Fatty Acid Composition of Submandibular Gland Lipids in Essential Fatty Acid Deficient Rats1-2
Salivary
ABSTRACT Essential fatty acid (EFA) deficiency was induced in young weanling rats by feeding a fat-free diet or a diet containing 1% Hydrogenated coconut oil ( HCO ) . At intervals of 4, 8, and 16 weeks, rats from the deficient and the control groups were killed and their Subman dibular Salivary Glands (SMSG) were dissected out and extracted for lipids. The fatty acid composition of total lipids, triglycérides(TG), free fatty acids ( FFA ), phosphatidyl choline ( PC ) , and phosphatidyl ethanolamine (PE) fractions was determined. The levels of 16:1 and 18:1 were increased whereas those of 18:2 and 20:4 were decreased in the EFAdeficient groups as compared to the controls. 5,8,11-eicosatrienoic acid (20:3 620:44'—26.7±0.4410.8»±1.209.4±0.9938.2«±0.883.3«±0.263.9±1.19—4.2«±0.3580.9±0.0623.0±0.357.4«±0.1811.6±0.3632.7"±0.671.4«±0.0611.1±0.63—5.3Â
1 HCO—Hydrogenated coconut oil. P < 0.001.
' Values are mean ±SEHof five rats/group.
« Different from respective
control value!
1646
SYED Q. ALAM AND BASSIMA S. ALAM TABLE 4 Major fatty acids of triglycéride(TG) fraction in SMSG of rats fed different diets
fedFatty
Type of diet
acid14:016:016:118:018:118:21(0% fat)4»2.731.314.43.544.41.981.7« oil)4'
HCOJi83.9±0.3334.7 (5% oil)4'6.733.012.83.531.86.784.0±0.3035.3 HCO + 2% corn
corn
4'7.132.113.53.334.91.63(7%
1.3 ±0.0633.4 ±0.1131.5 ±0.0529.1 25.1 ±1.8916.7 ±0.2913.8 ±0.8511.2 ±0.379.6 ±0.5411.8 ±0.7812.6 ±0.1711.9±0.275.4 19.8 ±2.93.9±0.6144.2' ±0.814.7 ±0.322.9 ±1.074.4±0.2636.9 ±0.175.1±0.2933.4 ±0.694.5±0.2844.3' ±0.345.3 1.4±0.2432.8 ±0.3146.7' ±0.1937.2 ±0.2146.4' 28.3 ±0.476.6 ±0.710.5182.7±0.1832.0 ±0.652(7%±0.3316.9 ±0.7919.9 ±0.656.3±0.45185.1±0.1631.4 ±1.080.8±0.484 24.2 ±0.10 ±0.57182.6 ±0.45Week, ±0.17184.9±0.0930.7±0.4811.5 1 HCO—Hydrogenated coconut oil. ' Pooled sample of five rats, from respective control values, P < 0.001.
1 Values are means ±SEUof five rats/ group.
'Different
posite direction with the course of the progress of the EFA-deficiency i.e., its levels in the gland of the deficient rats de creased with time especially between 4th to 8th week; thereafter, its levels remained
progressed from 4 to 8 weeks. As the de ficiency was further prolonged to 16 weeks, the levels of this fatty acid increased slightly more than those at 8 weeks. Linoleic acid (18:2) levels changed in the op
TABLE 5 Major fatty acids of FF A fraction in SMSG of rats fed different diets fedFatty oil)Weeks14:016:016: acid1 (0% fat)2
Type of diet (7% corn oil)3
(7% HCO)'4
(5% HCO + 2%corn
84.1 0.7±0.2023.3 18.7±1.326.1
118:018:118:220:8,
12.8'±1.4213.9 8.8±1.1030.0 51.1«±2.422.4
»920:3,
4.5±0.69—
Downloaded from https://academic.oup.com/jn/article-abstract/108/10/1642/4769129 by guest on 19 November 2018
82.7
—4.0 »620:44'4.028.38.616.039.01.41.3—3.18—22.5±0.649.0«±0.6112.1±0.2347.7«±2.09^_3.4±0.88—2.7«±0.38181.0'±0.0721.0±0.5410.0'±0.7013.2± .±0.2719.6±0.43180.5±0.0317.1±0.512.1±0.3118.1±0.5616.6±0.3413.8±0.65—3.0±0.2527.8±1.174
2.4«±0.40te1.2±0.1615.9±0.747.9«±0.2911.7±0.5338.4'±1.221.2±0.191 1 HCO—Hydrogenated coconut oil. * Pooled sample of five rats, from respective control values, P < 0.001.
»Values are means ±BEMof five rats'group.
* Different
EFA-DEFICIENCY AND SALIVARY GLAND LIPIDS
Fatty acid composition of PC and PE, the two major phospholipids of the SMSG, is shown in table 6 and 7, respectively. EFAdeficiency induced by a fat-free diet or a diet containing 7% HCO resulted in similar changes in these two fractions as were ob served in the total lipids, i.e., an increase in monoenoic ( 16:1 and 18:1 ) fatty acids, a decrease in 18:2 and 20:4, and an accumu lation of 20:3 «9.The levels of 5,8,11eicosatrienoic acid (20:3 w9) increased in PC and PE fractions as the EFA-deficiency progressed from 4 to 8 to 16 weeks. By 16 weeks, it constituted as much as 15.8% of the total fatty acids in PC fractions and 21A% in PE fraction. As compared to the PC fraction, PE contained much higher levels of 20:3 «9and 20:4 in the deficient gland. Even after 16 weeks of feeding the deficient diet, the SMSG contained rela tively higher levels of arachidonic acid in their PE fraction (6.6% in group 1 and 11.7% in group 3). In the control groups
TABLE 6 Fatty acid composition of phosphatidyl choline (PC) in SMSG of rats fed different diets fedFatty oil)Weeks14:0ISO acid1(0%
Type of diet fat)2
(7% corn oil)3
(7% HCO)'4(5%
HCO + 2%corn
80.4
0.52.2±0.2651.7 16:0*16:016:118:018:118:220:3, 39.4±1.361.6±0.18.8
18.9±1.1114.1 15.9±0.6310.1 8.0±0.75— u920:3,
—2.4
Downloaded from https://academic.oup.com/jn/article-abstract/108/10/1642/4769129 by guest on 19 November 2018
fairly constant. The proportions of 20:4 in the total lipids of the SMSG from the de ficient rats remained essentially unchanged with time. The fatty acid composition of TG frac tion is shown in table 4. As compared to the controls, EFA-deficient groups contained significantly higher levels of 18:1 and lower levels of 18:2. This was true whether the rats were killed at 4, 8, or 16 weeks after feeding the deficient diets. The levels of 18:2 in the TG fraction of the SMSG from EFA-deficient rats decreased from about 2% to almost trace as the deficiency pro gressed from 4 to 16 weeks. FFA fractions (table 5) show similar trends as were ob served in total lipids i.e., a marked increase in 16:1 and 18:1, a lowering of 18:2 and 20:4 and an accumulation of 20:3 9levels of the FFA fraction.
1647
u620:4-Õ«2.40.830.37.49.029.32.47.9—4.580.4»±0.072.4±0.6633.8±0.815.7»±0.4310.4±0.8036.3«±0.550.77.1±0.99—1.8«±0.39181.2±0.160.7±0. 2.4±0.5011.4
8.6±1.71180.8±0.040.6±0.0432.5±0.253.3±0.098.3±0.0911.2±0.1914.2±0.39—7.6±0.1418.7±0.364*4.5 1 HCO—Hydrogenated coconut oil. ' Pooled sample of five rats. • Values are means ±BEMof five rats/group. * Tentative identification. ' Different from respective control values, P < 0.01 (Student's "I" test). • Different from respective control values, P < 0.001 (Student's "I" test).
1648
SYED Q. ALAM AND BASSIMA S. ALAM
TABLE 7 Folly acid composition of phosphatidyl elhanolamine (PE) in SMSG lipids of rats fed different diets fedFatty acid1 oil)Weeks14:0ISO
Type of diet (0% fat)2
(7% corn oil)3
(7% HCO)'4(5%
HCO + 2% corn
80.50.912.6
11.6±0.630.9±0.1215.5
20.2±1.4120.6 24.3±1.379.1 8.6±0.48— »920:3,
—2.6
Downloaded from https://academic.oup.com/jn/article-abstract/108/10/1642/4769129 by guest on 19 November 2018
16:0«16:016:118:018:118:220:3,
»620:44'1.22.49.45.113.931.92.610.5—16.08—0.4±0.0610.1±0.344.9»±0.0616.4±0.8338.8'±0.901.1»±0.0816.2±0.85—9.7»±0.83it:0.6*±0.170.8 2.737.3
33.5±2.4318—0.9±0.208.5±0.361.5±0.7517.6±0.3218.6±0.947.8±0.55—3.5±0.3135.8±1.754*3.80 ' HCO—Hydrogenated coconut oil. ' Pooled sample of five rats. " Values are means ±SEMof five rats/group, identification. ' Different from respective control values, P < 0.001 (Student's "I" test).
as well, PE contained higher levels of 20:4 as compared to PC. The fatty acid composition of total lipids in plasma at 16 weeks after feeding the diets is shown in table 8. Similar changes as observed in the SMSG as result of EFAdeficiency were found i.e., a marked in crease in 16:1 and 18:1 levels, a reduction in 18:2 and 20:4 and an accumulation of 20:3 co9. The flow rate of saliva was significantly lower in EFA-deficient rats as compared to the controls table 9). Total protein and a-amylase activity of saliva was the same in control and deficient rats. DISCUSSION Gland weight (mg/100 g body weight), was either the same or slightly higher in the EFA-deficient groups. Similar observa tions on organ weights in EFA-deficiency have been reported by other investigators (29). The results of the present study show that SMSG lipids undergo drastic modifi
• Tentative
cations in their fatty acid composition in EFA-deficient rats. Similar changes in the fatty acid composition have been reported in other tissues (5-12). The total lipids as well as FFA, TG, PC, and PE fractions from the SMSG exhibited changes in their fatty acid patterns which are characteristic of EFA-deficiency i.e., a significant increase in the relative proportions of 16:1 and 18:1, a drastic reduction in the levels of 18:2 and 20:4, and the presence of a large amount of 20:3 «)9.Similar changes in fatty acid composition of TG and FFA fractions of oral palatal epithelium (30), serum, liver and adipose tissue (31), and of PC and PE fractions of liver (32, 33), lungs (34), brain (35, 36), and palatal epithelium (30) have been observed in E FA deficiency. Triene to tetraene ratio expressed more precisely as 20:3
Salivary
ABSTRACT Essential fatty acid (EFA) deficiency was induced in young weanling rats by feeding a fat-free diet or a diet containing 1% Hydrogenated coconut oil ( HCO ) . At intervals of 4, 8, and 16 weeks, rats from the deficient and the control groups were killed and their Subman dibular Salivary Glands (SMSG) were dissected out and extracted for lipids. The fatty acid composition of total lipids, triglycérides(TG), free fatty acids ( FFA ), phosphatidyl choline ( PC ) , and phosphatidyl ethanolamine (PE) fractions was determined. The levels of 16:1 and 18:1 were increased whereas those of 18:2 and 20:4 were decreased in the EFAdeficient groups as compared to the controls. 5,8,11-eicosatrienoic acid (20:3 620:44'—26.7±0.4410.8»±1.209.4±0.9938.2«±0.883.3«±0.263.9±1.19—4.2«±0.3580.9±0.0623.0±0.357.4«±0.1811.6±0.3632.7"±0.671.4«±0.0611.1±0.63—5.3Â
1 HCO—Hydrogenated coconut oil. P < 0.001.
' Values are mean ±SEHof five rats/group.
« Different from respective
control value!
1646
SYED Q. ALAM AND BASSIMA S. ALAM TABLE 4 Major fatty acids of triglycéride(TG) fraction in SMSG of rats fed different diets
fedFatty
Type of diet
acid14:016:016:118:018:118:21(0% fat)4»2.731.314.43.544.41.981.7« oil)4'
HCOJi83.9±0.3334.7 (5% oil)4'6.733.012.83.531.86.784.0±0.3035.3 HCO + 2% corn
corn
4'7.132.113.53.334.91.63(7%
1.3 ±0.0633.4 ±0.1131.5 ±0.0529.1 25.1 ±1.8916.7 ±0.2913.8 ±0.8511.2 ±0.379.6 ±0.5411.8 ±0.7812.6 ±0.1711.9±0.275.4 19.8 ±2.93.9±0.6144.2' ±0.814.7 ±0.322.9 ±1.074.4±0.2636.9 ±0.175.1±0.2933.4 ±0.694.5±0.2844.3' ±0.345.3 1.4±0.2432.8 ±0.3146.7' ±0.1937.2 ±0.2146.4' 28.3 ±0.476.6 ±0.710.5182.7±0.1832.0 ±0.652(7%±0.3316.9 ±0.7919.9 ±0.656.3±0.45185.1±0.1631.4 ±1.080.8±0.484 24.2 ±0.10 ±0.57182.6 ±0.45Week, ±0.17184.9±0.0930.7±0.4811.5 1 HCO—Hydrogenated coconut oil. ' Pooled sample of five rats, from respective control values, P < 0.001.
1 Values are means ±SEUof five rats/ group.
'Different
posite direction with the course of the progress of the EFA-deficiency i.e., its levels in the gland of the deficient rats de creased with time especially between 4th to 8th week; thereafter, its levels remained
progressed from 4 to 8 weeks. As the de ficiency was further prolonged to 16 weeks, the levels of this fatty acid increased slightly more than those at 8 weeks. Linoleic acid (18:2) levels changed in the op
TABLE 5 Major fatty acids of FF A fraction in SMSG of rats fed different diets fedFatty oil)Weeks14:016:016: acid1 (0% fat)2
Type of diet (7% corn oil)3
(7% HCO)'4
(5% HCO + 2%corn
84.1 0.7±0.2023.3 18.7±1.326.1
118:018:118:220:8,
12.8'±1.4213.9 8.8±1.1030.0 51.1«±2.422.4
»920:3,
4.5±0.69—
Downloaded from https://academic.oup.com/jn/article-abstract/108/10/1642/4769129 by guest on 19 November 2018
82.7
—4.0 »620:44'4.028.38.616.039.01.41.3—3.18—22.5±0.649.0«±0.6112.1±0.2347.7«±2.09^_3.4±0.88—2.7«±0.38181.0'±0.0721.0±0.5410.0'±0.7013.2± .±0.2719.6±0.43180.5±0.0317.1±0.512.1±0.3118.1±0.5616.6±0.3413.8±0.65—3.0±0.2527.8±1.174
2.4«±0.40te1.2±0.1615.9±0.747.9«±0.2911.7±0.5338.4'±1.221.2±0.191 1 HCO—Hydrogenated coconut oil. * Pooled sample of five rats, from respective control values, P < 0.001.
»Values are means ±BEMof five rats'group.
* Different
EFA-DEFICIENCY AND SALIVARY GLAND LIPIDS
Fatty acid composition of PC and PE, the two major phospholipids of the SMSG, is shown in table 6 and 7, respectively. EFAdeficiency induced by a fat-free diet or a diet containing 7% HCO resulted in similar changes in these two fractions as were ob served in the total lipids, i.e., an increase in monoenoic ( 16:1 and 18:1 ) fatty acids, a decrease in 18:2 and 20:4, and an accumu lation of 20:3 «9.The levels of 5,8,11eicosatrienoic acid (20:3 w9) increased in PC and PE fractions as the EFA-deficiency progressed from 4 to 8 to 16 weeks. By 16 weeks, it constituted as much as 15.8% of the total fatty acids in PC fractions and 21A% in PE fraction. As compared to the PC fraction, PE contained much higher levels of 20:3 «9and 20:4 in the deficient gland. Even after 16 weeks of feeding the deficient diet, the SMSG contained rela tively higher levels of arachidonic acid in their PE fraction (6.6% in group 1 and 11.7% in group 3). In the control groups
TABLE 6 Fatty acid composition of phosphatidyl choline (PC) in SMSG of rats fed different diets fedFatty oil)Weeks14:0ISO acid1(0%
Type of diet fat)2
(7% corn oil)3
(7% HCO)'4(5%
HCO + 2%corn
80.4
0.52.2±0.2651.7 16:0*16:016:118:018:118:220:3, 39.4±1.361.6±0.18.8
18.9±1.1114.1 15.9±0.6310.1 8.0±0.75— u920:3,
—2.4
Downloaded from https://academic.oup.com/jn/article-abstract/108/10/1642/4769129 by guest on 19 November 2018
fairly constant. The proportions of 20:4 in the total lipids of the SMSG from the de ficient rats remained essentially unchanged with time. The fatty acid composition of TG frac tion is shown in table 4. As compared to the controls, EFA-deficient groups contained significantly higher levels of 18:1 and lower levels of 18:2. This was true whether the rats were killed at 4, 8, or 16 weeks after feeding the deficient diets. The levels of 18:2 in the TG fraction of the SMSG from EFA-deficient rats decreased from about 2% to almost trace as the deficiency pro gressed from 4 to 16 weeks. FFA fractions (table 5) show similar trends as were ob served in total lipids i.e., a marked increase in 16:1 and 18:1, a lowering of 18:2 and 20:4 and an accumulation of 20:3 9levels of the FFA fraction.
1647
u620:4-Õ«2.40.830.37.49.029.32.47.9—4.580.4»±0.072.4±0.6633.8±0.815.7»±0.4310.4±0.8036.3«±0.550.77.1±0.99—1.8«±0.39181.2±0.160.7±0. 2.4±0.5011.4
8.6±1.71180.8±0.040.6±0.0432.5±0.253.3±0.098.3±0.0911.2±0.1914.2±0.39—7.6±0.1418.7±0.364*4.5 1 HCO—Hydrogenated coconut oil. ' Pooled sample of five rats. • Values are means ±BEMof five rats/group. * Tentative identification. ' Different from respective control values, P < 0.01 (Student's "I" test). • Different from respective control values, P < 0.001 (Student's "I" test).
1648
SYED Q. ALAM AND BASSIMA S. ALAM
TABLE 7 Folly acid composition of phosphatidyl elhanolamine (PE) in SMSG lipids of rats fed different diets fedFatty acid1 oil)Weeks14:0ISO
Type of diet (0% fat)2
(7% corn oil)3
(7% HCO)'4(5%
HCO + 2% corn
80.50.912.6
11.6±0.630.9±0.1215.5
20.2±1.4120.6 24.3±1.379.1 8.6±0.48— »920:3,
—2.6
Downloaded from https://academic.oup.com/jn/article-abstract/108/10/1642/4769129 by guest on 19 November 2018
16:0«16:016:118:018:118:220:3,
»620:44'1.22.49.45.113.931.92.610.5—16.08—0.4±0.0610.1±0.344.9»±0.0616.4±0.8338.8'±0.901.1»±0.0816.2±0.85—9.7»±0.83it:0.6*±0.170.8 2.737.3
33.5±2.4318—0.9±0.208.5±0.361.5±0.7517.6±0.3218.6±0.947.8±0.55—3.5±0.3135.8±1.754*3.80 ' HCO—Hydrogenated coconut oil. ' Pooled sample of five rats. " Values are means ±SEMof five rats/group, identification. ' Different from respective control values, P < 0.001 (Student's "I" test).
as well, PE contained higher levels of 20:4 as compared to PC. The fatty acid composition of total lipids in plasma at 16 weeks after feeding the diets is shown in table 8. Similar changes as observed in the SMSG as result of EFAdeficiency were found i.e., a marked in crease in 16:1 and 18:1 levels, a reduction in 18:2 and 20:4 and an accumulation of 20:3 co9. The flow rate of saliva was significantly lower in EFA-deficient rats as compared to the controls table 9). Total protein and a-amylase activity of saliva was the same in control and deficient rats. DISCUSSION Gland weight (mg/100 g body weight), was either the same or slightly higher in the EFA-deficient groups. Similar observa tions on organ weights in EFA-deficiency have been reported by other investigators (29). The results of the present study show that SMSG lipids undergo drastic modifi
• Tentative
cations in their fatty acid composition in EFA-deficient rats. Similar changes in the fatty acid composition have been reported in other tissues (5-12). The total lipids as well as FFA, TG, PC, and PE fractions from the SMSG exhibited changes in their fatty acid patterns which are characteristic of EFA-deficiency i.e., a significant increase in the relative proportions of 16:1 and 18:1, a drastic reduction in the levels of 18:2 and 20:4, and the presence of a large amount of 20:3 «)9.Similar changes in fatty acid composition of TG and FFA fractions of oral palatal epithelium (30), serum, liver and adipose tissue (31), and of PC and PE fractions of liver (32, 33), lungs (34), brain (35, 36), and palatal epithelium (30) have been observed in E FA deficiency. Triene to tetraene ratio expressed more precisely as 20:3
