Dextro-amphetamine increases phosphoinositol cycle activity in volunteers: An MRS study

Aims. To help determine the effects of dextro-amphetamine on the phosphoinositol cycle (PI-cycle) in humans, ¹H and ³¹P magnetic resonance spectroscopy (MRS) was utilized in 17 healthy volunteers. This was an open-label study carried out before and after administration of 20mg oral dextro-amphetamine. Subjects also rated the subjective effects of dextro-amphetamine administration using visual analog scales (VAS). Major findings. Following dextro-amphetamine administration there was a significant increase in the concentrations of both myo-inositol and phosphomonoesters. Conclusions. These findings are in keeping with suggestions that dextro-amphetamine administration increases the activity of the phosphoinositol cycle, probably via an indirect release of dopamine and noradrenaline. These results are the first time that this has been confirmed in humans.