Bivalacqua T J, Champion H C, Purohit S K, Murphy W A, Coy D H, Kadowitz P J, Hellstrom W J
Department of Urology, Tulane University Medical School, New Orleans, Louisiana, 70112, USA.
Nitric Oxide. 2000 Apr;4(2):94-102. doi: 10.1006/niox.2000.0274.
The purpose of this study was to investigate the in vivo effects of intracavernosal injections of galanin and galantide (a specific galanin receptor antagonist) on penile erection in the anesthetized cat. Erectile responses to galanin and galantide were compared with responses to a standard triple drug combination [1.65 mg papaverine, 25 microg phentolamine, and 0.5 microg prostaglandin E(1) (PGE(1))]. Intracavernosal injections of galanin (3-100 nmol) and galantide (0. 1-3 nmol) induced penile erection in a dose-dependent manner. In terms of relative potency, galantide was approximately 100-fold more potent than galanin at increasing cavernosal pressure. The maximal increases in intracavernosal pressure in response to galanin and galantide were 83 and 95%, respectively, of the control triple drug combination. The total durations of erectile response caused by these peptides were significantly shorter (P<0.05) than those by the triple drug combination. The nitric oxide synthase inhibitor L-NAME (20 mg) significantly decreased the erectile response in the cat to galantide but not to galanin, while the K(+)(ATP) channel antagonist U-37883A (3 mg) had no effect on the erectile response to galanin nor galantide. The results of the present study demonstrate that galantide, a putative antagonist for the galanin receptor, has more potent agonist activity than galanin in increasing intracavernosal pressure in the cat. Moreover, these data suggest that galantide, but not galanin, causes penile erection by an NO/cGMP-dependent mechanism. This is the first study to demonstrate that galanin may play a role in the physiology of penile erection.
本研究的目的是探讨海绵体内注射甘丙肽和丙谷酰胺（一种特异性甘丙肽受体拮抗剂）对麻醉猫阴茎勃起的体内作用。将对甘丙肽和丙谷酰胺的勃起反应与对标准三联药物组合[1.65毫克罂粟碱、25微克酚妥拉明和0.5微克前列腺素E(1)（PGE(1)）]的反应进行比较。海绵体内注射甘丙肽（3 - 100纳摩尔）和丙谷酰胺（0.1 - 3纳摩尔）以剂量依赖的方式诱导阴茎勃起。就相对效力而言，在增加海绵体压力方面，丙谷酰胺的效力比甘丙肽强约100倍。对甘丙肽和丙谷酰胺反应的海绵体内压力最大增加分别为对照三联药物组合的83%和95%。这些肽引起的勃起反应总持续时间明显短于三联药物组合（P<0.05）。一氧化氮合酶抑制剂L - NAME（20毫克）显著降低猫对丙谷酰胺的勃起反应，但不影响对甘丙肽的反应，而K(+)（ATP）通道拮抗剂U - 37883A（3毫克）对甘丙肽和丙谷酰胺的勃起反应均无影响。本研究结果表明，作为甘丙肽受体的假定拮抗剂，丙谷酰胺在增加猫海绵体内压力方面比甘丙肽具有更强的激动剂活性。此外，这些数据表明，丙谷酰胺而非甘丙肽通过NO/cGMP依赖机制引起阴茎勃起。这是第一项证明甘丙肽可能在阴茎勃起生理过程中起作用的研究。
