[Effect of (-) stepholidine on dopamine turnover in various brain regions]

It has been shown before that DA antagonist (-) stepholidine [(-) SPD] changes the function of feedback regulation in the striatum. In order to compare the effect of the drug on other brain DA systems, the DA content and DOPAC level in brain areas or nuclei of rat were measured by HPLC-ECD. It was found that (-) SPD (10 mg/kg, ip) did not significantly affect the DA contents in the striatum, olfactory bulb, N. accumbens, substantia nigra, ventral tegmentum area, N. amygdala, hypothalamus, pituitary, piriform cortex, but did markedly increase the DOPAC levels in these brain areas or nuclei, and thus increase the DA turnover (DOPAC/DA). However, (-) SPD (10 mg/kg, ip) did not significantly affect either the DA contents or DOPAC levels in the prefrontal cortex and cingulate cortex, thus leaving the DA turnover in these areas unchanges. These results indicated that (-) SPD did affect the nigro-striatal, midbrain-limbic and hypothalamus-pituitary DA systems, but not the midbrain-cortex DA system. It is supposed that this difference may be due to the modulation by presynaptic DA autoreceptors in the major brain areas of DA nerve endings or neurosoma, but none in the cortex DA nerve endings.