Increase of vasopressin mRNA in the hypothalamus of inbred polydipsic mice

The genetically inbred polydipsic mice, STR/N strain, are characterized by extreme polydipsia and polyuria without arginine vasopressin (AVP) deficien cy. The expression of AVP gene in the hypothalamus of polydipsic and non-po lydipsic mice was examined by Northern blot analysis and in situ hybridizat ion histochemistry. Northern blot analysis revealed that the total amount o f AVP mRNA in the hypothalamus of the STR/N mice was approximately three-fo ld of that in the control, ICR mice. In situ hybridization histochemistry s howed that the signals of AVP mRNA in the paraventricular (PVN) and supraop tic nuclei (SCN) of the STR/N were stronger than those in the ICR. Although AVP gene transcripts were detected in the anteroventral parts of the PVN ( avPVN) in the STR/N, there was a few AVP transcripts in the same area (avPV N) in the ICR, There were no differences in plasma osmolality and hematocri t between STR/N and ICR mice. These results suggest that upregulation of AV P mRNA in the hypothalamus of STR/N may be involved in the central mechanis m responsible for the polydipsia in genetically polydipsic mice. (C) 1999 E lsevier Science inc.