Modulation of gut microbiota by dietary supplementation with tuna oil and algae oil alleviates the effects of D-galactose-induced ageing.

Previous studies have shown that dietary supplementation with tuna oil and algae oil can alleviate the effects of ageing on learning and memory in mouse models, but the mechanism of this effect remains unknown. This study aimed to determine whether dietary oil supplementation alters the composition of the gut microbiota during the prevention of age-related effects on cognition. Ageing mice received dietary oil supplementation continuously for 12 weeks. The supplementation was found to improve the animals' learning and cognition, and this effect was most marked in the TO200AO400 group, which received a 1:2 mixture of tuna oil and algae oil at 600 mg kg-1 day-1. Next-generation sequencing of the 16S rRNA gene present in faecal samples showed that the gut microbiota varied in the groups that received different oil treatments; the TO200AO400 treatment most closely restored the composition of the D-galactose-altered gut microbiota to that of the control. Moreover, 83 altered operational taxonomic units (OTUs) responsive to dietary oil supplementation were identified; five of these differed in one or more parameters associated with host ageing. In conclusion, this study confirmed the effect of dietary oil supplementation on the alleviation of age-related decline in cognitive function and showed that oil supplementation results in alterations in the composition of the gut microbiota. Further research will be needed to elucidate the causal relationship between the reversal of age-related cognitive decline and gut microbiota modulation and to explore the potential of gut microbial communities as a diagnostic biomarker and a therapeutic target in ageing.

Dietary Apostichopus japonicus Alleviates Diabetes Symptoms and Modulates Genes Expression in Kidney Tissues of db/db Mice.

The effects of Apostichopus japonicus enzymatic hydrolysate on the regulation of dyslipidemia, pathoglycemia, and transcription changes in kidney tissues of db/db mice were evaluated. In this study, the symptoms of diabetes in db/db mice were alleviated after 10 weeks of treatments with low (db/db + LD group) and high dose (db/db + HD group) of Apostichopus japonicus enzymatic hydrolysate, and the high dose treatment showed a better antidiabetic effect. Compared with the db/db group, the fasting blood glucose levels (36.84 ± 7.82 vs 25.18 ± 6.84 mmol/L, P < 0.01), the urine glucose levels (45.44 ± 3.93 vs 22.66 ± 5.58 mmol/L, P < 0.01), and the serum insulin sensitivity index (-4.65 ± 0.43 vs -4.74 ± 0.75, P > 0.05) in the db/db + HD group were decreased, whereas the fasting plasma insulin (3.12 ± 1.08 vs 5.54 ± 1.82 µg/L, P < 0.01) and the serum insulin resistance index (5.01 ± 2.02 vs 5.96 ± 2.49, P < 0.05) were increased. Subsequently, the kidney transcription profiles were measured in the db/db group and db/db + HD group via microarray, and the results show that Apostichopus japonicus hydrolysate induced differential expression of 77 genes. Among these genes, the down-regulation of genes ntrK1 and ptpN5 played vital roles, as this effect induced the further down-regulation of neurotrophin tyrosine kinase, protein tyrosine phosphatase, and other transcription factors, which are involved in the classical mitogen-activated protein kinases (MAPK) and p38MAPK signaling pathways. The inhibited MAPK and p38MAPK signaling pathways are involved in glycometabolism and the control of lipid metabolism, and they regulate the occurrence and development of diabetic nephropathy.

Microbial diversity and composition in different gut locations of hyperlipidemic mice receiving krill oil.

Low-dose (LD, 100 mg kg-1 day-1), moderate-dose (MD, 200 mg kg-1 day-1), and high-dose (HD, 600 mg kg-1 day-1) krill oil treatments have a stepwise, enhanced effect on alleviating hyperlipidemia, and 16S rRNA sequencing of the fecal samples demonstrates that krill oil treatment alters microbial communities. Feces may not represent all microbial communities in the gastrointestinal (GI) tract. Therefore, in this study, the stored ileal and colon samples collected from LD and HD groups were sequenced, and the location-specific modulations of microbial communities were observed after krill oil treatments. The 16S rRNA sequencing of the ileal samples showed that the LD and HD groups have similar patterns between control and high-fat diet (HFD) treatments, and six most abundant genera and 40 operational taxonomic units that respond to krill oil treatment were identified. However, the 16S rRNA sequencing of the colon samples showed that LD krill oil shifts the structure from the HFD to that of the control, whereas the HD group was distributed between the control and HFD groups. The corresponding most abundant genera and responsive OTUs totaled 4 and 45, respectively. In conclusion, different gastrointestinal tract locations contain different microbial communities. These results will help to provide a comprehensive understanding of the role of dietary krill oil in modulating the gut microbiota and alleviating hyperlipidemia.

Modulation of the gut microbiota by the mixture of fish oil and krill oil in high-fat diet-induced obesity mice.

Previous studies confirmed that dietary supplements of fish oil and krill oil can alleviate obesity in mice, but the underlying mechanism remains unclear. This study aims to discern whether oil treatment change the structure of the gut microbiota during the obesity alleviation. The ICR mice received high-fat diet (HFD) continuously for 12 weeks after two weeks of acclimatization with a standard chow diet, and the mice fed with a standard chow diet were used as the control. In the groups that received HFD with oil supplementation, the weight gains were attenuated and the liver index, total cholesterol, triglyceride and low-density lipoprotein cholesterol were reduced stepwise compared with the HFD group, and the overall structure of the gut microbiota, which was modulated in the HFD group, was shifted toward the structure found in the control group. Moreover, eighty-two altered operational taxonomic units responsive to oil treatment were identified and nineteen of them differing in one or more parameters associated with obesity. In conclusion, this study confirmed the effect of oil treatment on obesity alleviation, as well as on the microbiota structure alterations. We proposed that further researches are needed to elucidate the causal relationship between obesity alleviation and gut microbiota modulation.