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Changes of fatty acid composition in brain lipids of lysine and threonine deficient rats
Life Sciences Vol . 3, pp. 479-485, 1984. Pergamon Press, Inc . Printed in the United States.
CHANGES OF FATTY ACID COMPOSITION IN BRAIN LIPIDS OF LYSINE AND THRBANINE DEFICIENT RATS (+) R . Viviani, P . Borri (o) and G . Ronca ( ~o) Istituto di Chimica Biologics dell'Università di Bologna (Italy) (Received 21 March 1964) The present experiments are designed to investigate iP
a dietary essential amino acid deficiency might result in an
alteration of brain lipid constituents . It is well known, how ever, that a fatty liver of portal type has been described not only in children suffering from severe protein malnutrition (Kwashiorkor)
(1), but also in growing rats (2,3,4), pigs (5) and
monkeys (6) fed on low protein diets deficient in essential amino acids .
Dietary essential amino acids are also of importance in
the regulation of plasma levels of lipid constituents in children (?), men (7) and exp erimental animals (8,9) . On the other hand separate experiments in our laboratory have demonstrated in rate some changes in the composition of fatty acids in the fatty liver caused by lysine and threonine deficiency (10,11) and in carcasses in the same experimental conditions (12) . This report presents data on brain lipids and fatty acid composition in rats fed on low protein rice diets deficient in and supplemented with lysine (first limiting amino acid) and threonine (seeond physiologically limiting amino acid) (13) .
This work was performed with the aid of a grant from Consiglio Nazionale dells Ricerche .
(oo)
Present address : Clinics delle Malattie Nervosa e Mentali della Univereità di Parma, Parma (Italy) . Present address : Istituto di Chimica Biologics dell'Univereità di Pisa, Pisa (Italy) . 479
480
CHANGES OF FATTY ACID COMPOSITION
Vol . 3, No . 5
Methods Thirty-two weanling male rats oP the Wistar strain,
from
our inbred colony, weighing 44 + 2 g were divided in two groups and fed on the low protein rice diets deficient in and supplement ed with lysine and threonine . The composition of the diets is reported in a previous paper (11) . The diets are isonitrogenous . The supplementation with the limiting essential amino acids was made according to Rosenberg et al .
(12) to obtain better growth and a
physiological level oP liver lipids . The dietary Pat contained a high level oP linoleic acid and a small quantity of unsaturated fatty acids oP linolenic Family ; arachidonic acid was absent (11) . At the end oP the experimental period (six weeks)
16
rats of each group were weighed and killed by decapitation . The brains were immediately excised, weighed, Frozen and etorod at - 20~C . The total lipids from pools of two brains extracted and purified according to Folch et al . (14,15) were weighed . In the extracted lipids, total phosphorus (16), total cholesterol (17) and galactose (18) were determined .
Aliquots oP total lipids
were saponified in methanolic KOH and the amount oP total Patty acids was determined by titration (19) ;~I,Eq . oP fatty acids were converted to mg of fatty acids expressed as stearic acid . Methyl esters oP fatty acids prepared by refluxing in dry methanolic HC1 were analysed by gas-liquid chromatography (11) . Body weight, weight oP the brain, total brain lipids, phospholipids, total cholesterol, cerebrosides, total fatty acids and spectrum of singular fatty acids are reported in Table 1 . Statistical analyses were carried out by the "t" teat ; values oP P < 0 .05 were considered to be significant . Results and Discussion As it may be seen in table 1, the rate Fed the deficient diet exhibit a notable retarded growth ,while the weight of the brain of the same animals presents a small difference in comparison to that of the supplemented group .
The brains oP the lysine and
threonine deficient rats appear to continue growth at the expense
Vol. 3, No . 5
CHANGES OF FATTY ACID COMPOSITION
481
of other organs . Furthermore total lipids, total cholesterol, total phoapholipids, cerebrosides
and total Patty acids (ex-
pressed as stearic acid) in the two groups of animals do not change . Nevertheless, a comparison oP the spectrum oP Patty acids eapreased in mg per g of tissue in the two groups oP animals indicates that there is significantly more palmitic acid (16 :0) (p ~ 0 .001) and significantly leas docosaheaaenoic acid (22 :6) (p ~ 0 .001) in the lysine and threonine deficient animals . These results indicate that in circumstances (essential amino acid deficiency) when lipids in other parts of the body under go change Y also the content oP some lipid constituents in brain is varied . In other ezperiments in this laboratory it has been observed that the lysine and threonine deficiency induces in the rat an increase oP palmitic acid and a decrease oP 22 :6 in mg per g oP tissue not only in portal Patty liver (11), but also in the carcasses (12) . The higher levels of palmitic acid and the lower ones of 22 :6 in brains of lysine and threonine-deficient rate in comparison with supplemented rats, might Suggest some modifications in ratios of phospholipid fractions, that are the main source oP Patty acids of brain lipids . It has been demonstrated, in tact, that palmitic acid is much lower in brain cephalin than in lecithin, while 22:6 is characteristic of cephalins and is almost absent in whole brain lecithin (20) . The change oP these two fatty acids (16 :0 and 22 :6) may be a consequence of modification8 of metabolic processes in brain ibselP, or map depend also on a variation oP plasma lipid composition, which is in its turn influenced by the liver, adipose depots and limph lipid patterns . These possibilities are suggested Prom various studies indicating that in adult rata most of the brain lipids (21,22) and also saturated (23) and polyunsaturated (24) tatty acids are in a constant state oP renewal (synthesis and breakdov~m) and that the Patty acids oP dietary origin are incorporated in cerebral lipids ( 25, 26, 27) .
CAANGES OF FATTY ACID COMPOSITION
482
TABLE
Vol . 3, No. 5
1
Sffect of Lysine and Threonine Deficiency on Body Weight, Brain Weight and Brain Lipids of Rats at 6 weeks from Weanling .
Deficient Body weight
g(a)
Brain weight (wet tissue) g(a) Brain lipids (b)
82 .70 _+ 9 .19 ( g)(h)
Supplemented 176 .82 _+ 21 .99 (g)(h)
1,26 + 0 .08 (h)
1,43 +
total lipids mg/g
69 .30 + 2 .48 (7)
71 .42 +
4 .53 (8)
total phospholipida mg/g (c) total cholesterol mg/g
46 .30 ± 1 .99 (6)
45 .40 ±
1,78 (6)
15 .60 ± 1 .64 (4)
15 .48 +
3 .84 (4)
cerebrosides mg/g (d)
10 .15 ± 2 .06 (6)
9 .71 +
2 .67 (6)
28 .60 + 2 .11 (7)
28 .59 +
5 .66 (8)
0 .07 _+
16 : 0
0 .12 _+ 0 .06 (7) 6 .82 + 0 .42 (h)
5 .93 +
0 .03 (8) 0 .25 (h)
16 : 1
0 .79 + 0 .37
0 .64 +
0 .11
18 : 0
6 .30 + 0 .73
6 .45 +
0 .36
18 : 1
? .78 + 0 .90
7 .25 +
0 .22
18 : 2
0 .57 + 0 .05
0 .45 +
0 .06
E0 : 1
0 .60 + 0 .27
0 .72 +
0 .08
20 :3
0 .21 + 0 .12
0 .16 +
0 .05
20 : 4
2 .08 + 0 .44
2 .33 +
0 .21
22 : 4
0 .53 + 0 .2?
0 .74 +
0 .30
22s 5
0 .20 _+ 0 .05
0 .30 _+
0 .19
total fatty acids mg/g (e) fatty acids mg/g (f) 14 :0
22 : 6
2 .11 + 0 .40 (h)
3 .09 +
0 .03 (h)
0 .23 (h)
(a) 16 rats per group ; (b) figures in parentheses indicate the number of determinations (brains of two animals pooled per determination) ; (c) total lipid P z 25 ; (d) lipid galactose z 4 .55 ; (e)1^&I . of fatty acids z 0 .284 ; (f) values were derived lrom the percentage of the individual fatty said of gas-liquid chromatographic elution diagram times the toted amount of tatty acids per g of brain, divided by 100 ; (g) mean ± S .D . ; (h) significant difference (P C 0 .001) .
Vol . 3, No. 5
CAANGEB OF FATTY ACID COMPOSITION
483
It is worthnoting that Patty acids which mostly are inPluenced by essential amino acid deficiency have in the brain some particular metabolic and biological characteristics . As Por palmitic acid it is possible that a control of its metabolism is done by the palmityl-CoA-deacylase that is much more active in the brain than in other tissues (28) . Concerning the 22:6, it appears to have a compartimentalization in the brain since it has been found only present in the lipids of grey matter (29) in the cells oP cortex (30) and absent in the white matter, Particularly rich oP 22 :6 are cephalinsoP mitochondria and microsomes and, differently than in whole brain, 22:6 can be detected in appreciable amount also in lecithine (20) . The levels oP this fatty acid in the brain have been correlated to the life and death in the essential fatty acids (SFA) deficient rats (31), In conclusion, onr studies indicate that the fatty acids oP cerebral lipids can be modified besides by an $fA deficiency (31) or by dietRry lipids (25,26,27) also by a deficiency oP lysine and threonine . Since in severe protein malnutrition
(Kwashiorkor) neuro-
psychic disturbances have been observed (32,33), the possible, relationships between the changes in metabolism oP brain Patty acids Prom amino acids deficiency and the development of neuropeychic disturbances cannot be overlooked . Summary The composition of lipids and oP the fatty acids in the brain of rate fed on low protein rice diets deficient in and supplemented with lysine and threonine has been studied . An increase in total amount oP palmitic acid and a decrease oP 22 :6 in brain lipids of lysine and threonine deficient rats in comparison with the supplemented animals have been observed . These results indicate that the lysine and threonine dePiciency modifies also the Patty acid composition in brain in circumstances when Patty acids in other part of the body (liver, carcasses) undergo changes .
CHANGES OF FATTY ACID COMPOSITION
484
Vol . 3, No. 5
References 1.
I .N .P . DAVISS, Lancet 254, 317 (1948) .
2.
M .S,SHILS, R, DS GIOVANNI and W .B, STSWART,
J . Nutrition 56 , 95
(1955) . 3,
S .A . SINGAL, S .7 . HAZAN, V .P, SYD~iSTRICKER and J .M, LITTLSJOHN, 7 .Biol .Chem .
200 , 867 (1953) .
4.
H . SIDRANSKY and T. BABA,
5.
R,H . BARN SS,
J . Nutrition 70, 463 (1960),
S. KWONG, W. POND, R . LOWRY and 7 .K . LOOSLI,
Nutrition 69 ,
J,
269 (1959) .
6,
M,G, DSO and V. RAMALINGSWAbiI, Lab . Invest . 9 , 319 (1960) .
?.
O,W . PORTMAN and F .7 . STARS, Physiol .Rev, 39 , 40? (1959) .
8.
R,S, OLSON and J .W . VSSTER, Phyaiol Rev . 40 , 677 (1960) .
9.
R,S . OLSON, Ann .Rev .Biochem . 28 , 467 (1959)
10 . R . VIVIANI and A,M . SSCHI, Bo11 .Soc .it .Bi o l .sper . 37, 11 . R, VIVIANI, A .M . SSCHI and G . LENAZ,
1762 (1961),
J . Lipid Rea . 5, 52 (1964) .
12 . R . VIVIANI A .M . SSCHI and G . LENAZ, Biochim .Bioph3 "s .Acta , in press .
(1964) .
13 . H . ROSSNBERG, R, CULIK and R,E . ECKERT, 7 . Nutrition 69 ,
217
(1959) . 14 . 7 . FOLCH, M . LESS and G,H . SLOANE STANLEY,
J . Biol .Chem, 226 ,
497 (1957) . 15 . S . McIL59AIN and R . RODNIGHT, Practical Nenxochemiatry p .64 Churchill Ltd ;, London (1962) . J6 . G,R, BARTLSTT, J . Biol .Chem . 234 , 466 (1959) . 17 . W,M . SPERRY and W . WSBB, J . Biol .Chem . 187, 97 (1950) . 18 . L . SVSNNERHOLM, 7 . Neurochem, 1, 42 (1956) . 19 . V,P . DOLS, J . Clin . Invest . 35,
150 (1956) .
20 . L,A .BIRAN and W. BARTLSY, Biochem .7 . 79 , 159 (1961), 21 . H, WA$LSCH, W.M . SPSRRY and V,A . STOYANOFF, J . Biol . Chem . 135 , 291 (1940) ;
140, 885 (1941) .
22 . R .7 . ROSSÎTBit, Metabolism oP the Nervous System (Sd, by D . Richter) p .355, Pergamon Press ., London (1957) . ~3 . P.M . VIGNAIS, C,H, GALLAGHER and I . ZABIN, J . Neurochem . 2 , 288 (1958) .
Vol . 3, No. 5
CHANGES OF FATTY ACID COMP03ITION
485
24 . E . RLBniK, Metabolism of the Nervous System (Ed .by D . Richter) p .396, Pergamon Presa, London (195?) . 25 . I .G, RIECKEHOLT, R .T . HOLMAN and G .O . BURR, Arch .Biochem .20 331 (1949) . 26 . L .A . WITTING, C .C . HARVEY, B .CENTURY and M,K . HORWITT, Res . 2 ,
J . Lipid
412 (1961) .
27 . G .7 . MARCO, L .J . MACHLILA, Biophys . 94 ,
E. B~:ERY and R .S . CORDON, Arch .Biochem .
115 (1961) .
28 . P .A. SRSRE, W. SEUBERT and F, hYNEN, Biochim .Biophys .Acta 33 ~ 313 (1959) . 29 . M . BEAUVALLET, G . BLANCH SR and P . MAY,
7 . Physiol .
(Paris) 45 ,
29(1953) . 30, R .W .R . BAKER, Biochem . J .
79,
642 (1961),
31, E . LE BRETON and S . FERRET, Ann .Nutr .Aliment . 13 , A 505 (1959) . 32 . M . CLARK, E . Afr .~ded .J . 28 ,
229 (1951),
33 . 7 .F, BROCK and M . AUTRET, Le K~rashiorkor en Afrigue . Serie de O .M .S . monographies Nr .B, p .28 (1952) .
CHANGES OF FATTY ACID COMPOSITION IN BRAIN LIPIDS OF LYSINE AND THRBANINE DEFICIENT RATS (+) R . Viviani, P . Borri (o) and G . Ronca ( ~o) Istituto di Chimica Biologics dell'Università di Bologna (Italy) (Received 21 March 1964) The present experiments are designed to investigate iP
a dietary essential amino acid deficiency might result in an
alteration of brain lipid constituents . It is well known, how ever, that a fatty liver of portal type has been described not only in children suffering from severe protein malnutrition (Kwashiorkor)
(1), but also in growing rats (2,3,4), pigs (5) and
monkeys (6) fed on low protein diets deficient in essential amino acids .
Dietary essential amino acids are also of importance in
the regulation of plasma levels of lipid constituents in children (?), men (7) and exp erimental animals (8,9) . On the other hand separate experiments in our laboratory have demonstrated in rate some changes in the composition of fatty acids in the fatty liver caused by lysine and threonine deficiency (10,11) and in carcasses in the same experimental conditions (12) . This report presents data on brain lipids and fatty acid composition in rats fed on low protein rice diets deficient in and supplemented with lysine (first limiting amino acid) and threonine (seeond physiologically limiting amino acid) (13) .
This work was performed with the aid of a grant from Consiglio Nazionale dells Ricerche .
(oo)
Present address : Clinics delle Malattie Nervosa e Mentali della Univereità di Parma, Parma (Italy) . Present address : Istituto di Chimica Biologics dell'Univereità di Pisa, Pisa (Italy) . 479
480
CHANGES OF FATTY ACID COMPOSITION
Vol . 3, No . 5
Methods Thirty-two weanling male rats oP the Wistar strain,
from
our inbred colony, weighing 44 + 2 g were divided in two groups and fed on the low protein rice diets deficient in and supplement ed with lysine and threonine . The composition of the diets is reported in a previous paper (11) . The diets are isonitrogenous . The supplementation with the limiting essential amino acids was made according to Rosenberg et al .
(12) to obtain better growth and a
physiological level oP liver lipids . The dietary Pat contained a high level oP linoleic acid and a small quantity of unsaturated fatty acids oP linolenic Family ; arachidonic acid was absent (11) . At the end oP the experimental period (six weeks)
16
rats of each group were weighed and killed by decapitation . The brains were immediately excised, weighed, Frozen and etorod at - 20~C . The total lipids from pools of two brains extracted and purified according to Folch et al . (14,15) were weighed . In the extracted lipids, total phosphorus (16), total cholesterol (17) and galactose (18) were determined .
Aliquots oP total lipids
were saponified in methanolic KOH and the amount oP total Patty acids was determined by titration (19) ;~I,Eq . oP fatty acids were converted to mg of fatty acids expressed as stearic acid . Methyl esters oP fatty acids prepared by refluxing in dry methanolic HC1 were analysed by gas-liquid chromatography (11) . Body weight, weight oP the brain, total brain lipids, phospholipids, total cholesterol, cerebrosides, total fatty acids and spectrum of singular fatty acids are reported in Table 1 . Statistical analyses were carried out by the "t" teat ; values oP P < 0 .05 were considered to be significant . Results and Discussion As it may be seen in table 1, the rate Fed the deficient diet exhibit a notable retarded growth ,while the weight of the brain of the same animals presents a small difference in comparison to that of the supplemented group .
The brains oP the lysine and
threonine deficient rats appear to continue growth at the expense
Vol. 3, No . 5
CHANGES OF FATTY ACID COMPOSITION
481
of other organs . Furthermore total lipids, total cholesterol, total phoapholipids, cerebrosides
and total Patty acids (ex-
pressed as stearic acid) in the two groups of animals do not change . Nevertheless, a comparison oP the spectrum oP Patty acids eapreased in mg per g of tissue in the two groups oP animals indicates that there is significantly more palmitic acid (16 :0) (p ~ 0 .001) and significantly leas docosaheaaenoic acid (22 :6) (p ~ 0 .001) in the lysine and threonine deficient animals . These results indicate that in circumstances (essential amino acid deficiency) when lipids in other parts of the body under go change Y also the content oP some lipid constituents in brain is varied . In other ezperiments in this laboratory it has been observed that the lysine and threonine deficiency induces in the rat an increase oP palmitic acid and a decrease oP 22 :6 in mg per g oP tissue not only in portal Patty liver (11), but also in the carcasses (12) . The higher levels of palmitic acid and the lower ones of 22 :6 in brains of lysine and threonine-deficient rate in comparison with supplemented rats, might Suggest some modifications in ratios of phospholipid fractions, that are the main source oP Patty acids of brain lipids . It has been demonstrated, in tact, that palmitic acid is much lower in brain cephalin than in lecithin, while 22:6 is characteristic of cephalins and is almost absent in whole brain lecithin (20) . The change oP these two fatty acids (16 :0 and 22 :6) may be a consequence of modification8 of metabolic processes in brain ibselP, or map depend also on a variation oP plasma lipid composition, which is in its turn influenced by the liver, adipose depots and limph lipid patterns . These possibilities are suggested Prom various studies indicating that in adult rata most of the brain lipids (21,22) and also saturated (23) and polyunsaturated (24) tatty acids are in a constant state oP renewal (synthesis and breakdov~m) and that the Patty acids oP dietary origin are incorporated in cerebral lipids ( 25, 26, 27) .
CAANGES OF FATTY ACID COMPOSITION
482
TABLE
Vol . 3, No. 5
1
Sffect of Lysine and Threonine Deficiency on Body Weight, Brain Weight and Brain Lipids of Rats at 6 weeks from Weanling .
Deficient Body weight
g(a)
Brain weight (wet tissue) g(a) Brain lipids (b)
82 .70 _+ 9 .19 ( g)(h)
Supplemented 176 .82 _+ 21 .99 (g)(h)
1,26 + 0 .08 (h)
1,43 +
total lipids mg/g
69 .30 + 2 .48 (7)
71 .42 +
4 .53 (8)
total phospholipida mg/g (c) total cholesterol mg/g
46 .30 ± 1 .99 (6)
45 .40 ±
1,78 (6)
15 .60 ± 1 .64 (4)
15 .48 +
3 .84 (4)
cerebrosides mg/g (d)
10 .15 ± 2 .06 (6)
9 .71 +
2 .67 (6)
28 .60 + 2 .11 (7)
28 .59 +
5 .66 (8)
0 .07 _+
16 : 0
0 .12 _+ 0 .06 (7) 6 .82 + 0 .42 (h)
5 .93 +
0 .03 (8) 0 .25 (h)
16 : 1
0 .79 + 0 .37
0 .64 +
0 .11
18 : 0
6 .30 + 0 .73
6 .45 +
0 .36
18 : 1
? .78 + 0 .90
7 .25 +
0 .22
18 : 2
0 .57 + 0 .05
0 .45 +
0 .06
E0 : 1
0 .60 + 0 .27
0 .72 +
0 .08
20 :3
0 .21 + 0 .12
0 .16 +
0 .05
20 : 4
2 .08 + 0 .44
2 .33 +
0 .21
22 : 4
0 .53 + 0 .2?
0 .74 +
0 .30
22s 5
0 .20 _+ 0 .05
0 .30 _+
0 .19
total fatty acids mg/g (e) fatty acids mg/g (f) 14 :0
22 : 6
2 .11 + 0 .40 (h)
3 .09 +
0 .03 (h)
0 .23 (h)
(a) 16 rats per group ; (b) figures in parentheses indicate the number of determinations (brains of two animals pooled per determination) ; (c) total lipid P z 25 ; (d) lipid galactose z 4 .55 ; (e)1^&I . of fatty acids z 0 .284 ; (f) values were derived lrom the percentage of the individual fatty said of gas-liquid chromatographic elution diagram times the toted amount of tatty acids per g of brain, divided by 100 ; (g) mean ± S .D . ; (h) significant difference (P C 0 .001) .
Vol . 3, No. 5
CAANGEB OF FATTY ACID COMPOSITION
483
It is worthnoting that Patty acids which mostly are inPluenced by essential amino acid deficiency have in the brain some particular metabolic and biological characteristics . As Por palmitic acid it is possible that a control of its metabolism is done by the palmityl-CoA-deacylase that is much more active in the brain than in other tissues (28) . Concerning the 22:6, it appears to have a compartimentalization in the brain since it has been found only present in the lipids of grey matter (29) in the cells oP cortex (30) and absent in the white matter, Particularly rich oP 22 :6 are cephalinsoP mitochondria and microsomes and, differently than in whole brain, 22:6 can be detected in appreciable amount also in lecithine (20) . The levels oP this fatty acid in the brain have been correlated to the life and death in the essential fatty acids (SFA) deficient rats (31), In conclusion, onr studies indicate that the fatty acids oP cerebral lipids can be modified besides by an $fA deficiency (31) or by dietRry lipids (25,26,27) also by a deficiency oP lysine and threonine . Since in severe protein malnutrition
(Kwashiorkor) neuro-
psychic disturbances have been observed (32,33), the possible, relationships between the changes in metabolism oP brain Patty acids Prom amino acids deficiency and the development of neuropeychic disturbances cannot be overlooked . Summary The composition of lipids and oP the fatty acids in the brain of rate fed on low protein rice diets deficient in and supplemented with lysine and threonine has been studied . An increase in total amount oP palmitic acid and a decrease oP 22 :6 in brain lipids of lysine and threonine deficient rats in comparison with the supplemented animals have been observed . These results indicate that the lysine and threonine dePiciency modifies also the Patty acid composition in brain in circumstances when Patty acids in other part of the body (liver, carcasses) undergo changes .
CHANGES OF FATTY ACID COMPOSITION
484
Vol . 3, No. 5
References 1.
I .N .P . DAVISS, Lancet 254, 317 (1948) .
2.
M .S,SHILS, R, DS GIOVANNI and W .B, STSWART,
J . Nutrition 56 , 95
(1955) . 3,
S .A . SINGAL, S .7 . HAZAN, V .P, SYD~iSTRICKER and J .M, LITTLSJOHN, 7 .Biol .Chem .
200 , 867 (1953) .
4.
H . SIDRANSKY and T. BABA,
5.
R,H . BARN SS,
J . Nutrition 70, 463 (1960),
S. KWONG, W. POND, R . LOWRY and 7 .K . LOOSLI,
Nutrition 69 ,
J,
269 (1959) .
6,
M,G, DSO and V. RAMALINGSWAbiI, Lab . Invest . 9 , 319 (1960) .
?.
O,W . PORTMAN and F .7 . STARS, Physiol .Rev, 39 , 40? (1959) .
8.
R,S, OLSON and J .W . VSSTER, Phyaiol Rev . 40 , 677 (1960) .
9.
R,S . OLSON, Ann .Rev .Biochem . 28 , 467 (1959)
10 . R . VIVIANI and A,M . SSCHI, Bo11 .Soc .it .Bi o l .sper . 37, 11 . R, VIVIANI, A .M . SSCHI and G . LENAZ,
1762 (1961),
J . Lipid Rea . 5, 52 (1964) .
12 . R . VIVIANI A .M . SSCHI and G . LENAZ, Biochim .Bioph3 "s .Acta , in press .
(1964) .
13 . H . ROSSNBERG, R, CULIK and R,E . ECKERT, 7 . Nutrition 69 ,
217
(1959) . 14 . 7 . FOLCH, M . LESS and G,H . SLOANE STANLEY,
J . Biol .Chem, 226 ,
497 (1957) . 15 . S . McIL59AIN and R . RODNIGHT, Practical Nenxochemiatry p .64 Churchill Ltd ;, London (1962) . J6 . G,R, BARTLSTT, J . Biol .Chem . 234 , 466 (1959) . 17 . W,M . SPERRY and W . WSBB, J . Biol .Chem . 187, 97 (1950) . 18 . L . SVSNNERHOLM, 7 . Neurochem, 1, 42 (1956) . 19 . V,P . DOLS, J . Clin . Invest . 35,
150 (1956) .
20 . L,A .BIRAN and W. BARTLSY, Biochem .7 . 79 , 159 (1961), 21 . H, WA$LSCH, W.M . SPSRRY and V,A . STOYANOFF, J . Biol . Chem . 135 , 291 (1940) ;
140, 885 (1941) .
22 . R .7 . ROSSÎTBit, Metabolism oP the Nervous System (Sd, by D . Richter) p .355, Pergamon Press ., London (1957) . ~3 . P.M . VIGNAIS, C,H, GALLAGHER and I . ZABIN, J . Neurochem . 2 , 288 (1958) .
Vol . 3, No. 5
CHANGES OF FATTY ACID COMP03ITION
485
24 . E . RLBniK, Metabolism of the Nervous System (Ed .by D . Richter) p .396, Pergamon Presa, London (195?) . 25 . I .G, RIECKEHOLT, R .T . HOLMAN and G .O . BURR, Arch .Biochem .20 331 (1949) . 26 . L .A . WITTING, C .C . HARVEY, B .CENTURY and M,K . HORWITT, Res . 2 ,
J . Lipid
412 (1961) .
27 . G .7 . MARCO, L .J . MACHLILA, Biophys . 94 ,
E. B~:ERY and R .S . CORDON, Arch .Biochem .
115 (1961) .
28 . P .A. SRSRE, W. SEUBERT and F, hYNEN, Biochim .Biophys .Acta 33 ~ 313 (1959) . 29 . M . BEAUVALLET, G . BLANCH SR and P . MAY,
7 . Physiol .
(Paris) 45 ,
29(1953) . 30, R .W .R . BAKER, Biochem . J .
79,
642 (1961),
31, E . LE BRETON and S . FERRET, Ann .Nutr .Aliment . 13 , A 505 (1959) . 32 . M . CLARK, E . Afr .~ded .J . 28 ,
229 (1951),
33 . 7 .F, BROCK and M . AUTRET, Le K~rashiorkor en Afrigue . Serie de O .M .S . monographies Nr .B, p .28 (1952) .