The Effects of High levels of Glucose and Insulin on Type I Collagen Synthesis in Mature Human Odontoblasts and Pulp Tissue in vitro

• Published in: Advances in dental research 2001-08, Vol.15 (1), p.72-75
• Main Authors: Valikangas, L., Pekkala, E., Larmas, M., Risteli, J., Salo, T., Tjäderhane, L.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Analysis of Variance; Cell Culture Techniques; Cell Differentiation; Collagen Type I - biosynthesis; Collagen Type I - drug effects; Culture Media; Culture Techniques; Dental Pulp - drug effects; Dental Pulp - metabolism; Dental Pulp - pathology; Dentistry; Down-Regulation; Glucose - pharmacology; Humans; Insulin - pharmacology; Odontoblasts - drug effects; Odontoblasts - metabolism; Odontoblasts - pathology; Peptide Fragments - drug effects; Peptide Fragments - secretion; Procollagen - drug effects; Procollagen - secretion; Statistics as Topic
• ISSN: 0895-9374; 1544-0737
• DOI: 10.1177/08959374010150011801

High levels of dietary sucrose affect the metabolism of the pulp-dentin complex and enhance the caries process in dentin. The high-sucrose diet reduces dentin formation in young rats (Tjaderhane et al., 1994; Hietala and Larmas, 1995; Tjaderhane, 1996) and in pups of rat dams fed high-sucrose diet during lactation (Pekkala et al., 2000a). However, the mechanisms behind the effects are unknown. A direct effect of elevated blood glucose or an indirect effect via insulin has been suggested. We investigated the effects of high glucose and insulin on type I collagen synthesis in human odontoblasts and pulp tissue in vitro, using an organ culture method for functional post-mitotic odontoblasts. Odontoblasts and pulp tissue were cultured separately for 10 days in DMEM with 15% FBS containing additional glucose (G) (4.45 g/L) or insulin (I) (0.6 μg/mL) or both together (GI). We evaluated type I collagen synthesis with RIA, measuring the level of N-terminal propeptide of type I collagen (PINP) secreted into the culture media. PINP secretion decreased in odontoblasts and pulp tissue in G and GI groups when compared with the control and insulin samples (p = 0.001 in both groups in the pulp samples). Insulin alone did not affect PINP secretion distinctly. The results indicate that high levels of glucose, but not insulin, directly down-regulate the type I collagen synthesis in young, differentiated human odontoblasts and pulp tissue. Insulin does not affect the inhibitory effect of high sucrose. These in vitro findings indicate that the high-sucrose diet mav alter odontoblast function independently of insulin.