S-Space College of Veterinary Medicine (수의과대학) Dept. of Veterinary Medicine (수의학과) Journal Papers (저널논문_수의학과)
Serotonin inhibits GABA synaptic transmission in presympathetic paraventricular nucleus neurons
- Lee, Kyu Seung; Han, Tae Hee; Jo, Ji Yoon; Kang, Gun; Lee, So Yeong; Ryu, Pan Dong; Im, Jae Hyeng; Jeon, Byeong Hwa; Park, Jin Bong
- Issue Date
- Neurosci. Lett. 439 (2008) 138-142
- Activation of serotonin (5-hydroxytryptamine, 5-HT) receptors produces various autonomic and neuroendocrine responses in the hypothalamic paraventricular nucleus (PVN), including increased blood pressure and heart rate. However, the role(s) of 5-HT on the local GABA synaptic circuit have not been well understood in the PVN, where the inhibitory neurotransmitter GABA plays a key role in the modulation of sympathoexcitatory outflow. In the present study, we examined the effects of 5-HT on GABA synaptic transmission in presympathetic PVN neurons projecting to spinal cord using patch-clamp electrophysiology combined with tract-tracing techniques. Bath application of 5-HT (0.01–100 μM) reversibly decreased the frequency of spontaneous GABAergic inhibitory postsynaptic currents (sIPSC) in a concentration dependent manner (IC50, 0.07 μM), with no significant changes in the amplitudes and decay kinetics of sIPSC. The sIPSC inhibition of 5-HT was mimicked by 5-HT1A agonist, 8-OH-DPAT (8-hydroxy-2(di-n-propylamino)tetralin, 10 μM), and blocked by 5-HT1A antagonist WAY-100635 but not by 5-HT1B antagonist SB224289. 5-HT also reduced the frequency of miniature IPSC (mIPSC) (2.59 ± 0.51 Hz, control vs. 1.25 ± 0.31 Hz, 5-HT, n = 16) in similar extent with 5-HT induced reduction of sIPSC frequency (sIPSCs, 55.8 ± 6.2%, n = 11 vs. mIPSCs, 52.30 ± 5.85%, n = 16; p > 0.5). All together, our results indicate that 5-HT can inhibit presynaptic GABA release via presynaptic 5-HT1A receptors in presympathetic PVN neurons projecting to spinal cord.
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