Chlorimipramine, electroconvulsive shock and combination thereof: differential effects of chronic treatment on apomorphine-induced behaviours and on striatal and mesocortical dopamine turnover.

Abstract

We studied the influence of different pretreatment regimens (Chlorimipramine-Cmi, electroconvulsive shock-ECS, and Cmi + ECS all regimens being applied for either 2 or 15 days) on the open field behaviour, on the striatal and on the prefrontal dopamine-PFC DA turnover in rats injected with either apomorphine-AP 25 micrograms/kg (stimulating presynaptic DA receptors), AP 200 micrograms/kg (stimulating post-synaptic DA receptors), or vehicle (control). In the controls, AP 25 micrograms/kg reduced the locomotor activity and the striatal, but not the PFC DA turnover. AP 200 micrograms/kg increased the locomotor activity and reduced the striatal but not the PFC DA turnover. Short-term pretreatment: ECS and Cmi + ECS prevented the decrease of striatal DA turnover after AP 25 micrograms/kg. No other influence of any pretreatment on behaviour or DA-turnover became significant. Long-term pretreatment: Chronic Cmi: marginally increased the open field behaviour and marginally decreased the PFC DA turnover; significantly increased the effect of AP (200 micrograms/kg) on striatal DA turnover and the effect of AP (25 and 200 micrograms/kg) on PFC DA turnover. Repeated ECS: decreased locomotion and rearing and increased PFC DA turnover; increased the effect of AP (200 micrograms/kg) on locomotion and on striatal DA turnover; decreased the effect of AP (25 and 200 micrograms/kg) on PFC DA turnover. Chronic Cmi + ECS: decreased locomotion and rearing and marginally decreased PFC DA turnover; increased the effect of AP on hyperlocomotion and on striatal DA turnover.(ABSTRACT TRUNCATED AT 250 WORDS)