Effects of neuroleptics on hippocampal stimulation-induced 'wet-dog shaking' in rats

The relationship between wet-dog shaking (WDS) and after-discharge (AD), and the effects of neuroleptics on WDS and AD elicited by hippocampal stimulation, were investigated. AD elicited by hippocampal stimulation consisted of primary and secondary phases. The intensity of the WDS during a 150 sec observation period showed two peaks. The intensity of WDS was reached at the 1st and 2nd peak in the 1st and the 2nd phase of AD, respectively. Haloperidol and chlorpromazine significantly and dose-dependently blocked the appearance of WDS. In particular, the number of WDS decreased during the early 1st phase and the 2nd phase of AD, after hippocampal stimulation. When the hippocampus was stimulated at intervals of 24 hr for 3 successive days a week, the number of WDS during 10-40 sec after stimulation decreased gradually and a small peak appeared during 40-60 sec in the 3rd and 4th week group. This pattern is similar to that seen in the chlorpromazine- and haloperidol-injected group. The possibility that seizure susceptibility, when the hippocampus is stimulated repeatedly, mimicks findings in case of blockage of dopaminergic function by the injection of neuroleptics, has to be considered.