Expression and immunolocalisation of PPARγ in reproductive tissues of rabbits fed n-3 PUFA-enriched diets

Background: Since fatty acids are natural ligands of peroxisome proliferator-activated receptors (PPARs), involved in a wide spectrum of metabolic activities, we explored the protein expression and localisation of PPARγ, as well as susceptibility to lipoperoxidation (LPO), in reproductive tissues of rabbits fed n-3 polyunsaturated fatty acid (PUFA)-enriched diets. Methods: Nine rabbit bucks were divided into three groups and fed different diets: FLAX diet supplemented with 10% extruded flaxseed, FISH diet containing 3.5% fish oil and standard diet as control. Protein expression by western blot analysis, localisation of PPARγ by immunofluorescence and susceptibility to LPO by measuring F2-Isoprostanes (F2-IsoPs) were explored. Results: Down-regulation of PPARγ expression was observed in control rabbit testes compared with FLAX (p < 0.01) and FISH (p < 0.05) dietary groups. On the contrary, an up-regulation in rabbit epididymis was observed in both n-3 PUFAs dietary groups compared with the control (p < 0.001). Immunofluorescent staining of PPARγ showed a strong expression in the interstitial tissue and seminiferous tubules of testes from groups fed n-3 PUFA-enriched diets compared to controls; the PPARγ signal was brighter in the epididymis of controls than in those of rabbits fed n-3 PUFA-enriched diets. Interestingly, F2-IsoP levels were significantly higher in testis and epididymal tissue of control compared to n-3 PUFAs dietary groups (p < 0.001). Conclusion: PPARγ is present in male reproductive tissues, in particular in the epididymis and interstitial testicular tissue. PPARγ expression appears to be influenced by n-3 PUFAs dietary sources and to play a role in supporting sperm maturation. n-3 PUFAs diets, reducing F2-IsoP levels, commonly considered proinflammatory molecules linked to oxidative injuries, may also support PPARγ activity.