| Abstrakt: |
The effects of intraventricular injection of serotonin (5-HT) and its agonists and antagonists on the amplitude of the vestibulo-ocular reflex were studied in chronic implanted rats. 5-HT (10-5 M) triggers an increase of the amplitude of the reflex which lasts 30 min. Similar results are obtained when N,N-dimethyl-5-methoxytryptamine (10-3 M) is introduced into the ventricular cannula. The increasing effects observed both with 5-HT and N,N-dimethyl-5-methyoxy-tryptamine are abolished by methiothepin, a potent antagonist of 5-HT receptors. Injection of indirect agonists like pargyline, a monoamine oxidase inhibitor, or fluoxetine, a potent inhibibitor of 5-HT reuptake, is followed by an increase of the amplitude of the vestibulo-ocular reflex. These results indicate that 5-HT can modulate the activity of the vestibulo-ocular pathway and muscular tone of extraocular muscles. Location and involvement of various modulating 5-HT sites are discussed. |
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