Lycopene and Garcinia cambogia Induce White-to-Brown Adipose Differentiation: An Innovative Strategy to Curb Obesity

Abstract

Obesity is considered one of the main risk factors for cardiovascular diseases. The browning process has been recently recognized as a promising anti-obesity therapy. Lycopene (LYC) and Garcinia cambogia fruit extract (GE) might be important resources for anti-obesity drugs; therefore, the aim of this study was to investigate the anti-obesity effects of LYC and GE on 3T3-L1 adipocytes and Zucker rats. Mouse 3T3-L1 pre-adipocytes were differentiated in mature adipocytes and then treated with LYC (0.5 μM), GE (30 mg/mL) or LYC + GE for 24 h. Moreover, male Zucker Crl:ZUC-Leprfa rats were randomly assigned to 5 groups of 10 animals to orally receive Vehicle (Ctrl), Orlistat (20 mg/kg), LYC (5 mg/kg), GE (1000 mg/kg) or LYC + GE for 28 days. LYC, GC extracts and even more LYC + GE stimulated the mRNA and protein expression of thermogenic genes UCP1, CIDEA and DIO2, significantly reduced lipid droplet size and increased lipid droplet number in adipocytes. UCP1 mRNA and protein expression was also increased in the visceral adipose tissue of the rats that received the dietary intake of LYC, GE and even more LYC + GE. Moreover, LYC + GE induced the reorganization of visceral fat depots that showed a great number of small adipocytes and a significant reduction in weight gain and food intake compared to the control group. The obtained results demonstrated that LYC + GE might be used as new approaches for obesity management in order to induce the browning process and achieve a metabolically active tissue instead of a tissue characterized by lipid depot accumulation.

Keywords: Garcinia cambogia; adipocyte differentiation; browning process; lycopene; obesity; uncoupling protein 1 (UCP1).

Figure 1

Panels (A–D) show cytotoxicity evaluated by Trypan Blue exclusion test in 3T3-L1 cells; Ctrl (A), LYC (B), GE (C) and LYC + GE (D). Panel (E) summarizes the results of the Trypan Blue exclusion test; all images were captured at 10× magnification. Values are expressed as the mean and SD of three experiment.

Figure 2

Cell viability evaluated in 3T3-L1 cells treated with LYC, GE and LYC + GE at 24 h by MTT assay. Values are expressed as the mean and SD.

Figure 3

The panels show differentiated adipocytes stained with ORO staining of Ctrl (A), LYC (B), GE (C) and LYC + GE (D). The graphs represent average diameter of lipid droplets (E), number of lipid droplets (F), % differentiation rate (G) and ORO absorption (H) obtained from each group. Values are expressed as the mean and SD of three experiment; * p < 0.05 vs. Ctrl; # p < 0.05 vs. LYC; § p < 0.05 vs. GE.

Figure 4

The graphs represent UCP1 (A), DIO2 (B) and CIDEA (C) mRNA expression (RTqPCR analysis) and UCP1 (D), DIO2 (E) and CIDEA (F) protein expression (western blot analysis) obtained from 3T3-L1 cells. Values are expressed as the mean and SD; * p < 0.05 vs. Ctrl; # p < 0.05 vs. LYC; § p < 0.05 vs. GE.

Figure 5

The graphs show the body weight gain percentage (A) and the food intake (B) from day 0 until the end of the experiment. Values were obtained from 10 animals per group and are expressed as means and SD; * p < 0.05 vs. Ctrl; # p < 0.05 vs. LYC; § p < 0.05 vs. GE.

Figure 6

Panel of H&E sections of visceral fat depots. Ctrl animals (A) exhibit the typical structure of large unilocular adipocytes of the same size; orlistat (B) and GE (C) treated animals show the presence of unilocular adipocytes of different size; LYC-treated animals (D) show the presence of large unilocular adipocytes and small unilocular adipocytes; LYC + GE treated rats (E) show a visceral adipose tissue organized by adipocytes of different dimension with an inhomogeneous aspect and small lipid droplets. Panel (F) shows the quantitative difference in adipocytes size; the values were obtained from 10 slides for each group and the diameter of 10 adipocytes randomly selected for each slide was measured; all images were captured at 20× magnification. The data are expressed as means and SD. * p < 0.05 vs. Ctrl; # p < 0.05 vs. LYC; § p < 0.05 vs. GE.

Figure 7

Immunofluorescence reactions with anti-UCP1 (green channel) and anti-PGC1α (red channel) in visceral fat depots of Zucker rats. Ctrl animals (A) show large unilocular adipocytes positive for PGC1α but negative for UCP1; orlistat (B) treated animals show visceral fat depots with unilocular adipocytes positive for PGC1α only but negative for UCP1; GE (C) and LYC (D) treated animals show unilocular adipocytes with different size positive for both PGC1α and UCP1. LYC + GE (E) treated animals show visceral fat depots with great number of small adipocytes positive for both PGC1α and UCP1; many adipocytes are reorganizing their structure with numerous lipid droplets delimited by membrane (arrow). Panel (F) shows the fluorescent intensity of UCP1 obtained by the confocal laser. Values were obtained from 10 animals per group and are expressed as means and SD; * p < 0.05 vs. Ctrl; # p < 0.05 vs. LYC; § p < 0.05 vs. GE.

Figure 8

The graphs represent UCP1 mRNA expression (A) and UCP1 protein expression (B) obtained from visceral fat depots of Zucker rats. Values are expressed as the mean and SD; * p < 0.05 vs. Ctrl; # p < 0.05 vs. LYC; § p < 0.05 vs. GE.