Search

Heat stroke is characterized by hyperthermia, systemic inflammation, and multiple organ failure including arterial hypotension. This definition can be fulfilled by a rat model of heat stroke used in the present study. Anesthetized animals were exposed to heat exposure (43 °C for 70 min) and then returned to room temperature (26 °C) for recovery. One hour before heat exposure, an intraperitoneal dose of quercetin (30 mg/kg) or vehicle (normal saline 1 ml/kg) was administered to the experimental groups of rats. Additional injection was administered immediately after the onset of heat stroke. Immediately after the onset of heat stroke. Vehicle-treated rats displayed (i) hyperthermia; (ii) suppressed left ventricular function; (iii) decreased contents of cardiac total antioxiant capacity (e.g., superoxide dismutase, glutathione peroxidase, catalase); (iv) increased contents of cardiac oxidative capacity malondialdehyde and thiobarbituric acid reactive substances; (v) increased cardiac levels of pro-inflammatory cytokines tumor necrosis factor-α and interleukin-6; and (vi) decreased cardiac levels of an anti-inflammatory cytokine interleukin 10. Histopathologic and survival observation provided supportive evidence for biochemical analyses. These heat stroke reactions all can be significantly attenuated by quercetin therapy. Our data suggest that quercetin therapy might improve outcomes of heat stroke in rats by attenuating excessive hyperthermia as well as myocardial injury. The protective effects of quercetin could be attributed to anti-lipid peroxidative, anti-oxidant, and anti-inflammatory properties. [ABSTRACT FROM AUTHOR]

• 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. [ABSTRACT FROM AUTHOR]

Pregnant women are vulnerable to heat stroke reactions caused by high environmental temperatures. Heat intolerance is associated with hypothalamic impairment. Here, we aim to ascertain whether pregnancy causes heat intolerance by inducing hypothalamic impairment in mice. In the heated groups, mice were exposed to whole body heating (WBH; 41.2 °C for 1 h) in an environment-controlled chamber. Then, they were returned to normal room temperature (26 °C) immediately after WBH. In the hyperbaric oxygen therapy (HBO 2 T) groups, mice were exposed to 100% O 2 at 2.0 atm absolute (ATA) for 4 h immediately post-WBH. Mice that survived after 4 h of WBH were considered survivors. Here, we show that when pregnant mice underwent non-HBO 2 T (21% O 2 at 1.0 ATA for 4 h) after WBH, the survival rate was 4/20, and the core temperature at 4 h post-WBH was 31.2 ± 0.2 °C. Both the survival rate and core temperature of HBO 2 T pregnant mice (10/10 and 35.2 ± 0.3 °C, respectively) were significantly greater than those in non-HBO 2 T pregnant mice. Compared to non-HBO 2 T heated mice, the HBO 2 T heated mice exhibited lower neurological severity scores, reduced hypothalamic neuronal damage, fewer apoptotic cells, reduced multiorgan damage scores, and lower hypothalamic levels of proinflammatory cytokines and nitrogen and oxygen radical species. Compared to non-HBO 2 T heated mice, the HBO 2 T-treated heated mice had significantly higher hypothalamic-pituitary-adrenal axis activity (evidenced by higher serum levels of both adrenocorticotrophic hormone and corticosterone). In conclusion, pregnancy induces heat intolerance by inducing hypothalamic impairment in mice. Additionally, HBO 2 T protects against heat intolerance in pregnant mice by preserving hypothalamic integrity. • Pregnant women constitute the most at-risk population for heat stress. • Hypothalamic impairment causes heat intolerance in pregnant mice. • Hypothalamic dysfunction and heat intolerance can be prevented by hyperbaric oxygen treatment. [ABSTRACT FROM AUTHOR]

Testicular hyperthermia has been noted in men who work in high ambient temperatures. Scrotal temperatures above the normal range caused germ cell loss in the testes and resulted in male subfertility. In adult male rats, exercising at a higher environmental temperature (36 °C with relative humidity of 50%, 52 min) caused exertional heat stroke (EHS) characterized by scrotal hyperthermia, impaired sperm quality, dysmorphology in testes, prostates and bladders, and erectile dysfunction. Here, we aim to ascertain whether hyperbaric oxygen preconditioning (HBOP: 100% O 2 at 2.0 atm absolute [ATA] for 2 h daily for 14 days consequently before the onset of EHS) is able to prevent the problem of EHS-induced sterility, testes, prostates, and bladders dysmorphology and erectile dysfunction. At the end of exertional heat stress compared to normobaric air (NBA or non-HBOP) rats, the HBOP rats exhibited lower body core temperature (40 °C vs. 43 °C), lower scrotal temperature (34 °C vs. 36 °C), lower neurological severity scores (2.8 vs. 5.8), higher erectile ability, (5984 mmHg-sec vs. 3788 mmHg-sec), higher plasma testosterone (6.8 ng/mL vs. 3.5 ng/mL), lower plasma follicle stimulating hormone (196.3 mIU/mL vs. 513.8 mIU/mL), lower plasma luteinizing hormone (131 IU/L vs. 189 IU/L), lower plasma adrenocorticotropic hormone (5136 pg/mL vs. 6129 pg/mL), lower plasma corticosterone (0.56 ng/mL vs. 1.18 ng/mL), lower sperm loss and lower values of histopathological scores for epididymis, testis, seminal vesicle, prostate, and bladder. Our data suggest that HBOP reduces body core and scrotal hyperthermia and improves sperm loss, testis/prostate/bladder dysmorphology, and erectile dysfunction after EHS in rats. • HBOP reverses the scrotal hyperthermia by EHS. • HBOP reverses the impaired erectile function by EHS. • HBOP reverses the reduced sperm count, reduced sperm motility, and sperm dysmorphology by EHS. • HBOP reverses the dysmorphology in epididymis, testes, prostate, seminal vesicle, and bladder by EHS. [ABSTRACT FROM AUTHOR]