Department of Pharmacology, School of Molecular and Systems Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
J Neurosci. 2010 Dec 15;30(50):16970-82. doi: 10.1523/JNEUROSCI.2306-10.2010.
Stress and anxiety-related behaviors controlled by the basolateral amygdala (BLA) are regulated in vivo by neuropeptide Y (NPY) and corticotrophin-releasing factor (CRF): NPY produces anxiolytic effects, whereas CRF produces anxiogenic effects. These opposing actions are likely mediated via regulation of excitatory output from the BLA to afferent targets. In these studies, we examined mechanisms underlying the effects of NPY and CRF in the BLA using whole-cell patch-clamp electrophysiology in rat brain slices. NPY, even with tetrodotoxin present, caused a dose-dependent membrane hyperpolarization in BLA pyramidal neurons. The hyperpolarization resulted in the inhibition of pyramidal cells, despite arising from a reduction in a voltage-dependent membrane conductance. The Y(1) receptor agonist, F(7)P(34) NPY, produced a similar membrane hyperpolarization, whereas the Y(1) antagonist, BIBO3304 [(R)-N-[[4-(aminocarbonylaminomethyl)-phenyl]methyl]-N(2)-(diphenylacetyl)-argininamide trifluoroacetate], blocked the effect of NPY. The NPY-inhibited current was identified as I(h), which is active at and hyperpolarized to rest. Responses to NPY were occluded by either Cs(+) or ZD7288 (4-ethylphenylamino-1,2-dimethyl-6-methylaminopyrimidinium chloride), but unaffected by the G(IRK)-preferring blockers Ba(2+) and SCH23390 [(R)-(+)-7-chloro-8-hydroxy-3-methyl-l-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride]. Application of CRF, with or without TTX present, depolarized NPY-sensitive BLA pyramidal neurons, resulting from an increase in I(h). Electrophysiological and immunocytochemical data were consistent with a major role for the HCN1 subunit. Our results indicate that NPY, via Y(1) receptors, directly inhibits BLA pyramidal neurons by suppressing a postsynaptic I(h), whereas CRF enhances resting I(h), causing an increased excitability of BLA pyramidal neurons. The opposing actions of these two peptides on the excitability of BLA output cells are consistent with the observed behavioral actions of NPY and CRF in the BLA.
外侧杏仁核（BLA）控制的应激和焦虑相关行为在体内受到神经肽 Y（NPY）和促肾上腺皮质释放因子（CRF）的调节：NPY 产生抗焦虑作用，而 CRF 产生焦虑作用。这些相反的作用可能是通过调节从 BLA 到传入靶标的兴奋性输出来介导的。在这些研究中，我们使用大鼠脑切片中的全细胞膜片钳电生理学研究了 NPY 和 CRF 在 BLA 中的作用机制。NPY 即使存在河豚毒素，也会导致 BLA 锥体神经元的剂量依赖性膜超极化。超极化导致锥体细胞抑制，尽管它源于电压依赖性膜电导的降低。Y1 受体激动剂 F(7)P(34)NPY 产生类似的膜超极化，而 Y1 拮抗剂 BIBO3304[(R)-N-[[4-(氨甲酰基氨基甲基)-苯基]甲基]-N2-(二苯乙酰基)-精氨酸酰胺三氟乙酸盐]，阻断了 NPY 的作用。NPY 抑制电流被鉴定为 I(h)，它在和超极化到静息状态时活跃。NPY 的反应被 Cs(+)或 ZD7288(4-乙基苯氨基-1,2-二甲基-6-甲基氨基嘧啶盐酸盐)阻断，但不受 G(IRK)优先阻断剂 Ba(2+)和 SCH23390[(R)-(+)-7-氯-8-羟基-3-甲基-1-苯基-2,3,4,5-四氢-1H-3-苯并氮杂环庚烷盐酸盐]的影响。应用 CRF，无论是否存在 TTX，都会使 NPY 敏感的 BLA 锥体神经元去极化，这是由于 I(h)的增加。电生理和免疫细胞化学数据表明 HCN1 亚基起主要作用。我们的结果表明，NPY 通过 Y1 受体，通过抑制突触后 I(h)，直接抑制 BLA 锥体神经元，而 CRF 增强静息 I(h)，导致 BLA 锥体神经元兴奋性增加。这两种肽对 BLA 输出细胞兴奋性的相反作用与 NPY 和 CRF 在 BLA 中的观察到的行为作用一致。
