[Electroacupuncture intervention improves lipid metabolism and promotes browning of white adipose tissue by activating AMPK/Sirt1 pathway and up-regulating Nrg4 content in middle-aged and aged obese rats].

OBJECTIVE: To investigate the mechanism of electroacupuncture （EA） in promoting the browning of white adipose tissue in middle-aged and aged obese rats induced by high fat by regulating AMP-activated protein kinase （AMPK） /silence-information regulatory factor 1 （Sirt1） pathway and neuregulin 4 （Nrg4）. METHODS: Twenty-four male SD rats were randomized into blank control, model and EA groups （n=8 per group）. The obesity model was established by feeding the rats with high-fat diet for 6 weeks. For the EA group, EA （2 Hz/15 Hz, 1.5 mA） was applied to "Guanyuan" （CV4） and bilateral "Shenshu" （BL23）, "Fenglong" （ST40） and "Tianshu" （ST25） for 20 min, once a day, 5 days a week for 6 weeks. Rats of the blank control and model groups were also restrained for 20 min. The body mass and food intake were measured every week, and the Lee's index, epididymal fat, perirenal fat and brown adipose tissue were weighed. The contents of serum total cholesterol （TC）, triglyceride （TG）, high density lipoprotein cholesterol （HDL-C）, low density lipoprotein cholesterol （LDL-C） and norepinephrine （NE） were determined by ELISA. H.E. staining was used to observe the morphological changes of white and brown adipose tissue. The mRNA expression levels of mitochondrial uncoupling protein 1 （UCP1）, peroxisome proliferator activated receptor γ co-activator 1α （PGC-1α）, PR-domain protein 16 （PRDM16）, peroxisome proliferator activated receptor γ （PPARγ） and Nrg4 in the adipose tissue were detected by quantitative real time PCR, and the protein expression levels of Nrg4, AMPKα, Sirt1 and interleukin-6 （IL-6） in the white and brown adipose tissue were detected by Western blot. RESULTS: Compared with the blank control group, the body mass, food intake, the Lee's index, epididymal fat and perirenal fat mass, and serum TG, TC and LDL-C contents and the expression level of IL-6 protein were significantly increased （P<0.01, P<0.05, P<0.001）, and the brown adipose mass, serum HDL-C and NE contents, the expression levels of UCP1, PGC-1α, PRDM16, PPARγ and Nrg4 mRNAs, and the protein expression levels of AMPKα, Sirt1 and Nrg4 proteins in both white and brown adipose tissues were significantly decreased in the model group （P<0.01, P<0.05）. After EA intervention, the increased levels of body mass, food intake, Lee's index, epididymal fat and perirenal fat mass, serum TG, TC and LDL-C contents, and the expression of IL-6 protein, and the decreased levels of brown adipose mass, serum HDL-C and NE contents, expression levels of UCP1, PGC-1α, PRDM16, PPARγ and Nrg4 mRNAs, and those of AMPKα, Sirt1 and Nrg4 proteins in both white and brown adipose tissues were apparently reversed（P<0.05, P<0.01, P<0.001）. H.E. staining showed an increase of the volume and content of intracellular vacuoles of both white and brown adipose tissues, disordered arrangement of cells with vague boundary in the model group, which was relatively milder including a decrease of volume and content of vacuoles of both white and brown adipose, neat arrangement of cells with clear boundary. CONCLUSION: EA intervention can improve lipid metabolism and promote white adipose tissue browning in middle-aged and aged obese rats, which is possibly associated with its functions in activating AMPK/Sirt1 signaling pathway and up-regulating the level of Nrg4.

Behavioral responses of two captive bottlenose dolphins (Tursiops truncatus) to a continuous 50 kHz tone.

At present, the fundamental frequencies of signals of most commercially available acoustic alarms to deter small cetaceans are below 20 kHz, but it is not well ascertained whether higher frequencies have a deterrent effect on bottlenose dolphins (Tursiops truncatus). Two captive bottlenose dolphins housed in a floating pen were subjected to a continuous pure tone at 50 kHz with a source level of 160 ± 2 dB (re 1 µPa, rms). The behavioral responses of dolphins were judged by comparing surfacing distance relative to the sound source, number of surfacings, and number of echolocation clicks produced, during forty 15 min baseline periods with forty 15 min test periods (four sessions per day, 40 sessions in total). On all 10 study days, surfacing distance and the number of surfacings increased while click production decreased during broadcasts of test sound. The avoidance threshold sound pressure level for a continuous 50 kHz tone for the bottlenose dolphins, in the context of this study, was estimated to be 144 ± 2 dB (re 1 µPa, rms). The results indicated that a continuous 50 kHz tonal signal can deter bottlenose dolphins from an area.