8565 Impact of Mild Blast Traumatic Brain Injury on Pituitary Hormone Secretion Trajectory in Male and Female Mice in Response to Restraint

Abstract Disclosure: H. Donaldson: None. T.J. Wu: None. Over 10 million people suffer from traumatic brain injury (TBI) annually. Mild blast TBI (mbTBI) account for about 80% of TBIs in service members. One third of people exposed to mbTBIs have prolonged neuroendocrine defects, particularly anterior pituitary dysfunction. Previous studies in our laboratory have shown that male and female mice demonstrate different neuroendocrine defects in response to mbTBI. Specifically, male mice with mbTBI have an increase (p<0.05) in corticosterone (CORT) response at 30 min after the initiation of restraint. Conversely, female mice show attenuated (p<0.05) levels of CORT at the same timepoint after the initiation of restraint. It is not known, however, what the trajectory of anterior pituitary hormone changes is in response to mbTBI. Our project aims to characterize the temporal relationship of peripheral anterior pituitary hormones in male and female mice in response to mbTBI and restraint. Male and female mice were randomly assigned to undergo sham or mbTBI injury using the Advanced Blast System (ABS). At 1 week after mbTBI, mice within each group were randomly assigned to be killed at 0-, 5-, 10-, 20-, 30-, or 90-min after the initiation of a 20-min restraint. At the appropriate timepoint, tissue was collected after the mice were euthanized. Prolactin (PRL) and adrenocorticotropin hormone (ACTH). were measured using commercially available ELISA. Analysis of the data show that the peak response to restraint was altered in mice exposed to the ABS. PRL increased (p<0.05) starting at 5 min in both males and females after the initiation of restraint and returned to baseline by 90 min. ACTH increased (p<0.05) starting at 10 min and 20 min after the initiation of restraint and returned to baseline by 90 min in males and females, respectively. Peak PRL was delayed in both males (20 min vs 5 min) and females (10 min vs 5 min) whereas peak ACTH advanced in both males (10 min vs 30 min) and females (20 min vs 30 min). Area under the curve analysis show that ABS decreased overall PRL in both males and females whereas ACTH was lower in males and higher in females. The results of the current study showed that mice of both sexes have different serum PRL and ACTH trajectories in response to restraint when exposed to mbTBI. Presentation: 6/2/2024