The starch-rich diet causes lipidemia while the fat-rich diet induces visceral adiposity, meta-inflammation, and insulin resistance differentially in immune biased mouse strains

Neuroprotective effect of niacin in a rat model of obesity induced by high-fat-rich diet

This study investigates the impact of a high-fat-rich diet (HFRD) on behavioral, biochemical, neurochemical, and histopathological studies using the hypothalamus of rats following niacin (NCN) administration. The rats were divided into HFRD and normal diet (ND)-fed groups and administered selected doses of NCN, i.e., 25 mg/mL/kg (low dose) and 50 mg/mL/kg (high dose), for 8 weeks. The grouping of male rats (n = 8) was as follows: (i) Vehicle (Veh) + ND; (ii) ND + NCN (low dose); (iii) ND + NCN (high dose); (iv) Veh + HFRD; (v) HFRD + NCN (low dose); and (vi) HFRD + NCN (high dose). Behavioral tests assessed depression-like symptoms and spatial memory; after that, the hypothalamus was isolated for various analyses of sacrificed animals. NCN at both doses decreased food intake and growth rate in both diet groups and demonstrated antidepressant and memory-enhancing effects. HFRD-induced oxido-neuroinflammation decreased with both doses of NCN. HFRD-induced decreases in serotonergic neurotransmission, 5-HT1A receptor expression, and morphological alterations in the rat's hypothalamus were normalized by both doses of NCN. In conclusion, NCN, as a potential antioxidant and neuromodulator, can normalize feeding behavior and produce antidepressant and memory-improving effects in a rat model of obesity following HFRD intake.

Antibiotic induced adipose tissue browning in C57BL/6 mice: An association with the metabolic profile and the gut microbiota

AIMS

The use of antibiotics affects health. The gut microbial dysbiosis by antibiotics is thought to be an essential pathway to influence health. It is important to have optimized energy utilization, in which adipose tissues (AT) play crucial roles in maintaining health. Adipocytes regulate the balance between energy expenditure and storage. While it is known that white adipose tissue (WAT) stores energy and brown adipose tissue (BAT) produces energy by thermogenesis, the role of an intermediate AT plays an important role in balancing host internal energy. In the current study, we tried to understand how treating an antibiotic cocktail transforms WAT into BAT or, more precisely, into beige adipose tissue (BeAT).

METHODS

Since antibiotic treatment perturbs the host microbiota, we wanted to understand the role of gut microbial dysbiosis in transforming WAT into BeAT in C57BL/6 mice. We further correlated the metabolic profile at the systemic level with this BeAT transformation and gut microbiota profile.

KEY FINDINGS

In the present study, we have reported that the antibiotic cocktail treatment increases the Proteobacteria and Actinobacteria while reducing the Bacteroidetes phylum. We observed that prolonged antibiotic treatment could induce the formation of BeAT in the inguinal and perigonadal AT. The correlation analysis showed an association between the gut microbiota phyla, beige adipose tissue markers, and serum metabolites.

SIGNIFICANCE

Our study revealed that the gut microbiota has a significant role in regulating the metabolic health of the host via microbiota-adipose axis communication.

Effects of starch-rich or fat-rich diets on metabolism, adiposity, and glycemia in immune-biased, C57BL/6 and BALB/c mice

Diet is an essential factor to maintain health by regulating host metabolism and immunity. Host immunity acts as a critical regulator of metabolic changes. By using differentially immune-biased mice C57BL/6 and BALB/c, we demonstrated the metabolic consequence of consuming diets rich in non-resistant starch (starch-rich), unsaturated fat (sunflower oil-rich), and saturated fat (coconut oil-rich) for shorter (four weeks) or longer (eight weeks) duration. Time kinetics of various diets on two differentially immune-biased mice revealed that starch-rich and unsaturated fat-rich diets reduced insulin resistance (IR) and visceral adiposity in BALB/c mice. In contrast, a saturated fat-rich diet enhanced both parameters. In C57BL/6 mice, a fat-rich diet enhanced IR with time while visceral adiposity remained unchanged. Eight weeks' consumption of a saturated fat-rich diet led to the highest visceral adiposity in C57BL/6 mice, while the same diet resulted in the maximum IR in BALB/c mice. The current report presented a detailed metabolomic analysis of treatments with various diets using a) uni- and b) multi-variate analyses. We also calculated the differential index for each treatment for each mouse strain using a vector analysis of the multivariate linear discriminant data. The outcome of the vector analysis of metabolite profiles identified metabolites that affected lipid and glucose metabolism to establish the inter-strain physiological differences.