The Relationship Between Vitamin D And Vitamin D Receptor With The Lipometabolism In Adipocyte

Objective:To investigate the relationship between vitamin D and vitamin D receptor (VDR) with the lipometabolism in adipocytes. Methods: ①82 surgical patients were selected and divided into 3 groups, including control group(20 cases, BMI:18.5-23.9), overweight group (35 cases, BMI:24-27.9), obesity group (27 cases, BMI>28). The levels of serum TG, TC, LDL-C, HDL-C were checked by automatic biochemistry analyzer. The mRNA levels of VDR, sterol regulatory element binding transcription factor 1c (SREBP-1c), hormone sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) in subcutaneous adipose tissue (SAT) and omental adipose tissue (OAT) were assayed by RT-PCR. VDR protein expression was measured by Western blotting,②cells were divided into control group (C), high glucose group (G) and high glucose with high free fatty acids group (GF), and then were induced to differentiation into mature fat cells with or without adding 1,25(OH)2D3(VD3) which is the active form of vitamin D; Oil red staining was employed to detect the total amount of the fat in different groups; RT-PCR was used to evaluate the VDR, SREBP-lc and HSL mRNA levels. Results: ①The rate of dyslipidemia in overweight group and obesity group was higher than control group (P<0.05); in SAT, VDR mRNA and protein level of obesity group expressed lower than normal and overweight group (P<0.05); SREBP-lc mRNA expression level of obesity group was higher than control group (P<0.05) and both overweight and obesity group expressed lower HSL,ATGL mRNA than control group (P<0.05); in OAT, VDR mRNA and protein expression level was higher in overweight group (P <0.05). Compared with overweight group, VDR mRNA and protein expression level was lower in obesity group (P< 0.05); Compared with control group, overweight and obesity group expressed higher SREBP-1c, ATGL mRNA while the HSL mRNA expression was lower in both group(P<0.05). ②Fat amount was increased in G and GF groups (P<0.05), VD3 decreased the fat amount in C group but had no effect on G and GF groups (P>0.05); the VDR mRNA level was decreased in G and GF groups, VD3 can increase the VDR mRNA level (P< 0.05);the SREBP-1c, HSL mRNA level were upgraded in G and GF groups (P< 0.05); VD3 decreased the SREBP-1c mRNA level in C group, but had no effect on SREBP-lc and HSL mRNA. Conclusion:The lipid metabolism in SAT and OAT of the overweight and obesity group people is in disorder and the obesity group expressed lower VDR, which may be one of the mechanisms of the poor clinical outcome of vitamin D intervention therapy and may cause them more susceptible to dyslipidemia, endocrine, metabolic and cardiovascular diseases. VD3 had lost the ability to inhibit the fat accumulation in 3T3-L1 cells when exposed under the high glucose and high free fatty acids environment, which hints us that if VD3 is used to intervene obesity, the patients’ blood glucose and lipid should also be improved at the same time.