Effects of mastication on the secretory and proliferative capabilities of parotid gland in male rat

用东方酵母公司的固体或粉末MF饲料喂养4周龄大鼠3周（4周龄大鼠）-9周（13周龄大鼠），并用在硅化透镜纸上培养的腮腺外植体检查腮腺对促涎剂（卡巴胆碱和异丙肾上腺素）的反应性（Kawano等，J.Dent.Res.71，1885 - 1890，1992）。1）体重增加，90 g（4周龄大鼠）至450 g（13周龄大鼠），两个饲料组之间的腮腺重量相同，但腮腺的平均重量较重在3-9周的治疗大鼠中，固体组比粉末组约高20（7-13周龄大鼠）。2）固体组淀粉酶分泌的促涎素依赖性增加高于粉末组（7周龄大鼠），但在大于9周龄的两组大鼠之间没有观察到显著差异。3）催涎剂诱导的c-fos mRNA水平的增加，在整个实验过程中，固体组c-myc和鸟氨酸脱羧酶及其活性均高于粉末组上述结果表明，卡巴胆碱和异丙肾上腺素对腮腺淀粉酶分泌和细胞增殖的影响，固体组显著高于粉末组，提示物理压力和咀嚼频率参与了腮腺对交感神经和副交感神经刺激的反应。

Four week-old rats were fed for3 (4-week-old rat)-9 weeks (13-week-old rat) with solid or powdered MF feed of Oriental Yeast Co.and the responsiveness of parotid gland to sialagogues (carbachol and isoproterenol) was examined with parotid explants which were cultured on siliconized lens paper (Kawano et al., J.Dent.Res.71,1885-1890,1992).The results were as follows ;1) The increases of body weights, 90g (4-week-old rats) to 450g (13-week-old rats), were the same among the two feed groups but an average weight of parotid gland was heavier (about 20%) in solid group than in powder group in 3-9-week-treated rats (7-13-week-old rats).2) Sialagogue-dependent increase in amylase secretion was higher in solid group than in powder group (7-week-old rats), but no significant difference was observed between two groups of older than 9-week-old rats.3) Sialagogue-induced increases in mRNA levels of c-fos, c-myc and ornithine decarboxylase and activity of the enzyme were higher in solid group than powder group during entire period of experiment (7-13-week-old rats).These results indicate that the effects of carbachol and isoproterenol on amylase secretion and cell proliferation in parotid gland were marked in solid group than in powder group, suggesting that physical pressure and frequency of mastication participate the responsiveness of parotid gland to both sympathetic and parasympathetic stimuli.