Deficits in Motor Function After Repeated Exertional Heat Stroke Exposure in Female Mice

Abstract

Exertional Heat Stroke (EHS) is a life‐threatening illness that can result in a number of negative health outcomes. Once exposed to EHS, patients are considered to be at greater risk of subsequent EHS. In this study we hypothesized that a single EHS exposure would result in greater susceptibility to a second EHS, and that the consequences of EHS on skeletal muscle/motor function would be more profound. Twelve female mice were exposed to an initial EHS, allowed to rest for 2 weeks and then exposed to a second EHS and followed for 1 week. All mice reached symptom limitation (loss of consciousness) at lower maximum core temperatures (Tc, max) in their second EHS. Mice also had lower durations of unconsciousness after the second EHS. We evaluated motor function, before and after the EHS using behavior assessments including trunk curl, horizontal rotation response, catalepsy and a ‘weight test’ protocol. Mice showed a significant decrease in the strength (P = 0.0182) after the second EHS, as measured by the weight test protocol, an impaired rotation response (P = 0.0061), catalepsy (P = 0.0398) and trunk curl (P = .0001). These measures indicate reductions in strength and/or motor coordination. In conclusion, we identified that exposure to EHS increases the susceptibility to a second EHS with worsening outcomes in motor function after the second EHS. These data suggest that following a single exposure to EHS there is a prolonged period of increased vulnerability to EHS and greater potential risk of deficits in organ function.Support or Funding InformationSupported by the BK and Betty Stevens Endowment and a Fellowship from King Saud University, Saudi Arabia.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.