Maternal hyperthyroidism increases the synthesis activity and the osteogenic markers expression of calvarial osteoblasts from offspringin a murine model br

To evaluate the characteristics and synthesis activity of osteoblasts extracted from the calvaria of offspring ofrats exposed to maternal hyperthyroidism. Twelve adult Wistar rats were divided into two groups, one control and onetreated with daily administration of L-thyroxine by an orogastric tube (50 mu g/animal/day) during pregnancy. Three daysafter delivery and confirmation of the mothers'hyperthyroidism, the offspring were euthanized for the extraction ofosteoblasts from the calvaria. At 7, 14, and 21 days, proliferation activity was assessed using MTT assay, while alkalinephosphatase (ALP) activity was assessed by the BCIP/NBT method. At 21 days, the total area of the mineralizedmatrix stained by von Kossa was evaluated by morphometry. The expression of gene transcripts for Runx2, Bmp2,Fgfr1, collagen type 1 (Col1), osteocalcin (Oc), and osteopontin (Op) were evaluated by real-time RT-PCR. Meanswere compared using the Student'st-test. FA activity was significantly higher at 14 and 21 days in cultures ofosteoblasts extracted from offspring exposed to maternal hyperthyroidism, while MTT conversion was significantlylower at 21 days in this group. Osteoblast cultures of neonates exposed to maternal hyperthyroidism also showed alarger total area of mineralized matrix and greater expression of gene transcripts for Oc and Op. Maternalhyperthyroidism increases the activity of matrix synthesis, alkaline phosphatase activity, and expression of genetranscripts for osteocalcin and osteopontin in the osteoblasts, extracted from the calvaria of the offspring, which maybe one of the mechanisms of premature fusion of cranial sutures