THE EFFECT OF ESSENTIAL FATTY-ACID DEFICIENCY ON THE FATTY-ACID COMPOSITION OF DIFFERENT SALIVARY-GLANDS AND SALIVA IN RATS

The main purpose was to compare the changes in fatty acid composition of lipids induced by essential fatty acid (EFA) deficiency in the rat submandibular, parotid and sublingual glands. Three groups of rats wer e fed for 28 weeks (1 week gestation, 3 weeks lactation and 24 weeks t hereafter) diets containing 7% hydrogenated coconut oil (HCO) (EFA-def icient in both n-6 and n-3), 7% soybean oil (SBO) (control) and 7% saf flower oil (SFO) (deficient in n-3). Rats were killed and salivary gla nds were dissected out. Lipids were extracted and the fatty acid compo sition of total lipids and phospholipids was determined by gas chromat ography-mass spectrometry. The fatty-acid compositional changes indica tive of an EFA deficiency; such as decreases in the levels of 18:2 dag ger n-6, along with an accumulation of 20:3 n-9, were generally observ ed in all the salivary glands of rats fed 7% HCO diet. In the submandi bular glands, the proportions of 16:1, 18:1 n-9 and 18:1 n-7 were also higher in the HCO-fed group than in the other two groups. There were some differences in the fatty acid composition of the three glands. To tal lipids of parotid gland had higher levels of 12:0 and 18:1 n-9 as compared to the other two glands. The levels of 18:0, 20:3 n-9, 20:3 n -6 and 20:4 n-6 were, however, lower in the parotid Bland as compared with the other glands. In total phospholipids of rats fed SBO- and SFO -containing diets, the sublingual gland had lower levels of 18:2 n-6 a nd higher levels of 20:4 n-6 than the parotid or the submandibular. Th ese differences in fatty acid composition may be related to possible d ifferences in chain elongation/desaturation. The changes in fatty acid composition were also reflected in total lipids of plasma, liver and whole saliva of rats fed the various diets. A number of fatty acids we re identified in saliva by gas chromatography-mass spectrometry. (C) 1 997 Elsevier Science Ltd.