Dietary EPA Increases Rat Mortality in Diabetes Mellitus, A Phenomenon Which Is Compensated by Green Tea Extract

Impact of chronic psychological stress on platelet membrane fatty acid composition in a rat model of type 1 diabetes Mellitus

BACKGROUND

Chronic stress and diabetes mellitus are highly associated with oxidative stress and inflammation, resulting in cell membrane disruption and platelet activity. This study aims to evaluate the impact of chronic psychological stress on the composition of the platelet phospholipid membrane and platelet activation in type 1 diabetes mellitus (T1DM).

METHODS

We enrolled 35 mature healthy female Wistar rats and randomly divided them into 4 groups, namely the control group (n = 9), stress group (n = 10), T1DM group (n = 8), and T1DM + Stress group (n = 8). The Wistar rats were treated in different experimental conditions for 28 days while being provided free access to feed and water. The concentration of corticosterone in blood serum and hair samples was measured using a competitive enzyme-linked immunosorbent assay. Gas chromatography-mass spectrometry was conducted to identify the methyl esters of fatty acids (FAs) in the platelet phospholipid membrane. A quantitative determination of 11-dehydro-thromboxane B2 in the blood serum was also performed using a competitive enzyme-linked immunosorbent assay.

RESULTS

After 28 days, the concentration of corticosterone in blood serum (ng/mL) was observed to be higher in the stress group as compared to the T1DM and T1DM + Stress groups (P = 0.031 and P = 0.008, respectively). The percentage of C 16:0 FA in the platelet membrane was greater in the T1DM + Stress group, but its levels of C 20:1 omega (ω) 9 FA, including C 18:3ω3 FA, C 20:5ω3 FA, and the total sum of ω3 FAs, were lower as compared to the control group (P = 0.016; P = 0.016; P = 0.031; P = 0.016, P = 0.031). The concentration of 11-dehydro-thromboxane B2 in blood serum (pg/mL) was observed to be higher in the stress group than in rats with T1DM (P = 0.063).

CONCLUSION

Chronic psychological stress is related to higher levels of corticosterone, saturated FAs acids in the platelet membrane, and greater platelet activation. This study proves how a low percentage of unsaturated fatty acids in the DM and stress groups indicates the disturbing impact of the oxidative/inflammatory environment to lipid metabolism and neuroendocrine response.

DEHP and DBP, common phthalates, induce glucose metabolism disorders in rats via oxidative damage of PI3K/Akt/GLUT4 signaling

Phthalic acid esters (PAEs) are environmental endocrine disruptors thought to interfere with glucose metabolism in humans. Most of the related research has focused on population epidemiological studies, with the underlying mechanisms remaining unresolved. Using an in vivo animal model, we examined the effects of oral administration of two commonly used PAEs [di(2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP)] on glucose homeostasis and insulin secretion. DEHP (750 mg/kg, 1/40 LD50), DBP (500 mg/kg, 1/40 LD50), and DEHP (750 mg/kg) + DBP (500 mg/kg) exert an influence on glucose metabolism and elicit a reduction in insulin sensitivity in rats. Furthermore, these substances induce detrimental effects on the structure and functionality of pancreatic β-cells. DEHP and/or DBP triggered an increase in plasma malondialdehyde (MDA) and reduction in superoxide dismutase (SOD) activity; a reduction in the phosphorylation of phosphatidyl inositol 3 kinase (PI3K) and phospho-protein kinase B (p-Akt473) proteins; an increase in the relative expression of Bax, Caspase-8, cleaved-Caspase-9, and cleaved-Caspase-3; and a reduction in the relative expression of Bcl-2-related Bax in pancreatic tissue and of gastrocnemius glucose transporter 4 (GLUT4) in the gastrocnemius muscle. Based on these findings, these PAEs can disrupt glucose metabolism, possibly via oxidative damage of the PI3K/Akt/GLUT4 pathway; this damage induces pancreatic β-cell apoptosis, affects pancreatic β-cell function, and affects glucose metabolism and insulin resistance in rats. To the best of our knowledge, this study was the first to show that the combined effect of the two PAEs affects glucose metabolism and insulin resistance in rats that is significantly higher than the effects of each PAE. Thus, safety standards and studies do not consider this effect as a significant oversight when blending PAEs. We assert that this must be addressed and corrected for establishing more impactful and safer standards.

Trimethylamine N-oxide facilitates the progression of atrial fibrillation in rats with type 2 diabetes by aggravating cardiac inflammation and connexin remodeling

Diabetes is an independent risk factor for atrial fibrillation (AF). This study aimed to elucidate the pathophysiology of diabetes-related AF from the perspective of the gut microbial metabolite trimethylamine N-oxide (TMAO). In the present study, male rats received either a normal diet to serve as the control group or a high-fat diet/streptozotocin to induce type 2 diabetes mellitus. Then, diabetic rats were divided into two groups based on the presence or absence of 3,3-dimethyl-1-butanol (DMB, a specific TMAO inhibitor) in drinking water: the diabetic cardiomyopathy (DCM) group and the DCM + DMB group. Eight weeks later, compared with control rats, rats in the DCM group exhibited gut microbiota dysbiosis and systemic TMAO elevation. The inflammatory cytokines IL-1β, IL-6, and TNF-α were markedly increased in the atria of rats in the DCM group. Downregulated expression of connexin 40 and lateralized distribution of connexin 43 were also observed in the atria of DCM rats. AF inducibility was significantly higher in DCM rats than in control rats. Furthermore, DMB treatment effectively ameliorated atrial inflammation and connexin remodeling while markedly reducing plasma TMAO levels. DMB treatment also decreased the vulnerability of diabetic rats to AF. In conclusion, TMAO might promote atrial inflammation and connexin remodeling in the development of diabetes, which may play a key role in mediating diabetes-related AF.