• Mengyun Dou, Zhenxiao Ma, Xueying Cheng, Guichang Zou, Yan Xu, Cheng Huang, Wei Xiong, Shufang He, and Ye Zhang.
• Department of Anaesthesiology and Perioperative Medicine, The Second Hospital of Anhui Medical University, Hefei, China; Key Laboratory of Anaesthesiology and Perioperative Medicine of Anhui Higher Education Institutes, Anhui Medical University, Hefei, China.
• Br J Anaesth. 2019 Oct 1; 123 (4): 439-449.

BackgroundNerve growth factor (NGF) has been implicated in hyperalgesia by sensitising nociceptors. A role for NGF in modulating myocardial injury through ischaemic nociceptive signalling is plausible. We examined whether inhibition of spinal NGF attenuates myocardial ischaemia-reperfusion injury and explored the underlying mechanisms.MethodsIn adult rats, lentivirus-mediated short-hairpin RNA targeted at reducing NGF gene expression (NGF-shRNA) or a transient receptor potential vanilloid 1 (TRPV1) antagonist (capsazepine) was injected intrathecally before myocardial ischaemia-reperfusion. Infarct size (expressed as the ratio of area at risk) and risk of arrhythmias were quantified. Whole-cell clamp patch electrophysiology was used to record capsaicin currents in primary dorsal root ganglion neurones. The co-expression of substance P (SP) and calcitonin gene-related peptide (CGRP), plus activation of TRPV1, protein kinase B (Akt) and extracellular signal-regulated kinase (ERK) were also quantified.ResultsNGF levels increased by 2.95 (0.34)-fold in dorsal root ganglion and 2.12 (0.27)-fold in spinal cord after myocardial ischaemia-reperfusion injury. Intrathecal injection of NGF-shRNA reduced infarct area at risk from 0.58 (0.02) to 0.37 (0.02) (P<0.01) and reduced arrhythmia score from 3.67 (0.33) to 1.67 (0.33) (P<0.01). Intrathecal capsazepine was similarly cardioprotective. NGF-shRNA suppressed expression of SP/CGRP and activation of Akt/ERK and TRPV1 in spinal cord. NGF increased capsaicin current amplitude from 144 (42) to 840 (132) pA (P<0.05), which was blocked by the TRPV1 antagonist 5'-iodoresiniferatoxin. Exogenous NGF enhanced capsaicin-induced Akt/ERK and TRPV1 activation in PC12 neuroendocrine tumour cells in culture.ConclusionsSpinal NGF contributes to myocardial ischaemia-reperfusion injury by mediating nociceptive signal transmission.Copyright © 2019. Published by Elsevier Ltd.

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