Limited detection of Gulf War illness-like behavioral phenotypes in Charles River male Sprague-Dawley rats across multiple chemical and stress exposure paradigms

Gulf War illness (GWI) is characterized by a range of neurological and neuropsychiatric symptoms, including chronic pain, fatigue, mood problems, and cognitive impairment. The pathophysiology is associated with war-related environmental chemical exposure and psychological stress, which are known to disrupt glutamatergic synaptic structure and function. The original objective of this study was to evaluate the efficacy of LH-001, an investigational compound designed to enhance tripartite glutamatergic synapses, in a rat model of GWI. We initially attempted to induce GWI-like behavioral phenotypes in Charles River male Sprague–Dawley (SD) rats using a previously published protocol employed for male SD rats from Harlan involving exposure to Gulf War-related chemical agents and mild stress. Because robust behavioral phenotypes were not detected, we subsequently modified the induction protocol by increasing chemical exposure intensity and stress levels. Despite these adjustments, GWI-like behavioral phenotypes were not detected under the experimental conditions evaluated. To better interpret these findings, we compared our protocol and outcomes with previously published GWI rat studies. This comparison revealed substantial variability across studies in exposure paradigms, animal sources, timing of behavioral assessments, and reported outcomes. Collectively, our findings suggest that detection of GWI-like behavioral phenotypes in rats may be sensitive to experimental conditions and highlight the importance of continued efforts to validate, optimize, and standardize animal models to improve translational rigor and support preclinical therapeutic development.