Diffuse traumatic brain injury affects chronic corticosterone function in the rat.
As many as 20-55% of patients with a history of traumatic brain injury (TBI) experience chronic endocrine dysfunction, leading to impaired quality of life, impaired rehabilitation efforts and lowered life expectancy. Endocrine dysfunction after TBI is thought to result from acceleration-deceleration forces to the brain within the skull, creating enduring hypothalamic and pituitary neuropathology, and subsequent hypothalamic-pituitary endocrine (HPE) dysfunction. These experiments were designed to test the hypothesis that a single diffuse TBI results in chronic dysfunction of corticosterone (CORT), a glucocorticoid released in response to stress and testosterone. We used a rodent model of diffuse TBI induced by midline fluid percussion injury (mFPI). At 2months postinjury compared with uninjured control animals, circulating levels of CORT were evaluated at rest, under restraint stress and in response to dexamethasone, a synthetic glucocorticoid commonly used to test HPE axis regulation. Testosterone was evaluated at rest. Further, we assessed changes in injury-induced neuron morphology (Golgi stain), neuropathology (silver stain) and activated astrocytes (GFAP) in the paraventricular nucleus (PVN) of the hypothalamus. Resting plasma CORT levels were decreased at 2months postinjury and there was a blunted CORT increase in response to restraint induced stress. No changes in testosterone were measured. These changes in CORT were observed concomitantly with altered complexity of neuron processes in the PVN over time, devoid of neuropathology or astrocytosis. Results provide evidence that a single moderate diffuse TBI leads to changes in CORT function, which can contribute to the persistence of symptoms related to endocrine dysfunction. Future experiments aim to evaluate additional HP-related hormones and endocrine circuit pathology following diffuse TBI.
Phoenix Veterans Affairs Health Care SystemPhoenix, Arizona, USA BARROW Neurological Institute at Phoenix Children's HospitalPhoenix, Arizona, USA Department of Child HealthUniversity of Arizona College of Medicine - Phoenix, Phoenix, Arizona, USA.
Rachel K
RK
Rowe
BARROW Neurological Institute at Phoenix Children's HospitalPhoenix, Arizona, USA Department of Child HealthUniversity of Arizona College of Medicine - Phoenix, Phoenix, Arizona, USA Department of Biology and BiochemistryUniversity of Bath, UK.
Benjamin M
BM
Rumney
BARROW Neurological Institute at Phoenix Children's HospitalPhoenix, Arizona, USA Department of Child HealthUniversity of Arizona College of Medicine - Phoenix, Phoenix, Arizona, USA Department of Biology and BiochemistryUniversity of Bath, UK.
Hazel G
HG
May
Phoenix Veterans Affairs Health Care SystemPhoenix, Arizona, USA.
Paska
P
Permana
BARROW Neurological Institute at Phoenix Children's HospitalPhoenix, Arizona, USA Department of Child HealthUniversity of Arizona College of Medicine - Phoenix, Phoenix, Arizona, USA School of Biological and Health Systems EngineeringArizona State University, Tempe, Arizona, USA.
P David
PD
Adelson
Phoenix Veterans Affairs Health Care SystemPhoenix, Arizona, USA.
S Mitchell
SM
Harman
Phoenix Veterans Affairs Health Care SystemPhoenix, Arizona, USA BARROW Neurological Institute at Phoenix Children's HospitalPhoenix, Arizona, USA Department of Child HealthUniversity of Arizona College of Medicine - Phoenix, Phoenix, Arizona, USA.
Jonathan
J
Lifshitz
Phoenix Veterans Affairs Health Care SystemPhoenix, Arizona, USA BARROW Neurological Institute at Phoenix Children's HospitalPhoenix, Arizona, USA Department of Child HealthUniversity of Arizona College of Medicine - Phoenix, Phoenix, Arizona, USA theresathomas@email.arizona.edu.
Theresa C
TC
Thomas
TBI; concussion; corticosterone; stress