Diets enriched with coconut, fish, or olive oil modify peripheral metabolic effects of ozone in rats

Serum metabolome and liver transcriptome reveal acrolein inhalation-induced sex-specific homeostatic dysfunction

Acrolein, a respiratory irritant, induces systemic neuroendocrine stress. However, peripheral metabolic effects have not been examined. Male and female WKY rats were exposed to air (0 ppm) or acrolein (3.16 ppm) for 4 h, followed by immediate serum and liver tissue collection. Serum metabolomics in both sexes and liver transcriptomics in males were evaluated to characterize the systemic metabolic response. Of 887 identified metabolites, > 400 differed between sexes at baseline. An acrolein biomarker, 3-hydroxypropyl mercapturic acid, increased 18-fold in males and 33-fold in females, indicating greater metabolic detoxification in females than males. Acrolein exposure changed 174 metabolites in males but only 50 in females. Metabolic process assessment identified higher circulating free-fatty acids, glycerols, and other lipids in male but not female rats exposed to acrolein. In males, acrolein also increased branched-chain amino acids, which was linked with metabolites of nitrogen imbalance within the gut microbiome. The contribution of neuroendocrine stress was evident by increased corticosterone in males but not females. Male liver transcriptomics revealed acrolein-induced over-representation of lipid and protein metabolic processes, and pathway alterations including Sirtuin, insulin-receptor, acute-phase, and glucocorticoid signaling. In sum, acute acrolein inhalation resulted in sex-specific serum metabolomic and liver transcriptomic derangement, which may have connections to chronic metabolic-related diseases.

Antioxidant Activity of Crocodile Oil (Crocodylus siamensis) on Cognitive Function in Rats

Crocodile oil (CO) is rich in monounsaturated fatty acids and polyunsaturated fatty acids. The antioxidant activity and cognitive effect of monounsaturated fatty acids and polyunsaturated fatty acids have been largely reported. This work aimed to investigate the effect of CO on antioxidant activity and cognitive function in rats. Twenty-one rats were divided into three treatment groups: (1) sterile water (NS), (2) 1 mL/kg of CO (NC1), and (3) 3 mL/kg of CO (NC3). Rats underwent oral gavage once daily for 8 weeks. CO treatment decreased the triglycerides level significantly compared with that in the NS group. CO had a free radical scavenging ability greater than that of olive oil but had no effect on levels of antioxidant markers in the brain. Expression of unique proteins in the CO-treatment group were correlated with the detoxification of hydrogen peroxide. Rats in the NC1 group had better memory function than rats in the NC3 group. Expression of unique proteins in the NC1 group was correlated with memory function. However, CO did not cause a decline in cognitive function in rats. CO can be an alternative dietary oil because it has a hypolipidemia effect and antioxidant activity. In addition, CO did not cause a negative effect on cognitive function.

Serum branched-chain amino acids modifies the associations between air pollutants and insulin resistance

Growing evidence supports that air pollution exposure has become a risk factor of type II diabetes mellitus through the induction of insulin resistance (IR), but the presented findings did not provide a consistent relationship between air pollution exposure and IR in the temporal scale and the magnitude. Reported associated with IR and air pollution exposure, branched-chain amino acids (BCAAs) in blood might modify the association between air pollution exposure and IR. We took advantage of an existing panel study on elderly people who were healthy or with pre-diabetes. Amino acids were analyzed from the serum samples using a UPLC-QQQ-MS, and the homeostasis model assessment of insulin resistance (HOMA-IR) values were calculated to represent the levels of IR in each visit. Exposures to PM_2.5, NO₂, SO₂, CO, O₃, and black carbon (BC) were estimated using data from a monitoring station. Linear mixed-effects models were applied to estimate the associations between the air pollution and HOMA-IR, as well as the modifying effects of BCAAs. We found significantly higher concentrations of BCAAs in the pre-diabetic subjects than healthy ones. The concentrations of BCAAs were all significantly associated with HOMA-IR. For subjects with high-level BCAAs, HOMA-IR was positively associated with an IQR increase in PM_2.5, NO₂, BC, and CO at lag day 2 and in PM_2.5, SO₂, NO₂, BC, and CO at lag day 7. While for subjects with low-level BCAAs, there was no significant association observed at any lag day except for CO at lag day 5. The study provided evidence that circulating BCAAs may modify the relationship between air pollution exposure and the level of insulin resistance in humans.

Peripheral metabolic effects of ozone exposure in healthy and diabetic rats on normal or high-cholesterol diet

Epidemiological studies show that individuals with underlying diabetes and diet-associated ailments are more susceptible than healthy individuals to adverse health effects of air pollution. Exposure to air pollutants can induce metabolic stress and increase cardiometabolic disease risk. Using male Wistar and Wistar-derived Goto-Kakizaki (GK) rats, which exhibit a non-obese type-2 diabetes phenotype, we investigated whether two key metabolic stressors, type-2 diabetes and a high-cholesterol atherogenic diet, exacerbate ozone-induced metabolic effects. Rats were fed a normal control diet (ND) or high-cholesterol diet (HCD) for 12 weeks and then exposed to filtered air or 1.0-ppm ozone (6 h/day) for 1 or 2 days. Metabolic responses were analyzed at the end of each day and after an 18-h recovery period following the 2-day exposure. In GK rats, baseline hyperglycemia and glucose intolerance were exacerbated by HCD vs. ND and by ozone vs. air. HCD also resulted in higher insulin in ozone-exposed GK rats and circulating lipase, aspartate transaminase, and alanine transaminase in all groups (Wistar>GK). Histopathological effects induced by HCD in the liver, which included macrovesicular vacuolation and hepatocellular necrosis, were more severe in Wistar vs. GK rats. Liver gene expression in Wistar and GK rats fed ND showed numerous strain differences, including evidence of increased lipid metabolizing activity and ozone-induced alterations in glucose and lipid transporters, specifically in GK rats. Collectively, these findings indicate that peripheral metabolic alterations induced by diabetes and high-cholesterol diet can enhance susceptibility to the metabolic effects of inhaled pollutants.