Effects of amitriptyline and isocarboxazid on 5-hydroxytryptophan induced head twitches in mice

Abstract

Effects of amitriptyline and isocarboxazid on brain 5-HT and 5-HIAA were examined in relation to their action on 5-HTP induced head twitches. Amitriptyline reduced 5-HTP induced head twitches but isocarboxazid increased them. Both amitriptyline and isocarboxazid caused a significant increase of brain 5-HT concentration in 5-HTP treated mice. Amitriptyline also caused a significant increase of 5-HIAA concentration, while isocarboxazid reduced 5-HIAA concentration in the brains of 5-HTP treated mice. Probenecid, which significantly increased 5-HIAA concentration without affecting brain 5-HT concentration in 5-HTP treated mice, reduced 5-HTP induced heat twitches. These results suggest that 5-HTP induced head twitches might be induced by an increase of 5-HT concentration, and reduced by an increase of 5-HIAA or a decrease of 5-HT concentration in the brains of mice.

Neurochemical and behavioural effects of hypidone hydrochloride (YL‐0919): a novel combined selective 5‐HT reuptake inhibitor and partial 5‐HT1A agonist

“…Although 5‐HTP‐induced head twitches are known to be mainly mediated by the 5‐HT 2A receptor, the elevated 5‐HT levels in the brains of mice induced by several types of antidepressants (e.g. fluoxetine and moclobemide) have been reported to increase the number of head twitches (Nakamura et al, ). Furthermore, our previous study showed that except for the 5‐HT 1A receptor and SERT, YL‐0919 showed no affinity for the 5‐HT 2A receptor (Chen et al, ).…”