Reaction of the paraventricular nucleus to dehydration in the garden lizard, Calotes versicolor

Adult garden lizards of both sexes were subjected to dehydration by giving them intraperitoneal injections of sodium chloride solution, the concentration of which varied from 0.5 M to 1.0 M. Each animal was given one injection daily up to 5 days and sacrificed 6 to 8 hours after the last injection. In the early phases of dehydration, the cells of the Paraventricular nucleus showed high secretory activity by nuclear and nucleolar enlargement. In more severe cases, signs of cell degeneration and death were seen. The supraoptic nucleus showed no changes except in the most severe dehydration. It is concluded that in the garden lizard the Paraventricular nucleus is the seat of production of the antidiuretic hormone, which in mammals and birds is elaborated by the supraoptic nucleus.