Nutrient Requirements
and Interactions
The Magnitude of the Acute Phase Protein Response is Attenuated by Protein Deficiency in Rats Medical Research
Council, Dunn Nutrition Unit, Cambridge
CB4 1XJ, U.K.
animal model of injury to show that protein defi ciency attenuates the acute phase response as mea sured by the circulating concentration of ci2-macroglobulin ((X2-M)to a standard form of trauma (7, 8). Q.IMacroglobulin, a major acute phase reactant in the rat, is a broad spectrum protease inhibitor (9) that has the capacity to bind cytokines (10) and is also thought to be involved in regulating tissue damage and tissue restructuring by complex formation with growth factors (11). However, our previous work was under taken using only one degree of protein deficiency (3% protein diet). This diet, which was given with ad libitum access, was sufficient to maintain weight in rats that would otherwise grow normally. It is not known whether the acute phase protein response in creases or decreases if the level of protein in the diet increases or decreases and whether this is associated with changes in the temporal pattern of the acute phase protein response. Previous work by Lunn and Austin (12) has shown that the rate of growth is not inhibited until the protein content of the diet is reduced below 10 g/100 g. Growth is not abolished until the protein concentration of the diet is decreased to 3 g/100 g, and loss of body weight occurs when the protein concentration of the diet is reduced to less than 3 g/100 g. We have therefore investigated the effects on the acute phase response in rats fed diets that will reduce growth (6.0 and 4.5 g protein/ 100 g diet), prevent growth (3.0 g protein/100 g diet) or cause weight loss (1.5 and 0.5 g protein/100 g diet).
ABSTRACT We assessed the growth rate and changes in plasma albumin, total protein and cx2-macroglobulin concentrations (a major acute phase protein in rats) before and after a subcutaneous injection of turpentine (0.5 mg/kg body wt) in groups of rats receiving one of a series of protein-deficient diets (protein concentrations of 0.5, 1.5, 3.0, 4.5 or 6.0 g/100 g) or a diet containing an adequate level of protein (20 g/100 g) for maximal growth. Increasing protein deficiency in the different groups of animals reduced the basal albumin and total protein concentrations and attenuated the total protein and cc2-macroglobulin responses to turpentine. In creasing protein deficiency delayed the time taken for (X2-macroglobulin to reach peak concentrations postinjection and its return to basal concentrations. The turpentine-induced hypoalbuminemia was similar in all groups of animals (-10 g/L depression) but restoration to values that were present before turpentine injection was increasingly delayed with increasing protein defi ciency. The magnitude of the acute phase response (peak 0.2-macroglobulin concentration) was found to be directly related to growth rate (r «0.70, P < 0.001). We concluded that protein deficiency can alter the pattern and magnitude of the acute phase responses in circu lating protein concentrations to an extent that is de pendent on the severity of protein deficiency. J. Nutr. 122: 1325-1331, 1992. INDEXING KEY WORDS:
•protein deficiency •rats •acute phase protein response •a.2-macroglobulln
Nutritional status may modify the metabolic re sponse to infection or injury (1-5) and this may in fluence morbidity and mortality. For example, the negative nitrogen balance after injury tends to be greater in young muscular and well-nourished in dividuals than in thin elderly or malnourished in dividuals (1, 2, 4). Furthermore, the acute phase protein response, which has been used to monitor the severity of injury or disease activity, may be at tenuated by malnutrition (5, 6). However, in view of the obvious difficulties associated with undertaking well-controlled human studies, we have used an
METHODS The animals used in this study were bred from the Dunn Nutrition Unit's colony of rats. This research was conducted in accordance with the Animal (Scien tific Procedures) Act 1986 of the United Kingdom. Male Dunn hooded rats (n = 42) were weaned at 21 d of age, caged individually and given free access to water and a 20% (wt/wt) protein (casein-based) syn thetic diet (13) (Table 1). After 7 d, the animals were randomly assigned to either continue receiving the control diet (20 g protein/100 g diet), or to receive one
0022-3166/92 $3.00 ©1992 American Institute of Nutrition. Received 29 August 1991. Accepted 6 January 1992. 1325
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GRAHAM JENNINGS, CHRISTELLE BOURGEOIS AND MARINOS ELIA
1326
JENNINGS
ET AL. 300
TABLE 1 Composition of the control diet1
Turpentine 200
Amount
Casein, g Cystine, g Sucrose, g Starch, g Corn oil, g Salt mixture2, g
210 3 355 355 30 50 1003
Total, g B-vitamin and choline chloride mixture, ml/kg3 Fat-soluble vitamin mixture, ml/kg4 Energy content, Mf/kg Carbohydrate, g/kg Protein, g/kg
D) "9
100
10
10 2 16.70 701 209
'The energy density of all the diets was 16.7 kj/g. Diets defi
20
30
Days
FIGURE 1 Changes in the body weights of rats fed diets differing in protein concentration. The arrow indicates the time of the subcutaneous injection of turpentine (d 15). Dotted lines indicate the predicted body weights extrapo lated from the period before turpentine injection. Values are means, n = 7. Representative SEM are shown.
cient in protein had the energy replaced with isocaloric quantities of carbohydrate (sucrose plus starch in equal amounts). ^Containing (g/kg): calcium carbonate, 205; calcium hydrogen phosphate, 325; disodium hydrogen phosphate, 185; potassium chloride, 205; magnesium sulphate, 4.5; ferric citrate, 4.35; copper sulphate, 0.375; zinc carbonate, 0.75; potassium iodate, 0.025. Salt mixture was commercially prepared by Arthur H. Cox, Brighton, U.K. 3Containing: choline chloride, 2 g; calcium pantothenate, 20 mg; thiamin, 3 mg; pyridoxine, 3 mg; riboflavin, 3 mg; nicotinamide, 25 mg; biotin, 0.1 mg; cyanocobalamin, 0.05 mg. The mixture was made up to 10 mL with water and added to 1 kg of each diet. 4Fat-soluble vitamins were added in arachis oil: retinyl acetate, 12.5 g; ergocalciferol, 0.02 g; KÄK-a-tocopheryl, 50 g and menadione, 4 g/L oil.
of the following low protein diets (n = 7 in each group): 6.0, 4.5, 3.0, 1.5 or 0.5 g/100 g protein for the duration of the study. After 14 d of feeding the experimental diets, an acute phase reaction was induced in all rats by a subcutaneous injection of turpentine (5 mL/kg body wt), divided between two dorsal-lumbar sites. Blood samples (-200 uL) were obtained from the tail tip of each animal just before turpentine injection (d 0) and at the same time on d 1, 2, 3, 4, 7, 10, 14 and 17 after turpentine injection. Previous work (7) had shown that this amount of blood withdrawal had no effect on the total protein, albumin or aj-M concen trations in the plasma of control rats (saline-injected) receiving either an adequate protein diet (20 g/100 g) or a low protein diet (3 g/100 g). Blood was collected in tubes containing am monium heparin, and the plasma separated and stored at -20°C until it was analyzed for total protein, al bumin and CC2-M.Total protein was measured using the BCA protein assay reagent (Pierce Chemical, Rockford, IL), albumin by nephelometry (8) on a cen trifugal analyser (Cobas Bio, Roche, Welwyn Garden City, U.K.) and ct2-M by single radial diffusion as previously described (8).
Body weights and food intake were measured daily both before and after turpentine injection. Statistics. All results are expressed as the mean ± SEMof seven animals per dietary group. Growth rates and protein concentrations were analyzed using ANO VA. When ANOVA indicated a significant result (P < 0.05) within a dietary group, individual compar isons between pre-turpentine concentrations (d 0) and post-turpentine concentration were carried out by Student's i-test. Results were considered significant at P < 0.05. Linear regression analysis was also em ployed.
RESULTS Before turpentine injection Effect of experimental diets on body weight and food intake. The growth rate of the animals was related to the protein concentration of the diets (Fig. 1, Table 2). Body weight was maintained in the rats fed the 3 g/100 g protein diet, increased in those fed 4.5, 6.0 and 20 g/100 g protein diets, and decreased in rats fed 0.5 and 1.5 g/100 g protein diets. Food intake per day increased progressively in the groups that were gaining weight; it remained stable in the rats with a stable weight and decreased in the groups that were losing body weight (data not shown). When food intake was expressed in relation to body weight the variation between groups was less marked, although the values tended to be higher in the growing animals. At the start of the study (d 1) intakes were 16.7 ±0.4, 17.5 ±0.7, 17.7 ±0.7, 14.8 ±1.1, 16.3 ±0.7 and 13.1 ±1.2 g/100 g body wt for the rats fed the 20, 6.0, 4.5, 3.0, 1.5 and 0.5 g/100 g protein diets, respec tively. Only the food intake of the 0.5 g/100 g protein
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Constituent
PROTEIN
DEFICIENCY AND THE ACUTE PHASE RESPONSE
1327
TABLE 2 Effect of dietary protein and turpentine on growth rates of rats fed diets differing in protein concentration1 Growth Dietary protein
4.5
20
1.5
0.5
0.10-0.31 ±
0.11-0.94 ±
3.0
g/äPre-turpentinePost-turpentine2'30-4 0.33-0.61 ± d4-8 d8-12 d12-16 d6.50
0.13-0.1±
0.46+++5.04 ± 0.41+++2.65 ± 0.52+8.90 ± 0.29+4.21 ± 0.46**8.47 ± 0.384.17 ± ±0.55**3.43 ±0.351.52
0.100.68 ±
±0.110.17
0.12+++0.72 ± 0.21++1.98 ± 0.191.84 ± ±0.140.47
0.10-0.41 ± 0.08-0.63 ± 0.160.11 ± 0.110.33 ± 0.08-0.23 ± 0.190.74 ± ±0.13**0.21 0.16*-0.38 ± 0.140.42 ± ±0.08**-O.72 ±0.09* ±0.23-0.31
Values are means ±SEM,n = 7. Analysis of pre-turpentine growth rates by ANOVA was significant (P < 0.001); t test was significant for growth rate for all protein deficient diets when compared with the 20% protein diet [P < 0.01 for 6.0% diet, and P < 0.001 for all other diets). 2Analysis of growth rates with time for each dietary group by ANOVA was significant (P < 0.001) for all groups except the 3.0% protein group (nonsignificant). 3Growth rates significantly less than corresponding pre-turpentine rates are indicated: +P < 0.05; ++P < 0.01; +++P < 0.001. Growth rates significantly greater than the corresponding pre-turpentine rates are indicated: 'P < 0.05; "P < 0.01.
group was significantly different (P < 0.05) from that of the 20 g/100 g protein group. Food intake, ex pressed in relation to body weight, gradually declined with age. Linear regression equations and correlation coefficients were calculated from the food intake data before turpentine injection (i.e., d 1-14 of the study) for each dietary group. Correlation coefficients for the various dietary groups were: 20% diet, r = 0.92; 6% diet, r = 0.80; 4.5% diet, r = 0.61; 3.0% diet, r = 0.72; 1.5% diet, r = 0.78; and 0.5% diet, r = 0.70; all were significant (P < 0.05). Plasma proteins. The plasma albumin and plasma total protein concentrations (Table 3) were signifi cantly lower than in the control group in all animals given protein-deficient diets. The concentration of albumin and total protein decreased with increasing protein deficiency, hi contrast, the plasma ot2-Mcon centration was significantly higher in all groups of rats fed protein-deficient diets than in controls.
vious work in our laboratory has established that the food intakes of rats (with no turpentine injection) fed either a control diet (20 g protein/100 g diet) or a protein-deficient diet (3 g protein/100 g diet) decrease in an essentially linear manner during the amount of time covered by this study. Thus the linear regression equations obtained using the food intakes for the 14 d before turpentine injection are adequate to predict the theoretical intake over the next 14 d (i.e., no tur pentine injection). The food intake of rats in all di etary groups was lower than predicted amounts
TABLE 3
Effect of protein deficiency on the plasma concentration of total protein, albumin and a^-macroglobulia fn2-M) before turpentine injections1 concentrationsDietaryproteing/100 Plasma protein
After turpentine
injection
Body weight and food intake. Turpentine injection caused a transient decrease in daily food intake (grams per day) in all groups of animals, but the duration and magnitude of the decrease tended to be greater in the rats fed the diets with the higher protein concentration. These groups of rats also showed the greatest change in weight in the first 2 d after turpentine injection (Fig. 1). Food intakes after turpentine injection are given in Table 4, both as grams per 100 g body wt per day and as a percentage of the predicted normal intake. Pre
g20.06.04.53.01.50.5Totalprotein59.6 1.755.0 ± 0.728.3 ± 0.0040.08 ± 0.8*54.2 ± 0.5**27.1 ± 0.01*0.09 ± 1.4*52.2 ± 0.7***26.2 ± 0.01**0.10 ± 1.3**52.6 ± 0.7***25.8 ± 0.01***0.10 ± 1.8**45.2 ± ±0.5***21.7 0.01***0.09 ± ±1.1***Albuming/L31.5 ±0.8***OC2-M0.05 ±0.01*** 'Values are means ±SEM,n = 7 per dietary group. ANOVA was significant for the effect of diet on plasma total protein (P < 0.001), albumin (P < 0.001) and a2-M, (P < 0.001). Values that are signifi cantly different from the controls (20% protein diet ) are indicated: *P < 0.05, **P < 0.01, ***P < 0.001.
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g/100 g
1328
JENNINGS ET AL.
O O O —i
§ -H-H-H-H-H-H-H-H-H-H ^ qr^^Hffjr^^HLrjOTth-. "xi r-!c!
and Interactions
The Magnitude of the Acute Phase Protein Response is Attenuated by Protein Deficiency in Rats Medical Research
Council, Dunn Nutrition Unit, Cambridge
CB4 1XJ, U.K.
animal model of injury to show that protein defi ciency attenuates the acute phase response as mea sured by the circulating concentration of ci2-macroglobulin ((X2-M)to a standard form of trauma (7, 8). Q.IMacroglobulin, a major acute phase reactant in the rat, is a broad spectrum protease inhibitor (9) that has the capacity to bind cytokines (10) and is also thought to be involved in regulating tissue damage and tissue restructuring by complex formation with growth factors (11). However, our previous work was under taken using only one degree of protein deficiency (3% protein diet). This diet, which was given with ad libitum access, was sufficient to maintain weight in rats that would otherwise grow normally. It is not known whether the acute phase protein response in creases or decreases if the level of protein in the diet increases or decreases and whether this is associated with changes in the temporal pattern of the acute phase protein response. Previous work by Lunn and Austin (12) has shown that the rate of growth is not inhibited until the protein content of the diet is reduced below 10 g/100 g. Growth is not abolished until the protein concentration of the diet is decreased to 3 g/100 g, and loss of body weight occurs when the protein concentration of the diet is reduced to less than 3 g/100 g. We have therefore investigated the effects on the acute phase response in rats fed diets that will reduce growth (6.0 and 4.5 g protein/ 100 g diet), prevent growth (3.0 g protein/100 g diet) or cause weight loss (1.5 and 0.5 g protein/100 g diet).
ABSTRACT We assessed the growth rate and changes in plasma albumin, total protein and cx2-macroglobulin concentrations (a major acute phase protein in rats) before and after a subcutaneous injection of turpentine (0.5 mg/kg body wt) in groups of rats receiving one of a series of protein-deficient diets (protein concentrations of 0.5, 1.5, 3.0, 4.5 or 6.0 g/100 g) or a diet containing an adequate level of protein (20 g/100 g) for maximal growth. Increasing protein deficiency in the different groups of animals reduced the basal albumin and total protein concentrations and attenuated the total protein and cc2-macroglobulin responses to turpentine. In creasing protein deficiency delayed the time taken for (X2-macroglobulin to reach peak concentrations postinjection and its return to basal concentrations. The turpentine-induced hypoalbuminemia was similar in all groups of animals (-10 g/L depression) but restoration to values that were present before turpentine injection was increasingly delayed with increasing protein defi ciency. The magnitude of the acute phase response (peak 0.2-macroglobulin concentration) was found to be directly related to growth rate (r «0.70, P < 0.001). We concluded that protein deficiency can alter the pattern and magnitude of the acute phase responses in circu lating protein concentrations to an extent that is de pendent on the severity of protein deficiency. J. Nutr. 122: 1325-1331, 1992. INDEXING KEY WORDS:
•protein deficiency •rats •acute phase protein response •a.2-macroglobulln
Nutritional status may modify the metabolic re sponse to infection or injury (1-5) and this may in fluence morbidity and mortality. For example, the negative nitrogen balance after injury tends to be greater in young muscular and well-nourished in dividuals than in thin elderly or malnourished in dividuals (1, 2, 4). Furthermore, the acute phase protein response, which has been used to monitor the severity of injury or disease activity, may be at tenuated by malnutrition (5, 6). However, in view of the obvious difficulties associated with undertaking well-controlled human studies, we have used an
METHODS The animals used in this study were bred from the Dunn Nutrition Unit's colony of rats. This research was conducted in accordance with the Animal (Scien tific Procedures) Act 1986 of the United Kingdom. Male Dunn hooded rats (n = 42) were weaned at 21 d of age, caged individually and given free access to water and a 20% (wt/wt) protein (casein-based) syn thetic diet (13) (Table 1). After 7 d, the animals were randomly assigned to either continue receiving the control diet (20 g protein/100 g diet), or to receive one
0022-3166/92 $3.00 ©1992 American Institute of Nutrition. Received 29 August 1991. Accepted 6 January 1992. 1325
Downloaded from https://academic.oup.com/jn/article-abstract/122/6/1325/4754923 by Boston University Libraries user on 13 January 2019
GRAHAM JENNINGS, CHRISTELLE BOURGEOIS AND MARINOS ELIA
1326
JENNINGS
ET AL. 300
TABLE 1 Composition of the control diet1
Turpentine 200
Amount
Casein, g Cystine, g Sucrose, g Starch, g Corn oil, g Salt mixture2, g
210 3 355 355 30 50 1003
Total, g B-vitamin and choline chloride mixture, ml/kg3 Fat-soluble vitamin mixture, ml/kg4 Energy content, Mf/kg Carbohydrate, g/kg Protein, g/kg
D) "9
100
10
10 2 16.70 701 209
'The energy density of all the diets was 16.7 kj/g. Diets defi
20
30
Days
FIGURE 1 Changes in the body weights of rats fed diets differing in protein concentration. The arrow indicates the time of the subcutaneous injection of turpentine (d 15). Dotted lines indicate the predicted body weights extrapo lated from the period before turpentine injection. Values are means, n = 7. Representative SEM are shown.
cient in protein had the energy replaced with isocaloric quantities of carbohydrate (sucrose plus starch in equal amounts). ^Containing (g/kg): calcium carbonate, 205; calcium hydrogen phosphate, 325; disodium hydrogen phosphate, 185; potassium chloride, 205; magnesium sulphate, 4.5; ferric citrate, 4.35; copper sulphate, 0.375; zinc carbonate, 0.75; potassium iodate, 0.025. Salt mixture was commercially prepared by Arthur H. Cox, Brighton, U.K. 3Containing: choline chloride, 2 g; calcium pantothenate, 20 mg; thiamin, 3 mg; pyridoxine, 3 mg; riboflavin, 3 mg; nicotinamide, 25 mg; biotin, 0.1 mg; cyanocobalamin, 0.05 mg. The mixture was made up to 10 mL with water and added to 1 kg of each diet. 4Fat-soluble vitamins were added in arachis oil: retinyl acetate, 12.5 g; ergocalciferol, 0.02 g; KÄK-a-tocopheryl, 50 g and menadione, 4 g/L oil.
of the following low protein diets (n = 7 in each group): 6.0, 4.5, 3.0, 1.5 or 0.5 g/100 g protein for the duration of the study. After 14 d of feeding the experimental diets, an acute phase reaction was induced in all rats by a subcutaneous injection of turpentine (5 mL/kg body wt), divided between two dorsal-lumbar sites. Blood samples (-200 uL) were obtained from the tail tip of each animal just before turpentine injection (d 0) and at the same time on d 1, 2, 3, 4, 7, 10, 14 and 17 after turpentine injection. Previous work (7) had shown that this amount of blood withdrawal had no effect on the total protein, albumin or aj-M concen trations in the plasma of control rats (saline-injected) receiving either an adequate protein diet (20 g/100 g) or a low protein diet (3 g/100 g). Blood was collected in tubes containing am monium heparin, and the plasma separated and stored at -20°C until it was analyzed for total protein, al bumin and CC2-M.Total protein was measured using the BCA protein assay reagent (Pierce Chemical, Rockford, IL), albumin by nephelometry (8) on a cen trifugal analyser (Cobas Bio, Roche, Welwyn Garden City, U.K.) and ct2-M by single radial diffusion as previously described (8).
Body weights and food intake were measured daily both before and after turpentine injection. Statistics. All results are expressed as the mean ± SEMof seven animals per dietary group. Growth rates and protein concentrations were analyzed using ANO VA. When ANOVA indicated a significant result (P < 0.05) within a dietary group, individual compar isons between pre-turpentine concentrations (d 0) and post-turpentine concentration were carried out by Student's i-test. Results were considered significant at P < 0.05. Linear regression analysis was also em ployed.
RESULTS Before turpentine injection Effect of experimental diets on body weight and food intake. The growth rate of the animals was related to the protein concentration of the diets (Fig. 1, Table 2). Body weight was maintained in the rats fed the 3 g/100 g protein diet, increased in those fed 4.5, 6.0 and 20 g/100 g protein diets, and decreased in rats fed 0.5 and 1.5 g/100 g protein diets. Food intake per day increased progressively in the groups that were gaining weight; it remained stable in the rats with a stable weight and decreased in the groups that were losing body weight (data not shown). When food intake was expressed in relation to body weight the variation between groups was less marked, although the values tended to be higher in the growing animals. At the start of the study (d 1) intakes were 16.7 ±0.4, 17.5 ±0.7, 17.7 ±0.7, 14.8 ±1.1, 16.3 ±0.7 and 13.1 ±1.2 g/100 g body wt for the rats fed the 20, 6.0, 4.5, 3.0, 1.5 and 0.5 g/100 g protein diets, respec tively. Only the food intake of the 0.5 g/100 g protein
Downloaded from https://academic.oup.com/jn/article-abstract/122/6/1325/4754923 by Boston University Libraries user on 13 January 2019
Constituent
PROTEIN
DEFICIENCY AND THE ACUTE PHASE RESPONSE
1327
TABLE 2 Effect of dietary protein and turpentine on growth rates of rats fed diets differing in protein concentration1 Growth Dietary protein
4.5
20
1.5
0.5
0.10-0.31 ±
0.11-0.94 ±
3.0
g/äPre-turpentinePost-turpentine2'30-4 0.33-0.61 ± d4-8 d8-12 d12-16 d6.50
0.13-0.1±
0.46+++5.04 ± 0.41+++2.65 ± 0.52+8.90 ± 0.29+4.21 ± 0.46**8.47 ± 0.384.17 ± ±0.55**3.43 ±0.351.52
0.100.68 ±
±0.110.17
0.12+++0.72 ± 0.21++1.98 ± 0.191.84 ± ±0.140.47
0.10-0.41 ± 0.08-0.63 ± 0.160.11 ± 0.110.33 ± 0.08-0.23 ± 0.190.74 ± ±0.13**0.21 0.16*-0.38 ± 0.140.42 ± ±0.08**-O.72 ±0.09* ±0.23-0.31
Values are means ±SEM,n = 7. Analysis of pre-turpentine growth rates by ANOVA was significant (P < 0.001); t test was significant for growth rate for all protein deficient diets when compared with the 20% protein diet [P < 0.01 for 6.0% diet, and P < 0.001 for all other diets). 2Analysis of growth rates with time for each dietary group by ANOVA was significant (P < 0.001) for all groups except the 3.0% protein group (nonsignificant). 3Growth rates significantly less than corresponding pre-turpentine rates are indicated: +P < 0.05; ++P < 0.01; +++P < 0.001. Growth rates significantly greater than the corresponding pre-turpentine rates are indicated: 'P < 0.05; "P < 0.01.
group was significantly different (P < 0.05) from that of the 20 g/100 g protein group. Food intake, ex pressed in relation to body weight, gradually declined with age. Linear regression equations and correlation coefficients were calculated from the food intake data before turpentine injection (i.e., d 1-14 of the study) for each dietary group. Correlation coefficients for the various dietary groups were: 20% diet, r = 0.92; 6% diet, r = 0.80; 4.5% diet, r = 0.61; 3.0% diet, r = 0.72; 1.5% diet, r = 0.78; and 0.5% diet, r = 0.70; all were significant (P < 0.05). Plasma proteins. The plasma albumin and plasma total protein concentrations (Table 3) were signifi cantly lower than in the control group in all animals given protein-deficient diets. The concentration of albumin and total protein decreased with increasing protein deficiency, hi contrast, the plasma ot2-Mcon centration was significantly higher in all groups of rats fed protein-deficient diets than in controls.
vious work in our laboratory has established that the food intakes of rats (with no turpentine injection) fed either a control diet (20 g protein/100 g diet) or a protein-deficient diet (3 g protein/100 g diet) decrease in an essentially linear manner during the amount of time covered by this study. Thus the linear regression equations obtained using the food intakes for the 14 d before turpentine injection are adequate to predict the theoretical intake over the next 14 d (i.e., no tur pentine injection). The food intake of rats in all di etary groups was lower than predicted amounts
TABLE 3
Effect of protein deficiency on the plasma concentration of total protein, albumin and a^-macroglobulia fn2-M) before turpentine injections1 concentrationsDietaryproteing/100 Plasma protein
After turpentine
injection
Body weight and food intake. Turpentine injection caused a transient decrease in daily food intake (grams per day) in all groups of animals, but the duration and magnitude of the decrease tended to be greater in the rats fed the diets with the higher protein concentration. These groups of rats also showed the greatest change in weight in the first 2 d after turpentine injection (Fig. 1). Food intakes after turpentine injection are given in Table 4, both as grams per 100 g body wt per day and as a percentage of the predicted normal intake. Pre
g20.06.04.53.01.50.5Totalprotein59.6 1.755.0 ± 0.728.3 ± 0.0040.08 ± 0.8*54.2 ± 0.5**27.1 ± 0.01*0.09 ± 1.4*52.2 ± 0.7***26.2 ± 0.01**0.10 ± 1.3**52.6 ± 0.7***25.8 ± 0.01***0.10 ± 1.8**45.2 ± ±0.5***21.7 0.01***0.09 ± ±1.1***Albuming/L31.5 ±0.8***OC2-M0.05 ±0.01*** 'Values are means ±SEM,n = 7 per dietary group. ANOVA was significant for the effect of diet on plasma total protein (P < 0.001), albumin (P < 0.001) and a2-M, (P < 0.001). Values that are signifi cantly different from the controls (20% protein diet ) are indicated: *P < 0.05, **P < 0.01, ***P < 0.001.
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g/100 g
1328
JENNINGS ET AL.
O O O —i
§ -H-H-H-H-H-H-H-H-H-H ^ qr^^Hffjr^^HLrjOTth-. "xi r-!c!
