Upregulation of neuronal NOS mRNA in the PVN and SON of inherited diabetes insipidus rats.

We investigated the expression of neuronal nitric oxide synthase (nNOS) gene in the paraventricular (PVN) and supraoptic nuclei (SON) of rats with inherited diabetes insipidus (DI), using in situ hybridization histochemistry. The DI rats showed hypo-osmotic polyuria and polydipsia with arginine vasopressin (AVP) deficiency. The expression of nNOS gene in the PVN and SON in homozygous (di/di) rats was significantly increased in comparison to normal Wistar and heterozygous (di/+) rats. nNOS gene-expressing cells were distributed throughout the PVN and SON, including the divisions of AVP and oxytocin gene expressing cells in di/di rats. These results suggest that the expression of nNOS gene is upregulated in the magnocellular neurons in the PVN and SON of inherited DI rats.