Serotonin agonists reduce dopamine synthesis in the striatum only when the impulse flow of nigro-striatal neurons is intact.
Journal of neurochemistry September 1, 1985 U Spampinato, E Esposito, R Samanin 36 citations
In rats, two serotonin agonists, 5-MeO-DMT and CPP, did not reduce dopamine synthesis in the striatum when impulse flow in dopamine neurons was blocked by gamma-butyrolactone, unlike the dopamine agonist apomorphine. However, when impulse flow was intact, both serotonin agonists did reduce dopamine synthesis. Injecting serotonin directly into the substantia nigra increased dopamine synthesis, similar to blocking impulse flow. The findings suggest that serotonin agonists affect dopamine synthesis indirectly, possibly through other neurons like cholinergic or GABA-ergic ones, and only when dopamine neurons are active.