Effect of calcitonin gene-related peptide on isoprenaline-induced cardiac fibroblast proliferation and collagen expression.

OBJECTIVE:To explore the inhibitory effect of calcitonin gene-related peptide (CGRP) on cardiac fibroblast proliferation and collagen synthesis induced by isoprenaline and the underlying mechanism. METHODS:The primary cultured cardiac fibroblasts were incubated with isoprenaline (10(-5) mol/L) for 48 h after pretreatment with CGRP (10(-8) or 10(-7) mol/L) for 1 h. Cell activity was detected by MTT. The mRNA expression of collagen (types I and III) and connective tissue growth factor (CTGF) was determined by RT-PCR, and the levels of intracellular ROS were determined by DCFH-DA fluorescent probe. RESULTS:Isoprenaline significantly promoted fibroblast proliferation and up-regulated collagen (types I and III) and CTGF mRNA expression concomitantly with an increase in ROS production, which were attenuated by CGRP. The effect of CGRP on cardiac fibroblasts was inhibited by CGRP8-37, a selective antagonist of CGRP receptor. CONCLUSION:CGRP is able to protect cardiac fibroblasts against isoprenaline-induced proliferation and collagen expression, which might be related to the down-regulation of CTGF expression through inhibition of ROS production.