Intracerebral dialysis coupled to a novel activity box--a method to monitor dopamine release during behaviour

This paper describes a method for monitoring drug-induced changes in brain dopamine (DA) release and metabolism in the awake rat simultaneous to measurements of behavioural activation. Intracerebral dialysis was combined with a novel activity box based on a circular running track and a simple method for perfusate collection. "Locomotor" and "general" activity were automatically monitored using a system of photobeams lining the track, and stereotyped behaviours were scored by direct observation. Striatal perfusates were analysed for endogenous DA and its main metabolites, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), using HPLC with electrochemical detection. This methodology was tested by comparing the behavioural effects of systemically administered amphetamine (2 mg/kg SC) and its central DA releasing action. Amphetamine caused a marked increase in striatal DA release (16-fold) which was followed over the time course by increased locomotion and stereotyped sniffing and head and forepaw movements. The limitations and wider applications of the methodology are discussed.