Subregional variation in the effects of unilateral vestibular deafferentation on nitric oxide synthase activity and nitrite formation in the guinea pig hippocampus

Increasing evidence indicates that vestibular sensory input is important fo r spatial information processing by the hipppocampus. The present study inv estigated the effects of acute unilateral vestibular deafferentation (UVD) on nitric oxide synthase (NOS) activity and nitrite formation in different subregions of the guinea pig hippocampus. At 10 hs post-op., UVD! but not s ham temporal bone surgery or anesthesia alone, resulted in an increase in N OS activity in the bilateral CA1 region of the hippocampus, and a decrease and increase in nitrite formation in the bilateral CA1 and ipsilateral dent ate gyrus, respectively. However, there were no significant differences bet ween sham and labyrinthine-intact animals. These results add to the increas ing evidence that UVD causes specific neurochemical changes in the hippocam pus.