RhoA/Rho-kinase In The Mechanisms Of Erectile Dysfunction Induced By Hyperlipidemic Rabbit

PartⅠExperimental study on improvement of erectile function by rho-kinase inhibitor fasudil in hypercholesterolemic rabbitObjective:To investigate the effects of Rho-kinase in hyperlipidemia-induced erectile dysfunction through studying the improvement on erectile function by rho-kinase inhibitor fasudil in hypercholesterolemic rabbit in vivo.Methods:Male New Zealand white rabbits were randomly divided into control group and experimental group. The control group (n= 25) received a regular diet for 8 weeks, while the experimental group (n= 25) was fed a 1% cholesterol diet for 8 weeks. Total serum cholesterol, weight, mean arterial pressure (MAP), the change of intracavernous pressure (ICP) before and after1.5mg/kg intracavernous papaverine hydrochloride injection were detected at the start of the experiment and after feeding a diet for 8 weeks. After these rabbits were fed for 8 weeks, the changes of arterial blood pressure and ICP by intracavern-ous several doses (0.375mg/kg,0.75mg/kg,1.5mg/kg) fasudil injection were detected.Results:The weight and total serum cholesterol were not different between control group and experimental group at the start of the experiment. The weight and total serum cholesterol were significantly improved (2.454±0.214Kg Vs 1.922±0.130 Kg,22.191±3.142mmol/L Vs 3.166±0.093mmol/L) in experimental group after feeding a 1% cholesterol diet for 8 weeks (P=0.000). The weight was significantly improved (2.109±0.145Kg Vs 1.914±0.206Kg) in control group after feeding a regular diet for 8 weeks(P=0.000). The total serum cholesterol was not different in control group between at the start of the experiment and after feeding a regular diet for 8 weeks. The weight and total serum cholesterol were significantly improved (2.454±0.214Kg Vs 2.109±0.145 Kg, 22.191±3.142mmol/L mmol/L Vs 3.238±0.128mmol/L) in the experimental group after feeding a diet for 8weeks than the control group (P=0.000). After intracavernous 1.5mg/Kg papaverine hydrochloride injection, the change of experimental rabbits ICP was significant-ly reduced (8.339±0.829mmHg Vs 19.354±2.125mmHg) after feeding a 1% cholesterol diet for 8 weeks (P=0.000), the change of control rabbits ICP was not different between at the start of the experiment and after feeding a regular diet for 8 weeks, the change of exper-imental rabbits ICP was significantly reduced (8.339±0.829mmHg Vs 18.997±2.232 mm Hg) than control rabbits ICP after feeding a diet for 8 weeks (P=0.000). The improvement of experimental rabbits ICP was 4.912±0.574 mmHg,8.400±1.063 mmHg,14.848±1.350 mmHg after intracavernous 0.375mg/Kg,0.75mg/Kg,1.5mg/Kg fasudil injection. The improvement of control rabbits ICP was 3.336±0.889mmHg,5.465±0.609mmHg, 11.952±1.290 mmHg after intracavernous 0.375mg/Kg,0.75mg/Kg,1.5 mg/Kg fasudil injection. The improvement of ICP after intracavernous 0.375 mg/Kg,0.75 mg/Kg, 1.5mg/Kg fasudil injection was significantly increased in the experimental group than the control group.Conclusions:The rho-kinase inhibitor fasudil can improve erectile function on hypercholesterolemic rabbit. It was maybe related with the overactivity of Rho-kinase induced by hyperlipidemia PartⅡThe change of contractility and relaxation on the corpus cavernosum of hyperlipidemia rabbit in vitroObjective:To investigate the mechanisms of erectile dysfunction induced by hyperlipidemia through researching the change of contractility and relaxation on the corpus cavernosum of hypercholesterolemic rabbit in vitro.Methods:Male New Zealand white rabbits were randomly divided into control group and experimental group. The control group (n= 25) received a regular diet for 8 weeks, while the experimental group (n= 25) was fed a 1% cholesterol diet for 8 weeks.We conducted isometric tension studies with phenylephrine, endothelium-dependent vasodilators (acetylcholine), endothelium-independent vasodilators (sodium nitroprusside) and rho kinase inhibitor (Fasudil) on isolated strips of corpus cavernosum.Results:The weight and total serum cholesterol were not different between control group and experimental group at the start of the experiment. The weight and total serum cholesterol were significantly improved (2.454±0.214Kg Vs 1.922±0.130 Kg,22.191±3.142mmol/L Vs 3.166±0.093mmol/L) in experimental group after feeding a 1% cholesterol diet for 8 weeks (P=0.000). The weight was significantly improved (2.109±0.145Kg Vs 1.914±0.206Kg) in control group after feeding a regular diet for 8 weeks (P=0.000). The total serum cholesterol was not different in control group between at the start of the experiment and after feeding a regular diet for 8 weeks. The weight and total serum cholesterol were significantly improved (2.454±0.214Kg Vs 2.109±0.145 Kg, 22.191±3.142mmol/L mmol/L Vs 3.238±0.128mmol/L) in the experimental group than the control group after feeding a diet for 8 weeks (P=0.000). The contractility responses to phenylephrine in experimental group in doses (0.5,1,5,10,50,100μmol/l) were 4.36±1.20%,8.65±1.97%,13.17±3.10%,17.06±4.63%,24.49±5.01% and 32.33±6.24%. The contractility responses to phenylephrine in control group were 1.12±0.29%,2.51±0.56%,4.40±0.77%,6.14±1.28%,7.61±3.40% and 6.40±5.13%. The contractility responses to phenylephrine were significantly improved (P=0.000) in the experimental group in these doses, compared with the control group. The relaxation responses to acetylcholine in experimental group in doses (1,10 and 100μmol/l) were 34.95±3.83%, 45.58±6.07% and 58.46±4.01%. The relaxation responses to acetylcholine in control group were 47.44±3.94%,65.85±4.77% and 75.36±4.18%. There were significantly reduced (P=0.000) in the experimental group in these doses, compared with the control group. No differences were found among the two groups in the relaxation responses to sodium nitroprusside. The relaxation responses to fasudil in experimental group in doses (0.5,1,5 and 10μmol/l) were 1.83%±0.49%,5.60%±1.71%,10.20%±3.40% and 18.95%±4.16%. The relaxation responses to fasudil in control group were 4.31%±1.33%, 9.98%±1.33%,16.10%±2.23% and 25.67%±2.68%. There were significantly reduced (P=0.000) in the experimental group in these doses, compared with the control group.Conclusions:It is demonstrated that the improvement of cavernous smooth muscle contractility which may be related with overactivity of Rho-kinase and the impairment of cavernous smooth muscle relaxation in response to endothelium-mediated stimuli were the mechanisms of erectile dysfunction induced by hyperlipidemia. Part III The Expression of RhoA/Rho-kinase on the corpus cavernosum smooth muscle of hyperlipidemic RabbitObjective:To investigate the expression and significance of RhoA/Rho-kinase in penile corporal cavernosum smooth muscles of hyperlipidemic rabbits.Methods:Male New Zealand rabbits were randomly divided into control group and experimental group. The control group (n= 25) received a regular diet for 8 weeks, while the experimental group (n= 25) was fed a 1% cholesterol diet. Total serum cholesterol, weight, mean arterial pressure (MAP), the change of intracavernous pressure (ICP) before and after 1.5mg/kg intracavernous papaverine hydrochloride injection were detected at the start of the experiment and after feeding a diet for 8 weeks. Western blot and Real time quantitative RT-PCR were used to detect the protein and gene expression levels of RhoA and Rho-kinase respectively.Results:The weight and total serum cholesterol were not different between control group and experimental group at the start of the experiment. The weight and total serum cholesterol were significantly improved (2.454±0.214Kg Vs 1.922±0.130 Kg,22.191±3.142mmol/L Vs 3.166±0.093mmol/L) in experimental group after feeding a 1% cholesterol diet for 8 weeks (P=0.000). The weight was significantly improved (2.109±0.145Kg Vs 1.914±0.206Kg) in control group after feeding a regular diet for 8 weeks(P=0.000). The total serum cholesterol was not different in control group between at the start of the experiment and after feeding a regular diet for 8 weeks. The weight and total serum cholesterol were significantly improved (2.454±0.214Kg Vs 2.109±0.145 Kg, 22.191±3.142mmol/L mmol/L Vs 3.238±0.128mmol/L) between the experimental group and the control group after feeding a diet for 8 weeks (P=0.000). After intracavernous 1.5mg/Kg papaverine hydrochloride injection, the change of experimental rabbits ICP was significantly reduced (8.339±0.829mmHg Vs 19.354±2.125mmHg) after feeding a 1% cholesterol diet for 8 weeks (P=0.000), the change of control rabbits ICP was not different between at the start of the experiment and after feeding a regular diet for 8 weeks, the change of experimental rabbits ICP was significantly reduced (8.339±0.829mmHg Vs 18.997±2.232 mm Hg) than control rabbits ICP after feeding a diet for 8 weeks (P=0.000). The RhoA mRNA levels were 0.95 fold higher in the experimental group compared with that in the control group. The ROCK1 mRNA levels were 1.09 fold higher in the experimental group compared with that in the control group. The total RhoA and ROCK1 protein levels were not different between the control group and the experimental group. The membrane RhoA and ROCK2 protein levels were higher in the experimental group than that in the control group. The cytosolic RhoA protein level was lower in the experimental group than that in the control group.Conclusions:It is demonstrated that elevated active RhoA and ROCK2 may contribute to hyperlipidemia-related erectile dysfunction.