Panaxadiol Improves Obesity By Promoting White Fat Beigeing

Obesity is an important cause of a range of metabolic diseases.However,the complex mechanisms of obesity and its related diseases make some weight loss methods ineffective or have safety issues.It is imperative to find medicinal herbs that can be used as both medicine and food with anti-obesity effects.Ginseng,a specialty of Jilin Province,contains mainly ginsenosides and other components,and is a plant with both edible and medicinal value.Modern pharmacology has also repeatedly mentioned the weight loss and hypoglycemic effects of ginseng.The specific action mechanism of ginseng is unclear due to its multi-component and multi-target characteristics.In this study,we used network pharmacology to predict and screen the active ingredients,action targets and signaling pathways of ginseng.We found Panaxadiol（PD）is a more desirable active ingredient due to its high drug-like properties and high bioavailability.Moreover,it is closely related to c AMP pathway which is more important in metabolism regulation.The corresponding pharmacodynamic targets of PD include ADRB2（the gene encoding theβ₂receptor）.The c AMP pathway has been reported to be associated with thermogenesis,and the classical activation pathway in adipocytes is that theβreceptor increases intracellular c AMP and activates protein kinase A（PKA）,which phosphorylates c AMP-response element binding protein（CREB）and increases the expression of downstream thermogenic genes such as UCP1.Previous studies have suggested that only brown adipocytes can produce heat,but recent studies have shown that there is a potential cell type called beige adipocytes,which can be transformed from white adipocytes and can specifically express brown-specific genes such as UCP1,PRDM16 and PGC-1αwhen induced by specific external conditions to increase energy expenditure for the purpose of disease treatment.Objective:To investigate whether Panaxadiol can promote white adipocyte beigeing and increase thermogenesis through modulating theβ₂/c AMP/CREB pathway to exert anti-obesity effects.Methods and Results:1.Study of the association between the anti-obesity effect of Panaxadiol and the c AMP pathway for thermogenesisIn vivo study,we established a high-fat feeding obesity model,and administered PD（10mg/kg）for 5 weeks.Firstly,we examined body weight changes,blood lipids,oral glucose tolerance and fast glucose.The morphology of adipose tissue was also observed by HE staining.Then the expression of thermogenic proteins UCP1,PRDM16,PGC-1αand mitochondrial biogenesis related protein TFAM and the expression of c AMP pathway protein CREB phosphorylation were detected in adipose tissue.Compared with the control group,the results show that obese mice（fed with high fat）had higher body weight and significantly impaired glucose tolerance,increase low density lipoprotein,total cholesterol,and triglyceride.HE staining showed a significant increase in the volume of adipocytes.Western blotting showed that the expression of UCP1,PRDM16,PGC-1α,TFAM was significantly down-regulated and CREB phosphorylation（P-CREB）was reduced.Compared with the obese mice,body weight,impaired glucose tolerance,total cholesterol,and triglycerides decreased significantly after PD administration.HE staining showed that PD reduced the size of adipocytes.Western blotting showed that the expression of UCP1,PRDM16,PGC-1αand TFAM increased in the administered group with enhanced P-CREB,suggesting that PD might promote the expression of thermogenic proteins in adipocytes through the c AMP/CREB pathway and thus exert anti-obesity effects.In vitro,differentiated mature 3T3-L1 cells were given palmitate（PA）to induce hypertrophy model along with PD（20μM）for 24 hours.Oil Red O staining were used for showing lipid droplet.Heat producing proteins PRDM16 and CREB phosphorylation were detected.The results showed that the lipid droplets of adipocytes were significantly increased and the expression of PRDM16,UCP1 and P-CREB were down-regulated after PA stimulation.When PD treatment was given along with PA stimulation,the lipid droplets were reduced and the expression of PRDM16 and P-CREB was increased.This indicates that PD has an ameliorative effect on hypertrophic adipocytes,which may act through phosphorylation of CREB.2.Clarified that Panaxadiol can promote CREB phosphorylation throughβ₂receptors and thus exert anti-obesity effectsFirstly,Autodock Tools was used for molecular simulation to predict the existence of interaction between PD andβ₂.Then we also used PD to prevent obesity in ob/ob mice withβ₂intervention.In vivo,ob/ob mice model was established,C57mice was set up as control group,PD（10mg/kg）was administrated for 8 weeks,PD treatment along withβ₂receptor inhibitor ICI118551（1 mg/kg）was given at the same time.The assays were consistent with the high-fat fed obesity model.Molecular docking results showed a low binding energy betweenβ₂receptors and PD,indicating an affinity between theβ₂receptor and PD.While the results of ob/ob mice given PD were essentially identical to those of mice given PD after high-fat diet induction.The mice in the group administered with PD along withβ₂receptor inhibitor had higher body weight and higher blood lipid level than the PD administered group.HE staining also showed an increase in adipocyte volume.The protein of thermogenesis and P-CREB decreased at the same time.To some extent,we can believe that the anti-obesity effect of PD was weakened by theβ₂receptor inhibitor.Conclusion:1.Panaxadiol has a weight loss effect on both high-fat diet-induced and genotypically obese mice.2.Panaxadiol can act onβ₂receptor,regulate downstream c AMP pathway,make CREB phosphorylation,promote white adipocytes beigeing,and exert thermogenic and anti-obesity effects.