Behavioural and biochemical effects of haloperidol during the oestrous cycle of the rat

The effects of two doses (1 and 2 mg/kg, i.p.) of haloperidol (HAL) on catalepsy, on concentrations of DA and DOPAC in frontal cortex, nucleus accumbens and striatum and on serum levels of oestradiol were investigated in intact female rats during the 4-day oestrous cycle. Catalepsy induced by haloperidol did not vary much during phases of the cycle. The turnover of DA in the cortex induced by haloperidol was significantly greater on proestrus and smaller on oestrus. The effect of haloperidol on the turnover of DA in the nucleus accumbens and in striatum was marginally affected by the oestrous cycle being greatest on oestrus. The levels of serum oestradiol were higher on proestrus and lower on oestrus. No significant differences were detected between diestrus and metestrus. After haloperidol there was a dramatic increase in serum oestradiol on oestrus, a slight increase on metestrus and diestrus and a decrease on proestrus. However, serum levels of oestradiol were not significantly different between phases of the cycle in rats treated with haloperidol. The results indicate that the oestrous cycle has a detectable influence on DAergic mechanisms in the frontal cortex and possibly in the tuberoinfudibular system, brought about by treatment with haloperidol.