title: CB1 cannabinoid receptor antagonist attenuates left ventricular hypertrophy and Akt-mediated cardiac fibrosis in experimental uremia.
abstract: Cannabinoid receptor type 1 (CB1R) plays an important role in the development of myocardial hypertrophy and fibrosis-2 pathological features of uremic cardiomyopathy. However, it remains unknown whether CB1R is involved in the pathogenesis of uremic cardiomyopathy. Here, we aimed to elucidate the role of CB1R in the development of uremic cardiomyopathy via modulation of Akt signalling. The heart size and myocardial fibrosis were evaluated by echocardiography and immunohistochemical staining, respectively, in 5/6 nephrectomy chronic kidney disease (CKD) mice treated with a CB1R antagonist. CB1R and fibrosis marker expression levels were determined by immunoblotting in H9c2 cells exposed to the uremic toxin indoxyl sulfate (IS), with an organic anion transporter 1 inhibitor or a CB1R antagonist or agonist. Akt phosphorylation was also assessed to examine the signaling pathways downstream of CB1R activation induced by IS in H9c2 cells. CKD mice exhibited marked left ventricular hypertrophy and myocardial fibrosis, which were reversed by treatment with the CB1R antagonist. CB1R, collagen I, transforming growth factor (TGF)-β, and α-smooth muscle actin (SMA) expression showed time- and dose-dependent upregulation in H9c2 cells treated with IS. The inhibition of CB1R by either CB1R antagonist or small interfering RNA-mediated knockdown attenuated the expression of collagen I, TGF-β, and α-SMA in IS-treated H9c2 cells, while Akt phosphorylation was enhanced by CB1R agonist and abrogated by CB1R antagonist in these cells. In summary, we conclude that CB1R blockade attenuates LVH and Akt-mediated cardiac fibrosis in a CKD mouse model. Uremic toxin IS stimulates the expression of CB1R and fibrotic markers and CB1R inhibition exerts anti-fibrotic effects via modulation of Akt signaling in H9c2 myofibroblasts. Therefore, the development of drugs targeting CB1R may have therapeutic potential in the treatment of uremic cardiomyopathy.
authors.affiliation: Division of Cardiovascular Surgery, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Chih-Yuan
authors.initials: CY
authors.lastname: Lin
authors.affiliation: Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Yu-Juei
authors.initials: YJ
authors.lastname: Hsu
authors.affiliation: Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Shih-Che
authors.initials: SC
authors.lastname: Hsu
authors.affiliation: Department and Graduate Institute of Biology and Anatomy, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Ying
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Pathology and Laboratory Medicine, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan.
authors.forename: Herng-Sheng
authors.initials: HS
authors.lastname: Lee
authors.affiliation: Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Shih-Hua
authors.initials: SH
authors.lastname: Lin
authors.affiliation: Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Shih-Ming
authors.initials: SM
authors.lastname: Huang
authors.affiliation: Division of Cardiovascular Surgery, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Chien-Sung
authors.initials: CS
authors.lastname: Tsai
authors.affiliation: Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan. Electronic address: ccshih@vghtpe.gov.tw.
authors.forename: Chun-Che
authors.initials: CC
authors.lastname: Shih
mesh_terms: D000818:Animals; D063387:Cannabinoid Receptor Antagonists / Q000494:pharmacology* / Q000627:therapeutic use; D002460:Cell Line; D003094:Collagen / Q000378:metabolism; D004353:Drug Evaluation, Preclinical; D005355:Fibrosis; D017379:Hypertrophy, Left Ventricular / Q000188:drug therapy* / Q000209:etiology; D008297:Male; D008810:Mice, Inbred C57BL; D011339:Probenecid / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D043884:Receptor, Cannabinoid, CB1 / Q000037:antagonists & inhibitors*; D051436:Renal Insufficiency, Chronic / Q000188:drug therapy / Q000378:metabolism; D014511:Uremia / Q000150:complications / Q000188:drug therapy*
chemical_list: D063387:Cannabinoid Receptor Antagonists; D043884:Receptor, Cannabinoid, CB1; D003094:Collagen; D051057:Proto-Oncogene Proteins c-akt; D011339:Probenecid
keywords: Akt; Chronic kidney disease; Fibrosis; Left ventricular hypertrophy; Uremic cardiomyopathy