ABSTRACT
In the male, metabolic syndrome (MetS) is associated to an increased risk of benign prostatic hyperplasia (BPH) and lower urinary tract symptoms (LUTS). A recently established rabbit model of high fat diet (HFD)-induced MetS showed hypogonadism and the presence of prostate gland alterations, including inflammation, hypoxia and fibrosis. The present study investigated whether HFD-induced MetS might also alter bladder structure and function. Testosterone and the farnesoid X receptor (FXR) agonist INT-747, were evaluated for possible effects on HFD bladder. MetS rabbits develop bladder alterations, including fibrosis (reduced muscle/fiber ratio), hypoxia [2-fold increase as compared to regular diet (RD) group], low-grade inflammation (increased leukocyte infiltration and inflammatory markers) and RhoA/ROCK hyperactivity. Bladder strips from HFD rabbits, pre-contracted with carbachol, showed an overactive response to the selective ROCK inhibitor Y-27632. All these HFD-induced bladder alterations were partially blunted by testosterone and almost completely reverted by INT-747. Both treatments prevented some MetS features (glucose intolerance and visceral fat increase), thus suggesting that their effects on bladder could be ascribed to an improvement of the metabolic and/or hypogonadal state. However, a pathogenetic role for hypogonadism has been ruled out as GnRH analog-induced hypogonadal rabbits, fed a regular diet, did not show any detectable bladder alterations. In addition, INT-747 did not revert the MetS-induced hypogonadal state. FXR mRNA was highly expressed in rabbit bladder and positively associated with visceral fat increase. A direct effect of INT-747 on bladder smooth muscle was further suggested by inhibition of RhoA/ROCK-mediated activity by in vitro experiments on isolated cells. In conclusion, HFD-related MetS features are associated to bladder derangements, which are ameliorated by testosterone or INT-747 administration. INT-747 showed the most marked effects in counteracting MetS-related RhoA/ROCK overactivity, thus opening novel therapeutic opportunities for this drug.
Subject(s)
Androgens/therapeutic use , Chenodeoxycholic Acid/analogs & derivatives , Hypogonadism/drug therapy , Metabolic Syndrome/drug therapy , Receptors, Cytoplasmic and Nuclear/agonists , Testosterone/therapeutic use , Animals , Blood Glucose/analysis , Cell Movement , Chenodeoxycholic Acid/therapeutic use , Cholesterol/blood , Diet, High-Fat , Disease Models, Animal , Hypogonadism/chemically induced , Hypogonadism/pathology , Hypogonadism/physiopathology , Male , Metabolic Syndrome/etiology , Metabolic Syndrome/pathology , Metabolic Syndrome/physiopathology , Muscle Contraction/drug effects , Myocytes, Smooth Muscle/drug effects , Myocytes, Smooth Muscle/pathology , Myocytes, Smooth Muscle/physiology , Prostate/drug effects , Prostate/metabolism , Prostate/pathology , RNA, Messenger/metabolism , Rabbits , Receptors, Androgen/genetics , Receptors, Cytoplasmic and Nuclear/genetics , Triglycerides/blood , Triptorelin Pamoate , Urinary Bladder/drug effects , Urinary Bladder/pathology , Urinary Bladder/physiologyABSTRACT
BACKGROUND: Nephrotic syndrome (NS) is a clinical state characterized by massive proteinuria and excessive fluid retention. The effects of early versus late treatment with low or high doses of oral everolimus, a mammalian target of rapamycin inhibitor, on proteinuria in NS have not been previously described. METHODS: The effects of early treatment (2 days prior to NS induction) versus late treatment (beginning 2 weeks following the establishment of NS) with a low (20 mg/L) or high (100 mg/L) dose of everolimus for 5-7 weeks on proteinuria and nephrin/podocin abundance were assessed in male adult SD rats with adriamycin-induced NS. RESULTS: Adriamycin caused a significant increase in daily and cumulative proteinuria throughout the experimental period. Early, and to a lesser extent late treatment, with a low dose of everolimus, significantly decreased both daily and cumulative proteinuria and improved renal function. The anti-proteinuric effects of low-dose everolimus were associated with restoration of the disruptive glomerular nephrin/podocin abundance. In contrast, administration of a high dose of everolimus resulted in a decrease in proteinuria in NS rats, subsequently to deterioration of renal function. CONCLUSIONS: Early, and to a lesser extent late treatment, with a low but not a high dose of everolimus is effective in reducing proteinuria in nephrotic rats. The mechanism may be via nephrin/podocin protection.
Subject(s)
Antibiotics, Antineoplastic/toxicity , Cytoprotection/drug effects , Doxorubicin/toxicity , Immunosuppressive Agents/therapeutic use , Kidney Diseases/prevention & control , Nephrotic Syndrome/prevention & control , Sirolimus/analogs & derivatives , Animals , Everolimus , Immunoenzyme Techniques , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Kidney Diseases/chemically induced , Kidney Diseases/pathology , Male , Membrane Proteins/genetics , Membrane Proteins/metabolism , Nephrotic Syndrome/chemically induced , Nephrotic Syndrome/pathology , RNA, Messenger/genetics , Rats , Rats, Sprague-Dawley , Real-Time Polymerase Chain Reaction , Reverse Transcriptase Polymerase Chain Reaction , Sirolimus/therapeutic useABSTRACT
INTRODUCTION: The farnesoid X receptor (FXR) is critically involved in the regulation of the hepato-biliary system. Recent data suggest a role for FXR in modulating other metabolic pathways and vascular function. AIM: To investigate whether long-term administration of the selective FXR agonist INT-747 ameliorates erectile function, we tested it in two animal models of metabolic derangements: a rabbit model of high-fat diet (HFD)-induced metabolic syndrome (MetS) and a rat model of streptozotocin (STZ)-induced type 1 diabetes. METHODS: HFD rabbit or STZ rats with or without chronic INT-747 dosing (10 mg/kg/day for 12 weeks). INT-747 addition to rabbit penile smooth muscle cells (rpSMCs). MAIN OUTCOME MEASURE: Effects of INT-747 on metabolic features and erectile function in animal models and clarification of mechanism of action in isolated cells. RESULTS: INT-747 dosing normalized visceral adiposity and glucose intolerance in HFD rabbits. INT-747 increased penile FXR expression and partially restored endothelial nitric oxide synthase and dimethylarginine dimethylaminohydrolase 1 expression as well as impaired nitric oxide (NO)-dependent relaxation (improved responsiveness to acetylcholine and electrical field stimulation). INT-747 was also effective in regulating NO downstream events, as shown by increased sodium nitroprusside-induced relaxation. Because phosphodiesterase type 5 and protein kinase G (PKG) were unaltered by INT-747, we analyzed the calcium-sensitizing RhoA/ROCK pathway. HFD increased, and INT-747 normalized, RhoA membrane translocation/activation. RhoA/ROCK signaling inhibition by INT-747 was confirmed in rpSMCs by confocal microscopy, MYPT1-phosphorylation, cytoskeleton remodeling, cell migration, and smooth muscle-related genes expression. In STZ rats, FXR penile expression was not altered but was significantly upregulated by INT-747 dosing. In this model, INT-747 improved penile erection induced by electrical stimulation of cavernous nerve and hypersensitivity to intracavernous injection of a ROCK-inhibitor, Y-27632, without improving hyperglycemia. CONCLUSION: In HFD rabbits, INT-747 dosing improved glucose sensitivity and MetS-associated erectile dysfunction, via upregulation of NO transmission and inhibition of RhoA/ROCK pathway. In STZ rats, INT-747 restored in vivo penile erection and sensitivity to ROCK inhibition, independently of effects on glycemia.
