UP-REGULATION OF NITRIC-OXIDE SYNTHASE AND ITS MESSENGER-RNA IN VAGALMOTOR NUCLEI FOLLOWING AXOTOMY IN RAT

Effects of vagotomy on nitric oxide synthase (NOS) protein and mRNA le vels in the dorsal motor nucleus of vagus (DMV) and nucleus ambiguus ( NA) of rats were examined by nicotinamide adenine dinucleotide phospha te-diaphorase (NADPH-d) staining, brain NOS (bNOS) immunostaining and in situ hybridization. NADPH-d staining and bNOS immunoreactivity incr eased in neurons of the ipsilateral DMV and NA 5, 10, and 20 days afte r vagotomy. These changes were not observed in unoperated or sham-oper ated rats. In situ hybridization showed that bNOS mRNA levels were als o elevated in neurons of DMV and NA on the operated side. Our results suggest that transection of vagal efferents up-regulates bNOS and its mRNA expression in the DMV and NA. (C) 1997 Elsevier Science Ireland L td.