Shigemura Noriatsu, Miura Hirohito, Kusakabe Yuko, Hino Akihiro, Ninomiya Yuzo
Section of Oral Neuroscience, Graduate School of Dental Science, Kyushu University, Fukuoka, Japan.
Arch Histol Cytol. 2003 Aug;66(3):253-60. doi: 10.1679/aohc.66.253.
Leptin is a hormone that regulates food intake, energy expenditure and body weight. Our previous studies have demonstrated that the taste organ is a new peripheral target for leptin in mice. Leptin selectively inhibits the responses of taste nerves and receptor cells to sweet substances without affecting responses to sour, salty, and bitter substances. Still, there is no convincing evidence for the existence of leptin receptors (Ob-Rs) in taste receptor cells, especially the functional isoform Ob-Rb. We investigated the expression of 5 different Ob-R isoforms (a-e) and 6 STAT (signal transducers and activators of transcription) members in mouse taste cells. STATs are considered to be involved in the leptin signaling via Ob-Rb. Semiquantitative RT-PCR analysis showed that Ob-Rb was expressed in the taste buds of the fungiform and circumvallate papillae, but not so clearly in the surrounding epithelial tissue. The expression pattern among the three different tissues was similar to that of the taste cell specific G-protein, alpha-gustducin. The other Ob-R isoforms were widely detected in either the taste papillae or the epithelial tissue. Among 6 STAT members, STAT3 showed the highest relative abundance of mRNA in the taste buds. Consistently, in situ hybridization analysis showed that while Ob-Rb and STAT3 signals were detected in some taste bud cells, the signals were not clearly observed in the epithelial tissue cells. In conclusion, the present study provides evidence of the existence of the leptin receptor, Ob-Rb, and STAT3 in the mouse taste bud cells. This finding further confirms the involvement of leptin in the control of taste sensitivities to sweet substances in mice.
瘦素是一种调节食物摄入、能量消耗和体重的激素。我们之前的研究表明，味觉器官是小鼠体内瘦素的一个新的外周靶点。瘦素选择性地抑制味觉神经和受体细胞对甜味物质的反应，而不影响对酸味、咸味和苦味物质的反应。然而，目前尚无确凿证据表明味觉受体细胞中存在瘦素受体（Ob-Rs），尤其是功能性异构体Ob-Rb。我们研究了5种不同的Ob-R异构体（a-e）和6种信号转导子和转录激活子（STAT）成员在小鼠味觉细胞中的表达。STATs被认为通过Ob-Rb参与瘦素信号传导。半定量RT-PCR分析显示，Ob-Rb在菌状乳头和轮廓乳头的味蕾中表达，但在周围上皮组织中表达不明显。三种不同组织中的表达模式与味觉细胞特异性G蛋白α-味导素相似。其他Ob-R异构体在味觉乳头或上皮组织中广泛检测到。在6种STAT成员中，STAT3在味蕾中的mRNA相对丰度最高。同样，原位杂交分析表明，虽然在一些味蕾细胞中检测到Ob-Rb和STAT3信号，但在上皮组织细胞中未明显观察到这些信号。总之，本研究提供了小鼠味蕾细胞中存在瘦素受体Ob-Rb和STAT3的证据。这一发现进一步证实了瘦素参与小鼠对甜味物质味觉敏感性的控制。
