Temporal bone surgery causes reduced nitric oxide synthase activity in theipsilateral guinea pig hippocampus

There is a lack of data on the neurochemical basis for the interaction betw een the vestibular system and the hippocampus. The aim of the present study was to determine levels of nitric oxide synthase (NOS) activity in the ips ilateral and contralateral hippocampi at 10 h following unilateral deaffere ntation of the peripheral vestibular nerve (UVD) in guinea pig, using a rad ioenzymatic technique. The levels of NOS activity were similar in the contr alateral hippocampus following either a sham temporal bone operation or the UVD. However, NOS activity was significantly lower in the ipsilateral hipp ocampus following both the UVD and the sham temporal bone surgery (P < 0.05 for both comparisons). These results suggest that even sham temporal bone surgery results in a reduction in NOS activity in the ipsilateral hippocamp us. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.