| Objective To investigate the effect of NGF on improving bone microstructure and increasing bone strength in osteoporosis rats by mediating the expression of serum lipid carrier protein 2 (FABP4 /LCN-2). Effect of NGF mediated FABP4 /LCN-2 protein (serum lipid carrier protein 2) on bone microstructure and strength in osteoporosis rats. Methods Sixty rats were randomly divided into normal group, OP group, NGF group and intervention control group, with 15 rats in each group. Rats in OP group, NGF group and intervention control group were given retinoic acid suspension for continuous intragastric administration, once a day, 70 mg/kg each time, for 4 weeks, osteoporosis model was established. After successful modeling, NGF group and intervention control group were intraperitoneally injected NGF and MSCs with a dose of 2.0 μ/kg, respectively. Normal group and OP group were intraperitoneally injected with equal volume of PBS normal saline once a day for 3 consecutive days,biochemical indexes in serum were detected by ELISA. The femoral tissues were separated and the histopathological morphology was detected by HE staining. Micro CT was used to measure the microstructure of femur bone to observe the level of tissue morphology indexes. The bone strength of femoral tissue was measured by Hologic dual-energy X-ray absorptiometry. The protein content of FABP4 /LCN-2 in femoral tissues was detected by western blot. Results The expression levels of BGP, ALP and TRAP in serum of rats in OP group were increased, and there were differences compared with normal group (P<0.05). The levels of above indexes in serum of rats in NGF group and intervention control group were lower than that in OP group, and there were differences between groups (P<0.05). In the normal group, the femoral trabecula was red and purple with uniform thickness and compact arrangement. In the OP group, the fracture of femoral trabecula and the surface of bone marrow cavity were enlarged. In the NGF group and the intervention control group, the number of bone trabecula was increased, the distribution was more regular, and the structure was similar to that of the normal group. The contents of Tb·Th, Tb·N, BMD and BMC in OP group decreased, while the contents of Tb·SP increased, which were different from those in normal group (P<0.05). The levels of the above indexes in NGF group and intervention control group were different from those in OP group (P<0.05), but no difference was found in other groups (P>0.05). The level of FABP4 protein in the femoral tissue of the OP group was increased (1.80±0.33), while the level of LCN-2 protein was decreased (1.06±0.26), which was different from that of the normal group (1.39±0.15) and LCN-2 protein was 2.06±0.55 (P<0.05). FABP4 protein decreased by 1.52±0.20 and LCN-2 protein increased by 1.80±0.33 in the NGF group and the intervention control group, compared with the OP group (P<0.05). FABP4 protein decreased by 1.36±0.18 in the FABP4 inhibitor group, which was different from that in the NGF group (P<0.05). Conclusions Intraperitoneal injection of NGF in osteoporosis rats can improve the femoral microstructure, increase the proportion of bone trabecula and increase bone strength. The mechanism of this study is that NGF can activate the expression of LCN-2 and inhibit FABP4, thus playing an anti-osteoporosis role. |