Alam S Q, Mannino S J, Alam B S
Department of Biochemistry and Molecular Biology, Louisiana State University Medical Center, New Orleans 70119.
Arch Oral Biol. 1993 May;38(5):387-91. doi: 10.1016/0003-9969(93)90209-5.
This study sought to determine if the diet-induced changes in submandibular salivary glands can be reversed. Two groups of male weanling Sprague-Dawley rats were fed purified diets containing 9% butter + 1% corn oil (group I, control) or 9% ethyl ester concentrate of n-3 fatty acids + 1% corn oil (group II, experimental). After 5 weeks of feeding the respective diets, rats in group I were divided into two subgroups: Ia, which was maintained on the control diet, and Ib, which was shifted to the experimental diet for the reversal study. The rats in the experimental group were kept on their original diet. After five further weeks of feeding, the rats were killed, and membranes from submandibular glands were prepared and assayed for adenylate cyclase activity and for the fatty acid composition of total phospholipids. Changes characteristic of feeding n-3 fatty acids, including a significant increase in membrane fluidity as measured by the degree of unsaturation of fatty acids, were observed in the total phospholipids of membranes from the experimental group. The adenylate cyclase activity was two- to three-fold higher in membranes of rats fed the experimental diet (group II) than the control diet (group Ia). Whereas the diet-induced changes in fatty acid composition and membrane fluidity were largely reversed (group Ib, reversal study), changes in adenylate cyclase activity were only partially reversed. The results suggest that, in addition to the fatty acid composition and membrane fluidity, other factors may also be important in modifying adenylate cyclase activity.
本研究旨在确定饮食诱导的下颌下唾液腺变化是否可以逆转。将两组雄性断乳Sprague-Dawley大鼠分别喂食含9%黄油+1%玉米油的纯化饮食（I组，对照组）或含9%n-3脂肪酸乙酯浓缩物+1%玉米油的纯化饮食（II组，实验组）。在分别喂食相应饮食5周后，I组大鼠被分为两个亚组：Ia组继续喂食对照饮食，Ib组则转而喂食实验饮食以进行逆转研究。实验组大鼠继续喂食其原始饮食。在再喂食5周后，将大鼠处死，制备下颌下腺的膜，并检测其腺苷酸环化酶活性以及总磷脂的脂肪酸组成。在实验组大鼠膜的总磷脂中观察到了喂食n-3脂肪酸所特有的变化，包括通过脂肪酸不饱和度测量的膜流动性显著增加。喂食实验饮食（II组）的大鼠膜中的腺苷酸环化酶活性比喂食对照饮食（Ia组）的大鼠膜中的活性高两到三倍。虽然饮食诱导的脂肪酸组成和膜流动性变化在很大程度上得到了逆转（Ib组，逆转研究），但腺苷酸环化酶活性的变化仅得到了部分逆转。结果表明，除了脂肪酸组成和膜流动性外，其他因素在调节腺苷酸环化酶活性方面可能也很重要。
