Study realized in our laboratory showed that oxytocin promoted increased formation and inhibited alveolar bone resorption in rats with 24 months when compared with the same age group who did not receive the hormone. However, in rats of 12 months the treatment with oxytocin did not induce significant changes in the process of bone regeneration. Through these results, we question whether the osteoblasts of rats of different ages are able to maintain the ability to synthesize oxytocin and respond to their stimulus, and if there autocrine pathway between osteoblasts and oxytocin. Therefore, it is important investigate the cellular mechanisms involved in bone formation in response to oxytocin, understand the mechanisms involved in increased bone formation in senile organisms, in a period characterized by the estrous acyclicity (estropause - 24 months) compared with adult organisms with regular estrous cycle (12 months). This study will evaluate the influence of age and the action of oxytocin associated with classical inducers during differentiation in the osteogenic lineage of stem cells from bone marrow of Wistar rats with 12 and 24 months of age. The mesenchymal stem cells will be collected of the following groups: 1 = Control/12 months (proliferation medium); 2 = Control + oxytocin/12 months (proliferation medium + oxytocin); 3 = Medium osteogenic/12 months (ascorbic acid + dexamethasone + beta-glycerophosphate); 4 = Medium osteogenic oxytocin/12 months (ascorbic acid + beta-glycerophosphate + dexamethasone + oxytocin); Control/24 = 5 months (proliferation medium); 6 = Control + oxytocin/24 months (proliferation medium + oxytocin); 7 = Medium osteogenic/24 months (ascorbic acid + dexamethasone + beta-glycerophosphate) and 8 = Medium osteogenic oxytocin/24 + months (ascorbic acid + beta-glycerophosphate + dexamethasone + oxytocin). Will be performed to analyze cell proliferation, measuring alkaline phosphatase activity, detection and quantification of mineralization of extracellular matrix gene expression of oxytocin, oxytocin receptor (OTR) and matrix proteins collagen and non-collagen in cultured osteoblasts (Extraction and quantification of total RNA and reverse transcription, quantitative PCR), and is determined by ELISA the concentration of prostaglandin E2.
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