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目的探讨nesfatin-1对大鼠下丘脑弓状核(ARC)ghrelin敏感性胃牵张(GD)神经元放电活动和胃运动的调控作用。方法选用成年Wistar大鼠132只,采用细胞外单位神经元放电及核团微量注射方法,记录ARC注射ghrelin后GD敏感神经元的放电变化并鉴定ghrelin敏感性GD神经元;随后向ghrelin敏感性GD神经元注射nesfatin-1,观察其放电变化。另取大鼠48只,ARC分别微量注射0.5μL生理盐水(NS)、2×103 nmol/L的nesfatin-1、2×104 nmol/L的nesfatin-1、2×105 nmol/L的nesfatin-1、105 nmol/L的黑色素受体拮抗剂(SHU9119)及2×104 nmol/L的nesfatin-1+105 nmol/L的SHU9119混合液(各8只),采用胃内置入应力传感器的方法,记录各组清醒自由活动大鼠胃收缩幅度和频率的变化。结果 ARC共记录到246个神经元放电,164个为GD敏感神经元。在88个GD兴奋性(GD-E)神经元中,ARC微量注射ghrelin可兴奋其中62个神经元。而在76个GD抑制性(GD-I)神经元中,ghrelin可抑制其中47个神经元。ARC注射nesfatin-1可抑制其中39个ghrelin敏感性GD-E神经元,放电频率显著降低(t=8.57,P<0.01);而在47个ghrelin敏感性GD-I神经元中,nesfatin-1可兴奋其中25个神经元,放电频率显著增加(t=8.07,P<0.01)。nesfantin-1对ghrelin敏感性GD神经元电活动的作用可被SHU9119部分阻断(t=2.39、2.22,P<0.05)。体内胃运动研究结果显示,ARC微量注射不同浓度的nesfatin-1于5min后,胃收缩幅度和频率均显著降低(F=3.30~5.27,q=3.34~17.74,P<0.05)。SHU9119可以部分阻断nesfatin-1对胃运动的抑制效应(t=2.22、2.93,P<0.05)。结论下丘脑ARC的nesfatin-1能够影响大鼠ghrelin敏感性GD神经元的放电并抑制胃运动,而该效应可能通过黑色素神经通路来完成。
Objective To investigate the regulation of nesfatin-1 on ghrelin-sensitive gastric stretch (GD) neurons in the hypothalamus arcuate nucleus (ARC). Methods Thirty-two adult Wistar rats were randomly divided into two groups. The discharge of neurons in the extracellular unit and nuclei microinjection were used to record the changes of GD sensitive neurons after ARC injection of ghrelin and to identify ghrelin-sensitive GD neurons. Subsequently, ghrelin-sensitive GD Nesfatin-1 was injected into neurons to observe the change of discharge. Forty-eight rats were treated by ARC. Microinjection of 0.5 μL normal saline (NS), 2 × 103 nmol / L nesfatin-1,2 × 104 nmol / L nesfatin-1,2 × 105 nmol / L nesfatin- 1,105 nmol / L melanin receptor antagonist (SHU9119) and 2 × 104 nmol / L nesfatin-1 + 105 nmol / L SHU9119 mixture (8 each) The changes of gastric contraction amplitude and frequency in conscious and freely moving rats were recorded. Results ARC recorded a total of 246 neurons and 164 GD-sensitive neurons. Among 88 GD excitatory (GD-E) neurons, microinjection of ghrelin into ARC stimulated 62 of these neurons. In 76 GD-I neurons, ghrelin inhibited 47 neurons. Arc’s injection of nesfatin-1 inhibited 39 ghrelin-sensitive GD-E neurons and significantly reduced the discharge frequency (t = 8.57, P <0.01); while in 47 ghrelin-sensitive GD-I neurons, nesfatin-1 25 neurons were excited and the discharge frequency increased significantly (t = 8.07, P <0.01). The effect of nesfantin-1 on ghrelin-sensitive GD neurons was partially blocked by SHU9119 (t = 2.39,2.22, P <0.05). In vivo gastric motility study showed that microinjection of different concentrations of nesfatin-1 into ARC at 5 min significantly reduced the amplitude and frequency of gastric contractions (F = 3.30-5.27, q = 3.34-17.74, P <0.05). SHU9119 partially blocked the inhibitory effect of nesfatin-1 on gastric motility (t = 2.22, 2.93, P <0.05). Conclusions nesfatin-1 in hypothalamic ARC can affect the discharge of ghrelin-sensitive GD neurons and inhibit gastric motility in rats, which may be mediated through the melanin pathway.