Expressions Of S1P1-3in The Corpus Cavernosum Of Spontaneous Hypertensive Rats

Objective: Hypertension and erectile dysfunction (ED) hasclose relationship.The reason that hypertension causing ED is possiblyassociated with the dysfunction of corpus cavernosum endothelial cell, adecrease in eNOS expression and an increase in the RhoA/Rho kinase signalpathway.Upstream regulation of eNOS and RhoA/Rho kinase is associated withSphingosine-1-phosphate (S1P). S1P is a kind of bioactive sphingolipidsmedium.The main function of S1P is used as an extracellular mediator and itplays a wide range of biological effects by combining to the SIP receptors.While the relationship between S1P and eNOS, RhoA/Rho kinase inhypertension is not clear. The purpose of this study is to research theexpressions of S1P1-3in the corpus cavernosum of spontaneous hypertensiverats (SHR) and normotensive rats (WKY), and investigate their relationshipwith penile erectile and eNOS/NO,RhoA／Rho kinase pathways. Methods:Ten of SPF healthy adult male SHR and WKY rats,14weeks old,weighingabout250-300g,were randomly divided into SHR group and control group. Anesthesia before weighing,1%sodium pentobarbital anesthetized rats byintraperitoneal injection of30mg/kg.Then rats were exposed to the right carotidartery,26G needle which was filled with heparinized saline punctured thecarotid artery and connected the pressure converter,continuous monitoring andrecording the mean arterial pressure (MAP).Open the abdominal cavity, free the prostate leaves and find the cavernous pelvic ganglion as a stimulation spot.24G needle which was filled with heparinized saline successfully punctured thecorpus cavernosum and connected the pressure converter,measuring theintracavernous pressure(ICP).Electrical stimulation was applied to differentspecies(the stimulus intensity0V,3V and5V, amplitude5ms,12Hz stimulationfrequency,sustained stimulation45s,stimulus interval3min).Pressure transducerrecorded ICPmax/MAP value.After testing penile erectile function,take thecorpus cavernosum penis and blood samples. Serum testosterone was measuredin two groups.S1P was also measured in two groups.Penile specimens weredivided into two parts.One part was used for immunohistochemical analysisimmediately and the other part was stored in-80℃ultra low temperaturefreezer preservation,for the analysis of Western-blot.The expressions ofS1P1-3,P-eNOS,eNOS,ROCK1and ROCK2were detected by immunohisto-chemistry and Western-blot. Results: Serum testosterone in group SHR（430.89±98.67）ng/dl had no significant differences with control group（492.93±54.23）ng/dl. In0V electrical stimulation,ICPmax/MAP was significantlydecreased in group SHR（0.109±0.014）than control group（0.155±0.011）(P<0.05). In3V and5V electrical stimulation,ICPmax/MAP was significantlydecreased in group SHR （0.190±0.013,0.219±0.014） than control group（0.393±0.018,0.524±0.019）(P<0.01).S1P in group SHR（4.156±0.362）ng/mlalso had no significant differences with control group（4.549±0.876）ng/ml.The results of immunohistochemistry showed that S1P1is mainly expressed in the membrane of endothelial cells.S1P2is mainly expressed in the corpuscavernosum smooth muscle cells and vascular endothelial cells.S1P3is mainlyexpressed in the membrane of vascular endothelial cells and corpus cavernosumsmooth muscle cells.P-eNOS,eNOS is mainly expressed in the vascularendothelial cells and Cavernous sinus cavity.ROCK1,ROCK2is mainlyexpressed in the cytoplasm of corpus cavernosum smooth muscle cells.Immunolabeling of S1P1-3,P-eNOS,eNOS, OCK1and ROCK2was stained inbrown.Immunohistochemical data were analyzed by the Integrated OpticalDensity (IOD).The expressions of S1P1,eNOS and P-eNOS were significantlydecreased in group SHR than control group (P<0.05).Whlie the expressions ofS1P2,S1P3,ROCK1and ROCK2were significantly increased in group SHRthan control group (P<0.05).Western blot analysis were analyzed by theRelative Optical Density(ROD).The protein expressions of S1P1,eNOS andP-eNOS were significantly decreased in group SHR than control group(P<0.05).Whlie the protein expressions of S1P2,S1P3,ROCK1and ROCK2were significantly increased in group SHR than control group (P<0.05).Conclusion: Hypertension causing ED is possibly associated with the declineof S1P1in corpora cavernosum which may prohibit the eNOS/NO signalingpathway and the increased expression of S1P2and S1P3which may activatethe RhoA/Rho kinase signal pathway.