Electroencephalogram and behavioral changes induced by histamine application into the nasal cavity and the effects of some H(1)-receptor antagonists.

The present study was performed to measure the olfactory bulb with an electroencephalogram (EEG) to investigate the relationship between the EEG and behavioral changes of rats induced by the topical application of histamine into the nasal cavity. The effects of some H(1)-receptor antagonists on the EEG and behavioral changes induced by histamine were also studied. The topical application of histamine into the nasal cavity resulted in a significant and dose-dependent increase in the incidence of sneezing and nasal rubbing. The EEG spike at the olfactory bulb was also observed to be in parallel with the sneezing. In addition, there was an intimate relationship between the EEG spike and sneezing; however, no correlation was observed between the EEG spike and nasal rubbing. All the H(1)-receptor antagonists used in the present study caused an inhibition not only of sneezing but also of the EEG spike at the same dose level. These results suggested that the EEG spike observed in the olfactory bulb is an objective and reliable indication of sneezing induced by allergic rhinitis.