【Animal Modeling】-Effect of nicotine on changes of pain threshold plasticity and cardioprotection in rats with myocardial infarction

  Objective: To observe the plastic changes of pain threshold in rats with myocardial infarction, and to explore the effect of nicotine on visceral pain and whether it has a protective effect on ischemic myocardium.

  METHODS: Thirty SPF Sprague-Dawlay healthy male rats, weighing 180-200 g, were selected and randomly divided into sham operation group, model group and nicotine treatment group. Rats in each group were observed electrocardiogram (ECG), pain thresholds (thermal pain threshold PWL, mechanical pain threshold PWT), left ventricular pressure amplitude changes, cardiac body mass index, and creatine kinase isoenzyme (CK-MB) changes.

  Results: Compared with the sham-operated group, the mechanical pain threshold became smaller and the thermal pain threshold became larger in the model group (P<0.05); the plasma CK-MB activity, cardiac body mass index, and left ventricular pressure were significantly increased (P<0.05). . Compared with the model group, the nicotine treatment group had a larger mechanical pain threshold and a smaller thermal pain threshold; plasma CK-MB activity, cardiac body mass index, and left ventricular pressure were significantly decreased (P<0.05), and the differences were statistically significant.

  Conclusion: Nicotine can relieve myocardial ischemia symptoms and visceral pain caused by ischemia in rats with myocardial infarction, and its mechanism may be related to the activation of cholinergic anti-inflammatory pathway, thereby improving pain in rats. and protection of rat heart.