Dapagliflozin Exerts Adrenal Sympatholysis via G protein-Coupled Receptor Kinase-2 & Tyrosine Hydroxylase Downregulation

Abstract The sodium-glucose co-transporter (SGLT)-2 inhibitor dapagliflozin was recently reported to reduce renal tyrosine hydroxylase (TH) and norepinephrine levels, lowering blood pressure preventing endothelial dysfunction, in a murine model of neurogenic hypertension. This suggested that may combat sympathetic nervous system (SNS) hyperactivity, which is known accompany aggravate chronic heart failure (CHF). Adrenal G protein-coupled receptor kinase (GRK)-2 upregulation major driver circulating catecholamine (CA) elevation SNS especially CHF. GRK2 severely dysregulates adrenal sympatho-inhibitory α 2-adrenergic receptors (ARs), leading unchecked, chronically elevated CA secretion. Therefore, we hypothesized herein SGLT2 inhibition with lower hyperactivity the gland by antagonizing actions on 2ARs chromaffin cells. We used rat pheochromocytoma PC12 cell line expressing human 2AAR, as well freshly isolated glands from adult male Sprague-Dawley rats treated vivo. measured (NE) vivo via RIA, & TH expression levels real-time PCR immunoblotting, 2AR density (Bmax) saturation radioligand binding [methyl-3H]-rauwolscine, protein activation GTPγS assay. Dapagliflozin treatment for 7 consecutive days (20 mg/kg/d drinking water) led significant reduction NE (217+67 pg/ml, n=6), compared control, vehicle-treated (363+77 n=6, p<.05), suggesting reduced activity. accompanied mRNA dapagliflozin-treated adrenals vs. animal-derived glands, indicating synthesis Finally, higher dapagliflozin- (51.3+7.3 26.1+8.1 fmol/mg protein, respectively; n=12 6 animals per group, p<.05). These results (i.e. downregulation) were completely recapitulated 2AAR-expressing cells culture, 5 μM (or vehicle) 24 hours. Importantly, 2AR-dependent protein-mediated signaling towards secretion markedly enhanced at hrs post-dapagliflozin application result GRK2-dependent desensitization, since lacked this effect co-transfected GRK2-encoding adenovirus acutely overexpress GRK2. In conclusion, exerts sympatholytic action medulla downregulation both TH, reduces biosynthesis, GRK2, desensitization favor