Short and long-term motor and behavioral effects of diazoxide and dimethyl sulfoxide administration in the mouse after traumatic brain injury.

Traumatic brain injury (TBI) is a worldwide phenomenon that affects all ages and socioeconomic classes and results in varying degrees of immediate and delayed motor, cognitive, and emotional deficiencies. A plethora of pharmacologic interventions that target recognized initiators and propagators of pathology are being investigated in an attempt to ameliorate secondary injury processes that follow primary injury. Diazoxide (DZ), a K(ATP) channel activator, has been shown to provide short- and long-term protective effects in a variety of in vitro and in vivo cerebral ischemia models. However, the effects of DZ on behavioral outcome following TBI have not been investigated. TBI was induced in male C57BL/6J mice by controlled cortical impact (CCI) and followed by intraperitoneal administration of either normal saline, dimethyl sulfoxide (DMSO), or 2.5 mg/kg DZ in DMSO, 30 min post-injury and daily for three days. Open field and beam walk performances were used to assess motor and behavioral function 1, 7, and 14 days following injury. Spatial learning and memory were assessed three weeks following injury using the Morris water maze. Injured mice were significantly impaired on the beam-walk and Morris water maze tasks, and were hyperactive and anxious in an open field environment. On post-injury days 1 and 14, mice treated with DMSO exhibited an increase in the amount of time required to perform the beam walk task. In addition, animals exposed to DMSO or DZ+DMSO exhibited slower swimming speed in the Morris water maze on the final day of testing. There was no therapeutic effect, however, of the treatment or vehicle on open field behavior or learning and memory function in the Morris water maze. In summary, CCI produced significant long-term impairment of motor, memory, and behavioral performance measures, and DZ administration, under the conditions used, provided no functional benefits following injury.

Mouse brain PSA-NCAM levels are altered by graded-controlled cortical impact injury.

Traumatic brain injury (TBI) is a worldwide endemic that results in unacceptably high morbidity and mortality. Secondary injury processes following primary injury are composed of intricate interactions between assorted molecules that ultimately dictate the degree of longer-term neurological deficits. One comparatively unexplored molecule that may contribute to exacerbation of injury or enhancement of recovery is the posttranslationally modified polysialic acid form of neural cell adhesion molecule, PSA-NCAM. This molecule is a critical modulator of central nervous system plasticity and reorganization after injury. In this study, we used controlled cortical impact (CCI) to produce moderate or severe TBI in the mouse. Immunoblotting and immunohistochemical analysis were used to track the early (2, 24, and 48 hour) and late (1 and 3 week) time course and location of changes in the levels of PSA-NCAM after TBI. Variable and heterogeneous short- and long-term increases or decreases in expression were found. In general, alterations in PSA-NCAM levels were seen in the cerebral cortex immediately after injury, and these reductions persisted in brain regions distal to the primary injury site, especially after severe injury. This information provides a starting point to dissect the role of PSA-NCAM in TBI-related pathology and recovery.