Discrepancy of response of hPTH administration and its withdrawal between trabecular and cortical bone sites in ovx rats

We demonstrated the differences of response between trabecular and cortical bone sites in the rat induced by OVX and hPTH(1–34) administration [subcutaneous injection, 30μg/kg, 3 times/week, for 12 weeks] and its withdrawal [for 8 weeks]. We observed that hPTH(1–34) administration in OVX rats partially prevented OVX-induced cancellous bone loss in the proximal tiabial metaphysis and added cortical bone in the tibial shaft. After cessation of hPTH treatment, bone loss was observed both in trabecular and cortical bone; however, it was more dramatic on endocortical surfaces.