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Regulation of synaptic input to hypothalamic presympathetic neurons by GABA(B) receptors.
Neuroscience. 2006 Oct 13; 142(2):595-606.N

Abstract

The hypothalamic paraventricular (PVN) neurons projecting to the spinal cord and brainstem play an important role in the control of homeostasis and the sympathetic nervous system. Although GABA(B) receptors are present in the PVN, their function in the control of synaptic inputs to PVN presympathetic neurons is not clear. Using retrograde tracing and whole-cell patch-clamp recordings in rat brain slices, we determined the role of presynaptic GABA(B) receptors in regulation of glutamatergic and GABAergic inputs to spinally projecting PVN neurons. The GABA(B) receptor agonist baclofen (1-50 microM) dose-dependently decreased the frequency but not the amplitude of spontaneous excitatory postsynaptic currents (sEPSCs) and inhibitory postsynaptic currents (sIPSCs). The effect of baclofen on sEPSCs and sIPSCs was completely blocked by 10 microM CGP52432, a selective GABA(B) receptor antagonist. Baclofen also significantly reduced the frequency of both miniature excitatory and miniature inhibitory postsynaptic currents (mEPSCs and mIPSCs). Furthermore, uncoupling pertussis toxin-sensitive G(i/o) proteins with N-ethylmaleimide abolished baclofen-induced inhibition of mEPSCs and mIPSCs. However, the inhibitory effect of baclofen on the frequency of mIPSCs and mEPSCs persisted in the presence of either Cd2+, a voltage-gated Ca2+ channel blocker, or 4-aminopyridine, a blocker of voltage-gated K+ channels. Our results suggest that activation of presynaptic GABA(B) receptors inhibits synaptic GABA and glutamate release to PVN presympathetic neurons. This presynaptic action of GABA(B) receptors is mediated by the N-ethylmaleimide-sensitive G(i/o) proteins, but independent of voltage-gated Ca2+ and K+ channels.

Authors+Show Affiliations

Department of Anesthesiology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.No affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

16887273

Citation

Chen, Q, and H-L Pan. "Regulation of Synaptic Input to Hypothalamic Presympathetic Neurons By GABA(B) Receptors." Neuroscience, vol. 142, no. 2, 2006, pp. 595-606.
Chen Q, Pan HL. Regulation of synaptic input to hypothalamic presympathetic neurons by GABA(B) receptors. Neuroscience. 2006;142(2):595-606.
Chen, Q., & Pan, H. L. (2006). Regulation of synaptic input to hypothalamic presympathetic neurons by GABA(B) receptors. Neuroscience, 142(2), 595-606.
Chen Q, Pan HL. Regulation of Synaptic Input to Hypothalamic Presympathetic Neurons By GABA(B) Receptors. Neuroscience. 2006 Oct 13;142(2):595-606. PubMed PMID: 16887273.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Regulation of synaptic input to hypothalamic presympathetic neurons by GABA(B) receptors. AU - Chen,Q, AU - Pan,H-L, Y1 - 2006/08/02/ PY - 2006/04/25/received PY - 2006/06/21/revised PY - 2006/06/22/accepted PY - 2006/8/5/pubmed PY - 2007/1/24/medline PY - 2006/8/5/entrez SP - 595 EP - 606 JF - Neuroscience JO - Neuroscience VL - 142 IS - 2 N2 - The hypothalamic paraventricular (PVN) neurons projecting to the spinal cord and brainstem play an important role in the control of homeostasis and the sympathetic nervous system. Although GABA(B) receptors are present in the PVN, their function in the control of synaptic inputs to PVN presympathetic neurons is not clear. Using retrograde tracing and whole-cell patch-clamp recordings in rat brain slices, we determined the role of presynaptic GABA(B) receptors in regulation of glutamatergic and GABAergic inputs to spinally projecting PVN neurons. The GABA(B) receptor agonist baclofen (1-50 microM) dose-dependently decreased the frequency but not the amplitude of spontaneous excitatory postsynaptic currents (sEPSCs) and inhibitory postsynaptic currents (sIPSCs). The effect of baclofen on sEPSCs and sIPSCs was completely blocked by 10 microM CGP52432, a selective GABA(B) receptor antagonist. Baclofen also significantly reduced the frequency of both miniature excitatory and miniature inhibitory postsynaptic currents (mEPSCs and mIPSCs). Furthermore, uncoupling pertussis toxin-sensitive G(i/o) proteins with N-ethylmaleimide abolished baclofen-induced inhibition of mEPSCs and mIPSCs. However, the inhibitory effect of baclofen on the frequency of mIPSCs and mEPSCs persisted in the presence of either Cd2+, a voltage-gated Ca2+ channel blocker, or 4-aminopyridine, a blocker of voltage-gated K+ channels. Our results suggest that activation of presynaptic GABA(B) receptors inhibits synaptic GABA and glutamate release to PVN presympathetic neurons. This presynaptic action of GABA(B) receptors is mediated by the N-ethylmaleimide-sensitive G(i/o) proteins, but independent of voltage-gated Ca2+ and K+ channels. SN - 0306-4522 UR - https://www.unboundmedicine.com/medline/citation/16887273/Regulation_of_synaptic_input_to_hypothalamic_presympathetic_neurons_by_GABA_B__receptors_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0306-4522(06)00873-6 DB - PRIME DP - Unbound Medicine ER -