Evidence that 5-hydroxytryptamine release in rat dorsal raphe nucleus is controlled by 5-HT_(1A), 5-HT_(1B) and 5-HT_(1D) autoreceptors

摘要

Electrically stimulated 5-hydroxytryptamine (5-HT) release was monitored in slices of rat dorsal raphe nucleus (DRN) by fast cylic voltammetry. Pseudo-single pulse stimulations (5 pulses at 100 Hz) were used to enable the effect of various receptor agonists to be seen without competition from endogenously released transmitter. The selective 5-HT_(1A) receptor agonist, (+)-8-OH-DPAT (1.0 μM) decreased stimulated 5-HT release to 31 ± 3% of controls. This decrease was inhibited by the 5-HT_(1A) receptor antagonists, ( + )-WAY-100135 (1.0 μM) and WAY-100635 (0.1 μM) but not by the 5-HT_(1D/B) antagonist, GR127935 (0.05 μM). The selective 5-HT_(1B) receptor agonist, CP-93129 (0.3 μM) decreased stimulated 5-HT release to 61 ± 4% of control. This effect was antagonized by the 5-HT_(1B) receptor antagonist, isamoltane (0.5 μM) but not by ( + )-WAY-100135. The 5-HT_(1D) agonist, sumatriptan (0.5 μM) decreased stimulated 5-HT release to 52 ± 2 % of controls. This decrease was blocked by GR-127935 but not by WAY-100635. These results suggest that 5-HT release in the rat DRN is under the control of 5-HT_(1A), 5-HT_(1B) and 5-HT_(1D) autoreceptors.