Abstract P1014: Renal Autocrine Npff, Via Its Local Receptors, Regulates Blood Pressure Through Its Interaction With The Renal Dopaminergic System

Abstract

Neuropeptide FF (NPFF), a hormone originally isolated from the bovine brain, has been suggested to contribute to the pathogenesis of hypertension. However, the role of NPFF and its receptors, NPFF-R1 and NPFF-R2, in the regulation of blood pressure, via the kidney, is unknown. In this study, we found that NPFF ( NPFF , Npff ), NPFF-R1( NPFFR1 , Npffr1 ), and NPFF-R2( NPFFR2 , Npffr2 ) mRNAs and proteins were expressed in both mouse and human renal proximal tubules (RPTs), determined by RT-PCR, RNAScope, immunoblotting, and immunofluorescence microscopy. NPFF-R2, compared with NPFF-R1, was predominantly expressed in RPTs and RPT cells (RPTCs). In human and mouse RPTCs, NPFF decreased cAMP production in a concentration- and time-dependent manner, consistent with its receptors’ linkage to the inhibitory G protein, Gαi. The D 1 R, but not D 5 R, colocalized with NPFF-R2 in human RPTCs and human kidney tissue sections. The colocalization between D 1 R and NPFF-R2 was decreased by the treatment with NPFF (100 nM, 30 min) in mouse RPTCs. Consistent with these findings, D 1 R co-immunoprecipitated with NPFF-R2 in human RPTCs. Fenoldopam, a D1-like receptor agonist, increased the cellular cAMP production and intracellular Na + accumulation, which were attenuated by NPFF (100 nM, 30 min), indicating an antagonistic interaction between NPFF and D1-like receptors. Moreover, acute and chronic administration of NPFF (10 μg in 100 μL, 0.5 μL/hr) in C57Bl/6 mice increased their blood pressures (from 96.4±3 to 114±5 mmHg, n=4) that were blocked by RF9 (10 μg in 100 μL, 0.5 μL/hr), an antagonist of both NPFF-R1 and NPFF-R2. NPFF also decreased urinary sodium excretion (from 0.36±0.06 to 0.28±0.05 mEq/day, n=4). In summary, NPFF by its negative interaction with the renal dopaminergic system regulates sodium excretion and blood pressure.