Responses of plasma proenkephalin Peptide F in rats following 14 days of spaceflight
Matthew Sharman, Edith Cowan University
Aerospace Medical Association
Faculty of Computing, Health and Science
School of Exercise, Biomedical and Health Science / Centre for Alzheimer's Disease
Introduction. Proenkephalin peptide F [107–140] is related to the enhancement of immune function, while microgravity has been shown to cause immuno-suppression. We investigated the physiological response of proenkephalin peptide F to microgravity. Methods: There were 12 Fischer 344 female rats, ovariectomized at 10.5 wk of age, used to determine plasma concentrations of peptide F in response to a 14-d flight aboard the Columbia Space Shuttle mission STS-62. There were 36 other such rats that served as ground-based controls to separate the effects of microgravity from those of thermal stress, flight stress, and crowded habitats. Control groups of 12 rats each were kept under the following conditions: 1) 22°C vivarium, 2) 28°C vivarium, and 3) variable (Var) to mimic flight. The flight and control groups were housed in animal enclosure modules 21 d prior to flight and for the duration of the study. The rats were sacrificed within 4–5 h after landing, at which time blood samples were obtained. Results: Body weights were obtained prior to sacrifice; mean values were flight, 199 g; 22°C, 193 g; 28°C, 192 g; and Var, 194 g. The flight group produced a significantly greater (p ≤ 0.05) level of plasma peptide F (0.056 pmol · ml−1) compared with the controls (0.016, 0.022, and 0.016 pmol · ml−1 for 22°C, 28°C, and Var, respectively). Flight animals demonstrated higher corticosterone concentrations and reduced T and B cell splenocyte counts than controls. Conclusions: These data indicate that the increases in proenkephalin peptide F observed with exposure to microgravity may present an adrenal-medullary response to cope with the decreased immune function and increased stress experienced during spaceflight and landing.
Kraemer, W. J., Mastro, A. M., Gordon, S. E., Koziris, L. P., Bush, J. A., Volek, J. S., ... & Deschenes, M. R. (2004). Responses of plasma proenkephalin peptide F in rats following 14 days of spaceflight. Aviation, space, and environmental medicine, 75(2), 114-117.