Hypercholesterolemia is one of the most important risk factors for erectile dysfunction, mostly due to the impairment of oxidative stress and endothelial function in the penis. The cannabinoid system might regulate peripheral mechanisms of sexual function; however, its role is still poorly understood. We investigated the effects of CB2 activation on oxidative stress and fibrosis within the corpus cavernosum of hypercholesterolemic mice. Apolipoprotein-E-knockout mice were fed with a western-type diet for 11 weeks and treated with JWH-133 (selective CB2 agonist) or vehicle during the last 3 weeks. CB2 receptor expression, total collagen content, and reactive oxygen species (ROS) production within the penis were assessed. In vitro corpus cavernosum strips preparation was performed to evaluate the nitric oxide (NO) bioavailability. CB2 protein expression was shown in cavernosal endothelial and smooth muscle cells of wild type and hypercholesterolemic mice. Treatment with JWH-133 reduced ROS production and NADPH-oxidase expression in hypercholesterolemic mice penis. Furthermore, JWH-133 increased endothelial NO synthase expression in the corpus cavernosum and augmented NO bioavailability. The decrease in oxidative stress levels was accompanied with a reduction in corpus cavernosum collagen content. In summary, CB2 activation decreased histological features, which were associated with erectile dysfunction in hypercholesterolemic mice. 1. Introduction Penile erection occurs when there is a relaxation of the smooth muscle cells in cavernosal arterioles and surrounding sinuses, resulting in increased blood flow into the penis associated with a pressure-dependent veno-occlusive mechanism within the sinuses controlling the blood outflow [1, 2]. The major mechanism responsible for ED is an increase in the tone and/or contractility of the smooth muscle within the corpus cavernosum and penile arteries [3], which is mostly due to diminished production and function of nitric oxide (NO) and other vasoprotective factors, which is compounded by the exaggerated production of reactive oxygen species (ROS) and vasoconstrictors [4, 5]. Hypercholesterolemia is one of the most important risk factors for the development of ED [5]. This phenotype produces various functional and structural alterations in the vasculature, frequently leading to the development of atherosclerosis [1, 4]. These vascular changes alter tissue perfusion and can impair the ability of arteries to respond to vasodilators factors [5–7]. Chronically, this impairment may result in cavernosal fibrosis, which
References
[1]
R. C. Dean and T. F. Lue, “Physiology of penile erection and pathophysiology of erectile dysfunction,” Urologic Clinics of North America, vol. 32, no. 4, pp. 379–395, 2005.
[2]
R. A. Fraga-Silva, F. Montecucco, F. Mach, R. A. Santos, and N. Stergiopulos, “Pathophysiological role of the renin-angiotensin system on erectile dysfunction,” European Journal of Clinical Investigation, vol. 43, no. 9, pp. 978–985, 2013.
[3]
D. Shin, G. Pregenzer Jr., and J. M. Gardin, “Erectile dysfunction: a disease marker for cardiovascular disease,” Cardiology in Review, vol. 19, no. 1, pp. 5–11, 2011.
[4]
T. J. Bivalacqua, M. F. Usta, H. C. Champion, P. J. Kadowitz, and W. J. Hellstrom, “Endothelial dysfunction in erectile dysfunction: role of the endothelium in erectile physiology and disease,” Journal of Andrology, vol. 24, no. 6, pp. S17–S37, 2003.
[5]
B. Musicki, T. Liu, G. A. Lagoda et al., “Hypercholesterolemia-induced erectile dysfunction: endothelial Nitric Oxide Synthase (eNOS) uncoupling in the mouse penis by NAD(P)H oxidase,” The Journal of Sexual Medicine, vol. 7, no. 9, pp. 3023–3032, 2010.
[6]
J. H. Kim, M. L. Klyachkin, E. Svendsen, M. G. Davies, P.-O. Hagen, and C. C. Carson III, “Experimental hypercholesterolemia in rabbits induces cavernosal atherosclerosis with endothelial and smooth muscle cell dysfunction,” The Journal of Urology, vol. 151, no. 1, pp. 198–205, 1994.
[7]
D. Xie, S. I. Odronic, F. Wu, A. M. Pippen, C. F. Donatucci, and B. H. Annex, “A mouse model of hypercholesterolemia-induced erectile dysfunction,” The Journal of Sexual Medicine, vol. 4, no. 4, part 1, pp. 898–907, 2007.
[8]
A. Nehra, K. M. Azadzoi, R. B. Moreland et al., “Cavernosal expandability is an erectile tissue mechanical property which predicts trabecular histology in an animal model of vasculogenic erectile dysfunction,” The Journal of Urology, vol. 159, no. 6, pp. 2229–2236, 1998.
[9]
？. Ye？illi, ？. Yaman, and K. Anafarta, “Effect of experimental hypercholesterolemia on cavernosal structures,” Urology, vol. 57, no. 6, pp. 1184–1188, 2001.
[10]
S. C. Kim, I. K. Kim, K. K. Seo, K. J. Baek, and M. Y. Lee, “Involvement of superoxide radical in the impaired endothelium-dependent relaxation of cavernous smooth muscle in hypercholesterolemic rabbits,” Urological Research, vol. 25, no. 5, pp. 341–346, 1997.
[11]
K. M. Azadzoi and I. Saenz de Tejada, “Hypercholesterolemia impairs endothelium-dependent relaxation of rabbit corpus cavernosum smooth muscle,” The Journal of Urology, vol. 146, no. 1, pp. 238–240, 1991.
[12]
D. Behr-Roussel, J. Bernabe, S. Compagnie et al., “Distinct mechanisms implicated in atherosclerosis-induced erectile dysfunction in rabbits,” Atherosclerosis, vol. 162, no. 2, pp. 355–362, 2002.
[13]
S. C. Kim, K. K. Seo, H. W. Kim, and M. Y. Lee, “The effects if isolated lipoproteins and triglyceride, combined oxidized low density lipoprotein (LDL) plus triglyceride, and combined oxidized LDL plus high density lipoprotein on the contractile and relaxation response of rabbit cavernous smooth muscle,” International Journal of Andrology, vol. 23, supplement 2, pp. 26–29, 2000.
[14]
B. Musicki, T. Liu, T. Strong et al., “Low-fat diet and exercise preserve eNOS regulation and endothelial function in the penis of early atherosclerotic pigs: a molecular analysis,” The Journal of Sexual Medicine, vol. 5, no. 3, pp. 552–561, 2008.
[15]
T. W. Klein, C. Newton, K. Larsen et al., “The cannabinoid system and immune modulation,” Journal of Leukocyte Biology, vol. 74, no. 4, pp. 486–496, 2003.
[16]
T. W. Klein, “Cannabinoid-based drugs as anti-inflammatory therapeutics,” Nature Reviews Immunology, vol. 5, no. 5, pp. 400–411, 2005.
[17]
F. Mach, F. Montecucco, and S. Steffens, “Cannabinoid receptors in acute and chronic complications of atherosclerosis,” British Journal of Pharmacology, vol. 153, no. 2, pp. 290–298, 2008.
[18]
S. Steffens, N. R. Veillard, C. Arnaud et al., “Low dose oral cannabinoid therapy reduces progression of atherosclerosis in mice,” Nature, vol. 434, no. 7034, pp. 782–786, 2005.
[19]
S. Engeli, “Central and peripheral cannabinoid receptors as therapeutic targets in the control of food intake and body weight,” Handbook of Experimental Pharmacology, vol. 209, pp. 357–381, 2012.
[20]
C. Lagneux and D. Lamontagne, “Involvement of cannabinoids in the cardioprotection induced by lipopolysaccharide,” British Journal of Pharmacology, vol. 132, no. 4, pp. 793–796, 2001.
[21]
C. Di Filippo, F. Rossi, S. Rossi, and M. D'Amico, “Cannabinoid CB2 receptor activation reduces mouse myocardial ischemia-reperfusion injury: involvement of cytokine/chemokines and PMN,” Journal of Leukocyte Biology, vol. 75, no. 3, pp. 453–459, 2004.
[22]
R. T. Jones, “Cardiovascular system effects of marijuana,” Journal of Clinical Pharmacology, vol. 42, 11, supplement, pp. 58S–63S, 2002.
[23]
F. Montecucco, S. Lenglet, V. Braunersreuther et al., “CB2 cannabinoid receptor activation is cardioprotective in a mouse model of ischemia/reperfusion,” Journal of Molecular and Cellular Cardiology, vol. 46, no. 5, pp. 612–620, 2009.
[24]
M. Ghasemi, H. Sadeghipour, and A. R. Dehpour, “Anandamide improves the impaired nitric oxide-mediated neurogenic relaxation of the corpus cavernosum in diabetic rats: involvement of cannabinoid CB1 and vanilloid VR1 receptors,” BJU International, vol. 100, no. 6, pp. 1385–1390, 2007.
[25]
M. Ghasemi, H. Sadeghipour, A. R. Mani et al., “Effect of anandamide on nonadrenergic noncholinergic-mediated relaxation of rat corpus cavernosum,” European Journal of Pharmacology, vol. 544, no. 1–3, pp. 138–145, 2006.
[26]
I. M. Vural, G. S. Ozturk, and Y. Sarioglu, “Functional characterization of nonadrenergic noncholinergic neurotransmitter release via endocannabinoids: an in vitro study in rabbit corpus cavernosum,” The Journal of Sexual Medicine, vol. 6, no. 3, pp. 717–729, 2009.
[27]
C. Gratzke, G. J. Christ, C. G. Stief, K.-E. Andersson, and P. Hedlund, “Localization and function of cannabinoid receptors in the corpus cavernosum: basis for modulation of nitric oxide synthase nerve activity,” European Urology, vol. 57, no. 2, pp. 342–348, 2010.
[28]
F. Montecucco, V. Di Marzo, R. F. da Silva et al., “The activation of the cannabinoid receptor type 2 reduces neutrophilic protease-mediated vulnerability in atherosclerotic plaques,” European Heart Journal, vol. 33, no. 7, pp. 846–856, 2011.
[29]
R. A. Fraga-Silva, F. P. Costa-Fraga FP, S. Q. Savergnini, et al., “An oral formulation of Angiotensin-(1-7) reverses corpus cavernosum damages induced by hypercholesterolemia,” The Journal of Sexual Medicine, vol. 10, no. 10, pp. 2430–2442, 2013.
[30]
M. Baumh？kel, F. Custodis, N. Schlimmer, U. Laufs, and M. B？hm, “Improvement of endothelial function of the corpus cavernosum in apolipoprotein E knockout mice treated with irbesartan,” Journal of Pharmacology and Experimental Therapeutics, vol. 327, no. 3, pp. 692–698, 2008.
[31]
E. Chung, L. De Young, and G. B. Brock, “Investigative models in erectile dysfunction: a state-of-the-art review of current animal models,” The Journal of Sexual Medicine, vol. 8, no. 12, pp. 3291–3305, 2011.
[32]
L. Jin, G. Lagoda, R. Leite, R. C. Webb, and A. L. Burnett, “NADPH oxidase activation: a mechanism of hypertension-associated erectile dysfunction,” The Journal of Sexual Medicine, vol. 5, no. 3, pp. 544–551, 2008.
[33]
V. C. Olivon, R. A. Fraga-Silva, D. Segers, et al., “Arginase inhibition prevents the low shear stress-induced development of vulnerable atherosclerotic plaques in ApoE-/- mice,” Atherosclerosis, vol. 227, no. 2, pp. 236–243, 2013.
[34]
K. K. Seo, H.-Y. Yun, H. Kim, and S. C. Kim, “Involvement of endothelial nitric oxide synthase in the impaired endothelium-dependent relaxation of cavernous smooth muscle in hypercholesterolemic rabbit,” Journal of Andrology, vol. 20, no. 2, pp. 298–306, 1999.
[35]
N. F. Gonzalez-Cadavid, “Mechanisms of penile fibrosis,” The Journal of Sexual Medicine, vol. 6, supplement 3, pp. 353–362, 2009.
[36]
S. Basu and B. N. Dittel, “Unraveling the complexities of cannabinoid receptor 2 (CB2) immune regulation in health and disease,” Immunologic Research, vol. 51, no. 1, pp. 26–38, 2011.
[37]
B. Julien, P. Grenard, F. Teixeira-Clerc et al., “Antifibrogenic role of the cannabinoid receptor CB2 in the liver,” Gastroenterology, vol. 128, no. 3, pp. 742–755, 2005.
[38]
Y. A. Shmist, I. Goncharov, M. Eichler et al., “Delta-9-tetrahydrocannabinol protects cardiac cells from hypoxia via CB2 receptor activation and nitric oxide production,” Molecular and Cellular Biochemistry, vol. 283, no. 1-2, pp. 75–83, 2006.
[39]
M. Rajesh, P. Mukhopadhyay, G. Haskó, J. W. Huffman, K. Mackie, and P. Pacher, “CB2 cannabinoid receptor agonists attenuate TNF-α-induced human vascular smooth muscle cell proliferation and migration,” British Journal of Pharmacology, vol. 153, no. 2, pp. 347–357, 2008.
[40]
M. Rajesh, P. Mukhopadhyay, S. Bátkai et al., “CB2-receptor stimulation attenuates TNF-α-induced human endothelial cell activation, transendothelial migration of monocytes, and monocyte-endothelial adhesion,” The American Journal of Physiology—Heart and Circulatory Physiology, vol. 293, no. 4, pp. H2210–H2218, 2007.
[41]
J. Mu？oz-Luque, J. Ros, G. Fernández-Varo et al., “Regression of fibrosis after chronic stimulation of cannabinoid CB2 receptor in cirrhotic rats,” Journal of Pharmacology and Experimental Therapeutics, vol. 324, no. 2, pp. 475–483, 2008.
[42]
F. Barutta, F. Piscitelli, S. Pinach et al., “Protective role of cannabinoid receptor type 2 in a mouse model of diabetic nephropathy,” Diabetes, vol. 60, no. 9, pp. 2386–2396, 2011.
[43]
S. D. Johnson, D. L. Phelps, and L. B. Cottler, “The association of sexual dysfunction and substance use among a community epidemiological sample,” Archives of Sexual Behavior, vol. 33, no. 1, pp. 55–63, 2004.
[44]
L. Callen, E. Moreno, P. Barroso-Chinea, et al., “Cannabinoid receptors CB1 and CB2 form functional heteromers in brain,” The Journal of Biological Chemistry, vol. 287, no. 25, pp. 20851–20865, 2012.
[45]
K.-S. C. Marriott and J. W. Huffman, “Recent advances in the development of selective ligands for the cannabinoid CB2 receptor,” Current Topics in Medicinal Chemistry, vol. 8, no. 3, pp. 187–204, 2008.
[46]
F. Molica, C. M. Matter, F. Burger et al., “Cannabinoid receptor CB2 protects against balloon-induced neointima formation,” The American Journal of Physiology—Heart and Circulatory Physiology, vol. 302, no. 5, pp. H1064–H1074, 2012.
[47]
R. C. Tostes, F. S. Carneiro, A. J. Lee et al., “Cigarette smoking and erectile dysfunction: focus on NO bioavailability and ROS generation,” The Journal of Sexual Medicine, vol. 5, no. 6, pp. 1284–1295, 2008.
[48]
N. Schlimmer, M. Kratz, M. B？hm, and M. Baumh？kel, “Telmisartan, ramipril and their combination improve endothelial function in different tissues in a murine model of cholesterol-induced atherosclerosis,” British Journal of Pharmacology, vol. 163, no. 4, pp. 804–814, 2011.
[49]
M. Rajesh, S. Bátkai, M. Kechrid et al., “Cannabinoid 1 receptor promotes cardiac dysfunction, oxidative stress, inflammation, and fibrosis in diabetic cardiomyopathy,” Diabetes, vol. 61, no. 3, pp. 716–727, 2012.
[50]
F. Montecucco and V. Di Marzo, “At the heart of the matter: the endocannabinoid system in cardiovascular function and dysfunction,” Trends in Pharmacological Sciences, vol. 33, no. 6, pp. 331–340, 2012.
[51]
B. Horvth, P. Mukhopadhyay, G. Hask, and P. Pacher, “The endocannabinoid system and plant-derived cannabinoids in diabetes and diabetic complications,” The American Journal of Pathology, vol. 180, no. 2, pp. 432–442, 2012.
[52]
A. B. El-Remessy, M. Rajesh, P. Mukhopadhyay et al., “Cannabinoid 1 receptor activation contributes to vascular inflammation and cell death in a mouse model of diabetic retinopathy and a human retinal cell line,” Diabetologia, vol. 54, no. 6, pp. 1567–1578, 2011.
[53]
J. Fernández-Ruiz, M. Moreno-Martet, C. Rodríguez-Cueto et al., “Prospects for cannabinoid therapies in basal ganglia disorders,” British Journal of Pharmacology, vol. 163, no. 7, pp. 1365–1378, 2011.
[54]
C. Costa and R. Virag, “The endothelial-erectile dysfunction connection: an essential update,” The Journal of Sexual Medicine, vol. 6, no. 9, pp. 2390–2404, 2009.
[55]
A. L. Burnett, C. J. Lowenstein, D. S. Bredt, T. S. Chang, and S. H. Snyder, “Nitric oxide: a physiologic mediator of penile erection,” Science, vol. 257, no. 5068, pp. 401–403, 1992.
[56]
M. Baumh？kel, N. Schlimmer, K. Büyükaf？ar, O. Arikan, and M. B？hm, “Nebivolol, but not metoprolol, improves endothelial function of the corpus cavernosum in apolipoprotein E-knockout mice,” The Journal of Pharmacology and Experimental Therapeutics, vol. 325, no. 3, pp. 818–823, 2008.
