Effects of preexposure to a subthreshold dose of helium particles on the changes in performance produced by exposure to helium particles

Authors: RABIN, BERNARD - University Of Maryland; MILLER, MARSHALL - Duke University; Shukitt-Hale, Barbara

Submitted to: Life Sciences in Space Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2023
Publication Date: 3/31/2023
Citation: Rabin, B.M., Miller, M.G., Shukitt Hale, B. 2023. Effects of preexposure to a subthreshold dose of helium particles on the changes in performance produced by exposure to helium particles. Life Sciences in Space Research. 37:88-96. https://doi.org/10.1016/j.lssr.2023.03.003.
DOI: https://doi.org/10.1016/j.lssr.2023.03.003

Interpretive Summary: Astronauts in deep space will be exposed to radiation particles which have been shown to negatively affect the brain and subsequent cognitive performance. Because a mission to Mars might take up to 3 years to complete, astronauts will be exposed to many smaller doses of radiation, which could add up over the length of the mission. It is unknown if these smaller radiation hits will be protective of subsequent hits, or if they will add up to produce the effects of a larger hit. Therefore, this study exposed rats to a below threshold dose of helium particles and either 2, 24 or 72 hr later gave them either a second below threshold dose or an above threshold dose of helium particles. Following radiation, the rats were tested on a behavioral task to measure their performance. The results indicate that preexposure to a below threshold dose of helium particles can either sensitize or attenuate the effects of the subsequent dose, depending upon the interval between exposures and the doses. These results suggest that exposure to multiple doses of heavy particles may have implications for astronaut health on exploratory class missions.

Technical Abstract: On exploratory class missions, such as a mission to Mars, astronauts will be exposed to doses of particles of high energy and charge and protons up to 30 to 40 cGy. These exposures will most likely occur at random intervals across the estimated 3-yr duration of the mission. As such, the possibility of an interaction between particles must be taken into account: a prior subthreshold exposure to one particle may prevent or minimize the effect of a subsequent exposure (adaptation), or there may be an additive effect such that the prior exposure may sensitize the individual to a subsequent exposure of the same or different radiations. Two identical replications were run in which rats were exposed to a below threshold dose of 4He particles and 2, 24 or 72 hr later given either a second below threshold or an above threshold dose of 4He particles and tested for performance on an operant task. The results indicate that preexposure to a subthreshold dose of 4He particles can either sensitize or attenuate the effects of the subsequent dose, depending upon the interval between exposures and the doses. These results suggest that exposure to multiple doses of heavy particles may have implications for astronaut health on exploratory class missions.