Protective effect of myocardial calcitonin gene-related peptide gene transduction on myocardial ischemia/reperfusion injury in diabetic rats

Abstract

Objective To evaluate the feasibility of lentivirus (Lv) mediated calcitonin gene-related peptide(CGRP) gene transduction in diabetic rats by myocardial injection and whether this method has a protective effect on diabetic myocardium during ischemia/reperfusion(I/R) injury. Methods Sixty healthy male SD rats, weighing 200-220 g, were randomly divided into control group (group C), diabetes mellitus group (group DM), Sham transduction group (group Sham), myocardial injection control group (group MC) and myocardial injection experiment group(group ME), in accordance with a random number table. Rats in group Sham, group MC and group ME were given with normal saline, at a titer of 2×107 virus genomes(vg)/ml Lv-enhanced green fluorescent protein (eGFP) and Lv-CGRP-eGFP 50 μl respectively by myocardial injection. One week later, rats in group DM, group Sham, group MC and group ME received streptozocin(STZ) 50 mg/kg intraperitoneal injection to induce diabetes. Eight weeks after the injection of STZ, myocardial I/R was induced by occlusion and release of left anterior descending branch of coronary artery. The latency of tail flick reflection, the expression of eGFP, the transcription level of CGRP, the expression of CGRP in myocardium, spinal cord and dorsal root ganglion(DRG) and myocardial ischemia area, infarct size(IS) area were measured. Results Compared with group C, the latency of tail flick reflection in group DM, group Sham, group MC and group ME were significantly prolonged in the 4th week after diabetic model successfully manufactured(P<0.05). The transcription levels of CGRP in the ischemic myocardium, spinal cord T1-T5 and DRG T1-T5 in group DM, group Sham and group MC were lower than those in group C and group ME (P<0.05). The level of CGRP in ischemic myocardium and DRG T1-T5 of group ME was higher than that in group C(P<0.05). The content of CGRP in cord T1-T5, DRG T1-T5, ischemic myocardium and serum in group C and group ME were higher than those in group DM, group Sham and group MC (P<0.05). The content of CGRP in cord T1-T5, ischemic myocardium in group ME was higher than that in group C (P<0.05). The infarct size in group DM, group Sham, group MC were higher than that in group C and group ME(P<0.05), the infarct size of group ME was higher than that in group C(P<0.05). Conclusions Intramyocardial injection of CGRP gene can effectively enhance the expression of CGRP at I/R of diabetic rat′ heart. Increased CGRP may reduce cardiac I/R injury in diabetic rats. Key words: Calcitonin gene-related peptide; Diabetes mellitus; Myocardium; Ischemia-reperfusion