Growth hormone involvement in the regulation of tartrate-resistant acid phosphatase-positive cells that are active in cartilage and bone resorption

Abstract

Young male Sprague-Dawley rats (5-7 weeks old, 80-120 g) were hypophysectomized (HX) and maintained on thyroxin and dexamethasone replacement therapies. Ten days after surgery, some HX rats received a single injection of human growth hormone (hGH), and others five daily injections of hGH. Tartrate-resistant acid phosphatase (TRAP) histochemistry was employed in order to evaluate the number of cells of resorptive potential in the metaphyseal bone of the proximal tibiae of HX rats and was compared with normal rats and HX rats that further received hGH replacement therapy. In normal rats, two populations of TRAP-positive cells were identified: multinuclear cells, which showed histological characteristics of osteoclasts, and small mononuclear cells, the number of which was overwhelming when compared with the number of TRAP-positive multinuclear cells. Both populations were reduced in the HX rat, but more so the mononuclear cells, which were assumed to represent the precursor pool of mature osteoclasts and chondroclasts (P < 0.005). Five daily injections of hGH to HX rats brought about a significant increase in the number of TRAP-positive multinuclear cells, the number of nuclei of these cells, and the number of mononuclear TRAP-positive cells, throughout the metaphyseal bone (P < 0.05). A single injection of hGH increased only the number of TRAP-positive multinuclear cells in the trabecula/bone marrow interface (P < 0.05), indicating a very rapid fusion of precursor cells into mature osteoclasts in that particular location.(ABSTRACT TRUNCATED AT 250 WORDS)

Involvement of growth hormone-insulin-like growth factor I system in cranial remodeling during halibut metamorphosis as indicated by tissue- and stage-specific receptor gene expression and the presence of growth hormone receptor protein

“…TRAP, a lytic enzyme important for dissolving mineral in bone, is differentially expressed both temporally and spatially along the frontal bones during eye migration (Saele et al 2006). In mammals, GH and IGF-I stimulate bone resorption (Guicheux et al 1998) and stimulate TRAP-positive cells (Gevers et al 1996;Lewinson et al 1993). Although no detailed information exists about the role of GH and IGF-I in bone proliferation and resorption in fish, both hormones appear to be involved in seasonal vertebral growth in juvenile Atlantic salmon (Salmo salar; Wargelius et al 2005).…”

Synergistic Effect of Parathyroid Hormone and Growth Hormone on Trabecular and Cortical Bone Formation in Hypophysectomized Rats

“…Thus, the net bone mass and bone density were not completely restored to the level of the age-matched intact animals. In a similar study, Lewinson et al [33] found out that the number of osteoclasts in the metaphyseal bone of the proximal tibia of the HX rat was increased by GH, thereby increasing bone resorption. Wang et al [34], using pQCT densitometry, demonstrated that GH completely restored cortical bone in vertebra; however, both histomorphometric and pQCT measurements demonstrated that GH had no significant effect on the vertebral cancellous bone of aged, ovariectomized, osteopenic rats.…”

Role of growth hormone in enchondroplasia and chondral osteogenesis: evaluation by X-ray of the hand

“…Indeed, GH was shown to have specific effects on growth plate cells, as already reviewed (20). In a rat model, GH enhances the mobilization of tartrate-resistant acid phosphatase-positive osteoclasts that are active in cartilage and bone resorption in enchondral osteogenesis (21). Whereas the primary ossification centers of long bones are well ossified at birth, the carpal cuboid bones of the hands portray a unique opportunity to observe primary ossification centers in their making.…”