icatibant and Hyperglycemia

We examined renal kallikrein-kinin system (KKS) apoptosis and its related signaling pathway in rat podocytes. In addition, we studied the relationship of cannabinoid receptor 1 (CB(1)R) with high glucose and BK receptors.. Cell viability was determined by an MTT assay and apoptosis by DNA fragmentation assay, while gene expression was investigated by RT-PCR. Protein expression was analyzed by Western blot analysis. A chemical inhibitor or siRNA transfection was used to inhibit B1R, B2R, and CB(1)R signaling.. High glucose (25 mM) treatment decreased cell viability and increased DNA fragmentation. High glucose-induced DNA fragmentation and PARP and caspase-3 activations were blocked by both [des-Arg(10)]-HOE 140 (a B1R antagonist) and HOE 140 (a B2R antagonist). High glucose also increased Akt phosphorylation, ER stress-related protein expression, and NF-κB/I-κB phosphorylation in podocytes, which was blocked by both [des-Arg(10)]-HOE 140 and HOE 140. In addition, B1R and B2R siRNA transfections prevented high glucose-induced Akt and NF-κB activations in rat podocytes. Moreover, AM251 (a CB(1)R antagonist) treatment and CB(1)R siRNA transfection blocked the high glucose-induced stimulation of BK receptor expression, Akt activation, and NF-κB activation.. Our study suggests that hyperglycemia induces apoptosis via the stimulation of B1R and B2R expression through CB(1)R activation in rat podocytes in vitro, which is associated with the development of diabetic nephropathy.

Topics: Animals; Apoptosis; Bradykinin; Cell Survival; DNA Fragmentation; Endoplasmic Reticulum Stress; Gene Expression Regulation; Glucose; Hyperglycemia; Kallikrein-Kinin System; Piperidines; Podocytes; Pyrazoles; Rats; Receptor, Bradykinin B1; Receptor, Bradykinin B2; Receptor, Cannabinoid, CB1; Reverse Transcriptase Polymerase Chain Reaction; Tetrahydroisoquinolines

Rat uterus maintained in situ was used as a bioassay of kinins possibly released in vivo by hyperglycaemia or insulin. Intravenous injections of bradykinin induced contractions of rat uterus which were suppressed by HOE 140, a bradykinin B2 receptor antagonist. Des-Arg9-bradykinin, a kinin B1 receptor agonist, did not elicit any response. After propranolol, the effects of bradykinin were enhanced and dose-dependent. This potentiation did not appear in adrenalectomized rats. Captopril, an angiotensin-converting enzyme (ACE) inhibitor, largely increased the effects of bradykinin. In animals pretreated with propranolol, captopril and atosiban, an oxytocin antagonist, intravenous infusion of glucose induced hyperglycaemia and after a delay increased the uterine contractile activity. This contractile effect of glucose was abolished by HOE 140. Infusion of insulin with glucose induced contractions of the uterus. These responses did not appear or were suppressed by HOE 140 or by soya bean trypsin inhibitor (SBTI), a plasma kallikrein inhibitor. These results are direct evidence that insulin induces a release of kinins.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Blood Glucose; Bradykinin; Bradykinin Receptor Antagonists; Captopril; Female; Glucose; Hyperglycemia; Insulin; Isometric Contraction; Kinins; Rats; Rats, Wistar; Uterine Contraction