Post Doctoral Biomedical Support Fellow Walter Reed Army Institute of Research Silver Spring, Maryland
Abstract Text: The incidence of head impact acceleration and associated concussion is a significant concern in contact sports. Repeated sub-concussive events are not associated with acute neurological deficits, but has shown mood and behavioral problems at later stages of life. Hypopituitarism leading to decreased release of one or more hormones from the pituitary gland is implicated after traumatic brain injury. Decreased release of adrenocorticotropic hormone (ACTH) after hypopituitarism affects the release of the stress managing hormone, cortisol, from the adrenal gland. In this study, we have explored the potential role of the pituitary gland in the long-term neurological problems after repeated sub-concussive events. A modified Marmarou weight drop model for head impact acceleration was used in rats. A 450 gm weight was allowed to fall from 75 cm height on a metal disc affixed on the rat skull. For repeated sub-concussive events, the weight drop induced head impact acceleration was repeated after one week. The levels of ACTH and corticosterone were measured in the plasma on days 1, 14 and 28 after the second weight drop. No changes in ACTH levels were observed on day 1, but significant increase occurred on day 14 with further increase on day 28. Significant increase in plasma levels of corticosterone occurred on day 1, but no changes were observed on days 14 and 28. Thus, repeated sub-concussive events may lead to hyperpituitarism independent of the neuroendocrine changes occurring in the hypothalamic-pituitary-adrenal axis.
Disclaimer: The contents, opinions and assertions contained herein are private views of the authors and are not to be construed as official or reflecting the views of the Department of the Army or the Department of Defense.
Keywords: Traumatic brain injury, weight drop model , head acceleration impact, Adrenocorticotropic hormone
