethanol nor significantly reduced by hexamethonium. The results suggest that any synapse which exists at the supraoptic nuclei is dissimilar in its pharmacological properties to synapses at autonomic ganglia.