Dietary Garcinol Attenuates Hepatic Pyruvate and Triglyceride Accumulation by Inhibiting P300/CBP-Associated Factor in Mid-to-Late Pregnant Rats

Effects of garcinol supplementation on the performance, egg quality, and intestinal health of laying hens in the late laying period

The problem of rapid decline in egg production performance and poor egg quality is a key obstacle to improving the economic benefits of laying hens. Garcinol is an antioxidant polyphenol plant extract that has multiple physiological functions. Diets with the appropriate amount of garcinol might be able to improve the performance traits and health of late laying hens. Therefore, this study was conducted to evaluate the utilization of garcinol in late laying hens. A total of 400 healthy 59-wk-old Tingfen No. 6 hens were randomly allocated into 4 dietary treatment groups and fed a basal diet supplemented with 0, 100, 300, and 500 mg/kg garcinol for 12 wk, denoted the Con, LG, MG, and HG groups, respectively. The results showed that the addition of garcinol in the diet tended to increase the egg production rate compared with that of the control group (P = 0.080), while the average egg weight was significantly lower (P < 0.05) during the whole period of the experiment. The results showed that MG group hens had higher egg quality and strengthened antioxidant capacity in their serum (P < 0.05). Moreover, the laying hens in the MG group had significantly decreased crypt depth (CD) and increased villus height (VH) in the jejunum and ileum (P < 0.05), as well as an increased ratio of VH to CD (P < 0.05) and increased expression levels of Occludin (P < 0.05) and Claudin-2 (P < 0.05) in the jejunum to improve intestinal barrier function. In addition, dietary supplementation with garcinol influenced the cecal microbiota of laying hens, which was characterized by changes in the microbial community composition, including increased abundances of Firmicutes, Romboutsia, and Ruminococcus torques. In conclusion, dietary 300 mg/kg garcinol supplementation could increase the egg production and egg quality of late laying hens, which may be attributed to the antioxidant effects of garcinol and the improvement of intestinal morphology and epithelial barrier function as well as the regulation of mucosal immune status by altering microbial composition.

Garcinol Promotes the Formation of Slow-Twitch Muscle Fibers by Inhibiting p300-Dependent Acetylation of PGC-1α

The conversion of skeletal muscle fiber from fast-twitch to slow-twitch is crucial for sustained contractile and stretchable events, energy homeostasis, and anti-fatigue ability. The purpose of our study was to explore the mechanism and effects of garcinol on the regulation of skeletal muscle fiber type transformation. Forty 21-day-old male C57/BL6J mice (n = 10/diet) were fed a control diet or a control diet plus garcinol at 100 mg/kg (Low Gar), 300 mg/kg (Mid Gar), or 500 mg/kg (High Gar) for 12 weeks. The tibialis anterior (TA) and soleus muscles were collected for protein and immunoprecipitation analyses. Dietary garcinol significantly downregulated (p < 0.05) fast myosin heavy chain (MyHC) expression and upregulated (p < 0.05) slow MyHC expression in the TA and soleus muscles. Garcinol significantly increased (p < 0.05) the activity of peroxisome proliferator-activated receptor gamma co-activator 1α (PGC-1α) and markedly decreased (p < 0.05) the acetylation of PGC-1α. In vitro and in vivo experiments showed that garcinol decreased (p < 0.05) lactate dehydrogenase activity and increased (p < 0.05) the activities of malate dehydrogenase and succinic dehydrogenase. In addition, the results of C2C12 myotubes showed that garcinol treatment increased (p < 0.05) the transformation of glycolytic muscle fiber to oxidative muscle fiber by 45.9%. Garcinol treatment and p300 interference reduced (p < 0.05) the expression of fast MyHC but increased (p < 0.05) the expression of slow MyHC in vitro. Moreover, the acetylation of PGC-1α was significantly decreased (p < 0.05). Garcinol promotes the transformation of skeletal muscle fibers from the fast-glycolytic type to the slow-oxidative type through the p300/PGC-1α signaling pathway in C2C12 myotubes.

Downregulation of p300/CBP-associated factor inhibits cardiomyocyte apoptosis via suppression of NF-κB pathway in ischaemia/reperfusion injury rats

Cardiomyocyte apoptosis is the main reason of cardiac injury after myocardial ischaemia-reperfusion (I/R) injury (MIRI), but the role of p300/CBP-associated factor (PCAF) on myocardial apoptosis in MIRI is unknown. The aim of this study was to investigate the main mechanism of PCAF modulating cardiomyocyte apoptosis in MIRI. The MIRI model was constructed by ligation of the rat left anterior descending coronary vessel for 30 min and reperfusion for 24 h in vivo. H9c2 cells were harvested after induced by hypoxia for 6 h and then reoxygenation for 24 h (H/R) in vitro. The RNA interference PCAF expression adenovirus was transfected into rat myocardium and H9c2 cells. The area of myocardial infarction, cardiac function, myocardial injury marker levels, apoptosis, inflammation and oxidative stress were detected respectively. Both I/R and H/R remarkably upregulated the expression of PCAF, and downregulation of PCAF significantly attenuated myocardial apoptosis, inflammation and oxidative stress caused by I/R and H/R. In addition, downregulation of PCAF inhibited the activation of NF-κB signalling pathway in cardiomyocytes undergoing H/R. Pretreatment of lipopolysaccharide, a NF-κB pathway activator, could blunt these protective effects of PCAF downregulation on myocardial apoptosis in MIRI. These results highlight that downregulation of PCAF could reduce cardiomyocyte apoptosis by inhibiting the NF-κB pathway, thereby providing protection for MIRI. Therefore, PCAF might be a promising target for protecting against cardiac dysfunction induced by MIRI.