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Vasopeptidase inhibition (i.e., the simultaneous inhibition of both angiotensin-converting enzyme (ACE) and neutral endopeptidase) can ameliorate diabetic nephropathy. We investigated whether this nephroprotection is mediated by the bradykinin B2 receptor. In all, 43 obese Zucker diabetic fatty (ZDF/Gmi-fa/fa) rats aged 21 weeks were separated into four groups and treated for 26 weeks with either placebo, the bradykinin B2 receptor antagonist icatibant (500 μg kg−1 day−1 s.c. infusion), the vasopeptidase inhibitor AVE7688 (45 mg kg−1 day−1 in chow), or AVE7688 plus icatibant. Nephropathy was assessed as albuminuria at age 31 and 39 weeks, and by histopathologic scoring at the end of the treatment period. All animals had established diabetes mellitus (blood glucose >20 mmol l−1) and marked albuminuria at baseline. Blood glucose was not influenced by any treatment. Icatibant alone did not influence albuminuria (8.6±1.6 vs placebo 9.5±1.3 mg kg−1 h−1). AVE7688 reduced albuminuria at week 31 markedly to 1.1±0.1 mg kg−1 h−1 and reduced glomerular and tubulo-interstitial kidney damage at week 47. In the AVE7688 plus icatibant group, proteinuria was significantly higher than in the AVE7688 only group (2.0±0.6 mg kg−1 h−1), but still reduced compared to placebo. In addition, icatibant partly antagonized the tubulo-interstitial protection mediated by AVE7688. We conclude that vasopeptidase inhibition provides nephroprotection in rats with type II diabetic nephropathy, which is partly mediated by bradykinin B2 receptor activation. Keywords: Zucker diabetic fatty rat, diabetic nephropathy, vasopeptidase inhibition, AVE7688 Introduction Diabetic nephropathy is a devastating disease characterized by progressive impairment of glomerular function and, ultimately, end-stage renal disease. As a result of the diabetes epidemic in Westernized countries, the incidence of diabetic nephropathy is predicted to increase substantially over the next decade. In fact, type II diabetes has already become the most common single cause for renal replacement therapy in most industrialized countries (Ismail et al., 1999). Several landmark trials have demonstrated convincingly that blockade of the renin–angiotensin system, including inhibition of ACE, is effective to retard the progression of diabetic nephropathy and to prevent end-stage renal failure (Lewis et al., 1993; 2001; HOPE Study Investigators, 2000; Brenner et al., 2001). Part of the pharmacological action of ACE inhibitors is based on inhibition of bradykinin degradation, leading to increased stimulation of the bradykinin B2 receptor (Wirth et al., 1997). Blockade of the bradykinin B2 receptor partially prevented the cardiovascular benefits of ACE inhibition in different disease models, demonstrating the pharmacological relevance of bradykinin signaling in cardiovascular disease (for a review, see Linz et al., 1995). As bradykinin is degraded by both ACE and neutral endopeptidase, simultaneous inhibition of both enzymes by the novel vasopeptidase inhibitors is supposed to increase renal bradykinin concentrations and protect the diabetic kidney even more effectively than selective ACE inhibition alone (Molinaro et al., 2002). However, the relative role of bradykinin in the therapeutic action of vasopeptidase inhibitors in diabetic nephropathy has not been investigated so far. Recent data indicate that indeed, vasopeptidase inhibitors may be superior over pure ACE inhibitors, possibly related to their greater potency in increasing tissue bradykinin concentrations. The vasopeptidase inhibitor omapatrilat has shown superior nephroprotection over selective ACE inhibition in nondiabetic nephropathy (Taal et al., 2001) and in a hypoinsulinaemic, hypertensive model (Tikkanen et al., 1998; Davis et al., 2003). In the Zucker diabetic fatty (ZDF) rat, a type II diabetes animal model, the vasopeptidase inhibitor AVE7688 prevents nephropathy when treatment is started early (Schafer et al., 2003) and reduces proteinuria when diabetes and nephropathy are established (Schafer et al., 2004). In order to further elucidate the mechanism behind these nephroprotective effects, we investigated the effects of AVE7688 on functional and morphological end points in a setting of established diabetic nephropathy in the presence and absence of the bradykinin B2 receptor antagonist, icatibant. Our data indicate that the beneficial effects of vasopeptidase inhibition in type II diabetic nephropathy are partially, but not completely, mediated by the bradykinin B2 receptor.

Background: Blocking the renin–angiotensin system is an established therapeutic principle in diabetic nephropathy. We investigated whether inhibition of both neutral endopeptidase and ACE (vasopeptidase inhibition) can prevent functional and morphological features of nephropathy in the Zucker diabetic fatty (ZDF) rat, an animal model of type II diabetes. Methods: Homozygous (fa/fa) ZDF rats (each n = 15) aged 10 weeks were treated with placebo, ramipril (1 mg/kg/day in drinking water), or the vasopeptidase inhibitor AVE7688 (45 mg/kg/day in chow). Metabolic parameters and renal function (metabolic cages) were assessed at baseline (age 10 weeks), and at age 17, 27, and 37 weeks. Twenty heterozygous animals (fa/−) served as lean, nondiabetic controls. At age 37 weeks, the animals were sacrificed and the kidneys analyzed histopathologically. Results: Overt diabetes mellitus (blood glucose >20 mmol/l) was established at age 17 weeks in all homozygous ZDF rats. In the placebo group, urinary protein excretion increased progressively from 8±1 (baseline) to 342±56 mg/kg/day (week 37) whereas diabetes and proteinuria were absent in the lean control group. Ramipril tended to reduce albuminuria and morphological damage ( p = ns) but AVE7688 virtually prevented albuminuria (33±12 mg/kg/day, p

Stearoyl-CoA desaturase (SCD1) is linked to the pathogenesis of obesity, dyslipidemia and type 2 diabetes. It is the rate-limiting enzyme in the synthesis of monounsaturated 16:1 n-7 and 18:1 n-9 fatty acyl-CoAs and catalyzes an essential part of lipogenesis. Here, we describe the identification, in vitro properties and in vivo efficacy of a novel class of heterocyclic small molecule hexahydro-pyrrolopyrrole SCD1 inhibitors. SAR707, a compound representative for the series, was optimized to high in vitro potency, selectivity and favorable overall properties in enzymatic and cellular assays. In vivo, this compound reduced serum desaturation index, decreased body weight gain and improved lipid parameters and blood glucose levels of obese Zucker diabetic fatty rats treated for 4 weeks in a chronic study. In parallel, fissures of the eye lid, alopecia and inflammation of the skin were observed from day 11 on in all animals treated with the same metabolically active dose. In summary, we described in vitro and in vivo properties of a novel, potent and selective SCD1 inhibitor that improved body weight, blood glucose and triglycerides in an animal model of obesity, type 2 diabetes and dyslipidemia. However, the favorable in vivo properties of systemic SCD1 inhibition shown in our study were accompanied by dose-dependently occurring adverse target-related effects observed in skin. Thus, systemic SCD1 inhibition by small molecules might therefore not represent a feasible approach for the treatment of chronic metabolic diseases.

Hepatic uptake of organic anions, including bile salts, is mediated by members of the organic anion-transporting polypeptide (Oatp) family. In rat liver, Oatp1 (Slc21a1), Oatp2 (Slc21a5), and Oatp4 (Slca10) are expressed at the basolateral membrane of hepatocytes and may be differentially regulated under pathophysiologic conditions such as cholestasis. The aim of this study was to determine the effects of cholic acid (CA) and ursodeoxycholic acid (UDCA) on the expression of Oatp4 compared with Ntcp, Oatp1, and Oatp2. Wistar rats were fed with CA (0.5%) or both CA (0.5%) and UDCA (0.25%) for 3 weeks. Oatp expression was studied by Northern and Western blot analysis as well as immunofluorescence analysis. Transport function was compared measuring biliary secretion of (14)C-CA and (14)C-taurocholic acid (TCA). In CA-fed animals, biliary secretion of (14)C-CA and (14)C-TCA was markedly delayed over 40 minutes compared with controls. Accordingly, Oatp4 protein was significantly down-regulated in CA-fed animals together with Oatp1 and Ntcp. Cofeeding of CA plus UDCA prevented the impairment of (14)C-CA and (14)C-TCA secretion and the down-regulation of Oatp4. Oatp4 messenger RNA (mRNA) levels did not differ significantly between bile salt-fed groups, suggesting a posttranscriptional effect of CA on Oatp4 expression. In contrast to Oatp1 and Oatp4, Oatp2 protein expression was increased by CA feeding, indicating a differential regulation of Oatp transporters. In conclusion, we show that CA feeding may cause cholestasis associated with a posttranscriptional down-regulation of Oatp4. UDCA may prevent impairment of hepatic function by restoring hepatic transporter expression.

Animal models for osteoarthritis (OA) face the difficulty to display the key pathological events of a naturally slowly progressing disease in a protracted time frame. To serve as pharmacological models, in addition, these changes need to be meaningful and synchronous enough to allow predictions regarding the potential effects of new therapies. Therefore, high expectations have been placed in models where the OA-like pathology develops spontaneously, without any defined stimulus potentially limiting the true disease relevance of the tissue reactions thus induced.

In male Sprague Dawley rats with left ventricular hypertrophy (LVH) and hypertension induced by aortic constriction (AC) and subsequent myocardial infarction (MI) by occlusion of the left coronary artery the effects of ACE inhibition with ramipril (RA 1 mg/kg/day via the drinking water during 6 weeks) on survival as well as cardiac function and metabolism were investigated. Respective groups (sham AC; AC; AC + sham MI; normotensive animals with sham MI; MI; MI + RA) served as comparisons. Following MI hypertensive rats with AC and LVH revealed an increased postoperative mortality (68%) when compared to normotensives without AC (28%). ACE inhibition with ramipril significantly reduced mortality in hypertensive rats by 26%. Untreated hypertensive animals with LVH clearly showed reduced MI size (6.2 +/- 2.3%) in comparison with untreated normotensive animals and MI (31.0 +/- 3.3%). In hypertensive rats with MI which died during the study a significant increase in infarct size was found compared to those which survived MI. In normotensive animals ramipril reduced infarct size by 50%. Due to the quite small infarct size observed in hypertensive rats, ACE inhibition did not further reduce MI in these animals. LVH as well as hydroxyproline/proline ratio was diminished by ACE inhibitor treatment. In the isolated hearts of ramipril treated rats contractility was improved when compared to the respective untreated groups with MI. In the coronary effluent of isolated hearts from rats with AC and MI lactate dehydrogenase and creatine kinase activities as well as lactate levels were increased. Ramipril treatment starting one week before MI normalized these parameters and in addition increased prostacyclin output. Hearts with MI from treated normotensive animals contained increased energy rich phosphates when compared to hearts from untreated rats with MI.Hypertensive rats with LVH undergoing MI experience increased postoperative mortality probably due to a reduced tolerance to myocardial ischemia and occurrence of arrhythmias. In these animals ACE inhibition with ramipril increased survival. Both, increased survival in hypertensive and reduction in infarct size in normotensive rats by ACE inhibition with ramipril was accompanied by an improved myocardial metabolism.

Cytomegalovirus (CMV) was assayed by in situ hybridization with commercially available biotin-labeled CMV-DNA probes in 45 formalin-fixed paraffin-embedded autopsy specimens with Kaposi's sarcoma from 14 cases of the acquired immune deficiency syndrome (AIDS). In seven of the 14 cases, a few scattered hybridizing cells were detected in Kaposi's sarcoma, but not all specimens from the same case showed such cells. Most of the positive cells were peculiarly swollen and not typical of Kaposi's sarcoma cells. All positive cases had at least some CMV-infected organs with typical cytomegalic cells containing nuclear inclusions while five of the 7 negative cases revealed no CMV-infected tissue by conventional light microscopy. Our results suggest that this in situ hybridization procedure using biotin-labeled DNA probes only reveals generalized CMV infection that is a consequence of impairment of immune mechanisms in AIDS patients.