Evidence that alpha-methyl-p-tyramine is implicated in behavioural augmentation to amphetamine

Area of Science:

• Neuroscience
• Pharmacology
• Behavioral Science

Background:

• D-amphetamine (AMPHET) is a stimulant known to induce stereotyped behaviors.
• Alpha-methyl-p-tyramine (AMT) is a metabolite of amphetamines.
• The interaction between AMPHET and its metabolites in modulating behavior is not fully understood.

Purpose of the Study:

• To investigate the effect of alpha-methyl-p-tyramine (AMT) pretreatment on d-amphetamine (AMPHET)-induced behavioral augmentation in rats.
• To explore the neurochemical underpinnings of this behavioral interaction by examining dopamine metabolite levels.

Main Methods:

• Rats were administered AMT (10 mg/kg i.p.) 24 hours prior to AMPHET (4 mg/kg i.p.) treatment.
• Stereotyped activity was behaviorally assessed.
• Dopamine metabolites, specifically homovanillic acid (HVA), were measured electrochemically in the striatum.

Main Results:

• AMT pretreatment significantly augmented AMPHET-induced stereotyped activity.
• The decrease in striatal homovanillic acid (HVA) concentration caused by AMPHET was more pronounced in AMT-pretreated rats.
• This indicates an enhanced dopaminergic response or altered dopamine metabolism.

Conclusions:

• Alpha-methyl-p-tyramine (AMT) plays a role in the behavioral augmentation observed with d-amphetamine (AMPHET).
• The findings suggest that AMT, possibly derived from previous AMPHET doses, contributes to the heightened behavioral effects during chronic AMPHET administration.
• This highlights the importance of considering drug metabolites in understanding chronic stimulant effects.