Caviar Extract and Its Constituent DHA Inhibits UVB-Irradiated Skin Aging by Inducing Adiponectin Production

Abstract

In this study, caviar (sturgeon eggs) was used to elucidate its roles in adiponectin production and skin anti-aging. Recently, caviar has been largely used not only as a nutritional food, but also in cosmetic products. In particular, it has been reported that docosahexaenoic acid (DHA), as one of the main phospholipid components of caviar extract, induces intracellular lipid accumulation and the expression of adiponectin in adipocytes. Although adipocytes are well known to be associated with the skin dermis by secreting various factors (e.g., adiponectin), the effects of caviar extract and DHA on the skin are not well studied. Here, we demonstrate the effects of caviar extract and DHA on adipocyte differentiation and adiponectin production, resulting in a preventive role in UV-irradiated skin aging. Caviar extract and DHA enhanced adipocyte differentiation and promoted the synthesis of transcription factors controlling adipocyte differentiation and adiponectin. In addition, the mRNA expression levels of matrix metalloproteinase-1 (MMP-1) were decreased in UVB-irradiated Hs68 fibroblasts that were cultured in conditioned medium from caviar extract or DHA-treated differentiated adipocytes. Taken together, these results indicate that caviar extract and DHA induce adipocyte differentiation and adiponectin production, thereby inhibiting UVB-induced premature skin aging via the suppression of MMP-1 production.

Keywords: DHA; MMP; adipocyte differentiation; adiponectin; caviar extract; skin aging.

Figure 1

Caviar extract increased adipocyte differentiation. (A) 3T3-L1 cells were treated with caviar extract at the indicated concentrations for 2 days. Cell viability was examined by the MTT assay. The means ± SDs are the average of three independent experiments. (B) The differentiated 3T3-L1 adipocytes were induced with or without treatment of caviar extract for 6 days. Observation of morphology and Oil Red O staining of 3T3-L1 cells were photographed using a light microscope (Χ 200). Lipid droplets are stained red, and the data are representative of three independent experiments. (C) PPARγ, SREBP-1a, and C/EBPα mRNAs were measured by RT-qPCR. The means ± SEs are the average of three independent experiments. * p < 0.05, ** p < 0.01, and *** p < 0.001 indicate a significant difference from the control.

Figure 2

Caviar extract inhibited skin aging via an increase in adiponectin production. The 3T3-L1 cells were induced to differentiate with or without treatment of caviar extract for 6 days. (A) Adiponectin mRNA and (B) adiponectin protein levels were measured by RT-qPCR and immunoblot, respectively. (C) The 3T3-L1 cells were differentiated with caviar extract for 6 days, and the resulting conditioned medium was applied to UVB-irradiated Hs68 fibroblasts for 24 h. MMP-1 mRNA was then measured by RT-qPCR. The means ± SEs are the average of three independent experiments. ** p < 0.01, *** p < 0.001 compared to the control. ^† p < 0.05, ^†† p < 0.01 compared to the UVB-irradiated control.

Figure 3

DHA increased adipocyte differentiation. The 3T3-L1 cells were differentiated with treatment of DHA, caviar extract, or troglitazone for 6 days. (A) Observation of morphology and Oil Red O staining of differentiated 3T3-L1 cells were photographed using a light microscope (Χ200). Lipid droplets are stained red, and the data are representative of three independent experiments. PPARγ, SREBP-1a, and C/EBPα (B) mRNA and (C) protein levels were measured by RT-qPCR and immunoblotting. The means ± SEs are the average of three independent experiments. * p < 0.05, ** p < 0.01, and *** p < 0.001 indicate a significant difference from the control.

Figure 4

DHA inhibited MMP-1 mRNA expression via an increase in adiponectin production from adipocytes. The 3T3-L1 cells were induced to differentiate with or without treatment of DHA for 6 days, and the adiponectin (A) mRNA and (B) protein expression levels were measured by RT-qPCR and immunoblotting. The resulting conditioned medium was applied to UVB-irradiated Hs68 fibroblasts for 24 h. (C) MMP-1 mRNA was then measured by RT-qPCR. The means ± SEs are the average of three independent experiments. *** p < 0.001 compared to the control, ^†† p < 0.01 compared to the UVB-irradiated control.