Effects of repetitive mild traumatic brain injury on weight gain and chronic behavioral outcomes in male rats.

To assess the long-term behavioral effects of repetitive mild traumatic brain injury (rmTBI), we employed a preclinical model of rmTBI and performed a battery of behavioral tests starting 14 weeks post-injury. Male Sprague-Dawley rats received four unilateral mild (6 m/s; 0.5 mm depth) controlled cortical impacts (CCI), centered 4 mm posterior and 3-4 mm lateral to the bregma, administered at five-day intervals. The animals' weights were monitored throughout the study. We tested the rats for anxiety-like (elevated plus maze, open field test), depression-like (forced swim test), locomotor (rotarod, open field test), and spatial learning and memory (Morris water maze (MWM)) behavioral deficits. Overall, a mild behavioral phenotype was observed. Significant deficits were observed with the MWM, indicating that our injury model disrupts spatial learning and memory. An interesting aspect of these data is a directional/visual component to the spatial learning and memory deficits dependent on the zone in which the trial began. With the injury being unilateral, there may be an imbalance in visual acuity that contributes to the observed deficits. Analysis of weight gain data demonstrated that rmTBI reduces weight during the period while injuries are occurring. This may represent another measure that can be tracked to determine injury severity and recovery. RNA-seq analysis demonstrated that gene expression at the chronic endpoint could distinguish between the experimental groups even with a mild behavioral phenotype. Future studies would include a more severe injury paradigm to promote longer-lasting behavior changes.

Adolescent chronic restraint stress (aCRS) elicits robust depressive-like behavior in freely cycling, adult female rats without increasing anxiety-like behaviors.

Stress during times of rapid development is a risk factor for Major Depressive Disorder, a mood disorder that disproportionately affects women. We developed an adolescent chronic restraint stress (aCRS) protocol using female rats to address the impact of adolescent stress on female adult depressive-like behavior. Animals were divided into 4 treatment groups: not restrained:saline (NRSAL), not restrained:desipramine (NRDES), restrained:saline (RSAL), and restrained:desipramine (RDES). NRSAL and NRDES rats were housed in a separate colony room from RSAL and RDES rats. All animals were weighed and handled daily. Beginning postnatal day (PND) 34(±1), RSAL and RDES rats were restrained for 1 hour daily for 14 consecutive days. Beginning PND 55(±1), NRDES and RDES rats were given subcutaneous desipramine (5 mg/kg), which served as a positive control, daily for 14 consecutive days. During that same time period, NRSAL and RSAL rats were given subcutaneous saline daily. aCRS (RSAL and RDES) rats showed significantly attenuated weight gain compared with nonrestrained (NRSAL and NRDES) rats during the restraint period. Weight gain normalized after the final restraint session. Behavioral testing took place PND 68-69(±1), and included open field testing, the elevated plus maze, locomotor activity, and the forced swim test (FST). RSAL rats showed significantly more immobility in the FST versus all other groups, indicating depressive-like behavior. No differences between groups were observed in the other behavioral measures. These results indicate that aCRS elicits depressive-like behavioral characteristics in adult female rats without increasing anxiety-like behaviors. (PsycINFO Database Record

An overview of nonpathological geroneuropsychology: implications for nursing practice and research.

One aspect of successful aging is maintaining cognitive functioning, which includes both subjective cognitive functioning and objective cognitive functioning even in lieu of subtle cognitive deficits that occur with normal, nonpathological aging. Age-related cognitive deficits emerge across several domains including attention, memory, language, speed of processing, executive, and psychomotor, just to name a few. A primary theory explaining such cognitive deficits is cognitive reserve theory; it posits that biological factors such as demyelination and oxidative stress interfere with neuronal communication, which eventually produces observable deficits in cognitive functioning. Therefore, it is important to maintain or improve cognitive reserve to augment cognitive functioning in later life. This article provides a general overview of the principles of geroneuropsychology along with implications for nursing practice and research.