Determining the Differences in Acute Phase of Astrocytic Activation Between Male and Female Rats – A Research Protocol

Abstract

Introduction: Primary blast injuries are a common cause of mild traumatic brain injury (mTBI) and are the leading cause of both closed and open-skull brain injuries. Following mTBI, astrocytic activation and reactive gliosis occur which results in an upregulation of various astrocytic markers such as glial fibrillary acidic protein (GFAP). These markers can act as biomarkers for patients with mTBI. This protocol will examine how primary blast injury affects the acute phase of astrocytic activation in male and female rats.

Rationale: This experiment will determine the sex differences in astrocytic activation after male and female rodent mTBI to replicate the effects of primary blast injury resulting from improvised explosive device (IED) impact in humans. These injuries are the most common cause of concussions in deployed military personnel. Understanding sex differences in the extent of astrocytic activation and the time window between blast impact and initial activation will have implications for trauma treatment in the field to prevent excessive neurodegeneration. There is also a lack of research on the sex-specific acute astrocytic activation resulting from blast injuries.

Methods: Adult male and female wild-type Sprague Dawley rats will be randomly assigned to (a) male sham, (b) female sham, (c) male mTBI, or (d) female mTBI group. After each rat is exposed to the primary blast injury, coronal sections of the brains will be collected. Flow cytometry and quantitative polymerase chain reaction (qPCR) will be used to analyze astrocytic gene expression.

Expected Results: For the 48-hour duration following primary blast injuries, GFAP levels are expected to increase to different extents for both males and females. We expect this difference between males and females to occur due to hormonal suppression of astrogliosis in females.

Discussion: The analysis of astrocytic activation among female and male rats caused by closed skull blast-specific injury will help to determine sex-specific treatments and therapeutic applications for injured military soldiers.

Conclusion: This study will allow for a greater understanding of sex differences in astrocytic activation, which may benefit treatment plans for mTBI patients.