[Oleanolic acid-stimulated lipolysis in primary adipocytes and its mechanisms]

To investigate the effect and mechanism of oleanolic acid (OA)-stimulated lipolysis in primary adipocytes.

Adipocytes were isolated from the epididymal fat pads of SD rats. The non-cytotoxic dosage of OA for primary adipocytes was established by MTT test. Adipocytes were divided into four groups: a control group and 3 OA-treated groups (25, 50 and 100 micromol/L). Glycerol released in the culture medium of the control and three OA-treated adipocyte groups was determined after incubation with OA for 4 and 24 hours. The glycerol released in the culture medium of three OA-treated adipocyte groups with protein kinase A inhibitor H-89 (10 micromol/L) was also determined. The expression of native perilipin and hormone-sensitive lipase (HSL) translocation were examined by immunoblotting method.

Cytotoxicity was observed when the concentration of OA was 400 micromol/L. After incubation for 4 hours, the release of glycerol in the 50 micromol/L and 100 micromol/L OA groups was increased 12% and 20% (P < 0.05) respectively. After incubation for 24 hours, the release of glycerol was increased 14% (P > 0.05) and 23% (P < 0.05) respectively. There is no change of glycerol release in the three OA- and H-89-treated adipocyte groups. OA may down-regulate the expression of perilipin and promote HSL translocation.

OA may stimulate the release of glycerol from primary adipocytes, and the cellular mechanisms of lipolytic action may involve in augmenting perilipin expression and promoting HSL translocation.