The Influence of Growth Hormone on Bone Marrow Adipogenesis in Hypophysectomized Rats

The hypophysectomized rat has been used as a model to study the effects of growth hormone deficiency on bone. Here we have investigated the influence of growth hormone administration to hypophysectomized rats for 6 weeks on accumulation of triglycerides in bone marrow and, on the differentiation of primary marrow stromal cells into adipocytes under in vitro conditions. We found that hypophysectomy significantly increased triglyceride concentration in bone marrow which was attenuated by growth hormone administration. Primary bone marrow stromal cells derived from hypophysectomized rats (HX) also had more adipocytes at confluence compared to growth hormone treated rats (GH). When stimulated with IBMX/Dex, preadipocyte colony counts increased more significantly in GH. Markers of adipocyte differentiation were higher in HX than CT or GH at confluence. However, following stimulation with IBMX/Dex, increased expression of markers was seen in GH compared to HX. Conclusion: Growth hormone administration to hypophysectomized rats attenuated triglyceride accumulation in bone marrow, and inhibited the differentiation of stromal cells into adipocytes in vitro.