Developmental aspects of glutathione S-transferase B (ligandin) in rat liver.

The postnatal development in male Sprague-Dawley rats of hepatic glutathione S-transferase B (ligandin) in relation to the other glutathione S-transferases is described. The concentration of glutathione S-transferase B in 1-day-old male rats is about one-fifth of that in adult animals. The enzyme reaches adult concentrations 4-5 weeks later. When assessed by substrate specificity or immunologically, the proportion of transferase B relative to the other glutathione S-transferases is high during the first week after birth. At this age, 67.5% of the transferase activity towards 1-chloro-2,4-dinitrobenzene is immunoprecipitable by anti-(transferase B), compared with about 50% in adults and older pups. Between the second and the fifth postnatal week, the fraction of transferase B increases in parallel fashion with the other transferases in hepatic cytosol. Neither L-thyroxine nor cortisol induce a precocious increase in glutathione S-transferase activity. Phenobarbital did induce transferase activity towards 1-chloro-2,4-dinitrobenzene and 1,2-dichloro-4-nitrobenzene in both pups and adults. The extent of induction by phenobarbital was a function of basal activity during development such that the percentage stimulation remained constant from 5 days postnatally to adulthood.     

Osteocalcin is vitamin D-dependent during the perinatal period in the rat

The vitamin D-dependence of renal calbindin D-28K and osteocalcin during the perinatal period was studied in fetuses (days 18 and 21) and neonates (days 2, 12, 17 and 22) of rats fed either a standard diet (0.85% Ca-0.7% P; "high Ca-P diet" rats) or a mildly Ca-P restricted diet (0.2% Ca-0.2% P; "low Ca-P diet" rats). Body weight and plasma calcium levels were identical in both groups. Plasma 1,25(OH)2D concentrations were markedly higher in the low Ca-P diet rats at all stages of fetal and neonatal life (in 22-day-old neonates: 536 +/- 58 pg/ml versus 126 +/- 12 pg/ml). 1,25(OH)2D concentrations increased between day 18 and 21 of fetal life, remained constant between day 21 of fetal and day 12 of neonatal life, and increased sharply between day 12 and 17 in both groups; after day 17, 1,25(OH)2D concentrations increased further in pups fed the low Ca-P diet. Renal calbindin D-28K reached peak concentrations on day 12 of neonatal life; calbindin D-28K levels were similar in the high and low Ca-P diet rats at all stages of perinatal development. Plasma osteocalcin levels increased steadily during the perinatal period; at most stages of perinatal life, and already from the fetal period was osteocalcin higher in the low Ca-P diet rats than in the high Ca-P diet rats (in 22-day-old pups: 1106 +/- 47 ng/ml versus 429 +/- 14 ng/ml). Femoral osteocalcin concentrations were also increased in fetal and early neonatal (days 2 and 12) low Ca-P diet rats, while the femoral calcium content and concentration of these rats were decreased in the late neonatal period (days 12, 17 and 22). These studies indicate that osteocalcin is vitamin D-dependent in the fetal and neonatal rat.     

Effects of Maternal LPS Exposure during Pregnancy on Metabolic Phenotypes in Female Offspring

It is increasingly recognized that intra-uterine growth restriction (IUGR) is associated with an increased risk of metabolic disorders in late life. Previous studies showed that mice exposed to LPS in late gestation induced fetal IUGR. The present study investigated the effects of maternal LPS exposure during pregnancy on metabolic phenotypes in female adult offspring. Pregnant mice were intraperitoneally injected with LPS (50 µg/kg) daily from gestational day (GD)15 to GD17. After lactation, female pups were fed with standard-chow diets (SD) or high-fat diets (HFD). Glucose tolerance test (GTT) and insulin tolerance test (ITT) were assessed 8 and 12 weeks after diet intervention. Hepatic triglyceride content was examined 12 weeks after diet intervention. As expected, maternal LPS exposure during pregnancy resulted in fetal IUGR. Although there was an increasing trend on fat mass in female offspring whose dams were exposed to LPS during pregnancy, maternal LPS exposure during pregnancy did not elevate the levels of fasting blood glucose and serum insulin and hepatic triglyceride content in female adult offspring. Moreover, maternal LPS exposure during pregnancy did not alter insulin sensitivity in adipose tissue and liver in female adult offspring. Further analysis showed that maternal LPS exposure during pregnancy did not exacerbate HFD-induced glucose tolerance and insulin resistance in female adult offspring. In addition, maternal LPS exposure during pregnancy did not aggravate HFD-induced elevation of hepatic triglyceride content in female adult offspring. In conclusion, LPS-induced IUGR does not alter metabolic phenotypes in adulthood.     

Multiple mechanisms account for lower plasma iron in young copper deficient rats

Copper deficiency lowers brain copper and iron during development. The reduced iron content could be due to hypoferremia. Experiments were conducted to evaluate plasma iron and “ferroxidase” hypotheses by determining copper and iron status of Holtzman albino rats following gestational/lactational copper deficiency. Copper deficient (Cu−) dams on treatment for 5 weeks, two of gestation and three of lactation, had markedly lower copper content of milk and mammary tissue, and lower milk iron. Newborn pups from Cu− dams had lower copper and iron concentrations. Compared to Cu+ pups, Cu− pups, analyzed between postnatal age (P) 0 and P26, were smaller, anemic, had lower plasma iron, cardiac hypertrophy, and near zero ceruloplasmin activity. Liver copper in Cu+ pups increased then decreased during development and major reductions were evident in Cu− pups. Liver iron in Cu+ pups decreased with age while nursing but increased after eating solid food. Liver iron was lower in Cu− pups at P0 and P13 and normal at P20 and P26. Small intestinal copper decreased with age in Cu+ pups and was lower in Cu− pups. Intestinal iron levels in Cu− pups were higher than Cu+ pups postweaning in some experiments. Reduction in plasma iron in Cu− pups is likely due to a decreased “ferroxidase” function leading to lower placental iron transport, a lower milk iron diet, and partial block in iron uptake from intestine but is not due to failure to mobilize hepatic iron, in contrast to older rats eating diet with adequate iron.     

Insulin signaling during perinatal liver development in the rat

Insulin has long been assigned a key role in the regulation of growth and metabolism during fetal life. Our prior observations indicated that hepatic insulin signaling is attenuated in the late-gestation fetal rat. Therefore, we studied the perinatal ontogeny of hepatic insulin signaling extending from phosphatidylinositol 3-kinase (PI3K) to the ribosome. Initial studies demonstrated markedly decreased insulin-mediated activation of ribosomal protein S6 kinase 1 (S6K1) in the fetus. We found a similar pattern in the regulation of Akt, a kinase upstream from S6K1. Insulin produced minimal activation of insulin receptor substrate (IRS)-1-associated PI3K activity in fetal liver. A modest IRS-2-associated response was seen in the fetus. However, levels of both IRS-1 and IRS-2 were very low in fetal liver relative to adult liver. IRS-1 content and insulin responsiveness of PI3K, Akt, and S6K1 showed a transition to the adult phenotype during the first several postnatal weeks. Examination of downstream insulin signaling to the translational apparatus showed marked attenuation, relative to the adult, of fetal hepatic insulin-mediated phosphorylation of 4E-BP1, the regulatory protein for the eukaryotic initiation factor eIF4E, and ribosomal protein S6. The mammalian target of rapamycin (mTOR), a key integrator of nutritional and metabolic regulation of translation, was present in low amounts, was hypophosphorylated, and was not insulin sensitive in the fetus. Our results indicate that protein synthesis during late-gestation liver development may be mTOR and insulin independent. Reexamination of the role of insulin in fetal liver physiology may be warranted.     

Postnatal essential fatty acid deficiency in mice affects lipoproteins, hepatic lipids, fatty acids and mRNA expression

We have previously reported that essential fatty acid deficiency (EFAD) during suckling in mice resulted in an adult lean phenotype and a resistance to diet-induced obesity. We now hypothesized that postnatal EFAD would cause long-term effects on lipid metabolism. C57BL/6 mice were fed an EFAD or a control diet from the 16th day of gestation and throughout lactation. The pups were weaned to standard diet (STD) and at 15 weeks of age given either high fat diet (HFD) or STD. Lipoprotein profiles, hepatic lipids, fatty acids and mRNA expression were analyzed in 3-week-old and 25-week-old offspring. At weaning, the EFAD pups had higher cholesterol levels in both plasma and liver and 6-fold higher concentrations of hepatic cholesterol esters than control pups. Adult EFAD offspring had higher levels of hepatic cholesterol and linoleic acid, but lower levels of dihomo-γ-linolenic acid and Pparg mRNA expression in the liver. In addition, HFD fed EFAD offspring had lower plasma total cholesterol, lower hepatic triglycerides and lower liver weight compared to controls fed HFD. In conclusion, early postnatal EFAD resulted in short-term alterations with increased hepatic cholesterol accumulation and long-term protection against diet-induced liver steatosis and hypercholesterolemia.     

Gestational exposure to ethane dimethanesulfonate permanently alters reproductive competence in the CD-1 mouse

Although the adult mouse Leydig cell (LC) has been considered refractory to cytotoxic destruction by ethane dimethanesulfonate (EDS), the potential consequences of exposure during reproductive development in this species are unknown. Herein pregnant CD-1 mice were treated with 160 mg/kg on Gestation Days 11-17, and reproductive development in male offspring was evaluated. Prenatal administration of EDS compromised fetal testosterone (T) levels, compared with controls. EDS-exposed pups recovered their steroidogenic capacities after birth because T production by hCG-stimulated testis parenchyma from prepubertal male offspring was unchanged. However, prepubertal testes from prenatally exposed males contained seminiferous tubules (STs) devoid of germ cells, indicating a delay in spermatogenesis. In adults, some STs in exposed males still contained incomplete germ cell associations corroborating observed reductions in epididymal sperm reserves, fertility ratios, and litter size. Morphometry revealed an EDS-induced increase in interstitial area and a concomitant decrease in ST area, but stereology revealed an unexpected decrease in the number and size of the LCs per testis in exposed males. Paradoxically, there was an increase in both serum LH and T production by adult testis parenchyma, indicating that the LCs were hyperstimulated. These data demonstrate permanent lesions in LC development and spermatogenesis caused by prenatal exposure in mice. Thus, although adult mouse LCs are insensitive to EDS, EDS appears to have direct action on fetal LCs, resulting in abnormal testis development.     

Ontogenic changes in metabolism and transport of glutathione in the rat

Changes in the level of glutathione (GSH), the turnover rate, and gamma-glutamyltransferase (GGT) activity were examined in newborn, weanling, and adult male Wistar rats, the objective being to elucidate the mechanisms which control the hepatic GSH level during maturation as well as under conditions of different degrees of protein ingestion. The hepatic GGT activity in the newborn rats was high at birth, decreased within a few days to 1 to 2% of the initial level, and remained unchanged thereafter, when these rats were fed a normal diet after 3 weeks of age. In contrast, the hepatic GSH level increased 3-4-fold while total GGT activity in the kidney increased 6-8-fold. When weanling rats were fed a low protein diet (containing 10% soy protein) for 3 weeks, the hepatic GSH level decreased markedly while the GGT activity increased 5-6-fold. The turnover rate of hepatic GSH also increased, as determined by the use of buthionine sulfoximine, a specific inhibitor of GSH synthesis; a value of 2.1 h was obtained in comparison with 3.5 h for that of rats fed the normal laboratory chow (CRF-1). On the other hand, feeding adult rats on the low protein diet resulted in a marked decrease in hepatic GSH level with no effect on either hepatic or renal GGT activity. These results together with other observations may suggest that GSH translocated out of liver cells in the newborn rats is degraded mainly by these cells, while the tripeptide secreted by hepatocytes of adult rats is metabolized predominantly in extrahepatic tissues, such as the kidney.(ABSTRACT TRUNCATED AT 250 WORDS)     

Brain TRH and Cyclo (His-Pro) and brain protein in the newborn rat are altered by maternal liquid protein feeding

Liquid protein diet (LPD) has been shown previously to produce maternal and fetal weight loss and fetal congenital anomalies, including cataracts and craniofacial malformations. Therefore, to examine the effects of LPD in pregnancy upon the central nervous system of pups, pregnant dams were fed either a 20% casein diet ad libitum, a 20% LPD, or pair-fed with a 20% casein diet. LPD was associated with significant maternal weight loss, and pups had significantly lower birth weights (5.14 +/- 0.64) than pups from the pair-fed controls (5.70 +/- 0.46, p less than 0.05). Total brain protein content was reduced significantly in pups of both sexes from pregnant fed LPD. Moreover, the concentrations of two brain peptides neurotransmitters, thyrotropin-releasing hormone (TRH), and its biologically active metabolite, histidyl-proline diketopiperazine Cyclo (His-Pro), were elevated in the pups from LPD-fed mothers. In contrast, there was no significant difference in brain protein or brain peptides in pups from pair-fed mothers vs. pups from mothers fed ad libitum. These data suggest that qualitative alterations of the protein component in maternal dietary composition have deleterious effects upon the ontogeny of the rat fetal CNS, as reflected by reduced total protein and elevated concentrations of TRH and Cyclo (His-Pro).     

Pre- and postnatal protein undernutrition increases hepatic carnitine palmitoyltransferase I activity and decreases enzyme sensitivity to inhibitors in the suckling rat.

Rats were pair-fed isocaloric diets containing either 25% (control diet) or 6% protein (low-protein diet) during the 5 weeks prior to conception and through the gestation and lactation periods; then, carnitine palmitoyltransferase I (CPT-I) activity was determined in liver and skeletal muscle mitochondria isolated from the corresponding pups. Maternal protein undernutrition increased the activity of hepatic CPT-I all along the suckling period, whereas the activity of the skeletal muscle enzyme was unaffected. Moreover, the sensitivity of hepatic CPT-I to inhibition by both malonyl-CoA and 4-hydroxyphenylglyoxylate was decreased in the low-protein group. These alterations in the properties of hepatic CPT-I may be involved in the appearance of hyperketonemia in the rat pup upon maternal administration of low-protein diets.     

The growth, reproduction and food of the roach Rutilus rutilus (L.), of the River Lugg, Herefordshire

Checks were formed on the scales in June and July. A dominant 1959 year class accounted for half the population present in 1964. Females grew faster than males and attained greater ultimate size. Growth in the River Lugg was good in comparison with rates in other British waters. The sex ratio was found to change with age; a predominance of males in the youngest age classes changed to a preponderance of females in the older classes. The youngest fishes caught (3+) were already sexually mature. The gonads were found to be a constant proportion of the body weight for fishes of all sizes at a given season. Spawning was completed by June; males were ripe in May. The ovaries recovered more rapidly than the testes after spawning. Seasonal variation in feeding activity, with higher activity in summer, was observed and could be correlated with temperature. Seasonal changes in the diet could be related to availability. The diet was predominantly vegetable; the most important animal component, aquatic insect larvae, accounted for 11 % of the total diet. Aerial insects were rarely eaten. Diet varied with age: molluscs being particularly important to older roach; younger roach consumed large amounts of substrate material. There is some evidence that young roach indiscriminately ingest substrate material but older roach are more selective and reject inert material.     

Nutrition and fetal brain maturation : I. Responses in vitro and in vivo

The glycolytic enzyme enolase increases during the perinatal period of brain development and was utilized as a marker for examining the effect of culture environment on differentiation of cells from 20-day fetal rat brain. Enolase activity in cell cultures increased from 0.91 +/- 0.03 (Day 0) to 2.11 +/- 0.10 mumol/min/mg protein (Day 6). Comparable levels were not reached in vivo until neonatal pups were 15 days old. The in vitro increase was inhibited by both cycloheximide and actinomycin D. Enolase activity in the cells responded to alterations in both incubation media and homologous serum. After 6 days in culture, cells incubated in rat serum (10%) added to MEM or RPMI produced twice as much enolase activity as cells incubated similarly in Ham's medium, i.e., 1.96 +/- 0.09 and 1.85 +/- 0.21 vs 1.02 +/- 0.09, P less than 0.001. Results of a comparable magnitude were obtained when fetal calf serum replaced adult rat serum, but enolase production was somewhat lower when newborn calf serum replaced adult rat or fetal calf serum. When cells were incubated for 6 days with graded concentrations of adult rat serum (2.5-15%), enolase activity increased progressively. The pattern of enolase response suggests that the fetal rat brain cell model described herein will provide a sensitive probe with which to gain insight into nutrition and fetal brain development.     

Parental care and sexual interactions in Mongolian gerbils (Meriones unguiculatus) during the postpartum estrus

The behavior of male and female Mongolian gerbils was continuously video-recorded from 24 h before the parturition to the end of postpartum estrus. We noted that the mean interval between the delivery of the last pup and the first mounting was 13 h and 32 min. Over the whole duration of the postpartum estrus (7 h and 41+/-57 min), females spent significantly more time in crouching over, pup licking, nest building and "digging" activities, and were more recipient of allogrooming than males. Maternal pup retrievals were not very frequent (14.0+/-5.6 episodes), but males never retrieved pups nor exhibited a full sequence of nest building activity. Males spent a longer mean time in bodily interactions with females, as compared to the time they spent with pups, and engaged in intense copulatory activity (592.8+/-40.5 mounts or 1 episode per 46.7s); even during the delivery process males attempted to force copulation, but females rejected mounting in all cases. We conclude that females exhibited higher levels of parental care than males, and our findings suggest that males compete with pups in attracting the female's attention, since they actively disrupt maternal care or persistently persecute the female in order to copulate.     

Rapid induction of vitamin A deficiency in rabbits

Clinical and biochemical evidence of vitamin A deficiency was produced in rabbits as early as 4-5 weeks after weaning to a vitamin A deficient diet from dams maintained during lactation on the deficient diet. Mean serum retinol levels at the time of weaning for the deficient dams were 25 +/- 6 micrograms/dl compared with 74 +/- 8 micrograms/dl for the controls. Five weeks after weaning, 25% of pups fed the vitamin A deficient diet had ocular lesions characterized by the accumulation of sloughed epithelium on the cornea. At this time, mean serum values of the pups were 10 +/- 4 micrograms/dl for the deficient group and 73 +/- 8 micrograms/dl for the controls. Evidence of critically depleted liver stores was documented in the deficient rabbits by an elevated relative dose response test (54 +/- 18%) that did not occur in the control group (6 +/- 5%). Although food consumption was similar, weight gain was lower in the deficient group when compared to the control group.     

Characterization of hepatic epidermal growth factor receptors in the developing rat

Binding of 125I-labeled epidermal growth factor (EGF) was characterized in basolateral plasma membranes prepared from the livers of 21-day gestation fetuses, 14-day-old sucklings and adult Sprague-Dawley rats using a self-generating Percoll gradient method. The membrane preparations employed have been previously assayed in terms of plasma membrane protein yield, enrichment of various marker enzymes and sodium-dependent bile acid and amino acid transport. 125I-EGF binding was saturable and time and temperature dependent. Equilibrium analyses showed that the suckling period is characterized by a marked decrease in overall hepatic EGF binding capacity (460 +/- 50 fmol/mg protein) compared to either the fetal period (1290 +/- 160 fmol/mg) or to adults of either sex (males = 1540 +/- 230, females 1010 +/- 130 fmol/mg). Treatment of the suckling rat with parenteral EGF resulted in a 78% reduction in the observed binding capacity when assessed 2 h after growth factor administration. Comparison of binding affinities revealed no significant difference between the suckling and adult preparations (Kd = 0.40 +/- 0.03 vs. 0.39 +/- 0.02 nM, respectively); however, both preparations differed significantly from the fetal group which exhibited a decreased affinity of binding with a higher overall dissociation constant (Kd = 0.68 +/- 0.06 nM). Thus, it appears that major ontogenetic changes occur in the rat hepatic ligand/receptor system for epidermal growth factor. These changes are discussed in the context of transitional events in mammalian development such as birth and weaning.     

Cortisol induces perinatal hepatic gluconeogenesis in the lamb.

To examine the influence of a prenatal increase in plasma cortisol concentration on perinatal initiation of hepatic gluconeogenesis, we infused cortisol into seven fetal sheep at 137-140 days gestation. 14C-Lactate provided tracer substrate for estimation of gluconeogenesis. We measured hepatic blood flow using radionuclide-labeled microspheres. After delivery, fetal arterial blood glucose concentration (1.33 +/- 0.4 mmol/l) increased transiently, but returned to fetal levels within 1 h after delivery. Substantial hepatic gluconeogenesis was induced in the fetus after cortisol infusion, averaging 23.4 +/- 12.2 mumol/min/100 g liver (7.8 +/- 4.4 mumol/min/kg fetal weight). Fetal hepatic glucose output was 44.4 +/- 17.7 mumol/min/100 g liver. Hepatic glucose output did not change after delivery; estimated gluconeogenesis decreased immediately, then increased by 6 h after delivery. Lactate supply to the liver fell substantially, from 1.1 +/- 0.4 mmol/min/100 g in the fetus to 0.24 +/- 0.09 at 1 h after delivery. Lactate flux across the liver decreased from 75.3 +/- 23 mumol/min/100 g in the fetus to 20.2 +/- 15.7 at 1 h after delivery. Hepatic lactate flux was significantly related to gluconeogenesis (r = 0.734, P = 0.0001). We conclude that cortisol induces substantial hepatic gluconeogenesis in fetal sheep near term. After delivery, there appears to be a transient decline in gluconeogenesis from lactate, which may be secondary to limited hepatic oxygen and substrate supply. Onset of gluconeogenesis in the fetus fails to sustain increases in either fetal or postnatal blood glucose concentrations.     

Fetal rat islet insulin deficiency following maternal administration of streptozotocin

Pancreatic islets were isolated from the fetuses of normal rats and rats made diabetic by the iv administration of streptozotocin (STZ) on either Day 3 or 5 of pregnancy. Of the rats made diabetic on Day 3, one group also received insulin injections at the appearance of glucosuria. Maternal blood glucose on Day 20 of gestation was significantly different in the diabetic rats (405 +/- 27 mg/dl) from the normal (97 +/- 1 mg/dl) and insulin-treated diabetic rats (69 +/- 9 mg/dl). While fetal weight was significantly decreased in the STZ-treated rats (2.64 +/- 0.13 g vs 3.52 +/- 0.05 g for the control group, P less than 0.005), fetal glucose was significantly higher in the STZ-treated than in normal pups (342 +/- 11 vs 35 +/- 1 mg/dl, P less than 0.005). Both fetal weight and glucose were normalized by insulin treatment: 3.16 +/- 0.18 g and 31 +/- 7 mg/dl, respectively. Insulin release from fetal islets of diabetic dams was blunted after a week in culture both in basal and stimulated conditions. After 2 weeks in culture, there was partial recovery in the insulin response to glucose but it did not equal to that measured in fetal islets from the normal and insulin-treated diabetic rats. These data suggest maternal hyperglycemia severely impairs fetal weight and insulin release from fetal rat islets in vitro, and correction of the hyperglycemia by insulin treatment not only improves fetal weight and glucose concentrations, but it also normalizes insulin release from fetal rat islets in vitro.     

Increased maternal fat consumption during pregnancy alters body composition in neonatal mice

Maternal overnutrition prior to and during gestation causes pronounced metabolic dysfunction in the adult offspring. However, less is known about metabolic adaptations in the offspring that occur independently of postnatal growth and nutrition. Therefore, we evaluated the impact of excess maternal dietary lipid intake on the in utero programming of body composition, hepatic function, and hypothalamic development in newborn (P0) offspring. Female mice were fed a low-fat (LF) or high-fat (HF) diet and were mated after 4, 12, and 23 wk. A subset of the obese HF dams was switched to the LF diet during the second (DR2) or third (DR3) pregnancies. The HF offspring accrued more fat mass than the LF pups, regardless of duration of maternal HF diet consumption or prepregnancy maternal adiposity. Increased neonatal adiposity was not observed in the DR3 pups. Liver weights were reduced in the HF offspring but not in the DR2 or DR3 pups. Offspring hepatic triglyceride content was reduced in the HF pups, but hepatic inflammation and expression of lipid metabolism genes were largely unaffected by maternal diet. Maternal diet did not alter the hypothalamic expression of orexigenic and anorexigenic neuropeptides in the offspring. Thus, the intrauterine programming of increased neonatal adiposity and reduced liver size by maternal overnutrition is evident in mice at birth and occurs prior to the development of maternal obesity. These observations demonstrate that dietary intervention during pregnancy minimizes the deleterious effects of maternal obesity on offspring body composition, potentially reducing the offsprings' risk of developing obesity and related diseases later in life.     

Acetylcholinesterase activity in developing rat brain during undernutrition

The effect of low protein diet on rat brain AChE activity has been studied during gestation, lactation and postweaning periods. There was decrease in enzyme activity of pups undernourished either during gestation and lactation or lactation alone, the decrease being maximum in 18-day-old pups. In postweaning rats, a significant decrease was observed after 2 and 4 weeks of undernutrition compared to the control. However, the effect of undernutrition was annuled by 2-week rehabilitation, thereby indicating that imposed undernutrition only delays the normal level of the enzyme. Moreover, it appears that the enzyme activity depends both on the nutritional status and the development age.