Effects Of Subcutaneous Injection Of Prostaglandin E₂ On Bone Tissue Metabolism In Young Dogs

In the metabolic process of bone tissue,prostaglandin E₂?PGE₂?plays an important bidirectional regulatory role,which is reflected in the environment of cell culture at different concentrations and the way of drug administration to animals.By regulating the OPG/RANKL/RANK system,PGE₂ affects the dynamic balance between osteoblasts and osteoclasts,leading to changes in the metabolic state of bone tissue.Currently,PGE₂ has been partially studied in bone tissue metabolism of adult animals.However,the role of bone tissue in young animals,especially young dogs,is unknown.To investigate the effect of PGE₂ on bone tissue metabolism in young dogs,this study observed the effect of subcutaneous injection of PGE₂ on OPG/RANKL expression and bone tissue morphology in young dogs.Eleven healthy 4-month old beagle dogs with similar body weight?6.68±0.62kg?were selected for the experiment.The experimental groups were divided into group I?4 dogs?and group II?4 dogs?,and PGE₂ was injected under the skin for 4 weeks at 0.1mg/kg and0.3mg/kg respectively,and the control group?3 dogs?was injected with PGE₂ solvent.To investigate the effect of PGE₂ on bone tissue metabolism in young dogs.Blood samples were collected on day 0,7,14,21,28 to detect the levels of OPG,sRANKL and PGE₂ in serum.On day 28,all dogs were treated with anle to collect distal end of the ulna of the forelimb was2cm,and the expression levels of OPG and RANKL in the bone tissue of the forelimb were detected by Western blot.Bone tissue sections were made from the one third of the distal radius was collected,and quantitative indexes of bone tissue were detected and analyzed,including the trabecular area percentage?Tb.Ar%?,trabecular thickness?Tb.Th?,trabecular bones number?Tb.N?and Trabecular bone separation?Tb.Sp?.The results showed that subcutaneous injection of PGE₂ caused the increase of Tb.Ar%,Tb.Th,Tb.N and the decrease of Tb.N.Results:?1?Effects of subcutaneous injection of PGE₂ on serum OPG,sRANKL and PGE₂levelsAt day 0d and day 7d,there were no significant differences in serum OPG and PGE2levels between the control group,the group I and the group II?P>0.05?.On day 14 and 28,the serum levels of OPG and PGE2 in the group I and the group II were significantly higher than those in the control group?P<0.05?.On days 14 to 28,there was no significant difference in serum sRANKL levels between the three groups?P>0.05?.?2?Effect of subcutaneous injection of PGE₂ on the expression of OPG/RANKL in bone tissueWestern blot results showed that there was no significant change in the expression of OPG in bone tissue between the control group,the group I and the group II?P>0.05?,and the expression of RANKL in the group I and the group II was significantly lower than that in the control group?P<0.05?.The ratio of OPG/RANKL in the group I and the group II was significantly higher than that in the control group?P<0.05?.The results showed that subcutaneous injection of PGE₂ could reduce the expression of RANKL in bone tissue,inhibit bone resorption,and increase the expression of OPG,indicating a trend of promoting bone formation.?3?Effects of subcutaneous injection of PGE₂ on quantitative parameters of bone tissues.Bone tissue quantitative analysis showed that compared with the control group,the Tb.Ar%in the group I and the group II was significantly increased?P<0.05?.The Tb.Th of the group II was significantly higher than that of the control group?P<0.05?,while there was no significant difference between the group I and the control group?P>0.05?.The Tb.N in the group I and the group II was significantly higher than that in the control group?P<0.05?.The Tb.Sp in the group I and the group II was significantly lower than that in the control group?P<0.05?.The results showed that subcutaneous injection of PGE₂ caused the increase of Tb.Ar%,Tb.Th,Tb.N and the decrease of Tb.Sp,and morphological structure of bone tissue changes,resulting in increased bone mass.Conclusion:In young dogs,subcutaneous injection of PGE₂ at 0.1mg/kg and 0.3mg/kg once a day for28d can increase the level of OPG and PGE₂ in serum,reduce the expression of RANKL in bone tissue,increase Tb.Ar%,Tb.Th,Tb.N,and reduce Tb.Sp,indicating that subcutaneous injection of PGE₂ can promote bone formation and metabolism in bone tissue of young dogs and play a positive regulatory role.