The Relationship Between GPR30 And Longitudinal Bone Growth

Objection:Test the expression of GPR30 in growth plate at three different situations------normal growth, active growth, retarded growth and analysis the dynamic changes to explore the relationship between GPR30 and long bone growth.Method Catch-up growth after hypothyroidism model (B)was established by feeding with water of PTU till 4W to provide active longitudinal bone growth, comparing with control group(A). Ovariectomized growth group (D) was established by bilateral oophorectomy at 3w to provide retarded longitudinal bone growth, comparing with sham-operation group(C). Measure the tibial length, tail length and body weight to make the line chart and detect the serum T4 by RIA in group A , B at 4W, 8W as well as serum E2 in group C , D at 4W to analysis the growth trend and the change of hormones.Collect the growth plate of every group at 4w, 8w, 11w respectively to make paraffin sections by formaldehyde fixed, demineralization, dehydration, transparent, embedding and cut into 5 um .Then the sections were used to perform HE. And then the expression of Brdu and GPR30 were testified by SABC methods, artificially counting the rate of the positive cells to compare the difference of the dynamic changes among the group A , B and group C , D.Result : 1. There is a rapid growth of tail length, tibial length and body weight in group A, C. However, the growth speed after hypothyroidism in group B is faster than the corresponding group A. The growth in group D is steady, slower than the group C. 2. At 4W, the serum level of T4 in group B is lower than that in group A(P<0.05), while there is no difference at 11w.(P>0.05). At 8W, the serum level of E2 in group D is lower than that in group C (P<0.05). Then length of growth plate in group A is longer than that in group B, while the length in group C is longer than that in group D. But there is a rapid growth in group B at 8w and 11w.The positive rate of Brdu-labeling chondrocytes in group B at 8w is the highest, the next is that in group A and C at 8w, the least is that in group D at 11W. 3. The expression of GPR30 declines with development in all the groups. The most prominent reduction was the catch-up growth group, then the normal group, the ovariectomized group is the least.(the expression of GPR30 in A, B, C, D :is 22±7%, 17±3%, 25±5%, 12±4% at 4 W,19±5%, 16±6%, 19±7%, 9±6% at 8W ,15±6%, 9±4%, 14±5%, 7±5% at 11W)Conclusion: The expression of GPR30 declines with development. GPR30 declines more when there is a relative activer growth suggests that the GPR30 maybe play a negative role in the regulation of the long bone growth.