A Preliminary Study On Experssion Of Frizzleds Receptors In Implant Osseointegration In Hyperlipidemic Rats

ObjectiveBecause of the high incidence of hyperlipidemia and adverse effects on bone metabolism, it will be necessary to pay more attention to the potential risk factors involved with implants. The experiment aimed to explore the effects of hyperlipidemia on osseointegration and the regulation of frizzled receptors (fzd).Materials and methodsWistar adult male rats were randomly divided into control and experimental groups fed on a normal diet and a high fat diet respectively for six weeks.After 6 weeks on the diet, each rat received a titanium implant in the bilateral proximal metaphysis of the femurs. The animals were sacrificed at 0,5,10,15,20, and 28 days after the surgery.MicroCT and hard-tissue sections were used to analyze the osseointegration at 15 days and 28 days. The mRNA expression of the fzds was measured by relative fluorescence quantitative polymerase chain-reaction (RT-PCR) at 0,5,10,15 and 20 days.ResultsThe experimental group exhibited decreased new bone formation and a lower bone combination rate. RT-PCR revealed that in the control group, the expression of fzd2 significantly increased at 5 days after the implant surgery(P< 0.05), decreased at 10 days, (P< 0.05), and then, followed by a slow growth; the expression of fzd4 significantly increased at 5 days(P< 0.05), reduced at 10 days (P< 0.05), raised to the peak at 15 days (P< 0.05), then decreased at 20 days (P< 0.05); the expression of fzd8 obviously decreased at 5 days (P< 0.05), then continuously reduced, slightly elevated at 20 days (P< 0.05); the expression of fzd9 observably decreased at 5 days(P< 0.05), followed by lasting growth to 20 days (P< 0.05). Comparisons between the two groups, the expression of fzd2 of the experimental group were lower than that of control group at 0,5,15,20 days (P< 0.05), at 10 days there was no significant difference (P> 0.05); Fzd4,8,9, on the other hand, all had significant difference between the two groups (P< 0.05), expression of fzd4 at 0,5, and 15 days were lower than the control group, higher at 10 and 20 days; expression of fzd8 at 0, 20 days is higher than the control group, lower at 5,10,15 days; expression of fzd9 at 0,5,15,20 days were lower than the control group, was higher at 10 days.ConclusionWe conclude that fzd2,4,8, and 9 participate in the regulation of implant osseointegration. Fzd2,4,8 mainly regulate the osseointergration in the early stage, while fzd9 may mainly regalate the process in the middle and late stages. Whereas hyperlipidemia-compromised osseointegration maybe the result of the regulation of fzd2,4,8 and 9.