EXPRESSION OF THE MESSENGER-RNA FOR TYPE-I AND TYPE-II INTERLEUKIN-1 RECEPTORS IN DENTAL-TISSUES OF MICE DURING TOOTH DEVELOPMENT

Interleukin-l (IL-I) can exert its pleiotropic effects on nearly every tissue by binding to its cognate receptor. Two types of IL-1 receptor s have been identified. A large number of cell types have been shown t o possess IL-1 receptors in vitro and in vivo, but few studies have ad dressed the question of expression in dental tissues in vivo. Using in situ hybridization in normal newborn, young and adult mice, we have e xamined the cellular distribution of both types of IL-1 receptors in d ental tissues. In the ameloblast layer of incisors and molars, the mRN A for the type I IL-1 receptor (IL-1RI) and the type II IL-1 receptor (IL-1RII) was detected at the presecretory stage. The expression level markedly increased and remained during amelogenesis at the secretory stage. At the maturation stage, however, the transcripts for both IL-1 RI and -II mRNA disappeared. Expression of IL-1RI and -II mRNA was als o observed in odontoblasts after crown morphogenesis had been complete d, and continued in these cells during dentinogenesis. No transcripts were detected in stratum intermedium cells and other cells in dental f ollicle, stellate reticulum, dental papilla, or pulp. Additionally, bo th types of IL-1R mRNA were also detected in osteoclasts on surfaces o f alveolar bone. These results demonstrated for the first time that en amel-secreting ameloblasts and dentine-secreting odontoblasts express IL-1RI and -II mRNA, suggesting that IL-1 plays a regulatory role in t he function of ameloblasts and odontoblasts during tooth development o f mice.