Neuro-Behavioral Effects of Blast Injury on Neurohypophysial Hormone Producing Neurons in Sprague Dawley Rats: Impact on Allostasis
Abstract
Service members and civilians are exposed to mild blast-induced neurotrauma through combat, terrorist, and other man-made events. Mild blast traumatic brain injury (mbTBI) can cause neurodegeneration with cognitive and behavioral changes that negatively impact health and quality of life. Magnocellular and parvocellular neurons in the paraventricular nucleus (PVN) and supraoptic nucleus (SON) produce oxytocin and vasopressin. These neuropeptides act as allostatic mediators to influence the stress response and learning and memory that underlie social behaviors. Following mbTBI the anti-inflammatory effect of minocycline can mitigate damage to neuronal tissue, and housing in an enriched environment (EEN) may also aid in neuronal tissue recovery. This study used immunohistochemistry to visualize the PVN and SON of Sprague-Dawley rats (N=23) to determine the effect of an mbTBI (20 + or - 3 p.s.i.) on oxytocin and vasopressin producing neurons. We then compared the effect of EEN and minocycline therapy on oxytocin and vasopressin neurons following mbTBI. We also compared the mbTBI effect on these neurons to behavioral test results of the Elevated Plus Maze (EPM), Barnes Maze (BM), and Open Field Test (OFT). Our results showed that mbTBI resulted in complete absence of oxytocin and vasopressin immunostaining in the PVN and SON. Compared to controls, rats that were environmentally enriched had more oxytocin neurons in the PVN. Treatment with minocycline both immediately and at 3538 days after injury, reversed the effect of mbTBI on expression of oxytocin and vasopressin neurons. We did not find that negatively affected neurons were related to spatial learning and memory scores. Furthermore, decreased number of oxytocin and vasopressin neurons did not reflect increased anxiety, but locomotor activity did decrease over time possibly due to the stress of repetitive testing.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 29, 2015
- Accession Number
- AD1127853
Entities
People
- Susan Galloway
Organizations
- Uniformed Services University of the Health Sciences