Leptin and its receptor expression in dental and periodontal tissues of primates

Leptin and its receptor (OBR) have attracted much attention since their discovery. They have been reported to play central roles in energy balance, the immune-inflammatory response and bone metabolism. Evidence indicates that leptin and OBR are associated with inflammatory diseases of dental and periodontal tissues. The first step for establishing this is to determine the expression of leptin and OBR in these tissues. Our study is the first to examine systematically the expression of leptin and OBR in dental and periodontal tissues of monkeys (Macaca fascicularis) by immunohistochemistry and in primary cultured cells, isolated from human dental and periodontal tissues, by reverse transcription plus the polymerase chain reaction and immunocytochemistry. Our results show that leptin and OBR are constitutively expressed and widely distributed in dental and periodontal tissues of primates. Their immunoreaction is especially strong in junctional epithelium, a unique front-line defense around teeth and in mineralizing areas of the dental pulp and periodontal ligament. The expression of the long and also functional form of OBR (OBRb) indicates that leptin has a direct effect on these cells. Thus, we can reasonably infer that leptin and OBR exert effects on defense, mineralization and angiogenesis in dental and periodontal tissues of primates.