[Effect of calcitonin gene-related peptide receptor on expression of NF-kappa b in rat lung after ischemia reperfusion injury].

Objective: To study the effect of calcitonin gene-related peptide (CGRP) receptor on the expression of nuclear factor-kappa b (NF-kappa b) in rat lung after ischemia reperfusion injury.

Methods: Thirty-two adult male Sprague Dawley rats were divided into four groups (8 per group) as follows: sham group (sham thoracotomy), IR group (occlusion of the left pulmonary hilus for 0.5 h followed by reperfusion for 4 h), another two groups were pretreated with CGRP or CGRP8-37 (a CGRP receptor antagonist). Arterial blood was collected at the end of reperfusion to test blood gas, arterial oxygen pressure (PaO2) and alveolar arterial oxygen difference (A-aDO2). Lung tissue was collected to measure the expression level of NF-kappa b mRNA by using RT-PCR. Light microscopic changes of lung tissue were also examined.

Results: Compared with sham group, rats in the IR group had poorer gas exchange (lower PaO2, higher A-aDO2), upregulation of NF-kappa b mRNA expression (P < 0.05) and more severe histological injury. Pretreatment with CGRP improved gas exchange function, significantly decreased NF-kappa b mRNA expression (P < 0.05 versus IR and CGRP837 groups). Administration of CGRP also attenuated IR-induced pathological lesions. The pretreatment of CGRP8-37 showed the opposite results to those of CGRP.

Conclusion: CGRP receptor plays an important protective role in lung IR injury, which is closely related to the downregulation of NF-kappa b mRNA.