Galanin modulates neuronal and synaptic properties in the rat supraoptic nucleus in a use and state dependent manner
Galanin modulates neuronal and synaptic properties in the rat supraoptic nucleus in a use and state dependent manner
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DOI：
10.1152/jn.01028.2005
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发表时间：
2006-07-01
影响因子：
2.5
通讯作者：
Pittman, Quentin J.
中科院分区：
文献类型：
--
作者：
Kozoriz, Michael G.;Kuzmiski, J. Brent;Pittman, Quentin J.
下丘脑视上核（SON）的大细胞神经元由其树突合成并分泌催产素（OXT）和加压素（AVP）。这些肽和其他几种神经递质已被证明可以调节SON中的传入神经递质能神经传递。神经肽甘丙肽（GAL）也定位于SON大细胞神经元和核内的传入纤维中。我们发现，GAL剂量依赖性地减少诱发兴奋性突触后电流（eEPSC），改变成对脉冲比，降低mEPSC频率，但不是振幅或衰减动力学在OXT和AVP神经元。因此，GAL在可能的突触前受体处调节兴奋性神经传递。OXT/AVP、GABA（B）和大麻素拮抗剂均不能阻断这种作用。GAL 2/3激动剂模拟GAL的作用，而GAL 1拮抗剂不阻断GAL的作用，表明GAL 2/3受体介导突触前效应。在非脱水大鼠GAL引起一个小的突触后反应，通过输入电阻测量评估。当大鼠被剥夺水2天的GAL的突触前反应是不变的，但是，突触后输入电阻和超极化的减少增加，与先前描述的GAL 1受体表达的增加在脱水一致的效果。GAL 1受体拮抗剂阻断突触后效应。最后，当诱发一系列eEPSC时，发现GAL抑制一系列中的早期事件，但不抑制后者。这表明GAL可以比突触输入序列更有效地调制单个突触事件，从而充当高通滤波器。
The magnocellular neurons of the hypothalamic supraoptic nucleus (SON) synthesize and secrete oxytocin (OXT) and vasopressin (AVP) from their dendrites. These peptides, and several other neurotransmitters, have been shown to modulate afferent glutamatergic neurotransmission in the SON. The neuropeptide, galanin (GAL) is also localized in SON magnocellular neurons and in afferent fibers in the nucleus. We show that GAL dose-dependently reduces evoked excitatory postsynaptic currents (eEPSCs), alters paired pulse ratio and decreases mEPSC frequency, but not amplitude or decay kinetics in both OXT and AVP neurons. GAL therefore modulates excitatory neurotransmission at a likely presynaptic receptor. Neither OXT/AVP, GABA(B) nor cannabinoid antagonists blocked this effect. A GAL2/3 agonist mimicked GAL's action while GAL1 antagonist did not block GAL's effect, suggesting that GAL2/3 receptors mediate the presynaptic effect. In nondehydrated rats GAL causes a small postsynaptic response, as assessed by input resistance measurements. When the rats were water deprived for 2 days the presynaptic response to GAL was unaltered; however, the postsynaptic decrease in input resistance and hyperpolarization was increased, an effect consistent with a previously described increase in GAL1 receptor expression in dehydration. A GAL1 receptor antagonist blocked the postsynaptic effects. Last, when a train of eEPSCs was elicited, GAL was found to inhibit the earlier events in a train but not the latter. This indicates that GAL may modulate a single synaptic event more effectively than trains of synaptic inputs, thereby acting as a high-pass filter.