MK801 impairs thermoregulation in the heat

2002 ◽  
Vol 80 (3) ◽  
pp. 226-232 ◽  
Author(s):  
Frédéric Canini ◽  
Nadine Simler ◽  
Lionel Bourdon
Keyword(s):  
Locomotor Activity ◽  
Nmda Receptor ◽  
Receptor Antagonist ◽  
Core Temperature ◽  
Exposure Duration ◽  
Heat Exposure ◽  
Nmda Receptor Antagonist ◽  
Dopamine Metabolism ◽  
Body Core Temperature ◽  
Body Core

The effects of MK801 (dizocilpine), a glutamate NMDA receptor antagonist, on thermoregulation in the heat were studied in awake rats exposed to 40°C ambient temperature until their body core temperature reached 43°C. Under these conditions, MK801-treated rats exhibited enhanced locomotor activity and a steady rise in body core temperature, which reduced the heat exposure duration required to reach 43°C. Since MK801-treated rats also showed increased striatal dopaminergic metabolism at thermoneutrality, the role of dopamine in the MK801-induced impairment of thermoregulation in the heat was determined using co-treatment with SCH23390, a dopamine D1 receptor antagonist. SCH23390 normalized the locomotor activity in the heat without any effect on the heat exposure duration. These results suggest that the MK801-induced impairment of thermoregulation in the heat is related to neither a dopamine metabolism alteration nor a locomotor activity enhancement.Key words: heatstroke, NMDA receptor, thermoregulation, dopamine, locomotion.

The recommended Threshold Limit Values for heat exposure fail to maintain body core temperature within safe limits in older working adults

2017 ◽  
Vol 14 (9) ◽  
pp. 703-711 ◽  
Author(s):  
Dallon T. Lamarche ◽  
Robert D. Meade ◽  
Andrew W. D'Souza ◽  
Andreas D. Flouris ◽  
Stephen G. Hardcastle ◽  
...  
Keyword(s):  
Core Temperature ◽  
Heat Exposure ◽  
Body Core Temperature ◽  
Limit Values ◽  
Threshold Limit Values ◽  
Working Adults ◽  
Threshold Limit ◽  
Body Core ◽  
Safe Limits

scholarly journals Elevated Core Temperature in Florida Fernery Workers: Results of a Pilot Study

2019 ◽  
Vol 67 (9) ◽  
pp. 470-480
Author(s):  
Valerie Vi Thien Mac ◽  
Jose Antonio Tovar-Aguilar ◽  
Lisa Elon ◽  
Vicki Hertzberg ◽  
Eugenia Economos ◽  
...  
Keyword(s):  
Energy Expenditure ◽  
Core Temperature ◽  
Heat Exposure ◽  
Body Core Temperature ◽  
Adaptation Measures ◽  
Heat Stress Response ◽  
Increased Risk ◽  
Body Core ◽  
Outdoor Worker ◽  
Occupational Heat Exposure

With expected increases in extreme weather, there may be a greater risk of injury from extreme heat in outdoor worker populations. To plan for future adaptation measures, studies are needed that can characterize workers’ physiologic responses to heat in outdoor settings such as agriculture. The objective of this study was to characterize occupational heat exposure, key vulnerability factors (e.g., gender, energy expenditure), and physiologic heat stress response in a sample of fernery workers. Forty-three fernery workers over 86 workdays were examined regarding heat-related illness (HRI) during the summer months of 2012 and 2013. The key outcome measure was whether a participant’s body core temperature (Tc) reached or exceeded 38.0°C (100.4ºF; Tc38). Participants’ Tc exceeded 38.0°C on 49 (57%) of the workdays, with 30 of 40 participants reaching or exceeding Tc38 on at least one workday. Adjusting for sex, there was a 12% increase in the odds of Tc38 for every 100 kilocalories of energy expended (OR: 1.12; 95% Confidence Interval [CI]: [1.03, 1.21]). Adjusting for energy expenditure, females had 5 times greater odds of Tc38 compared with males (OR: 5.38; 95% CI: [1.03, 18.30]). These findings provide evidence of elevated Tc in Florida fernery workers, indicating an increased risk of occupational HRI, and the need for policy and interventions to address this health risk.

Thermoregulatory responses of rats acclimated to heat given daily at a fixed time

1995 ◽  
Vol 78 (5) ◽  
pp. 1720-1724 ◽  
Author(s):  
N. Sugimoto ◽  
O. Shido ◽  
S. Sakurada
Keyword(s):  
Core Temperature ◽  
Exposure Time ◽  
Heat Exposure ◽  
Fixed Time ◽  
Body Core Temperature ◽  
Electric Heater ◽  
Dark Phase ◽  
Thermoregulatory Responses ◽  
Body Core ◽  
Pronounced Reduction

Body core temperature of rats acclimated to heat given daily at a fixed time falls during the previous heat exposure time. In the present study, thermoregulatory responses of heat-acclimated rats were examined during the specific period. Heat-acclimated rats were subjected to an ambient temperature of 32 degrees C for approximately 5 h in the first half or last half of the dark phase for 14 days while control rats were kept at 24 degrees C. Then the rats were placed in a direct calorimeter and were warmed for 30 min with an intraperitoneal electric heater. Measurements were made twice in the first and last halves of the dark phase. Body warming significantly increased body core temperature in all rats. In the heat-acclimated rats, heat production (M) was significantly depressed during the previous heat exposure time but not during the other period. Body warming had little effect on M in the control rats during either period. The results suggest that rats acclimated to heat given at a fixed time daily respond to an acute heat load with a pronounced reduction of M. However, such a response was observed only during the period when the rats had been previously exposed to heat.

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