Neurological restorative effects of the flavanol (-)-epicatechin in a rodent model of Gulf War Illness.

Gulf War Illness (GWI) afflicts ~30% of the US military personnel who served in the 1990-91 Persian Gulf War. Symptoms include cognitive deficits, muscle pain, weakness, exercise intolerance and fatigue which are still present after 30 years in war Veterans. Suspect causal agents include exposure to the compounds pyridostigmine (PB), permetrim (PM) and N,N-diethyl-m-toluamide (DEET) which were used as protectants against nerve gases (PB) and insects. We previously reported a study to model GWI in which young male rats were provided PB, PM and DEET at equivalent human doses and physical restraint (to induce stress) for 3 weeks. In GWI animals, skeletal muscle weight was 35% lower vs. controls, which correlated with decreases in myofiber area, limb strength and treadmill time/distance. In a follow up study, we reported on the beneficial effects of the cacao flavanol (-)-epicatechin (epi) provided for 2 weeks by oral gavage on skeletal muscle atrophy and loss of function. In the current study, we wished to explore the potential of Epi to beneficially impact neurological measures of memory including multiple markers of hippocampus structure and function. Male Wistar rats underwent 3 weeks of exposure to either vehicles or DEET, PM, PB and stress. Subgroups of GWI rats (n=7/subgroup) received 15 days of either water (vehicle) or 1 mg/kg/day of Epi treatment by oral gavage and were compared to normal control (n=7). Object recognition tasks were performed to assess effects on memory and hippocampus samples were collected for histological and biochemical analysis. Results demonstrate that Epi treatment yields significant improvements in short and long-term memory vs. GWI rats yielding values similar to those of controls. The assessment of hippocampus oxidative stress (protein carbonylation) and pro-inflammatory cytokines levels (ELISA) of IL-1β, TNF-α and IFN-γ (figure) yielded significant increases with GWI that were fully normalized with Epi to become comparable to controls. Significant increases in markers of hippocampus neuroinflammation (Iba1 and GFAP) and cell death (caspase activity) were noted with GWI and were significantly reduced with Epi. The neuronal survival signaling pathways (TREM2, PI3K and AKT) were adversely impacted by GWI and were partially or fully restored by Epi. Multiple markers of mitochondrial function (citrate synthase activity and ATP levels) adversely impacted by GWI and were fully restored by Epi. Thus, in an animal model of GWI, Epi beneficially impacted markers of hippocampus neuroinflammation, oxidative stress, cell survival, neurotoxicity and mitochondrial function. Such effects translated into improvements in functional endpoints associated with memory centers. As per the recognized safety profile of Epi clinical studies are warranted to explore the effects of treatment in Gulf War Veterans.