Effect ofl-tetrahydropalmatine on dopamine release and metabolism in the rat striatum

✍ Scribed by Françoise Marcenac; Guo Zhang Jin; François Gonon

• Publisher: Springer
• Year: 1986
• Tongue: English
• Weight: 538 KB
• Volume: 89
• Category: Article
• ISSN: 0033-3158
• DOI: 10.1007/bf00175196

✦ Synopsis

In vivo voltammetric measurements of striatal extracellular DOPAC concentrations and of striatal DA release in combination with post-mortem analysis of striatal catechols were performed in the rat to study the effects on the nigro-striatal neurons of a Chinese neuroleptic, ltetrahydropalmatine (/-THP), which is known to block post-synaptic dopaminergic receptors. /-THP injected at doses that cause sedation in rats and mice (5-10 mg/kg) induced a marked increase in post-mortem DOPAC levels (+ 250%), while no significant effect was observed on postmortem DA levels. The extracellular DOPAC concentration was increased to 155___9% of the control value after /-THP administration (1 mg/kg, IP). Further, an injection of/-THP (1 mg/kg, IP) induced an increase in extracellular DA concentration (220% of the basal value), reversed the decrease in extracellular DA concentration induced by apomorphine (0.05 mg/kg, SC) and enhanced the effects of the electrical stimulation of the nigro-striatal pathway. These results confirm that /-THP acts on the nigro-striatal neurons as a dopaminergic antagonist that can block both postand presynaptic receptors.