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THE MECHANISMS FOR DIMINISHED ERECTILE FUNCTION IN AN ANIMAL MODEL OF BINGE COCAINE USE
P1
SEXUAL FUNCTION AND DYSFUNCTION: BASIC RESEARCH Wednesday, 5 April, 12.45-14.15, Room Ternes / Level 1 9 THE MECHANISMS FOR DIMINISHED ERECTILE FUNCTION IN AN ANIMAL MODEL OF BINGE COCAINE USE Kendirci M.1, Pradhan Hellstrom W.J.G.1
L.2, Trost
L.1,
Chandra
S.2, Agrawal
K.C.2,
10 EFFECTS OF HYPERTENSION AND CAPTOPRIL - TREATMENT ON SEXUAL FUNCTIONS IN FEMALE RATS Giraldi A.1, Nedergaard P.2, Andersson K.E.2, Kristensen E.1, Hedlund P.2 1
1
Tulane University Health Sciences Center, Urology, New Orleans, United States, Tulane University Health Sciences Center, Pharmacology, New Orleans, United States 2
INTRODUCTION & OBJECTIVES: To investigate the mechanisms for impaired erectile function due to binge cocaine administration in a rat model. MATERIAL & METHODS: Adult male Sprague-Dawley rats were divided into 2 groups: Group-1; control rats receiving vehicle (saline) and group-2; rats receiving binge cocaine injections (30 mg/kg tid i.p. For 3 consecutive days per week for 3 weeks). After three-weeks of binge cocaine or saline injections, both groups underwent an in vivo, neurogenic-mediated erectile response protocol to assess intracavernosal pressure-to-mean arterial pressure ratio (ICP/MAP) and total ICP values. Plasma levels of endothelin-1 (ET-1) were assessed using ELISA. Using western blot analysis, penile endothelin-A and –B receptors (ETAR and ETBR), and eNOS protein expression were monitored. Myeloperoxidase (MPO) activity was quantitated using the calorimetric TMB method. RESULTS: Plasma ET-1 levels were significantly increased in the 3-week binge cocaine treatment group compared to values in control animals. ETAR was predominantly expressed in the smooth muscle; whereas ETBR was in the endothelial cells. In the penis, binge cocaine administration significantly increased ETAR expression when compared to saline controls, while ETBR expression was not significantly altered. Cocaine-treated rats had significantly decreased eNOS expression and an increased activity of tissue MPO (a marker of oxidative stress) when compared to control rats. ICP/MAP and total ICP values in response to cavernosal nerve stimulation for 1 minute (2.5-7.5 volts) were significantly lower in the cocaine group compared to controls (p <0.05). CONCLUSIONS: This animal study demonstrates that binge cocaine administration significantly reduces erectile function. The possible pathophyisologic mechanisms involved include increased plasma ET-1 levels, increased penile ETAR expression, and increased penile MPO activity with decreased penile eNOS expression.
Rigshospitalet, Sexological Clinic, Copenhagen, Denmark, 2Lund University Hospital, Department of Clinical Pharmacology, Lund, Sweden INTRODUCTION & OBJECTIVES: Cardiovascular disease is a risk factor for erectile dysfunction and hypertension has been shown to affect sexual behaviours in male rats. The present study aimed to investigate the effect of hypertension and treatment with captopril on the function of the rat vaginal smooth muscle and to examine sexual motivation in spontaneously hypertensive rats (SHR) with or without captopril treatment. MATERIAL & METHODS: Ovariectomized female Wistar Kyoto rats (WKY; n=6), SHR (n=7) and SHR-captopril treated (SHR-Capt, n=7, 100 mg/kg/day)in oestrus were used. Female rat proceptive behaviours and stretches were recorded. Return latencies and exits were quantified. Isometric tension was registered in smooth muscle preparations from the distal vagina during nerve-induced or pharmacological activation/ modulation of contractile and relaxant responses. Statistical comparisons were made using one-way ANOVA, Mann-Withney and paired sample t-test.
RESULTS: Blood pressure (BP) was increased in SHR (171±7mmHg, p<0.05) compared to WKY (127±4mmHg). Normotension was achieved in SHR-Capt (119±8mmHg) after 8 weeks of treatment. Proceptive behaviours were decreased in SHR-Capt (p<0.05). Number of stretches were increased (p<0.05) in SHR (4.1±0.7) and SHR-Capt (5.7±2.1) at 12 weeks. Exits following mounts and intromissions were increased (p<0.05) in SHR (319% and 151%) and SHR-Capt (394% and 171%) compared to WKY. Fewer ejaculations were accepted by SHR-Capt (1.3±0.3, p<0.05) than by SHR (2.6±0.2). Norepinephrine (10-9–10-4M) produced concentration-dependent contractions with no difference within all three groups, but with a significantly reduced Emax in SHR-Capt (156±4% of 124mM K+, n=4) compared to WKY (229±24%, n=4, p<0.05). In oxytocin (10-6M) precontracted tissue electrical field stimulation (EFS) induced frequency-dependent nerve mediated relaxation in all groups with no significant differences within the groups. Sildenafil (3x10-4M) enhanced the EFS induced significantly (p<0.05) in the SHR (all frequencies) and SHR-Capt (0.5 – 8 Hz), but had no significant effect on WKY. SIN-1 (10-8–10-4M) induced concentration-dependent relaxation of oxytocin precontracted tissue in all three groups with no significant differences in Emax, but with a significant right-shift of the concentration-response curve in WKY (n=4) compared to SHR (n=7) and SHR-Capt (n=6) (p <0.05). CONCLUSIONS: Sexual motivation in female rats is decreased by hypertension and captopril-treatment. Increase in stretches in SHR and SHR-Capt suggest decreased sexual motivation. Higher rates of exits in SHR and SHR-Capt suggest that hypertension inhibits paced mating behaviour. SHR-Capt accepted fewer ejaculations than WKY indicating lower sexual motivation. Hypertension and treatment with captopril have affects the function of vaginal smooth muscle. This may have implication for further studies on the effect of hypertension and it’s treatment on the female sexual arousal response.
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12
ANDROGENS REGULATE SMOOTH MUSCLE CONTRACTILITY OF HUMAN CAVERNOUS ARTERIES AND CORPUS CAVERNOSUM BY NON-GENOMIC MECHANISMS
PLASMA CONCENTRATION OF ASYMMETRIC DIMETHYLARGININE (ADMA) IN RELATION TO ERECTILE DYSFUNCTION IN PATIENTS WITH AND WITHOUT CORONARY ARTERY DISEASE
Waldkirch E.1, Ückert S.1, Schultheiss D.1, Sohn M.2, Jonas U.1, Stief C.G.3, Andersson K.E.4, Hedlund P.4
Rokkas K., Vlachopoulos C., Ioakeimidis N., Vassiliadi C., Aznaouridis K., Toutouza M., Askitis A., Stefanadis C.
Hannover Medical School, Urology, Hanover, Germany, 2St. Markus Academic Hospital, Urology, Frankfurt, Germany, 3Grosshadern Academic Hospital, Urology, Munich, Germany, 4 Lund University Hospital, Clinical and Experimental Pharmacology, Lund, Sweden
Hippokration Hospital, 1st Department of Cardiology, Athens, Greece
1
INTRODUCTION & OBJECTIVES: Treatment with either testosterone (T) or dihydrotestosterone (DHT) restores erectile function in castrated animals (Traish AM et al. Endocrinology 1999; 140: 1861-1868). Studies have indicated that the NO/cGMP erectile pathway is androgen-dependent (Morelli A et al. Endocrinology 2004; 145(5): 2253-63). In castrated rats a reduced penile arterial inflow has been observed and a direct correlation between free testosterone levels and penile arterial inflow has been shown by means of dynamic colour duplex ultrasound in men with erectile dysfunction (ED; Aversa A et al. Clinical Endocrinology 2000; 53: 517-522). Besides the influence of genomic effects of androgens on smooth muscle physiology, testosterone has been shown to relax coronary arteries by nongenomic mechanisms (Jones RD et al. Clinical Science 2004; 107: 149-158). Therefore we evaluated the regulatory effects of T and DHT on the smooth muscle tone of central human cavernous arteries (HCA) and corpus cavernosum (HCC). MATERIAL & METHODS: Functional experiments were performed using circular segments of HCA and strip preparations of HCC. Relaxant effects induced by the cumulative addition of T and DHT (0.01, 0.1, 1, and 10 mikroM) were studied in preparations of HCA and HCC challenged by 1 mikroM norepinephrine (NE).
INTRODUCTION & OBJECTIVES: Erectile dysfunction (ED) shares common risk factors with coronary artery disease (CAD) and endothelial dysfunction appears to be a link between these conditions. The endogenous competitive inhibitor of the nitric oxide synthetase (NOS), asymmetric dimethylarginine (ADMA), has been recently identified as a risk factor for future cardiovascular events. The purpose of the present study was to assess whether increased plasma levels of ADMA are associated with ED in patients with and without CAD. MATERIAL & METHODS: A total of 120 men were studied: 39men (aged 58±11yrs) had ED without clinical evidence and exercise stress test evidence for CAD (ED w/o CAD), 31men (aged 61±8yrs) had ED and angiographically documented CAD (CAD plus ED), 19men (aged 59±11 yrs) had angiographically documented CAD and normal erectile function (CAD w/o ED) and 31 men (aged 57±6 yrs) were controls with normal erectile function and no CAD. Diagnosis of ED was based on the International Index of Erectile Function Score (IIEF-5). RESULTS: There was a progressive increase in plasma ADMA levels from control group to ED w/o CAD and CAD w/o ED group, and to ED plus CAD group, (p<0.001, figure 1). In univariate analysis, a positive correlation between ADMA levels and IIEF score was observed (figure 2). Moreover, in a multivariate linear regression model, ADMA levels were significantly (p=0.03) associated with severity of ED, after controlling for age, body-mass index, smoking habits, mean pressure, fasting glucose, LDL, HDL and hs CRP (adjusted R2 of model=0.24).
RESULTS: Cumulative addition of T and DHT dose-dependently reversed the NE-induced tension of the isolated vascular segments (HCA) and HCC strips. At a concentration of 1 mikroM T and DHT reduced the tension plateau to 87.96 ± 1.98%, and 90.53 ± 6.45%, respectively, of the maximum NE induced contraction (n = 5 for each compound). At 10 μM, tension was further attenuated to 79.80 ± 4.43% (T), and 83.93 ± 10.94% (DHT). There was no significant difference concerning the influence of T and DHT on the smooth muscle tone of HCA and HCC. CONCLUSIONS: Our findings are in support of an additional nongenomic regulation of smooth muscle contractility by androgens in human penile erectile tissue. To date, there is only limited evidence that the smooth muscle function of human vascular and cavernous tissue is androgen-dependent and the nongenomic mechanisms are not fully understood. Moreover, there is evidence that hypogonadism might be a component of metabolic syndrome, which itself significantly increases the risk of diabetes mellitus, cardiovascular diseases and ED. Therefore further studies are needed in order to elucidate genomic and non-genomic mechanisms in the regulation of the smooth muscle tone of human penile erectile tissue.
CONCLUSIONS: Elevated plasma levels of ADMA, the endogenous competitive inhibitor of the nitric oxide synthetase (NOS), are related to the presence and severity of ED. This finding may provide additional information to the pathophysiology of ED in men with and without CAD.
Eur Urol Suppl 2006;5(2):25
SEXUAL FUNCTION AND DYSFUNCTION: BASIC RESEARCH Wednesday, 5 April, 12.45-14.15, Room Ternes / Level 1 9 THE MECHANISMS FOR DIMINISHED ERECTILE FUNCTION IN AN ANIMAL MODEL OF BINGE COCAINE USE Kendirci M.1, Pradhan Hellstrom W.J.G.1
L.2, Trost
L.1,
Chandra
S.2, Agrawal
K.C.2,
10 EFFECTS OF HYPERTENSION AND CAPTOPRIL - TREATMENT ON SEXUAL FUNCTIONS IN FEMALE RATS Giraldi A.1, Nedergaard P.2, Andersson K.E.2, Kristensen E.1, Hedlund P.2 1
1
Tulane University Health Sciences Center, Urology, New Orleans, United States, Tulane University Health Sciences Center, Pharmacology, New Orleans, United States 2
INTRODUCTION & OBJECTIVES: To investigate the mechanisms for impaired erectile function due to binge cocaine administration in a rat model. MATERIAL & METHODS: Adult male Sprague-Dawley rats were divided into 2 groups: Group-1; control rats receiving vehicle (saline) and group-2; rats receiving binge cocaine injections (30 mg/kg tid i.p. For 3 consecutive days per week for 3 weeks). After three-weeks of binge cocaine or saline injections, both groups underwent an in vivo, neurogenic-mediated erectile response protocol to assess intracavernosal pressure-to-mean arterial pressure ratio (ICP/MAP) and total ICP values. Plasma levels of endothelin-1 (ET-1) were assessed using ELISA. Using western blot analysis, penile endothelin-A and –B receptors (ETAR and ETBR), and eNOS protein expression were monitored. Myeloperoxidase (MPO) activity was quantitated using the calorimetric TMB method. RESULTS: Plasma ET-1 levels were significantly increased in the 3-week binge cocaine treatment group compared to values in control animals. ETAR was predominantly expressed in the smooth muscle; whereas ETBR was in the endothelial cells. In the penis, binge cocaine administration significantly increased ETAR expression when compared to saline controls, while ETBR expression was not significantly altered. Cocaine-treated rats had significantly decreased eNOS expression and an increased activity of tissue MPO (a marker of oxidative stress) when compared to control rats. ICP/MAP and total ICP values in response to cavernosal nerve stimulation for 1 minute (2.5-7.5 volts) were significantly lower in the cocaine group compared to controls (p <0.05). CONCLUSIONS: This animal study demonstrates that binge cocaine administration significantly reduces erectile function. The possible pathophyisologic mechanisms involved include increased plasma ET-1 levels, increased penile ETAR expression, and increased penile MPO activity with decreased penile eNOS expression.
Rigshospitalet, Sexological Clinic, Copenhagen, Denmark, 2Lund University Hospital, Department of Clinical Pharmacology, Lund, Sweden INTRODUCTION & OBJECTIVES: Cardiovascular disease is a risk factor for erectile dysfunction and hypertension has been shown to affect sexual behaviours in male rats. The present study aimed to investigate the effect of hypertension and treatment with captopril on the function of the rat vaginal smooth muscle and to examine sexual motivation in spontaneously hypertensive rats (SHR) with or without captopril treatment. MATERIAL & METHODS: Ovariectomized female Wistar Kyoto rats (WKY; n=6), SHR (n=7) and SHR-captopril treated (SHR-Capt, n=7, 100 mg/kg/day)in oestrus were used. Female rat proceptive behaviours and stretches were recorded. Return latencies and exits were quantified. Isometric tension was registered in smooth muscle preparations from the distal vagina during nerve-induced or pharmacological activation/ modulation of contractile and relaxant responses. Statistical comparisons were made using one-way ANOVA, Mann-Withney and paired sample t-test.
RESULTS: Blood pressure (BP) was increased in SHR (171±7mmHg, p<0.05) compared to WKY (127±4mmHg). Normotension was achieved in SHR-Capt (119±8mmHg) after 8 weeks of treatment. Proceptive behaviours were decreased in SHR-Capt (p<0.05). Number of stretches were increased (p<0.05) in SHR (4.1±0.7) and SHR-Capt (5.7±2.1) at 12 weeks. Exits following mounts and intromissions were increased (p<0.05) in SHR (319% and 151%) and SHR-Capt (394% and 171%) compared to WKY. Fewer ejaculations were accepted by SHR-Capt (1.3±0.3, p<0.05) than by SHR (2.6±0.2). Norepinephrine (10-9–10-4M) produced concentration-dependent contractions with no difference within all three groups, but with a significantly reduced Emax in SHR-Capt (156±4% of 124mM K+, n=4) compared to WKY (229±24%, n=4, p<0.05). In oxytocin (10-6M) precontracted tissue electrical field stimulation (EFS) induced frequency-dependent nerve mediated relaxation in all groups with no significant differences within the groups. Sildenafil (3x10-4M) enhanced the EFS induced significantly (p<0.05) in the SHR (all frequencies) and SHR-Capt (0.5 – 8 Hz), but had no significant effect on WKY. SIN-1 (10-8–10-4M) induced concentration-dependent relaxation of oxytocin precontracted tissue in all three groups with no significant differences in Emax, but with a significant right-shift of the concentration-response curve in WKY (n=4) compared to SHR (n=7) and SHR-Capt (n=6) (p <0.05). CONCLUSIONS: Sexual motivation in female rats is decreased by hypertension and captopril-treatment. Increase in stretches in SHR and SHR-Capt suggest decreased sexual motivation. Higher rates of exits in SHR and SHR-Capt suggest that hypertension inhibits paced mating behaviour. SHR-Capt accepted fewer ejaculations than WKY indicating lower sexual motivation. Hypertension and treatment with captopril have affects the function of vaginal smooth muscle. This may have implication for further studies on the effect of hypertension and it’s treatment on the female sexual arousal response.
11
12
ANDROGENS REGULATE SMOOTH MUSCLE CONTRACTILITY OF HUMAN CAVERNOUS ARTERIES AND CORPUS CAVERNOSUM BY NON-GENOMIC MECHANISMS
PLASMA CONCENTRATION OF ASYMMETRIC DIMETHYLARGININE (ADMA) IN RELATION TO ERECTILE DYSFUNCTION IN PATIENTS WITH AND WITHOUT CORONARY ARTERY DISEASE
Waldkirch E.1, Ückert S.1, Schultheiss D.1, Sohn M.2, Jonas U.1, Stief C.G.3, Andersson K.E.4, Hedlund P.4
Rokkas K., Vlachopoulos C., Ioakeimidis N., Vassiliadi C., Aznaouridis K., Toutouza M., Askitis A., Stefanadis C.
Hannover Medical School, Urology, Hanover, Germany, 2St. Markus Academic Hospital, Urology, Frankfurt, Germany, 3Grosshadern Academic Hospital, Urology, Munich, Germany, 4 Lund University Hospital, Clinical and Experimental Pharmacology, Lund, Sweden
Hippokration Hospital, 1st Department of Cardiology, Athens, Greece
1
INTRODUCTION & OBJECTIVES: Treatment with either testosterone (T) or dihydrotestosterone (DHT) restores erectile function in castrated animals (Traish AM et al. Endocrinology 1999; 140: 1861-1868). Studies have indicated that the NO/cGMP erectile pathway is androgen-dependent (Morelli A et al. Endocrinology 2004; 145(5): 2253-63). In castrated rats a reduced penile arterial inflow has been observed and a direct correlation between free testosterone levels and penile arterial inflow has been shown by means of dynamic colour duplex ultrasound in men with erectile dysfunction (ED; Aversa A et al. Clinical Endocrinology 2000; 53: 517-522). Besides the influence of genomic effects of androgens on smooth muscle physiology, testosterone has been shown to relax coronary arteries by nongenomic mechanisms (Jones RD et al. Clinical Science 2004; 107: 149-158). Therefore we evaluated the regulatory effects of T and DHT on the smooth muscle tone of central human cavernous arteries (HCA) and corpus cavernosum (HCC). MATERIAL & METHODS: Functional experiments were performed using circular segments of HCA and strip preparations of HCC. Relaxant effects induced by the cumulative addition of T and DHT (0.01, 0.1, 1, and 10 mikroM) were studied in preparations of HCA and HCC challenged by 1 mikroM norepinephrine (NE).
INTRODUCTION & OBJECTIVES: Erectile dysfunction (ED) shares common risk factors with coronary artery disease (CAD) and endothelial dysfunction appears to be a link between these conditions. The endogenous competitive inhibitor of the nitric oxide synthetase (NOS), asymmetric dimethylarginine (ADMA), has been recently identified as a risk factor for future cardiovascular events. The purpose of the present study was to assess whether increased plasma levels of ADMA are associated with ED in patients with and without CAD. MATERIAL & METHODS: A total of 120 men were studied: 39men (aged 58±11yrs) had ED without clinical evidence and exercise stress test evidence for CAD (ED w/o CAD), 31men (aged 61±8yrs) had ED and angiographically documented CAD (CAD plus ED), 19men (aged 59±11 yrs) had angiographically documented CAD and normal erectile function (CAD w/o ED) and 31 men (aged 57±6 yrs) were controls with normal erectile function and no CAD. Diagnosis of ED was based on the International Index of Erectile Function Score (IIEF-5). RESULTS: There was a progressive increase in plasma ADMA levels from control group to ED w/o CAD and CAD w/o ED group, and to ED plus CAD group, (p<0.001, figure 1). In univariate analysis, a positive correlation between ADMA levels and IIEF score was observed (figure 2). Moreover, in a multivariate linear regression model, ADMA levels were significantly (p=0.03) associated with severity of ED, after controlling for age, body-mass index, smoking habits, mean pressure, fasting glucose, LDL, HDL and hs CRP (adjusted R2 of model=0.24).
RESULTS: Cumulative addition of T and DHT dose-dependently reversed the NE-induced tension of the isolated vascular segments (HCA) and HCC strips. At a concentration of 1 mikroM T and DHT reduced the tension plateau to 87.96 ± 1.98%, and 90.53 ± 6.45%, respectively, of the maximum NE induced contraction (n = 5 for each compound). At 10 μM, tension was further attenuated to 79.80 ± 4.43% (T), and 83.93 ± 10.94% (DHT). There was no significant difference concerning the influence of T and DHT on the smooth muscle tone of HCA and HCC. CONCLUSIONS: Our findings are in support of an additional nongenomic regulation of smooth muscle contractility by androgens in human penile erectile tissue. To date, there is only limited evidence that the smooth muscle function of human vascular and cavernous tissue is androgen-dependent and the nongenomic mechanisms are not fully understood. Moreover, there is evidence that hypogonadism might be a component of metabolic syndrome, which itself significantly increases the risk of diabetes mellitus, cardiovascular diseases and ED. Therefore further studies are needed in order to elucidate genomic and non-genomic mechanisms in the regulation of the smooth muscle tone of human penile erectile tissue.
CONCLUSIONS: Elevated plasma levels of ADMA, the endogenous competitive inhibitor of the nitric oxide synthetase (NOS), are related to the presence and severity of ED. This finding may provide additional information to the pathophysiology of ED in men with and without CAD.
Eur Urol Suppl 2006;5(2):25