Serotonin inhibits GABA synaptic transmission in presympathetic paraventricular nucleus neurons.
Neurosci Lett
; 439(2): 138-42, 2008 Jul 11.
Article
em En
| MEDLINE
| ID: mdl-18524490
ABSTRACT
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 microM) reversibly decreased the frequency of spontaneous GABAergic inhibitory postsynaptic currents (sIPSC) in a concentration dependent manner (IC50, 0.07 microM), 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 microM), 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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Base de dados:
MEDLINE
Assunto principal:
Núcleo Hipotalâmico Paraventricular
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Serotonina
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Transmissão Sináptica
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Ácido gama-Aminobutírico
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Inibição Neural
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Neurônios
Limite:
Animals
Idioma:
En
Ano de publicação:
2008
Tipo de documento:
Article