Myricetin against myocardial injury in rat heat stroke model

[Display omitted] •Heat stress induces hyperthermia, hypotension, cardiac injury and lethality.•Myricetin preconditioning significantly attenuates these heat stroke reactions.•The beneficial effects of myricetin are significantly abolished by heat shock protein 72 antiody. Heat stroke-induced mortality is rising across the globe. So, the design of prophylactic and/or therapeutic modalities for heat stroke is pressing need. The common plant derived flavonoid exhibits strong anti-oxidant and anti-inflammatory activities; however, its effects in heat stroke remain unknown. The study aimed to investigate the cardioprotective effects of myricetin on heat stroke induced acute myocardial injury as well as lethality in rats and to explore the underlying mechanisms. Myocardial injury was induced by subjecting the anesthetized rats to a high ambient temperature of 43 °C for 70 min. An intragastrical dose of myricetin (5−25 mg/kg body weight) was given to rats once per day for one week prior to the start of heat stress. Heat shock protein 72 antibodies was given intraperitoneally to rats 24 h before the start of heat stress. Myocardial injury severity was estimated by determing myocardial damage scores, myocardial injury indicators, myocardial oxidative and inflammatory factors. Western blot analysis was used for cardiac expression of heat shock protein (HSP)72. Significant (P < 0.05) up-regulation of HSP-72 after chronic administration of myricetin coincided with significant (P < 0.05) reduction in hyperthermia, hypotension, cardiac inflammatory and oxidative damage and lethality. Inhibition of HSP-72 showed a significant (P < 0.05) reversal in the cardiaprotection as well as survival. Our results indicate that myricetin diminishes myocardial injury as well as lethality in heat stroke by up-regulating HSP-72 and show promise as a novel prevention therapeutic for heat stroke.