Impact of diets rich in olive oil, palm oil or lard on myokine expression in rats

Roles of natural products on myokine expression and secretion in skeletal muscle atrophy

Skeletal muscles serve both in movement and as endocrine organs. Myokines secreted by skeletal muscles activate biological functions within muscles and throughout the body via autocrine, paracrine, and/or endocrine pathways. Skeletal muscle atrophy can influence myokine expression and secretion, while myokines can impact the structure and function of skeletal muscles. Regulating the expression and secretion of myokines through the pharmacological approach is a strategy for alleviating skeletal muscle atrophy. Natural products possess complex structures and chemical properties. Previous studies have demonstrated that various natural products exert beneficial effects on skeletal muscle atrophy. This article reviewed the regulatory effects of natural products on myokines and summarized the research progress on skeletal muscle atrophy associated with myokine regulation. The focus is on how small-molecule natural products affect the regulation of interleukin 6 (IL-6), irisin, myostatin, IGF-1, and FGF-21 expression. We contend that the development of small-molecule natural products targeting the regulation of myokines holds promise in combating skeletal muscle atrophy.

The Muscle-Conditioned Medium Containing Protocatechuic Acid Improves Insulin Resistance by Modulating Muscle Communication with Liver and Adipose Tissue

Diabetes mellitus is a public health concern, affecting 10.5% of the population. Protocatechuic acid (PCA), a polyphenol, exerts beneficial effects on insulin resistance and diabetes. This study investigated the role of PCA in improving insulin resistance and the crosstalk between muscle with liver and adipose tissue. C2C12 myotubes received four treatments: Control, PCA, insulin resistance (IR), and IR-PCA. Conditioned media from C2C12 was used to incubate HepG2 and 3T3-L1 adipocytes. The impact of PCA was analyzed on glucose uptake and signaling pathways. PCA (80 µM) significantly enhanced glucose uptake in C2C12, HepG2, and 3T3-L1 adipocytes (p < 0.05). In C2C12, PCA significantly elevated GLUT-4, IRS-1, IRS-2, PPAR-γ, P-AMPK, and P-Akt vs. Control (p ≤ 0.05), and modulated pathways in IR-PCA. In HepG2, PPAR-γ and P-Akt increased significantly in Control (CM) vs. No CM, and PCA dose upregulated PPAR-γ, P-AMPK, and P-AKT (p < 0.05). In the 3T3-L1 adipocytes, PI3K and GLUT-4 expression was elevated in PCA (CM) vs. No CM. A significant elevation of IRS-1, GLUT-4, and P-AMPK was observed in IR-PCA vs. IR (p ≤ 0.001). Herein, PCA strengthens insulin signaling by activating key proteins of that pathway and regulating glucose uptake. Further, conditioned media modulated crosstalk between muscle with liver and adipose tissue, thus regulating glucose metabolism.

Balancing functional and health benefits of food products formulated with palm oil as oil sources

Palm oil (PO) is widely utilised in the food industry and consumed in large quantities by humans. Owing to its bioactive components, such as fatty acids, carotenoids, vitamin E, and phenolic compounds, PO has been utilised for generations. However, public concern about their adverse effects on human health is growing. A literature search was conducted to identify fractionated palm oil processing techniques, proof of their health advantages, and potential food applications. Refined palm oil (RPO) is made from crude palm oil (CPO) and can be fractionated into palm olein (POl) and palm stearin (PS). Fractional crystallisation, dry fractionation, and solvent fractionation are the three basic fractionation procedures used in the PO industry. The composition of triacylglycerols and fatty acids in refined and fractionated palm oil and other vegetable oils is compared to elucidate the triacylglycerols and fatty acids that may be important in product development. It is well proven that RPO, POl, and PS extends the oil's shelf life in the food business. These oils have a more significant saturated fat content and antioxidant compounds than some vegetable oils, such as olive and coconut oils, making them more stable. Palm olein and stearin are also superior shortening agents and frying mediums for baking goods and meals. Furthermore, when ingested modestly daily, palm oils, especially RPO and POl, provide health benefits such as cardioprotective, antidiabetic, anti-inflammatory, and antithrombotic effects. Opportunities exist for fractionated palm oil to become a fat substitute; however, nutrition aspects need to be considered in further developing the market.

Impact of Highly Saturated versus Unsaturated Fat Intake on Carbohydrate Metabolism and Vascular Reactivity in Rat

Palm olein (PO) and lard are considered harmful to health because of their highly saturated fatty acid content. On the contrary, olive oil (OO) with its high level of polyunsaturated fatty acids is considered healthier. This study aims to evaluate the effects of high consumption of these oils on carbohydrate metabolism and vascular function. Male Wistar rats were fed ad libitum for 12 weeks with different high fat diets (HFD) containing 30% of each oil. Systemic glycemia, insulinemia, and lipidemia were assessed by routine methods or by ELISA. GLUT4 muscular expression and hepatic and muscular Akt phosphorylation were analyzed by western blot. Vascular function was evaluated, ex vivo, on aortic rings and on the variations of isometric tensions. The results show that fasting blood glucose was increased with PO and OO diets and decreased with lard. Compared to control diet, this increase was significant only with PO diet. The area under the curve of IPGTT was increased in all HFD groups. Compared to control diet, this increase was significant only with PO. In contrast, stimulation of the pathway with insulin showed a significant decrease in Akt phosphorylation in all HFD compared to control diet. KCl and phenylephrine induced strong, dose-dependent vasoconstriction of rat aortas in all groups, but KCl EC₅₀ values were increased with lard and OO diets. The inhibitory effect of tempol was absent in PO and lard and attenuated in OO. Vascular insulin sensitivity was decreased in all HFD groups. This decreased sensitivity of insulin was more important with PO and lard when compared to OO diet. In conclusion, the results of this study clearly show that high consumption of palm olein, olive oil, and lard can compromise glucose tolerance and thus insulin sensitivity. Furthermore, palm olein and lard have a more deleterious effect than olive oil on the contractile function of the aorta. Excessive consumption of saturated or unsaturated fatty acids is harmful to health, regardless of their vegetable or animal origin.

Effect of different types of oil intake on the blood index and the intestinal flora of rats

Dietary fat is an important part of human diet and has a close relationship with human health. However, it is still unclear how gut microbiota in adolescent responds to dietary fats at a normal dose. In this study, fat-free group (BC) was used as blank control group, we explored blood index and gut microbiota structure in growing rat(aged 1 months) after feeding a normal dose of 16.9% stewed lard(SL), refined lard(RL), fish oil(FO) and soybean oil(SO) for 6 weeks, respectively. The results showed that compared with RL group, SL group showed reduced fasting blood sugar and blood lipid levels and improved nutrient absorption capacity of the intestine. The blood indexes of glucose (Glu), total cholesterol (TC) and total triglyceride (TG) in FO treatment group were relatively low. The abundance of Bacteroidetes in the BC group decreased, and the abundance of Firmicutes increased. The Firmicutes/Bacteroidetes ratio of the FO group was relatively low, and the Firmicutes/Bacteroidetes ratio of the SL group and the SO group was lower than that of the RL group. The abundance of Bacteroidaceae in the SL group was increased. Research results showed that fat-free diets will increase the risk of obesity to a certain extent; compared with refined lard, stewed lard, soybean oil and fish oil can reduce the risk of obesity to a certain extent. The present study could find that the addition and types of dietary fat will affect the abundance and diversity of rat intestinal flora, and provide some information for nutritional evaluation about these dietary lipids.

Does a Vegetarian Diet Affect the Levels of Myokine and Adipokine in Prepubertal Children?

Myokines are cytokines secreted by muscle and exert autocrine, paracrine, or endocrine effects. Myokines mediate communication between muscle and other organs, including adipose tissue. The aim of the study was to assess serum myokines and their relationships with adipokines and anthropometric and nutritional parameters in children following vegetarian and omnivorous diets. One hundred and five prepubertal children were examined. Among them there were 55 children on a vegetarian diet and 50 children on an omnivorous diet. Concentrations of myokines (myostatin, irisin) and adipokines (leptin, adiponectin, omentin, visfatin) in serum were determined by enzyme-linked immunosorbent assay (ELISA). We observed comparable median values of serum myokines and adipokines (except of leptin concentration) in both of the studied groups of children. We also found several correlations between myokine and adipokine levels and certain nutritional parameters. Serum myostatin was positively correlated with omentin levels in vegetarians and omnivores (p = 0.002). Serum irisin was positively associated with omentin (p = 0.045) levels in omnivores and inversely with visfatin concentration (p = 0.037) in vegetarians. Myostatin concentration was negatively correlated with the percentage of energy from protein (p = 0.014), calcium (p = 0.046), and vitamin A (p = 0.028) intakes in vegetarians and with dietary vitamin C (p = 0.041) and vitamin E (p = 0.021) intakes in omnivores. In multivariate regression analyses, positive correlations of serum myostatin with omentin levels were revealed in both study groups (β = 0.437, p < 0.001 for vegetarians; and β = 0.359, p = 0.001 for omnivores). Consuming a lacto-ovo-vegetarian diet did not influence serum levels of myokines (myostatin, irisin) and adipokines such as adiponectin, visfatin, and omentin in prepubertal children. However, leptin levels were significantly lower in vegetarians compared with omnivores. The observed significant positive correlations between myostatin and omentin concentrations might suggest tissue cross-talk between skeletal muscle and fat tissue. Further studies, carried out in a larger group of children following different dietary patterns, could be important to fully understand the relations between muscle, adipose tissues, and nutrition.

Olive Leaf Extract Supplementation to Old Wistar Rats Attenuates Aging-Induced Sarcopenia and Increases Insulin Sensitivity in Adipose Tissue and Skeletal Muscle

Aging is associated with increased visceral adiposity and a decrease in the amount of brown adipose tissue and muscle mass, known as sarcopenia, which results in the development of metabolic alterations such as insulin resistance. In this study, we aimed to analyze whether 3-week supplementation with a phenolic-rich olive leaf extract (OLE) to 24 months-old male Wistar rats orally (100 mg/kg) attenuated the aging-induced alterations in body composition and insulin resistance. OLE treatment increased brown adipose tissue and attenuated the aging-induced decrease in protein content and gastrocnemius weight. Treatment with OLE prevented the aging-induced increase in the expression of PPAR-γ in visceral and brown adipose tissues, while it significantly increased the expression of PPAR-α in the gastrocnemius of old rats and reduced various markers related to sarcopenia such as myostatin, HDAC-4, myogenin and MyoD. OLE supplementation increased insulin sensitivity in explants of gastrocnemius and epididymal visceral adipose tissue from aged rats through a greater activation of the PI3K/Akt pathway, probably through the attenuation of inflammation in both tissues. In conclusion, supplementation with OLE prevents the loss of muscle mass associated with aging and exerts anti-inflammatory and insulin-sensitizing effects on adipose tissue and skeletal muscle.