Changes In SP And CGRP In Lung And Dorsal Root Ganglia Following Coronary Artery Occlusion And The Intervention In Rat

Objective To explore the function of neurogenic mechanism evoked byinjurios stimulation, the observation was made on the changes in SP and CGRPin lung and the changes in β-PPTmRNA and CGRPmRNA in dorsal rootganglia(DRG) and lungs induced by coronary artery occlusion(CAO) in rat andthe pre-interventive effects of morphine and tramadol on the above changes.This study can provide the reliable experiment data to clarify the initialmechenism of mutiple organs injury and furnish a new way to prevent and treatthe mutiple organs injury for the clinic work. . Methods Adult male SD rats, weight between 270g-300g, were randomlyseparated into four groups: non-CAO group, the control group, with shamoperation; CAO group; M+CAO group and T+CAO group. Each group wasdivided into three sub-group which were observed at 1h, 3h and 6h, respectively(n=6). Rats in M+CAO group were pre-administrated 1.25mg/kg morphine andT+CAO group 12.5mg/kg tramadol as well as non-CAO group and CAO group1ml salt water solution through caudul vein in 15 minutes before CAO. Thenrats were sacrificed in 1h, 3h and 6h, the right lung was excised and some partprocessed for SP and CGRP immunohistochemistry and immunofluorescence.Some part of right lung excised at 3h, for enzyme-linked immunosorbent assay(ELISA). Meanwhile the bilateral C6-T5 DRGs and right lung were removed at3h for semi-quantitative measurement the level of β-PPTmRNA and α,β-CGRPmRNA by reverse transcription-polymerase chain reaction (RT-PCR). Results Immunohistochemistry results showed SP and CGRP significantlyincreased in rat lung at 1h, 3h and 6h respectively after CAO compared withnon-CAO group (P<0.05), morphine and tramadol made the elevation of SP andCGRP significantly attenuate, which evoked by CAO in rat lung (P<0.05). InCAO group, the level of SP and CGRP in the lung were highest at CAO3h.ELISA results showed the content of SP and CGRP in the lung were muchhigher at CAO3h than that of non-CAO3h (P<0.05), morphine and tramadolmade the elevated content of SP and CGRP significantly reduce, which evokedby CAO in the lung as compared with CAO3h (P<0.05). RT-PCR resultsshowed there were expression of β-PPTmRNA, α-CGRPmRNA and β-CGRPmRNA in the DRGs and β-PPTmRNA and β-CGRPmRNA in thelung. Their expression significantly increased in CAO3h group as comparedwith non-CAO3h group (P<0.05), and decreased significantly in M+CAO3hgroup and T+CAO3h group as compared with CAO3h group (P<0.05). Conclusions The level of SP and CGRP in the lung and the synthsis of SPand CGRP in DRGs and lung were increased by only acute myocardial ischemia.The results show that in the lung activity of neurogenic mechanism can beinduced by acute myocardial ischemia. The results suggested neurogenicmechanism may play an important role in the pathologic processes of multipleorgan injury. Morphine and tramadol could make the content of SP and CGRP inthe lung and the synthsis of SP and CGRP in DRGs and lung decrease. Theireffects may derive from suppression of nociceptive afferent signals evoked byacute myocardial ischemia at different site.