Plasticity of adipose tissues in response to fasting and refeeding declines with aging in mice.

To explore the plasticity of adipose tissues, C57BL/6J mice at the age of 1 month, 3 months, and 15 months corresponding to adolescence, adulthood, and middle-aged transitional period, respectively, were fasted and refed subsequently at different times. Body adipose tissues ratio (BATR) was calculated, the morphology of adipose tissue and the area of adipocytes were observed by histological analysis, and the mitochondria in adipocytes were observed under the transmission electron microscope. Furthermore, the expression levels of Ucp-1, Cidea, Cox7a1, Cpt-1m, Atgl, and Hsl were detected by qRT-PCR. Our results showed a significant increase in the adipocytes area and body visceral adipose tissue (VAT) ratio in all groups of mice with aging. Moreover, body mesenteric white adipose tissue (mWAT) ratio decreased the most after 72 h fasting. In the middle-aged transitional mice, the white adipocytes did not decrease until 72 h fasting, and most of them still appeared as unaffected unilocular cells. Besides, the number of mitochondria and the expression of Ucp-1, Cidea, Cox7a1, Cpt-1m, Atgl and Hsl were lower in these mice. After 72h refeeding, the body subcutaneous white adipose tissue (sWAT) ratio returned to normal, while the VAT kept decreasing. The above results indicated an impairment in adipose tissue plasticity in mice with aging, suggesting that age modulated the metabolic adaptiveness of adipose tissues in mice.

Medium-chain fatty acid nanoliposomes suppress body fat accumulation in mice.

Medium-chain fatty acids (MCFA) are widely used in diets for patients with obesity. To develop a delivery system for suppressing dietary fat accumulation into adipose tissue, MCFA were encapsulated in nanoliposomes (NL), which can overcome the drawbacks of MCFA and keep their properties unchanged. In the present study, crude liposomes were first produced by the thin-layer dispersion method, and then dynamic high-pressure microfluidisation (DHPM) and DHPM combined with freeze-thawing methods were used to prepare MCFA NL (NL-1 and NL-2, respectively). NL-1 exhibited smaller average size (77.6 (SD 4.3) nm), higher zeta potential (- 40.8 (SD 1.7) mV) and entrapment efficiency (73.3 (SD 16.1) %) and better stability, while NL-2 showed narrower distribution (polydispersion index 0.193 (SD 0.016)). The body fat reduction property of NL-1 and NL-2 were evaluated by short-term (2 weeks) and long-term (6 weeks) experiments of mice. In contrast to the MCFA group, the NL groups had overcome the poor palatability of MCFA because the normal diet of mice was maintained. The body fat and total cholesterol (TCH) of NL-1 (1.54 (SD 0.30) g, P = 0.039 and 2.33 (SD 0.44) mmol/l, P = 0.021, respectively) and NL-2 (1.58 (SD 0.69) g, P = 0.041 and 2.29 (SD 0.38) mmol/l, P = 0.015, respectively) significantly decreased when compared with the control group (2.11 (SD 0.82) g and 2.99 (SD 0.48) mmol/l, respectively). The TAG concentration of the NL-1 group (0.55 (SD 0.14) mmol/l) was remarkably lower (P = 0.045) than the control group (0.94 (SD 0.37) mmol/l). No significant difference in weight and fat gain, TCH and TAG was detected between the MCFA NL and MCFA groups. Therefore, MCFA NL could be potential nutritional candidates for obesity to suppress body fat accumulation.

Medium-chain fatty acid nanoliposomes for easy energy supply.

OBJECTIVE: Developing a nanoliposome delivery system for an easy energy supply of medium-chain fatty acids (MCFAs) to improve oral doses and bioavailability. METHODS: Bangham's method and high-pressure microfluidization were used to prepare MCFA liposomes. The easy energy-supply property of MCFA nanoliposomes was estimated by the anti-fatigue experiments of mice including a weight-loaded swimming test and its corresponding parameters (serum urea nitrogen, blood lactic acid, and hepatic glycogen). For comparison, nanoliposomes without MCFAs and MCFAs not entrapped in nanoliposomes were used throughout. RESULTS: Compared with crude MCFA liposomes according to Bangham's method, the MCFA nanoliposomes made by high-pressure microfluidization exhibited great advantages in their characteristics, with a small average diameter (76.2 ± 34.7 nm), narrow size distribution (polydispersity index 0.207), high ζ-potential (-50.51 mV), great entrapment efficiency (70.5%) and drug loading (9.4%), and good stability. The high-dose group and the MCFA group (680 mg/kg) showed a longer weight-loaded swimming time (104 ± 29 min, P = 0.087, and 108 ± 11 min, P = 0.047, respectively) and significantly higher hepatic glycogen (16.40 ± 1.45 mg/g, P < 0.001 and 17.27 ± 2.13 mg/g, P < 0.001, respectively) than the control group (59 ± 11 min and 8.79 ± 2.76 mg/g, respectively). Moreover, serum urea nitrogen (891.5 ± 113.4 mg/L, P = 0.024, and 876.6 ± 70.8 mg/L, P = 0.015, respectively) and blood lactic acid (6.05 ± 1.40 mmol/L, P = 0.001, and 5.95 ± 1.27 mmol/L, P < 0.001, respectively) in the high-dose group and the group with an equivalent MCFA dose were significantly lower than those in the control group (1153.6 ± 102.5 mg/L and 12.53 ± 1.86 mmol/L, respectively). CONCLUSION: Similar to MCFAs, MCFA nanoliposomes prepared by high-pressure microfluidization showed a strong easy energy-supply property, which suggested that MCFA nanoliposomes could be a potential drug candidate for an easy energy supply.