ラット顎下腺アクアポリン5および1発現に対する自律神経切除および塩酸セビメリン投与の影響

[Purpose] The present study aimed to explore the role of autonomic nerves on the regulation of the expression of water channels, aquaporin 5 and aquaporin 1 (AQP5 and AQP1, respectively) in the submandibular gland (SMG) of rats. [Methods] Cervical sympathetic trunk denervation (CSTD) or chorda tympani denervation (CTD) was performed on 7-week-old male SD rats. From the 15th day after operation, cevimeline hydrochloride (10mg/kg) or pilocarpine (0.3mg/kg) or chloroquine (50mg/kg) was administered orally into CTD rats everyday for 7 days. Protein and mRNA levels of AQP5 and AQP1 in the SMG were determined by Western blotting, Northern blotting, and RT PCR. Activities of cathepsins and proteasomes, the enzyme involved in the protein degradation system, were measured using isolated acinar cells as well as the whole SMG tissue. [Results] Expression levels of AQP5 and AQP1 were not affected significantly at 4 weeks although the gland weight decreased to 80% of the control by CSTD ; However, by CTD both the SMG weight and AQP5 protein level had decreased, while the AQP1 protein level had not. On the other hand, the AQP5 mRNA level was not affected by CTD. Cevimeline hydrochloride, an M3 receptor agonist, recovered the AQP5 protein level which had been reduced by CTD, and increased the AQP1 protein level to more than the control level. Oral administration of pilocarpine showed no effect on the protein levels of AQP5 and AQP1. The AQP5 mRNA level of SMG in the CTD rat was not affected by the administration of cevimeline hydrochloride. The activity of cathepsin D/E was increased by CTD and this increase was inhibited by cevimeline hydrochloride. Submandibular acinar cells were isolated by Percoll gradient centrifugation from rats that received CTD and/or CTD plus cevimeline hydrochloride. Changes of cathepsin D/E activities by CTD and cevimeline hydrochloride were also observed in the isolated cells. Further, the administration of chloroquine, a denaturant of lysosome, recovered the AQP5 protein level decreased by CTD, suggesting the involvement of lysosomal enzyme(s) in the reduction of AQP5 protein level by CTD. [Conclusion] The autonomic regulation of the AQP5 protein level in rat SMG is suggested to be controlled by the lysosomal system, not by transcriptional regulation.

公開日:2010年1月24日で登録したコンテンツは、国立情報学研究所において電子化したものです。