Effects of 5‐HT1 receptor agonist on the excitability of medial vestibular nuclear neurons

The aim of this study is to explore the action of 5-HT1 receptor on spontaneous firing activity of the rat medial vestibular nuclear neurons by patch clamp experiments. The spontaneous firing was increased in 45.5% and decreased in 54.5% of the neurons tested with 5-carboxamidotryptamine, non-selective 5-HT1 receptor agonist. And the whole potassium currents of medial vestibular nuclear neurons was decreased in 64% and increased in 36% of cells tested with 5-carboxamidotryptamine. The spontaneous firing rate was increased by 8-OH-DPAT, selective 5-HT1A receptor agonist in 73.3% and was not changed in 26.7%. Whole potassium currents were decreased in 84.2% and was not affected in 15.8% by 8-OH-DPAT. These results suggest that 5-HTIA receptor of the medial vestibular nuclear neurons mediates excitatory effects whereas inhibitory effects are mediated by other 5-HT1 receptors.