Inhibition of L-Enk on LPS induced VSMC proliferation in vitro

Aim: To investigate the actions ofLeucineenkephalin (L-Enk) and lipopolysaccharide (LPS) on theproliferation of vascular smooth muscle cells (VSMC), andto observe their interactions in the presence of opioidreceptor blocker naloxone. Methods: VSMCs of SD rat aortawere cultured in vitro; MTT method and H-TdR incooporationwere used to examine the proliferation and DNAsynthesis of VSMC. Results: 10-7 kg/L ～10-5 kg/L LPSmarkedly stimulated the proliferation and DNA synthesis ofVSMC (P0. 05 ). 10-5 mol/L ～10-4 mol/L L-Enkinhibited the proliferation and DNA synthesis of VSMC (P0.01). No effect of Nal (10-8 mol/L～10-5 mol/L) aloneon the proliferation and DNA synthesis of VSMC wasobserved. The promotive effect of LPS on the proliferationand DNA synthesis of VSMC could be inhibited by L-Enk,while Nal could block the inhibitiveaction of L-Enk.Conclusion: LPS stimulated the proliferation and the DNAsynthesis of VSMC, L-Enk inhibited the promotive effect ofLPS. The inhibitive effect of L-Enk was at least partlymediated by opioid receptor subtype.