Pro-opiomelanocortin activation and simulated interceptor combat flight

Methods: To investigate the influence that psychological workload, associated with simulated combat military flight, has on secretion of stress hormones we measured concentrations of plasma corticotropin-releasing hormone (CRH), pro-opiomelanocortin (POMC) related adrenocorticotropin (ACTH), beta-endorphin (BE), and cortisol in 10 Finnish Air Force (FAF) military interceptor pilots. They performed the same 20-min combat flight mission in a Saab J35 Draken S simulator, including four radar attacks during one-on-one situations with increasing cognitive tasks and psychological strain. Blood samples were collected -35 min, 1 min, 30 min and 60 min after the flight mission. Control blood samples were collected from the subjects at the same time of day in randomized order before or after the flight mission. During the control period the subjects were allowed to perform ground duties. Results: Plasma CRH was undetectable in samples drawn before or after the flight and control period. Plasma ACTH was significantly (p < 0.05) elevated before the simulated combat flight when compared with the respective value in the control experiment. This is an anticipatory type of stress reaction. Plasma BE did not change significantly after the simulated flight. Plasma cortisol increased significantly (p < 0.05) 1 min after the simulated flight. One of the ten pilots had an extreme POMC and cortisol activation after the flight mission, suggesting that the pilot's stress tolerance was less than average. Conclusions: We conclude that stress, produced during simulated combat military flight, increases POMC and cortisol secretion. An anticipatory-type stress reaction was found to be associated with the simulated combat flight, as judged from the increased preflight plasma ACTH.