Lack of Vasopressin Response to Water Deprivation in Blind Hereditary Microphthalmic Rats with Abnormal Suprachiasmatic Nuclei

Abstract

We compared the plasma arginine-vasopressin (AVP) concentrations and hematocrit values before and after 24-h water-deprivation in normal Donryu rats and blind hereditary microphthalmic rats having a morphologically abnormal suprachiasmatic nucleus (SCN) in the hypothalamus, but a persistent circadian rhythm. We found that in the microphthalmic rats hypovolemia-induced elevation of the plasma AVP concentration was suppressed. The fact that these microphthalmic rats had a free-running circadian rhythm in their locomotor activity indicates that the cells comprising the circadian oscillator are functionally intact. Thus, we propose that SCN cells other than circadian pacemaker cells are involved in regulation of the plasma vasopressin concentration.