Background Gulf War Illness (GWI) is a chronic multi‐symptom disorder experienced by as many as a third of the veterans of the 1991 Gulf War. GWI mainly affects nervous and skeletal muscle (SkM) systems yielding cognitive deficit, depression, muscle pain, weakness, intolerance to exercise and fatigue. Military personnel was exposed to toxic substances such as insecticides and repellents like permetrim (PM), N;N‐diethyl‐m‐toluamide (DEET), and pyridostigmine (PB) provided as a prophylactic for a nerve gas attack. Methods Three months old male Wistar rats were used for all experiments (n=50). Control group (n=10) were provided water (oral), 70% ethanol (applied to back skin). The PB group (n=10) were given pyridostigmine 1.3 mg/kg/day by oral gavage. The PM group (n=10) were dosed at 0.13 mg/kg/day (back of shaved skin in 70% ethanol). The DEET group (n=10) were dosed at 40 mg/kg/day (back skin in ethanol). A physically restrained group (n=10) was also included with animals being restrained for 5 min/day (in rat plexiglass holders). Treatments were provided daily for 3 weeks. At 6 weeks, animals were subjected to treadmill and front limb strength testing followed by euthanasia and SkM (gastrocnemius) muscles collected for histological and biochemical analysis. Results Animals exposed to chemicals did not evidence changes in body weight or food intake. The front limb strength of the animals was recorded weekly. Significant strength increases were recorded in control, PM, DEET and restricted groups. However, in the PB group strength increases were not detected showing ~ 35% decrease vs. contros. At the end of the treatment phase, overall physical endurance was evaluated on a treadmill. This evaluation demonstrated that the groups administered with the different chemical agents (PM, PB and DEET) significantly blunted the fatigue resistance time (on average 12 minutes) vs. controls (18 min). The gastrocnemius mass (weight) of animals exposed to PB, PM and DEET were significantly decreased by ~15% vs. controls. Gastrocnemius myofiber cross area measurements (CSA) were measured and results demonstrate that in the PB, PM and DEET groups it is significantly decreased by ~13% vs. controls. Oxidative stress levels were assessed in muscles and we observed that groups administered with DEET, PM and PB increased carbonyl protein content (average >40 nmol/ml) vs. controls (25 nmol/ml). The plasma levels of the pro‐inflammatory cytokines IL‐1b, TNF‐a, and IFN‐g were elevated only in the PB group (vs. controls) with no differences noted with the other chemical agents. Conclusions Exposure of rodents to equivalent human doses of associated GWI chemicals leads to a loss of muscle mass and strength and/or function. These effects are likely related to increases in oxidative stress and/or pro‐inflammatory cytokines.

Background Menopausal women suffer from various symptoms due to estrogen deficiency. Menopause can occur as a natural progression of aging or following the surgical removal of the ovaries or their damage from treatments such as chemotherapy. In women, estrogens are known to play a key role in regulating metabolism, cardiovascular, brain and bone structure and function amongst other organs and systems. However, little is known about the impact that low estrogen levels have on skeletal muscle structure and function. The flavanol (−)‐epicatechin (Epi; which is present in large concentrations in cacao) decreases muscle fatigue and promotes skeletal muscle growth in animal models. In clinical studies, the administration of cocoa and/or Epi can (in normal subjects) enhance muscle function while limiting the organ damage seen in Becker or Duchenne muscular dystrophy patients. Objective This study aims to characterize the long‐term effects of ovarian hormone depletion on skeletal muscle (macro and microscopic) structure and function. We also wish to explore the capacity of Epi treatment to reverse the loss induced by hormone depletion in muscle mass and function. Methods Three month old female Wistar rats were used for the experiments (n=30). Animals were allocated into 3 groups: 1) sham, 2) ovariectomized (OVX, provided water by daily gavage) and, 3) OVX plus Epi treatment (provided Epi daily by oral gavage at 1 mg/kg/day dissolved in water). Once animals were allocated into their groups, they were subjected to surgery and allowed to recover for 1 week before gavage was initiated. Over the course of 3 months, the estrous cycle, body weight, and food intake of the rats was monitored. Animals were also subjected to treadmill and front limb strength testing. At the time of euthanasia, the gastrocnemius and EDL muscle were collected as well as blood samples for biochemical and/or histological analysis. Results After 3 month of ovariectomy, rats developed significant decreases in skeletal muscle mass, loss of front limb strength (~15%) and endurance as measured by treadmill testing (~50%). Histology analysis of gastrocnemius samples demonstrated significant decreases in myofiber cross sectional area. The analysis of skeletal muscle samples by Western blots also demonstrated significant increases in the content of atrophy pathway associated proteins (MURF, ATF1, atrogin) (~30%). In blood, significant increases in circulating levels of the proinflammatory cytokines occurred (~50%). Three week of treatment with Epi was able to fully restore the loss of muscle mass. Within1 week of treatment a recovery of front limb strength was noted to occur. Terminal treadmill testing also demonstrated a full recovery of exercise capacity of ovariectomized rats treated with Epi. Conclusions In this study we demonstrate the significant adverse impact that reductions in ovarian hormones play on skeletal muscle structure and function. Most strikingly, Epi was able to fully reverse the deleterious effects of ovariectomy. Of interest is that Epi h...

We examined in a rat model of Gulf War illness (GWI), the potential of (-)-epicatechin (Epi) to reverse skeletal muscle (SkM) atrophy and dysfunction, decrease mediators of inflammation and normalize metabolic perturbations. Male Wistar rats (n = 15) were provided orally with pyridostigmine bromide (PB) 1.3 mg/kg/day, permethrin (PM) 0.13 mg/kg/day (skin), DEET 40 mg/kg/day (skin) and were physically restrained for 5 min/day for 3 weeks. A one-week period ensued to fully develop the GWI-like profile followed by 2 weeks of either Epi treatment at 1 mg/kg/day by gavage (n = 8) or water (n = 7) for controls. A normal, control group (n = 15) was given vehicles and not restrained. At 6 weeks, animals were subjected to treadmill and limb strength testing followed by euthanasia. SkM and blood sampling was used for histological, biochemical and plasma pro-inflammatory cytokine and metabolomics assessments. GWI animals developed an intoxication profile characterized SkM atrophy and loss of function accompanied by increases in modulators of muscle atrophy, degradation markers and plasma pro-inflammatory cytokine levels. Treatment of GWI animals with Epi yielded either a significant partial or full normalization of the above stated indicators relative to normal controls. Plasma metabolomics revealed that metabolites linked to inflammation and SkM waste pathways were dysregulated in the GWI group whereas Epi, attenuated such changes. In conclusion, in a rat model of GWI, Epi reverses detrimental changes in SkM structure including modulators of atrophy, inflammation and select plasma metabolites yielding improved function.