Degree of lipid saturation affects depressive-like behaviour and gut microbiota in mice.

This study explored the effects of the degree of lipid saturation on depressive behaviour and gut microbiota in mice. Thirty-two mice were divided into normal (N), Prozac (NP), lard (L) and fish oil (F) groups. After a 12-week dietary intervention, the open field test (OFT) and the forced swim test (FST) were conducted before sacrifice. The mice in the L group exhibited anxiety-like behaviours in the OFT and depressive-like behaviours in the FST. A significant difference was observed in ß-diversity indices between the L group and the F group. The abundance of Allobaculum and Bifidobacterium was significantly higher in the F group than in the L and N groups. The prefrontal cortex fatty acid composition was altered in various lipid-treated groups and was highly correlated with depressive-like behaviours. In conclusion, the degree of lipid saturation affects depressive-like behaviour, gut microbiota composition, and the prefrontal cortex fatty acid profile in mice.

A high linoleic acid diet exacerbates metabolic responses and gut microbiota dysbiosis in obese rats with diabetes mellitus.

Dietary polyunsaturated fatty acid (PUFA) levels may affect inflammatory responses and lipid metabolism. Gut microbiota diversity is strongly associated with chronic inflammatory disease, diabetes mellitus (DM), and obesity through abnormal energy homeostasis. In this study, the association between metabolic responses and gut microbiota diversity at different dietary n-6/n-3 PUFA ratios was evaluated in DM rats. Obesity and DM were induced in rats by using a high-fat diet and streptozotocin (STZ), respectively. The obese DM rats were assigned to three groups and administered regular (R), high (H), and low (L) n-6/n-3 ratio diets (n-6/n-3 = 6.39, 3.02, and 9.29, respectively) for 6 weeks. Some metabolic parameters and gut microbiota of the rats were analysed. The results revealed that a high linoleic acid diet increased the plasma and kidney interleukin 6 levels, whereas a low n-6/n-3 ratio diet ameliorated blood glucose homeostasis, reduced plasma tumour necrosis factor α levels, and inhibited systematic inflammation. DM rats exhibited low gut microbiota diversity; however, compared with the R group, the L and H groups did not exhibit alterations in the α-diversity (Observed, Chao 1, Shannon and Simpson). The percentage of Firmicutes was lower in the DM groups than in the non-DM group; however, the L group showed a nonsignificantly higher Firmicutes/Bacteroidetes ratio than did the other groups. Thus, a low n-6/n-3 ratio diet can improve blood glucose homeostasis, reduce systematic inflammation, ameliorate glomerular basal membrane thickening, reduce the expression of receptors of advanced glycation end products in renal vessel walls, and prevent diabetic nephropathies.

n-3 polyunsaturated fatty acids prevent d-galactose-induced cognitive deficits in prediabetic rats.

Nutritional deficit of n-3 polyunsaturated fatty acids (PUFAs) is closely related to cognitive impairment and depression in later life. Cognitive impairment and depression lead to comorbidities, such as metabolic syndrome, in elderly people. The aim of this study is to evaluate the effects of dietary n-3 PUFAs on cognition and depressive-like behavior in an accelerated senescence rat model with prediabetic status. Rats were cotreated with d-gal and sucrose solution for 7 months and then fed fish-oil- or flaxseed-oil-rich diets for 3 months. Cognitive impairment analysis and depressive-like behavioral testing were conducted using the Morris water maze (MWM) test and forced swimming test (FST), respectively. The MWM test results revealed that the d-gal + sucrose + flaxseed oil (DSFS) group had a significantly shorter mean latency time in the short-term spatial memory trial on day 2 than did the d-gal + sucrose + fish oil (DSFO) group. The FST results demonstrated that the DSFO group exhibited a significantly shorter immobility time and longer climbing time than did the control group. Western blot analysis of the receptor for advanced glycation end-product (RAGE) level identified a significant difference in the DSFO group compared with the control group. Significantly lower n-6/n-3 PUFA ratios were observed in the frontal cortices of the DSFO and DSFS groups. In conclusion, fish and flaxseed oils exerted a protective effect on cognitive impairment and decreased the incidence of depressive-like behavior in d-gal- and sucrose-fed prediabetic aging rats. n-3 PUFA-rich oil diets, particularly the fish oil diet, reduced the plasma levels of nonesterified fatty acids, tumor necrosis factor-α, and brain dopamine and RAGE expression but not glycemic status, resulting in an improvement in the time of escape latency and the time spent in the target quadrant in the MWM test.