Characterization of 5-hydroxytryptamine3 receptors in the medial prefrontal cortex: a microiontophoretic study.

The microiontophoretic application of the selective 5-hydroxytryptamine3 (5-HT3) agonist 2-methylserotonin suppresses medial prefrontal cortex cell firing. This effect is blocked by the 5-HT3 antagonists BRL 43694 and ICS205930, but not by metergoline or (+/-)-pindolol. Continuous microiontophoretic administration of magnesium chloride or the gamma-aminobutyric acidA antagonist SR 95103 did not alter 2-methylserotonin's suppressant action, suggesting that this effect is direct. Our results suggest that 5-HT3 receptors have a functional role in the medial prefrontal cortex.