Synergistic attenuation of ovariectomy-induced bone loss by combined use of fish oil and 17 ss-oestradiol

摘要

Oestrogen and n-3 PUFA, especially EPA and DHA, have been reported to have beneficial effects on bone loss. Thus, the purpose of the present study was to investigate the synergistic bone-protective mechanism of combined treatments of EPA + DHA supplementation and oestrogen injection in ovariectomised rats. Rats were fed a modified American Institute of Nutrition-93G diet with 0, 1 or 2 n-3 PUFA (EPA + DHA) relative to the total energy intake for 12 weeks. Rats were surgically ovariectomised at week 8, and after a 1-week recovery period rats were injected with either 17 ss-oestradiol-3-benzoate (E-2) or maize oil for the last 3 weeks. Combined use of n-3 PUFA and E-2 synergistically increased femoral cortical bone volume, bone mineral content and the bone expression of runt-related transcription factor 2 (RUNX2), but decreased the bone expression of IL-1 ss. Both n-3 PUFA and E-2 decreased the bone expressions of IL-7, TNF-alpha and PPAR-gamma, and increased the bone expression of oestrogen receptor-alpha. n-3 PUFA in the presence of E-2 and E-2 alone significantly decreased the bone expressions of IL-1 ss and IL-6 and increased the bone expression of RUNX2. E-2 significantly decreased the serum levels of bone turnover markers and the bone expression of receptor activator of NF-kappa B ligand, but decreased the bone expression of osteoprotegerin. The combined use of n-3 PUFA and E-2 exerted synergistic bone-protective efficacy through up-regulation of RUNX2, an essential transcription factor for bone formation, as well as the suppression of bone-resorbing cytokine IL-1 ss.