Growth hormone induces bone morphogenetic proteins and bone-related proteins in the developing rat periodontium

The hypothesis that growth hormone (GH) up-regulates the expression of enzy mes, matrix proteins, and differentiation markers involved in mineralizatio n of tooth and bone matrices was tested by the treatment of Lewis dwarf rat s with GH over 5 days, The molar teeth and associated alveolar bone were pr ocessed for immunohistochemical demonstration of bone morphogenetic protein s 2 and 4 (BMP-2 and -4), bone morphogenetic protein type IA receptor (BMPR -IA), bone alkaline phosphatase (ALP), osteocalcin (OC), osteopontin (OPN), bone sialoprotein (BSP), and E11 protein (E11), The cementoblasts, osteobl asts, and periodontal ligament (PDL) cells responded to GH by expressing BM P-2 and -4, BMPR-IA, ALP, OC, and OPN and increasing the numbers of these c ells. No changes were found in patterns of expression of the late different iation markers BSP and E11 in response to GH, Thus, GH evokes expression of bone markers of early differentiation in cementoblasts, PDL cells, and ost eoblasts of the periodontium. We propose that the induction of BMP-2 and -4 and their receptor by GH compliments the role of GH-induced insulin-like g rowth factor 1 (IGF-1) in promoting bone and tooth root formation.