Effects of dietary fatty acids on the social life of male Guinea pigs from adolescence to adulthood

Metabolic rate and saliva cortisol concentrations in socially housed adolescent guinea pigs

An individual's energetic demands and hence metabolic rate can strongly change during adolescence, a phase characterized by profound morphological, physiological, and endocrine changes. Glucocorticoid hormones (e.g. cortisol) are released in response to hypothalamic-pituitary-adrenal-axis activity, modulate several metabolic processes, and can also be linked to increased metabolic rate. In domestic guinea pigs (Cavia aperea f. porcellus) housed in same-sex groups, cortisol concentrations increase during adolescence in males but remain stable in females, which was suggested to be related to different energetic demands by age. We therefore measured metabolic rate through oxygen (O2) consumption over 2.5 h in male and female guinea pigs housed in same-sex groups during adolescence at ages of 60, 120, and 180 days, which was paralleled by analyses of saliva cortisol concentrations before and after the measurement. The statistical analyses involved whole body metabolic rate (ml O2/h), body mass-corrected metabolic rate (ml O2/h/kg), and body mass-independent metabolic rate (ml O2/h statistically corrected for body mass). We found increasing cortisol concentrations with age in males only, but none of the three metabolic rate analyses revealed a sex difference by age. On the individual level, repeatability across ages was found in metabolic rate as well as in body mass and cortisol concentrations after the measurement, but not in "basal" cortisol concentrations. Our results suggest no sex-specific changes in metabolic rate and hence equal energetic demands in male and female guinea pigs during adolescence. Moreover, metabolic rate clearly represents a highly stable physiological trait already early in a guinea pig's life irrespective of rather fluctuating cortisol concentrations.

Boosted Meat Flavor by the Metabolomic Effects of Nile Tilapia Dietary Inclusion of Zophobas atratus Larval Meal

BACKGROUND

Zophobas atratus larval meal (ZLM) is a high-quality feed supplement with potential activities that can improve fish growth performance and promote meat quality. However, there have been limited recent studies investigating the metabolic effects of ZLM. Therefore, this study aims to uncover the metabolomic mechanism through which ZLM improves tilapia meat flavor using metabolomic strategies.

METHOD

In this study, soybean meal in the basal diets was replaced with 15%, 30%, or 60% ZLM, where anti-nutrient factors were destroyed by high temperature treatment. After being fed these ZLM supplements for 30 days, dorsal muscles were collected from tilapia for meat sensory evaluation tests. Liver samples were also collected for metabolomic analysis using the gas chromatography-mass spectrometry (GC-MS) platform and combined with biochemical assays to verify metabolism-related enzyme activities and reveal crucial metabolic pathways and critical biomarkers associated with ZLM's ability to improve meat flavor.

RESULTS

In tilapia livers, ZLM enhanced the activity of enzymes involved in energy metabolism including succinate dehydrogenase (SDH), pyruvate dehydrogenase (PDH), α-ketoglutarate dehydrogenase (α-KGDH), NADP-malate dehydrogenase (NAD-MDH) and mitochondrial isocitrate dehydrogenase (ICDHm). This resulted in increased levels of reduced nicotinamide adenine dinucleotide (NADH), acetyl CoA and ATP which led to accumulation of flavor fatty acids such as arachidonic acid, linoleic acid (9,12-Octadecadienoic acid), linolenic acid (9,12,15-Octadecatrienoic acid) and oleic acid (9-Octadecenoic acid). Additionally, there was an increase in flavor nucleotides like guanosine adenosine-5'-monophosphate and uridine-5'-monophosphate while off-flavor metabolites like inosine and hypoxanthine decreased. Furthermore, beneficial metabolomic responses led to a decrease in off-flavor metabolites such as 2-methylisoborneol trimethylamine and geosmin while increasing umami metabolites like 2-methyl-3-furanthiol and nonanal.

CONCLUSIONS

This metabolomic study demonstrates that inclusion of ZLM diets enhances the flavor profile of tilapia dorsal muscle. The accumulation of flavor compounds, coupled with a reduction in earthy taste and off-flavor metabolites, contributes to an improved meat flavor and freshness. Additionally, there is an increase in the levels of flavor-related amino acids and nucleotides. These previously unidentified metabolic effects highlight the potential significance of ZLM as a dietary supplement for enhancing the biosynthesis of flavor metabolites in tilapia.

Causal benefits of 25 dietary intakes on epigenetic ageing: a Mendelian randomisation study

DNA methylation GrimAge acceleration (DMGA) and intrinsic epigenetic age acceleration (IEAA) are important physiological markers for assessing the ageing process. Evidence from cross-sectional studies suggests that some dietary intake is associated with DMGA and IEAA. However, the causal relationship between them has yet to be elucidated. This Mendelian randomisation study uses genetic variants associated with different dietary intakes as instrumental variables to explore the causal benefits of multiple dietary intakes on DMGA and IEAA. Cheese intake, dark chocolate intake, average weekly red wine intake, dried fruit intake, fresh fruit intake, porridge intake, cereal intake, and liver intake had a negative causal association with DMGA, and poultry intake and doughnut intake had a positive causal association with DMGA (p < 0.05). Muesli and bran cereal intake had a negative causal association with IEAA, and pineapple intake had a positive causal association with IEAA (p < 0.05). Dietary intake positively causally associated with IEAA or DMGA may have accelerated biological ageing; conversely, dietary intake negatively causally associated with IEAA or DMGA may have contributed to delaying biological ageing. Based on genetic evidence, this study demonstrated some significant causal benefits of dietary intake on DMGA and IEAA, suggesting the possibility of intervening in DNA methylation acceleration and epigenetic age acceleration by adjusting these food intakes, thereby promoting health and delaying ageing. However, the findings of this study are exploratory and preliminary and need to be supported and validated by evidence from further clinical studies and mechanistic studies.

Research progress on Walnut oil: Bioactive compounds, health benefits, extraction methods, and medicinal uses

Walnut oil is extracted from walnut kernels (Juglans regia Linne) or iron walnut kernels (Juhlans sigillata Dode). The percentage of oil in walnuts is 52%-70%. The main constituents in oil are fatty acids, phenols, sterols, squalene, melatonin, vitamins, and minerals. Many extraction methods such as supercritical carbon dioxide extraction, maceration, modified "bligh and dyer extraction," aqueous enzymatic extraction, ultrasonic extraction, soxhlet extraction, and cold-press extraction methods are reported in the literature. Walnut oil showed anti-inflammatory, antitumor, antioxidant, immunomodulatory, neuroprotective, cardioprotective, antidiabetic, and antihyperlipidemic activities. The reported data in the literature suggest that walnut oil has many health benefits. This review summarizes the extraction methods, bioactive constituents, health benefits, and pharmacological actions of walnut oil. PRACTICAL APPLICATIONS: Walnut oil is a natural vegetable oil of significant importance due to their nutritional, and intelligence-boosting benefits. Several factors, including the processing parameters and the phytochemical profile, affect walnut oil products' flavor and color. In addition, storage environment of walnut oil can also affect walnut oil quality. Apart from the predominant ingredient fatty acids, the chemical composition of walnut oil comprises phenols, sterols, squalene, melatonin, vitamins, and minerals. These bioactive compounds are of potential value owing to their health-promoting benefits, including antioxidant, antitumor, and cholesterol-lowering effects. Many chemical constituents were isolated from walnut oil; however, all the compounds are not explored for their possible medicinal value. Thus, clinical studies, exploration of the therapeutic potential and the molecular mechanisms of all the compounds, and development of convenient dosage forms either for therapeutic or functional food purposes are warranted.

Metabolomic Effects of the Dietary Inclusion of Hermetia illucens Larva Meal in Tilapia

Black soldier fly (Hermetia illucens) larvae meal have been used as feed protein supplements in fish feed, but few researches have investigated the metabolomic effects of Hermetia illucens larvae meal supplements. Therefore, the metabolic effects on Nile tilapia were investigated by replacing 5%, 10%, and 20% of the dietary soybean meal in the basal diet with Hermetia illucens larvae meal, respectively. This study shows that 20% H. illucens larvae meal feed could promote tilapia average daily gain of upto 5.03 ± 0.18 g (mean ± SEM). It was found that the tricarboxylic acid cycle efficiency was improved by activating the enzymes of mitochondrial isocitrate dehydrogenase, NAD-malate dehydrogenase, succinate dehydrogenase, pyruvate dehydrogenase, and α-ketoglutarate dehydrogenase, which then increased the output of ATP and NADH. Furthermore, amino acid and protein biosynthesis was boosted by enhanced glutamine synthetase and glutamate synthase. In particular, GSH increased with increased H. illucens larvae meal. Unsaturated fatty acid biosynthesis was stimulated by higher levels of fatty acid synthase and acetyl CoA carboxylase. Additionally, there was no significant change in lipase levels. Thus, the higher acetyl Co-A content was primarily involved in fatty acid biosynthesis and energy metabolism. Flavor substances, such as nonanal and 2-methyl-3-furanthiol, also accumulated with the addition of H. illucens larvae meal, which increased the umami taste and meat flavor. Additionally, the flavor of tilapia was improved owing to a decrease in trimethylamine content, which causes an earthy and fishy taste. This study uncovers a previously unknown metabolic effect of dietary H. illucens larvae meal on Nile tilapia.

Flaxseed oil as omega-3 polyunsaturated fatty acid source modulates cortisol concentrations and social dominance in male and female guinea pigs

Flaxseed oil is an excellent source of the essential omega-3 polyunsaturated fatty acid (PUFA) alpha-linolenic acid (ALA). Omega-3 PUFAs are important neuronal components and can counteract aggressive, depressive, and anxiety-like behavior, reduce glucocorticoid (e.g. cortisol) concentrations under chronic stress but also increase acute glucocorticoid responses. As glucocorticoids per se and glucocorticoid responsiveness can modulate the establishment of dominance hierarchies, we investigated if flaxseed oil high in ALA can promote social dominance through effects on glucocorticoid concentrations. Two male and two female groups of domestic guinea pigs (n = 9 per group) were maintained on a control or a 5% (w/w) flaxseed oil diet for four weeks. Social behaviors, hierarchy indices, locomotion, and saliva cortisol concentrations were determined during basal group housing conditions and stressful social confrontations with unfamiliar individuals of the other groups. Flaxseed groups had increased basal cortisol concentrations and showed no cortisol increase during social confrontations. Cortisol concentrations in control groups significantly increased during social confrontations. Such higher cortisol responses positively affected individual hierarchy indices in control males. However, flaxseed males became dominant irrespective of cortisol concentrations. In females, the opposite was detected, namely a higher dominant status in control compared to flaxseed females. Open-field- and dark-light-tests for anxiety-like behavior revealed no pronounced differences, but flaxseed males showed the highest locomotor activity. Flaxseed oil as an ALA source sex-specifically promoted social dominance irrespective of cortisol concentrations and responses. The underlying neuronal mechanisms remain to be determined, but a sex-specific energetic advantage may have accounted for this effect.