Restoration of cardiac metabolic flexibility by acetate in high-fat diet-induced obesity is independent of ANP/BNP modulation.

The present study hypothesized that cardiac metabolic inflexibility is dependent on cardiac atrial natriuretic peptide/brain natriuretic peptide (ANP/BNP) alteration and histone deacetylase (HDAC) activity. We further sought to investigate the therapeutic potential of short-chain amino acid (SCFA) acetate in high-fat diet (HFD)-induced obese rat model. Adult male Wistar rats were assigned into groups (n = 6 per group): Control, Obese, and Sodium acetate (NaAc)-treated and Obese + NaAc-treated groups received distilled water once daily (oral gavage), 40% HFD ad libitum, 200 mg/kg NaAc once daily (oral gavage), and 40% HFD + NaAc, respectively. The treatments lasted for 12 weeks. HFD resulted in increased food intake, body weight, and cardiac mass. It also caused insulin resistance and enhanced ß-cell function, increased fasting insulin, lactate, plasma and cardiac triglyceride, total cholesterol, lipid peroxidation, tumor necrosis factor-α, interleukin-6, HDAC, and cardiac troponin T and γ-glutamyl transferase, and decreased plasma and cardiac glutathione with unaltered cardiac ANP and BNP. However, these alterations were averted when treated with acetate. Taken together, these results indicate that obesity induces defective cardiac metabolic flexibility, which is accompanied by an elevated level of HDAC and not ANP/BNP alteration. The results also suggest that acetate ameliorates obesity-induced cardiac metabolic inflexibility by suppression of HDAC and independent of ANP/BNP modulation.

Estrogen-progestin oral contraceptive and nicotine exposure synergistically confers cardio-renoprotection in female Wistar rats.

Approximately fifty percent of premenopausal women who smoke cigarettes or on nicotine replacement therapy are also on hormonal contraceptives, especially oral estrogen-progestin. Oral estrogen-progestin therapy has been reported to promote insulin resistance (IR) which causes lipid influx into non-adipose tissue and impairs Na+/K+ -ATPase activity, especially in the heart and kidney. However, the effects of nicotine on excess lipid and altered Na+/K+ -ATPase activity associated with the use of estrogen-progestin therapy have not been fully elucidated. This study therefore aimed at investigating the effect of nicotine on cardiac and renal lipid influx and Na+/K+ -ATPase activity during estrogen-progestin therapy. Twenty-four female Wistar rats grouped into 4 (n = 6/group) received (p.o.) vehicle, nicotine (1.0 mg/kg) with or without estrogen-progestin steroids (1.0 µg ethinyl estradiol and 5.0 µg levonorgestrel) and estrogen-progestin only daily for 6 weeks. Data showed that estrogen-progestin treatment or nicotine exposure caused IR, hyperinsulinemia, increased cardiac and renal uric acid, malondialdehyde, triglyceride, glycogen synthase kinase-3, plasminogen activator inhibitor-1, reduced bilirubin and circulating estradiol. Estrogen-progestin treatment led to decreased cardiac Na+/K+-ATPase activity while nicotine did not alter Na+/K+-ATPase activity but increased plasma and tissue cotinine. Renal Na+/K+-ATPase activity was not altered by the treatments. However, all these alterations were reversed following combined administration of oral estrogen-progestin therapy and nicotine. The present study therefore demonstrates that oral estrogen-progestin therapy and nicotine exposure synergistically prevents IR-linked cardio-renotoxicity with corresponding improvement in cardiac and renal lipid accumulation, oxidative stress, inflammation and Na+/K+-ATPase activity.

Sodium acetate protects against nicotine-induced excess hepatic lipid in male rats by suppressing xanthine oxidase activity.

Fatty liver is the hepatic consequence of chronic insulin resistance (IR) and related syndromes. It is mostly accompanied by inflammatory and oxidative molecules. Increased activity of xanthine oxidase (XO) exerts both inflammatory and oxidative effects and has been implicated in metabolic derangements including non-alcoholic fatty liver disease. Short chain fatty acids (SCFAs) elicit beneficial metabolic alterations in IR and related syndromes. In the present study, we evaluated the preventive effects of a SCFA, acetate, on nicotine-induced dysmetabolism and fatty liver. Twenty-four male Wistar rats (n = 6/group): vehicle-treatment (p.o.), nicotine-treated (1.0 mg/kg; p.o.), sodium acetate-treated (200 mg/kg; p.o.) and nicotine + sodium acetate-treated groups. The treatments lasted for 8 weeks. IR was estimated by oral glucose tolerance test and homeostatic model assessment of IR. Plasma and hepatic free fatty acid, triglyceride (TG), glutathione peroxidase, adenosine deaminase (ADA), XO and uric acid (UA) were measured. Nicotine exposure resulted in reduced body weight, liver weight, visceral adiposity, glycogen content and glycogen synthase activity. Conversely, exposure to nicotine increased fasting plasma glucose, lactate, IR, plasma and hepatic TG, free fatty acid, TG/HDL-cholesterol ratio, lipid peroxidation, liver function enzymes, plasma and hepatic UA, XO and ADA activities. However, plasma and hepatic glucose-6-phosphate dehydrogenase-dependent antioxidant defense was not affected by nicotine. Concomitant treatment with acetate ameliorated nicotine-induced effects. Taken together, these results indicate that nicotine exposure leads to excess deposition of lipid in the liver by enhancing XO activity. The results also imply that acetate confers hepatoprotection and is accompanied by decreased XO activity.