Regulation of Nervous Activity by Endogenous Prostaniods

神经刺激对输精管收缩的影响：在豚鼠输精管中，胃下神经的节前和节后刺激均诱导了由快速短暂期和延迟强直期组成的双相收缩。吲哚美辛部分抑制节前刺激引起的收缩，但对节后刺激反应无抑制作用。PGE_2对吲哚美辛的抑制作用被PGE_2逆转，PGE_2还能延缓相性收缩的发生，提高相性收缩和强直性收缩的高度，并显著增强真ATP和去甲肾上腺素诱导的收缩。甲哌嗪和PGE_2受体拮抗剂SC19220可抑制神经节前刺激引起的收缩。PGE_2和花生四烯酸逆转了这种抑制作用。提示内源性PGE_2在豚鼠脾神经节神经传递中起重要作用。对豚鼠回肠肌丛乙酰胆碱释放的影响：尼古丁或P物质对乙酰胆碱释放的影响降至吲哚美辛对照的40%左右，而5-羟色胺或电场刺激（EFS）对乙酰胆碱释放的影响不受影响。PGE_2可逆转吲哚美辛的抑制作用。甲哌辛是一种磷脂酶A_2抑制剂，对烟碱和P物质释放乙酰胆碱的抑制作用与吲哚美辛相同。PGI_2类似物OP-41483比PGE_2更有效地恢复了被抑制的尼古丁诱导释放。这种作用被a激酶抑制剂H-89所消除。PGD_2、PGF_<2alpha>和TXA_2类似物无效。制备过程中PGI_2的释放量为PGE_2的5倍。这些结果表明，内源性PGI_2和PGE_2均可调节肌肠丛胆碱能神经元的兴奋性，其作用是通过激活胞内环AMP系统介导的。5-脂氧合酶抑制剂对乙酰胆碱释放有抑制作用，而12-脂氧合酶抑制剂对乙酰胆碱释放无抑制作用。花生四烯酸、5-HETE、LTD_4和LTE_4均能逆转其抑制作用，而LTB_4和LTC_4则不能，说明5-脂氧合酶代谢物对efs诱导的乙酰胆碱释放有调节作用。综上所述，多种前列腺素对维持豚鼠回肠粘膜丛的活动有一定的作用，但所涉及的前列腺素种类可能因神经刺激的不同而不同。少

Effects on the contraction of vas deferens induced by nerve stimulation : In guinea pig vas deferens, both pre- and post-ganglionic stimulations of hypogastric nerve induced a biphasic contraction consisting of a rapig transient phas and delayed tonic Phase. Indomethacin partly inhibited the contraction induced by pre-ganglionic stimulation, but not the responses by post-ganglionic stimulation. The indomethacin inhibition was reversed by PGE_2- PGE_2 also delayed the onset of phasic contraction and increased the height of both phasic and tonic contractions, and significantly enhanced the contraction induced by authentic ATP and norepinephrine. The contraction induced by pre-ganglionic stimulation was inhibited by mepacrine and PGE_2 receptor antagonist, SC19220. PGE_2 and arachidonic acid reversed these inhibition. The findings suggest that endogenous PGE_2 is important in neurotransmission in the plevic ganglion of guinea pig.Effects on the release of ACh from the myenteric plexus of … More guinea pig ileum : The amount of ACh released in response to nicotine or substance P was depressed to about 40% of control by indomethacin, whereas that induced by 5-HT or electrical field stimulaltion(EFS)was not affected. The inhibitory effect of indomethacin were reversed by PGE_2. Mepacrine, an inhibitor of pbospbolipase A_2, depressed the release of ACh by nicotine and substance P to the same extent as indomethacin. OP-41483, an analogue of PGI_2, recovered inhibited nicotine-induced release more effectively than PGE_2. This effect was abolished by H-89, an A-kinase inhibitor. PGD_2, PGF_<2alpha> and TXA_2 analogue were ineffective. PGI_2 was released during incubation of preparation in the amount as much as 5 times of PGE_2. These results indicate that both endogenous PGI_2 and PGE_2 regulate the excitability of cholinergic neurons in the myenteric plexus and that the effects are mediated by the activation of intracellular cyclic AMP system. The ACh release by EFS was inhibited by 5-lipooxygenase inhibitors but not by 12-lipoxygenase inhibitor. The inhibitory effects were reversed by arachidonic acid, 5-HETE, LTD_4 and LTE_4, but not by LTB_4 and LTC_4, indicating the regulation5-lipoxygenase metavolites on efs induced ach release.In conclusion, many prostanoias contribute for maintaing the activity of the myeyerixc plecus of guinea pig iluem, but the kind of prostanoid concerned may diffe with different stimuli applied to nerve. Less