Whyment Andrew D, Blanks Andrew M, Lee Kevin, Renaud Leo P, Spanswick David
Warwick Medical School, University of Warwick, Coventry, CV4 7AL, United Kingdom.
J Neurophysiol. 2006 Apr;95(4):2492-500. doi: 10.1152/jn.01135.2004. Epub 2005 Dec 14.
The role of histamine in regulating excitability of sympathetic preganglionic neurons (SPNs) and the expression of histamine receptor mRNA in SPNs was investigated using whole-cell patch-clamp electrophysiological recording techniques combined with single-cell reverse transcriptase polymerase chain reaction (RT-PCR) in transverse neonatal rat spinal cord slices. Bath application of histamine (100 microM) or the H1 receptor agonist histamine trifluoromethyl toluidide dimaleate (HTMT; 10 microM) induced membrane depolarization associated with a decrease in membrane conductance in the majority (70%) of SPNs tested, via activation of postsynaptic H1 receptors negatively coupled to one or more unidentified K+ conductances. Histamine and HTMT application also induced or increased the amplitude and/or frequency of membrane potential oscillations in electrotonically coupled SPNs. The H2 receptor agonist dimaprit (10 microM) or the H3 receptor agonist imetit (100 nM) were without significant effect on the membrane properties of SPNs. Histamine responses were sensitive to the H1 receptor antagonist triprolidine (10 microM) and the nonselective potassium channel blocker barium (1 mM) but were unaffected by the H2 receptor antagonist tiotidine (10 microM) and the H3 receptor antagonist, clobenpropit (5 microM). Single cell RT-PCR revealed mRNA expression for H1 receptors in 75% of SPNs tested, with no expression of mRNA for H2, H3, or H4 receptors. These data represent the first demonstration of H1 receptor expression in SPNs and suggest that histamine acts to regulate excitability of these neurons via a direct postsynaptic effect on H1 receptors.
采用全细胞膜片钳电生理记录技术结合单细胞逆转录聚合酶链反应（RT-PCR），在新生大鼠脊髓横切片中研究了组胺在调节交感神经节前神经元（SPN）兴奋性以及SPN中组胺受体mRNA表达方面的作用。在浴槽中应用组胺（100μM）或H1受体激动剂三氟甲基甲苯胺二马来酸组胺（HTMT；10μM），通过激活与一种或多种未明确的钾离子电导负偶联的突触后H1受体，在大多数（70%）受试SPN中诱导膜去极化，并伴有膜电导降低。应用组胺和HTMT还可诱导或增加电耦合SPN中膜电位振荡的幅度和/或频率。H2受体激动剂二甲双胍（10μM）或H3受体激动剂依美替丁（100 nM）对SPN的膜特性无显著影响。组胺反应对H1受体拮抗剂曲普利啶（10μM）和非选择性钾通道阻滞剂钡（1 mM）敏感，但不受H2受体拮抗剂噻替丁（10μM）和H3受体拮抗剂氯苯丙哌嗪（5μM）的影响。单细胞RT-PCR显示，在75%的受试SPN中有H1受体的mRNA表达，而没有H2、H3或H4受体的mRNA表达。这些数据首次证明了SPN中H1受体的表达，并表明组胺通过对H1受体的直接突触后作用来调节这些神经元的兴奋性。
