Effect of undernutrition on cell formation in the rat brain

Restricted diet modifies carbohydrate metabolism in immature rats

The aim of the present work was to study the effect of a restricted diet on carbohydrate metabolism in submandibular glands of female prepuber rats and the influence of arachidonic acid derivatives. Rats of 21 days of age were divided into three groups. Group I: normally fed rats. Group II: restricted diet (50% of the normal food intake). Group III: normally restricted diet with re-feeding. The baseline concentration of tissue glycogen was significantly higher in Group II than in I or III and after 60 min of incubation in a glucose free medium all groups showed a glycogen drop. In addition, the glucose metabolism was increased in Group II. Cycloxigenase inhibitors failed to alter (14)CO(2) levels in Groups I and III. In Group II, indomethacin and acetylsalicylic acid inhibited glucose metabolism, which was reverted by PGE(2) addition. The exogenous arachidonic acid metabolism and different eicosanoids showed that restricted diet significantly increased the production of PGE(2) but diminished PGF(2)(alpha) production. Our results suggest that a restricted diet would lead to a new dynamic equilibrium of glucose homeostasis. Prostaglandins E(2) and F(2)(alpha) would participate by adapting the source of energy to tissue demands while maintaining the metabolic features that characterize puberty.

Effect of chronic prenatal ethanol exposure on nitric oxide synthase I and III proteins in the hippocampus of the near-term fetal guinea pig

Chronic prenatal ethanol exposure suppresses nitric oxide synthase (NOS) enzymatic activity, in the hippocampus of the near-term fetal guinea pig at gestational day (GD) 62. The objective of this study was to determine if this decrease in NOS activity is the result of decreased NOS I and NOS III protein expression. Pregnant guinea pigs received oral administration of 4 g ethanol/kg maternal body weight/day (n = 8), isocaloric-sucrose/pair feeding (n = 8), or water (n = 8) from GD 2 to GD 61. The NOS I and NOS III protein expression and localization in the hippocampus were determined using Western blot analysis and immunohistochemistry, respectively. The chronic ethanol regimen produced fetal body, brain, and hippocampal growth restriction compared with the isocaloric-sucrose/pair fed and water groups but did not affect the expression or localization of NOS I and NOS III proteins in the hippocampus. The decrease in NOS enzymatic activity induced by chronic prenatal ethanol exposure may be the result of posttranslational modification of NOS I and/or NOS III protein in the hippocampus of the near-term fetal guinea pig.

Chronic ethanol exposure alters MK-801 binding sites in the cerebral cortex of the near-term fetal guinea pig

The mechanism of ethanol central nervous system (CNS) teratogenesis, resulting from chronic maternal ingestion of high-dose ethanol during pregnancy, is not clearly understood. One of the target sites for ethanol-induced damage in the developing brain is the cerebral cortex. It has been proposed that chronic prenatal ethanol exposure alters NMDA receptors in the developing cerebral cortex. To test this hypothesis, timed pregnant guinea pigs were administered one of the following oral treatments throughout gestation: 4 g ethanol/kg maternal body weight/day; isocaloric sucrose/pair-feeding; water; or no treatment (ad lib). Near-term fetuses were studied at gestational day (GD) 63 (term, about GD 68). This ethanol regimen produced a maternal blood ethanol concentration of 66+/-4 mM (304+/-19 mg/dl) at 1 h after the daily dose on GD 58. The chronic ethanol regimen decreased near-term fetal body weight (12-26% decrease), brain weight (23% decrease), and cerebral cortical weight (21% decrease), compared with the isocaloric sucrose/pair-feeding, and combined water/ad lib experimental groups. Saturation analysis of near-term fetal cerebral cortical membranes using a [3H]MK-801 radioligand binding assay demonstrated a decreased affinity and increased number of MK-801 binding sites for the chronic ethanol regimen compared with the control treatments. These data support the suggestion that upregulation of NMDA receptors in the cerebral cortex after chronic prenatal ethanol exposure could lead to NMDA receptor-mediated excitotoxicity in this brain region.

Hippocampal nitric oxide synthase in the fetal guinea pig: effects of chronic prenatal ethanol exposure

The effects of chronic maternal administration of ethanol on nitric oxide synthase (NOS) activity and the numbers of NOS containing neurons, and CA1 and CA3 pyramidal neurons in the hippocampus of the near term fetal guinea pig at gestational day (GD) 62 were investigated. Pregnant guinea pigs received oral administration of 4 g ethanol/kg maternal body weight (n = 5), isocaloric sucrose/pair feeding (n = 5) or water (n = 5), or no treatment (NT; n = 5) from GD 2 to GD 61. NOS activity in the 25,000 x g supernatant of hippocampal homogenate was determined using a radiometric assay. The numbers of NOS containing neurons, and CA1 and CA3 pyramidal neurons were determined using NADPH diaphorase histochemistry and cresyl violet staining, respectively. The chronic ethanol regimen produced a maternal blood ethanol concentration of 193 +/- 13 mg/dl at 1 h after the second divided dose on GD 57. Chronic ethanol exposure produced fetal body, brain, and hippocampal growth restriction and decreased fetal hippocampal NOS activity compared with the isocaloric sucrose/pair feeding, water, and NT experimental groups, but did not affect the number of NOS containing and CA1 or CA3 pyramidal neurons. These data demonstrate that, in the near term fetus, chronic maternal administration of ethanol suppresses hippocampal NOS activity and consequent formation of NO, without loss of NOS containing neurons and prior to loss of CA1 pyramidal neurons that occurs in the adult.

Review of literature showing that undernutrition affects the growth rate of all processes in the brain to the same extent

The growth of the brain is certainly less affected by undernutrition than the growth of the rest of the body (brain sparing). We inquire whether a similar phenomenon occurs within the brain: whether there are differences in sensitivity to undernutrition amongst the brain's component growth processes. We conclude from our review of the literature that, contrary to popular belief, undernutrition depresses the growth rate of various processes within the brain to the same extent. The much quoted "selective" effect on the cerebellum is not an example of an especially sensitive process. It results from expressing deficits as "% of age control values" and disappears when proper comparisons of depression in rates of growth are made. The one growth process which does at first sight appear to be truly especially sensitive is myelin synthesis, in that undernutrition depresses its rate more than that of other growth processes in brain. However, undernutrition also results in fewer fibres being myelinated, and when rate of myelin synthesis is expressed per myelinated fibre the special sensitivity disappears.

Increased loss of brain DNA in the neonatal vasopressin-deficient Brattleboro rat, but not in normal rat treated with vasopressin antagonist

In order to establish whether vasopressin (VP) influences brain cell survival, [3H]thymidine was injected in 10-day-old vasopressin-deficient Brattleboro rat pups, as well as in Wistar pups treated, neonatally, with the VP antagonist dP[Tyr(Me)2]VP followed by subsequent measurement of [3H]DNA in olfactory bulbs and cerebellum days and weeks thereafter. Results show, first of all, that the incorporation of [3H]thymidine into DNA was enhanced in the homozygous (HOM) Brattleboro, when compared with the heterozygous (HET; non-vasopressin-deficient) controls. The difference is due to the greater and prolonged tissue availability of [3H]thymidine, possibly pointing to an altered thymidine uptake and/or metabolism. Between postnatal days 25 and 39 no differences were seen in [3H]DNA content of the brain parts of the HET and Wistar control rats. For the HOM rats, however, a loss of [3H]DNA was seen (up to 8%), indicating that increased postnatal brain cell death might occur in the mutant. The antagonist treatment in Wistar rat up to 21 days of age failed to show a similar effect. It is proposed that general growth impairments, rather than VP receptor-mediated effects, lead to the brain cell loss.

Effects of hyperbilirubinaemia on glutathione S-transferase isoenzymes in cerebellar cortex of the Gunn rat

The glutathione S-transferases (GSTs) are a family of isoenzymes involved in the detoxication of a variety of electrophilic xenobiotics. The present investigation demonstrates that GST activity and the concentration of cytosolic GSTs in cerebellar cortex of Gunn rats were increased in hyperbilirubinaemic animals compared with non-jaundiced controls. Age-dependent and region-specific increases in GST isoenzymes were seen in three regions of the cerebellar cortex of jaundiced Gunn rats, whereas GST concentrations were not altered in the brainstem, thalamus/hypothalamus, cortex or liver. Cytosolic GST activity was increased 1.3-fold in the flocculus and lateral hemispheres of 20-day-old and 1.7-fold in the flocculus, lateral hemispheres and vermis of 60-day-old jaundiced (jj; homozygous) Gunn rats compared with non-jaundiced (Jj; heterozygous) Gunn rats. H.p.l.c. was used to determine the GST subunit protein concentrations in cytosolic fractions isolated from liver and brain regions of jaundiced and non-jaundiced animals. In all regions of the cerebellum from 20-day-old animals, the levels of Alpha-class GST subunits 2 (Yc1; 3.0-fold) and 8 (Yk; 2.0-fold) were increased in jaundiced rats. In 60-day-old animals, the concentrations of Alpha-class GST subunits 2 (Yc1; 5.0-fold) and 8 (Yk; 3.0-fold), Mu-class subunit 11 (Yo; 2.5-fold) and Pi-class subunit 7 (Yp; 2.0-fold) were increased in all regions of cerebellar cortex of jaundiced animals. In cerebellum of 10-, 20- and 60-day-old non-jaundiced and jaundiced Gunn rats, the flocculus had the highest concentration of Mu-class GST subunit 4 (Yb2) and vermis the lowest; hyperbilirubinaemia increased the concentration of subunit 4 (Yb2; 3- to 5-fold) in the flocculus and lateral hemispheres, but not the vermis, of 20- and 60-day-old rats. Intraperitoneal injection of sulphadimethoxine, a long-acting sulphonamide which displaces bilirubin from its albumin-binding sites and increases the bilirubin levels in tissues, further increased the already elevated concentrations of GST subunits in the lateral regions of cerebellar cortex of hyperbilirubinaemic rats. For example, the concentration of subunit 4 (Yb2) was increased 2.2-fold (compared with non-jaundiced controls) in Gunn rats injected with saline and 7.4-fold in rats injected with 100 mg of sulphadimethoxine/kg body weight. In contrast, GSTs in the vermis of jaundiced animals were not affected by sulphadimethoxine injection. Sulphadimethoxine had no effect on GST concentrations in lateral regions and vermis of heterozygous (Jj) Gunn rats.(ABSTRACT TRUNCATED AT 400 WORDS)

The effect of low level lead exposure on the postnatal structuring of the rat cerebellum

Exposure of rat pups to lead (less than 45 micrograms/dl blood) caused no alterations in the rate of cerebellar cell acquisition, migration or final number when compared with age-matched controls. The rate of DNA biosynthesis was higher in the lead-exposed animals compared to controls and remained elevated until postnatal day 10. This observation suggests lengthening of the cell cycle. The expected increase in DNA biosynthetic rate was delayed in neuron-enriched fractions obtained from lead-exposed pups. This may have been due to the isolation procedure specifically selecting internal granular layer cells which migrated precociously during a protracted G1 phase in a lead-impaired cell cycle. Morphometric studies revealed no difference in the number, viability and migration of cells within and from the external granular layer of the cerebellum of lead-exposed animals. It is concluded that chronic low level lead exposure has no significant effect on the early structuring of the developing cerebellum.

Effects of altered thyroid states and undernutrition on the calbindin-D28K (calcium-binding protein) content of the hippocampal formation in the developing rat

A quantitative study of calbindin-D28K (calcium-binding protein) was carried out on the developing hippocampal formation in normal, hypothyroid, hyperthyroid, and underfed rats. In normal animals, the calbindin-D28K content increased after birth in agreement with the distribution of the protein previously reported by immunocytochemistry. Calbindin-D28K was strikingly spared, compared to the other proteins, from the effects of hypothyroidism. On the contrary, the calbindin-D28K:protein ratio was transiently reduced by hyperthyroidism. Corrective doses of thyroxine to hypothyroid rats increased the calbindin-D28K content whatever the period of the hormonal treatment, but they also had a marked effect on the hippocampal weight and the protein content, especially when the hormone was given on days 2-3. With this latter replacement therapy schedule, the calbindin-D28K:protein ratio dropped from the high value of the hypothyroid animal to normal. Taken together, the results obtained in hypothyroidism, hyperthyroidism and replacement therapy are consistent with a pronounced action of thyroid hormone on hippocampal structures other than those containing calbindin-D28K. Undernutrition, which, like hypo- or hyperthyroidism, also markedly impairs hippocampal growth, affected the calbindin-D28K content per hippocampus but not the calbindin-D28K:protein ratio. This emphasizes the unique influence of thyroid hormone on brain development. The relative preservation of calbindin-D28K in the hippocampal formation of animals lacking thyroid hormone suggests that calbindin-D28K function may be crucial in this brain region.

Aspirin augments alcohol in restricting brain growth in the neonatal rat

The purpose of this study was to determine whether the microencephaly in rats resulting from early postnatal alcohol exposure is altered by a concurrent administration of aspirin. Neonatal rats were artificially reared from postnatal day 4 to postnatal day 10, a period of the brain growth spurt in the rat that is similar to the third trimester of human brain development. The alcohol-treated groups received 6.6 g/kg/day of ethanol and either 0.0, 12.5, 25.0 or 50.0 mg/kg/day of aspirin in a milk solution. Control groups received either 0.0 (gastrostomy control), 12.5, 25.0 or 50.0 mg/kg/day of aspirin in a milk solution free of alcohol. Brainstem, cerebellum and total brain weights were measured on postnatal day 10. Alcohol alone significantly reduced the mean total brain weight, cerebellum and brainstem weight by 19.8%, 23.1% and 12.2%, respectively, relative to gastrostomy controls. A significant interaction between ethanol and aspirin was observed for total brain weight. The mean total brain weight of the group receiving both alcohol and 50 mg/kg/day aspirin was significantly lower than all other experimental groups and was reduced 29.5%, relative to gastrostomy controls. The highest dose of aspirin alone significantly reduced cerebellar weight, relative to gastrostomy controls but had no effect on brainstem or total brain weight.

Developing rat cerebellum--I. Effects of abnormal thyroid states and undernutrition on sulfated glycosaminoglycans

Sulfated glycosaminoglycans deposition during rat postnatal cerebellar developmental is affected by altered thyroid states and undernutrition. These ontogenetic alterations seem not to be specific but to be one aspect of the general acceleration, slowing down and reduction of the cerebellar development occurring in thyroid-deficient, hyperthyroid and undernourished rats, respectively.

Histological maturation of astroglial cells in the archicortex of young hypothyroid rats

The maturation of fibrous astrocytes was studied in the archicortex (hippocampus) of rats rendered hypothyroid by perinatal administration of propylthiouracil (PTU). A decrease in the number of protoplasmic processes and end-feet in fibrous astrocytes from the cortical molecular layer was observed. The diameter of the perikaryon and length of the prolongations were also decreased. In animals rehabilitated after weaning, the diameter of the perikaryon and length of protoplasmic processes returned to normal while that of number of prolongations per astroglial cell remained unchanged. It is postulated that hypothyroidism induced immediately after birth impairs differentiation of astroglia in the archicortex of the rat brain, probably as a response secondary to altered neuronal and capillary development.

Serotonin uptake in the central nervous system of rats fed a corn-diet

1. Endogenous serotonin (5-HT), 5-hydroxyindol acetic acid (5-HIAA) content and exogenous 5-HT uptake (Km and Vmax) were measured in different brain regions (cerebellum, diencephalon, brain stem and telencephalon) of rats fed with a corn diet and restricted protein (8%) diet during 6 weeks. 2. A reduction of 5-HT levels was found in all regions studied of animals fed a corn diet, whereas, 5-HIAA was only decreased in brain stem and diencephalon. 3. An important increase in Km and Vmax were registered in brain stem and diencephalon of protein restricted animals, whereas, an increase of 5-HT uptake affinity in cerebellum, brain stem and telencephalon (35, 42 and 33% respectively) was observed. Simultaneously, under corn diet conditions, the Vmax decreased 40, 30 and 34% respectively in those regions. 4. It is suggested that the brain stem was the more sensitive area under nutritional restricted conditions and the development of some possible compensatory mechanisms of the 5-HTergic system is discussed.

Nucleic acid content and residue determination in tissues of chicks born from 2,4-dichlorophenoxyacetic butyl ester treated eggs

The effects of 2,4-dichlorophenoxyacetic butyl ester (2,4-D b.e.) on protein and nucleic acid contents of different tissues of chicks born from externally treated hen's eggs were studied. Residues of 2,4-D b.e. were also determined and quantified by gas liquid chromatography (GLC). A diminished DNA content was observed in skeletal muscle and stomach, an increased one was found in cerebrum and cerebellum, whereas no variations were observed in the other analysed tissues. Protein levels were found decreased in kidney, cerebrum and heart. Besides, the GLC determinations revealed the presence of the 2,4-D b.e. in all the studied tissues finding the highest concentrations in kidney. 2,4-D did not appear to be a significant metabolite of 2,4-D b.e. in this experimental system. The dissimilar effects of 2,4-D b.e. on protein and nucleic acid contents of the studied tissues would be related to a different tissue susceptibility to the drug and/or to drug distribution.

Brain development in relation to fetal weight and maternal glucose tolerance during normal gestation

Parameters of brain development were studied in near term guinea-pigs in relation to fetal weight and maternal glucose tolerance during normal gestation. Seven litters (22 fetuses) were studied. Fetal weight ranged from 43 to 94 g (119% variability) and the maternal glucose index (sum of the 7 serum glucose levels during the oral glucose tolerance tests) from 921 to 1,528 mg/dl (66% variability). The weights of the cerebrum and cerebellum were less affected by changes of fetal weight compared to other fetal organs. Significant correlations were observed between the maternal glucose index and brain cell number (DNA) and myelination (cerebroside-sulfatide). These variables did not correlate with fetal weight. Liver weight (% fetal weight) and cell number also correlated with the maternal glucose index. It is speculated that the amount of glucose available to the brain could be responsible for the relative protection of the brain to fetal malnutrition and also for the link between maternal glucose index and parameters of fetal brain development.

Dendritic development in the neocortex of adult rats subjected to postnatal malnutrition

The Golgi-Cox method was used to study the maturation of the large pyramidal cells of the Vth cortical layer in two groups of adult rats, one subjected to early postnatal malnutrition and another malnourished only during the second month of life. The main alterations were observed in the pyramidal cells of cortical layer V of rats malnourished during the first month of life. They consist of a decrease in the number and span of dendritic basilar processes. In animals malnourished during the second month of life, the number and span of basilar dendritic processes in pyramidal cells of layer V, were normal. It is postulated that early postnatal malnutrition induced immediately after birth, profoundly disturbs the process of neuronal maturation in the neocortex of the rat brain, probably with permanent effects.

Effect of intrauterine growth retardation on developmental changes in DNA and [14C]thymidine metabolism in different regions of rat brain: histological and biochemical correlations

Intrauterine growth retardation was induced in the rat by clamping the uterine artery on day 17 of gestation. The effect of hypotrophy on DNA synthesis was studied in two different cerebral structures: hippocampus and cerebellum. Accumulation of DNA in these structures was biochemically measured in parallel to the incorporation of methyl-[14C]thymidine into nucleic acid at different ages and correlated with autoradiography. The various metabolites of thymidine in acid-soluble fraction were determined by using chromatographic procedures. Phosphorylation defects or reduced utilization of thymidine were found in hypotrophic rats and may delay the DNA synthesis. An essay of catch-up occurred with a different timing according to the cerebral region studied. A morphological and DNA synthesis. An essay of catch-up occurred with a different timing according to the cerebral region studied. A morphological and autoradiographic study after incorporation of [3H]thymidine was carried out in parallel. The neuronal and glial components of cytogenesis were analyzed separately and a good correlation was observed between histological and biochemical data in both groups of animals.

Effects of undernutrition and thyroid state on the ontogenetic changes of D1, D2, and D3 brain-specific proteins in rat cerebellum

Disturbances in metabolic balance brought about by alterations in thyroid state and undernutrition during early life had a marked effect on the concentrations of the brain-specific proteins, D1, D2, and D3 in the developing rat cerebellum. In normal rats, the concentrations of D1 and D3 increased and that of D2 decreased during the first 3 weeks after birth. In the hyperthyroid state a small but consistent advancement was observed in the developmental curves of these proteins. The hypothyroid state caused a marked retardation in the maturational pattern of D1 and D2 but not of D3. In undernutrition, at 6 days the concentrations of D1 and D3 proteins were higher than in controls, but thereafter the developmental increase was markedly delayed for D1 only. The concentration of D2 was normal at 6 days, but after the first week a marked retardation was observed in the maturational pattern of this protein in undernourished rats. In addition, the "anodic-immature" form of D2 predominated in 6-day-old controls, but this was gradually replaced by a "cathodic-mature" form which progressively became the dominant form of D2 in 35-day-old rat cerebellum. The developmental switch in terms of the two forms was also advanced in hyperthyroidism and retarded in thyroid deficiency and undernutrition. Furthermore, daily treatment of hypothyroid rats with physiological doses of thyroxine from birth restored the concentrations of D1 and D2 to normal, but that of D3 was increased above control levels, indicating differences between the proteins in their sensitivity to mechanisms of control by thyroid hormone. Also, the overall effects of undernutrition were markedly different from those of hypothyroidism.

Developmental changes in the amount of glial fibrillary acidic protein in three regions of the rat brain

Glial fibrillary acidic (GFA) protein, extractable in 50 mM phosphate buffer, pH 8, was measured in the olfactory bulbs, forebrain and cerebellum of the rat during development using a double antibody radioimmunoassay. Each brain region showed a different pattern of development for GFA protein. At birth GFA protein per mg protein was highest in olfactory bulbs followed by forebrain and cerebellum, and these amounted to 15, 10 and 8% of the adult values, respectively. The relative increase in GFA protein was more marked during the first 2 postnatal weeks than in the following 7 weeks after birth. When values were expressed per brain region, the developmental increase in the amount of GFA protein from birth to adulthood was about 100-fold in olfactory bulbs, 85-fold in forebrain and 485-fold in cerebellum. The patterns of developmental increases in GFA protein and in glutamine synthetase activity, another protein enriched in astrocytes, were similar in the forebrain and olfactory bulbs, but differed markedly in the cerebellum. The major increase in content of the GFA protein during development was found to correspond with the maturation of astrocytes rather than with their proliferation; however, a small but significant amount of GFA protein acquired at an early age may be related to increase in astroglial cell numbers in the cerebellum.

Effect of hyperphenylalaninemia induced during suckling on brain DNA metabolism in rat pups

We studied DNA metabolism (synthesis and degradation) in brain to investigate the effect of hyperphenylalaninemia induced in rats by treatment with PCPA or alpha MPA plus PHE during suckling (4th-20th days of postnatal age) on cell proliferation and naturally occurring cell death. The incorporation of 14C in DNA as percent of total radioactivity in the tissue, 30 min after administration of [14C]thymidine served as a measure of DNA synthesis in vivo, and the amount of radioactivity recovered in DNA as percent of total 14C in the tissues of 21 day old rats, injected with [14C]thymidine on 2nd day after birth, indicated the turnover (degradation) of DNA. The results showed that the DNA content of cerebellum as well as cerebrum was reduced by treatment with PCPA plus PHE, while treatment with alpha MPA plus PHE had no effect on DNA content in cerebellum but reduced the levels in cerebrum. Treatment with PCPA or alpha MPA plus PHE reduced the synthesis of DNA in cerebrum of 11 day old rats but not in 21 day old rats, and the treatments did not affect DNA synthesis in cerebellum of either 11 or 21 day old rats. The turnover (degradation) of DNA was increased in both cerebellum and cerebrum from rats treated with PCPA plus PHE but alpha MPA plus PHE treatment did not alter the DNA turnover either in cerebellum or in cerebrum. The activity of acid DNase was reduced in both cerebellum and cerebrum from 11 as well as 21 day old rats treated with PCPA plus PHE, but the enzyme activity was not altered in the tissues from rats of both ages treated with alpha MPA plus PHE. The data thus indicate that in rats treated with PCPA plus PHE the reduction in cerebral DNA levels occurs due to reduced synthesis and/or increased turnover (degradation) of DNA but that the reduction in cerebellar DNA may occur only as a result of increased turnover (degradation), and that in rats treated with alpha MPA plus PHE the reduction in cerebral DNA must occur due to reduced synthesis. This suggests that treatment of rats with PCPA plus PHE during suckling inhibits cell proliferation and/or increases naturally occurring cell death in both cerebellum and cerebrum while treatment with alpha MPA plus PHE inhibits only cell proliferation and in cerebrum alone.

Brain DNA metabolism in myelin deficient mutant jp, jpmsd and qk mice

We studied metabolism of brain DNA in three myelin deficient mutants qk, jp and jpmsd mice. The DNA content, the in vivo incorporation of [14C]thymidine in DNA and the activity of acid DNase in tissues (cerebellum and cerebrum) from normal littermates and affected mice were compared. The results showed that neither the DNA content, the incorporation of [14C]thymidine in DNA nor the activity of acid DNase in brain were altered in qk affected mice. In jpmsd mice, however, the DNA content as well as the incorporation of thymidine in DNA were reduced in both cerebellum and cerebrum, but the activity of acid DNase was reduced in cerebrum only. In jp mice, although the DNA content was reduced in both cerebellum and cerebrum, the incorporation of thymidine in DNA and the activity of acid DNase were reduced in cerebrum only. The data suggest a) that in qk mutants DNA metabolism and hence cell (glial) proliferation is not affected; b) that in jpmsd mutants DNA synthesis, and thus the cell proliferation is reduced in cerebellum as well as in cerebrum of the affected mice and c) that in jp mutants the synthesis of DNA and the cell proliferation is reduced in cerebrum but not in cerebellum.

Utilization of tyrosine and tryptophan for protein synthesis by undernourished developing rat brain

Incorporation of tracer doses of radiolabeled tryptophan and tyrosine into brain proteins was investigated in rats malnourished during gestation and lactation. Age and time dependent increases in the radioactivity was observed in the whole homogenate and in the TCA insoluble fraction. Protein malnourished rats showed increased incorporation of tryptophan and tyrosine. However the diet restricted (Pair-fed) animals showed increased incorporation of tyrosine only. The increased incorporation may probably be due to changes in the pool size of the amino acids and effective recycling of the amino acids. The enhanced utilization in protein synthesis may also probably offer a mechanism for conservation of these amino acids.

Histochemical and biochemical studies of butyrylcholinesterase activity in adult and developing cerebellum. Effects of abnormal thyroid state and undernutrition

The cellular and subcellular localization of BuchE activity (EC.3.1.1.8) was studied in the developing and adult rat cerebellum at light and electron microscope levels. In the adult cerebellum, BuchE activity was exclusively localized to glial cells, myelin and endothelial cells. In the immature cerebellum, BuchE activity was additionally found transiently localized to the neuroblasts of the external germinative layer and in Purkinje cells of the nodulus. In both the immature and the adult animals, the main part of the activity seemed to be membrane-bound. The developmental pattern of cerebellar BuchE activity was assayed in developing normal, hypothyroid, thyroxine-treated and undernourished rats. In normal newborn rats, the specific activity was higher than in adults and it showed one characteristic peak at 6 days (1.8 times the adult value reached at 30 days). At the age of 5 days, the ratio of BuchE-containing astrocytes (numbered in the ganglionic layer) to Purkinje cells was the same as the ratio of Bergmann astrocytes to Purkinje cells determined at 35 days in Nissl preparations; their nucleus size already represented 80% of the adult value and their processes were well developed. The three experimental conditions modified the timing of BuchE development. During the early post-natal period, it was accelerated in the thyroxine-treated and undernourished animals, while in the hypothyroid rats it was delayed. During the same period, the number of labelled astrocytes per Purkinje cell was modified only by hypothyroidism and undernourishment. On the basis of these histochemical and biochemical results, BuchE can be considered as a good marker for the study of Bergmann glia development in the early post-natal period.

Effect of undernutrition on some enzymes involved in the salvage pathway of purine nucleotides in different regions of developing rat brain

The effect of undernutrition on the activity of two key enzymes of purine salvage pathway, namely hypoxanthine-guanine phosphoribosyltransferase (HGPRTase) and adenine phosphoribosyltransferase (APRTase), in cerebral hemispheres, cerebellum and brain stem of rats at different days of postnatal development was studied. The activity of HGPRTase and of APRTase is significantly lower in all brain regions of undernourished animals at 5 days after birth; between 10 and 15 days of age there is a recovery of the enzymatic activity which is particularly evident in the cerebellum. Successively both enzymatic activities decrease reaching at 30 days of age values quite similar to those of controls. These results indicate that undernutrition during fetal and postnatal development, impairs and delays the activity of the enzymes of purine salvage pathway.

Effect of undernutrition on some enzymes of purine metabolism in different regions of developing rat brain

The effect of undernutrition on the activity of some enzymes involved in purine metabolism, ie, adenosine aminohydrolase, adenylate aminohydrolase, and inosine phosphorylase in cerebral hemispheres, cerebellum, and brain stem of rats at different days of postnatal development was studied. Adenosine aminohydrolase, adenylate aminohydrolase, and inosine phosphorylase were assayed by radiochemical methods which involve the measurement of the radioactive products formed, ie, inosine, IMP, and hypoxanthine, respectively. The results obtained indicate that undernutrition affects the activity of the enzymes which control the concentration of purine nucleotides to a different degree in the three brain regions examined.

Effect of central nervous system acting drugs on brain cell replication in vitro

The role in the regulation of cell replication of the neurotransmitter compounds and the drugs which affect their balance was studied in vitro, using morphologically preserved brain slices. Compounds affecting noradrenergic, dopaminergic and serotoninergic neurotransmitter systems reduced the brain cell replication, measured in terms of the rate of [3H]thymidine incorporation into DNA. The reduction was dose dependent and half-maximal effects were obtained at about 1-5 x 10(-4) M concentrations. Although agonists and antagonists both showed similar inhibitory effect, the action of agonists was reversed by the appropriate antagonists. Also, the pharmacologically active isomers were several-fold more effective than the inactive isomers in forebrain slices, although with cerebellar slices the selectivity was less marked. Cyclic nucleotides and drugs affecting cholinergic neurotransmitter systems were apparently ineffective. These results indicate that monoamines may be involved in the regulation of cell replication in the developing brain. Furthermore, as some of the CNS acting drugs tested are suspected behavioural teratogens the present results suggest that the reported behavioural abnormalities in the offspring may be related, in part, to a chronologically determined interference with the formation of certain cell types.

Effect of undernutrition on DNA and RNA synthesis in subcellular fractions from different regions of the developing rat brain

The effect of undernutrition on the incorporation of [methyl-3H] thymidine into DNA and of 5-[3H] uridine into RNA of cerebral hemispheres, cerebellum, and brain stem was studied in vivo and in vitro in rats. The labeling of DNA from nuclei and mitochondria and of RNA from nuclei, mitochondria, microsomes, and soluble fractions, was also measured in vitro. The results demonstrate that nucleic acid synthesis is impaired and delayed during undernutrition. Specific effects were observed for the different brain regions and subcellular fractions: at 10 days nuclear and mitochondrial DNA and RNA synthesis was impaired, whereas at 30 days only the mitochondrial nucleic acid synthesis was affected. The delay of DNA and RNA labeling, caused by undernutrition, was most evident in the cerebellum, probably due to its intense cell proliferation during postnatal development. The specific sensitivity of mitochondria as compared to other subcellular fractions, may by due to the intense biogenesis and/or turnover of nucleic acids in brain mitochondria not only during postnatal development, but also in the adult animal.

Myelin development and nutritional insufficiency

Postnatal undernourishment does not greatly retard the generation of rat brain cells, although there is a slight reduction in total cell numbers and brain size. Possibly the maturation of cells is more severely affected. The ratio of myelinated to non-myelinated fibers is greatly reduced in the corpus callosum and pyramidal tract, and presumably in other areas as well. There is only a slight reduction in the numbers of myelin lamellae for axons of a given size. The recovery of brain myelin and the incorporation of radioactive precursors into purified myelin proteins and lipids are all greatly reduced, leading to a comparatively severe reduction in the brain myelin concentration. The myelin composition is only slightly altered, possibly as a result of delay in its normal chemical maturation. The actual vulnerable period that produces a lasting myelin deficit is the early period that includes oligodendroglia cell proliferation, whereas undernutrition restricted to a later period that includes the actual peak of myelin does not cause a lasting reduction in the brain myelin concentration. The belief that stunting the postnatal proliferation of oligodendroglia largely accounts for the myelin effect has not been substantiated by direct analysis of cell numbers. Consequently, the observed hypomyelination likely results from a failure of oligodendroglia to mature and to initiate myelin formation. The myelin deficit appears largely uniform throughout the brain. Indirect evidence in human studies indicate that comparable effects appear in undernourished infants.

Impaired brain development of the diabetes insipidus Brattleboro rat

The Brattleboro homozygous diabetes insipidus (HOM-DI) mutant rat, incapable of synthesizing the neuropeptide vasopressin, has an impaired body growth of which the severity depends upon the conditions of reproduction. The comparison of homogeneously genotyped litters of HOM-DI and heterozygous (HET-DI) control pups, delivered and nursed by HOM-DI females, was regarded to be the only experimental design that practically excludes other influences on growth differences than the mutation itself. In this breeding scheme the postnatal growth of the HOM-DI brain is impaired, and the weight deficit persists into adulthood. Regionally, the neonatal development of cerebellum and medulla oblongata is most affected, and only slightly that of the cerebral cortex. The other separately isolated parts of the the brain seem to be unaffected (olfactory bulbs, hypothalamus, hippocampus, colliculi and thalamus plus basal ganglia). Cerebellum appeared to be the most consistently affected brain area of the HOM-DI Brattleboro rat since, unlike in the case of cerebral cortex and medulla oblongata, the weight deficit persisted throughout life. Olfactory bulb growth, on the other hand, appeared to continue after the first month of life, resulting in an increased weight at day 180. Water content of cerebral cortex and cerebellum of HOM-DI adults appeared slightly higher and might be explained by the generation of different brain water regulation systems for HET- and HOM-DI Brattleboro rats. Protein and DNA estimations of cerebral cortex, cerebellum and olfactory bulbs of male brains during development and in adulthood reflect the differences as found for weight, indicating no obvious changes in cell densities. It is concluded after comparison with other types of brain growth malformations, that the HOM-DI Brattleboro brain has its own particular etiology. The possible involvement of the action of vasopressin is postulated and discussed.

De novo biosynthesis of nucleotides and of nucleic acids in different regions of developing rat brain: effect of undernutrition

The effect of undernutrition on the de novo biosynthesis of nucleic acids in cerebral hemispheres, cerebellum, and brain stem of rats at different days of postnatal development was studied. The experiments were carried out in vitro by measuring the incorporation of [14C]-formate into the adenine nucleotide of the acid-soluble fraction of RNA and DNA, as well as into the thymine of DNA. The results obtained indicate that undernutrition during fetal and postnatal development impairs the de novo synthesis of the purine nucleotides of RNA and DNA at 5 days of age and delays it thereafter in the various brain regions examined, particularly in the cerebellum.

Alterations in cerebellar germinal cell division induced by graft-versus-host disease

A systemic immunological syndrome, graft-versus-host disease (GVHD), which does not cause inflammation or cell death in the cerebellum, is shown to retard granule cell production by decreasing the rate of DNA synthesis (S phase) and prolonging mitosis (M), at metaphase. The rate of cell production in diseased animals at postnatal day 14, quantitated by analysis of the rate of labeling of DNA with 3H-thymidine (3H-Tdr), revealed decreased ability to synthesize new DNA. The number of cells taking up 3H-Tdr label per mm2, as detected by autoradiography, was similar in 14-day-old GVHD and control tissue as was the area of the germinal matrix zone and the number of mitotically active germinal cells per mm2 in sagittal sections near the midline. However, because the total volume of the cerebellum was less, the total number of mitotically active cells in the whole cerebellum of 11-, 14-, and 17-day-old diseased animals was less than in littermate controls. Furthermore, DNA synthesis per mitotically active germinal cell was less in diseased animals at each age examined. The mitotic index was unaffected until late in the disease (day 17), suggesting that a prolongation of the cell cycle was responsible for this GVHD-induced decrease in DNA synthesis. Consistent with a prolongation of the cell cycle was the finding that the mitotic figures in 14-day-old GVHD cerebella were mostly metaphase figures, whereas those in control cerebella were, as predicted, mostly prophase. Prolongation of the cerebellar cell cycle in 11- and 14-day-old diseased animals may explain the dramatic decrease in the mitotic index, the thickness of the germinal matrix zone, and the number of germinal cells at postnatal day 17.

Influence of prenatal hypoxia on brain development: effects on body weight, brain weight, DNA, protein, acetylcholinesterase, 3-quinuclidinyl benzilate binding, and in vivo incorporation of [14C]lysine into subcellular fractions

The influence of prenatal hypoxia on subsequent brain development in the young rat was investigated by examining body and brain weight, cerebral cortex wet weight, protein and DNA concentrations, acetylcholinesterase (AChE) activity, 3-quinuclidinyl benzilate (QNB)-binding levels, the relative amounts of protein in various subcellular fractions, and the in vivo incorporation of [14C]lysine into the protein of homogenate and subcellular fractions. Exposure of pregnant females to a mild hypoxia (9.1% O2, 10 h per day for the 9--11 days preceding birth) resulted in a reduced body weight in the pups and days 1 and 5 after birth; total cortical DNA was reduced but brain weight and protein content were unaffected, leading to a higher protein/DNA ratio in prenatally hypoxic pups. By 10 days of age these differences between prenatally hypoxic and control animals were no longer apparent. There were no differences between prenatally hypoxic and control animals in AChE and QNB binding per milligram cortex protein. The relative amount of synaptic membrane protein from the cerebral cortex was reduced at day 1 in prenatally hypoxic animals and the synaptic membrane fraction showed a higher level of incorporation of [14C]lysine on days 1, 5, and 10. The developmental profile of [14C]lysine incorporation showed a peak on day 10 which was higher in prenatally hypoxic rats. By 46 days after birth little difference could be found between prenatally hypoxic and control animals.

The relative numbers of oligodendroglia in different brain regions of normal and postnatally undernourished rats

The relative numbers of oligodendroglia were compared in representative brain regions of 21 day old undernourished and control rats. As a result of postnatal undernutrition which produced half normal body weights and a 10-15 percent reduction in brain weight, the relative numbers of oligodendroglia were slightly increased in photomicrographs of corticospinal tract (a motor tract), medial lemniscus (a sensory tract), red nucleus (a motor nucleus) and somatosensory cortex. Relative numbers were reduced in the corpus callosum, and the thickness of the corpus callosum was significantly reduced. Cell sizes of oligodendroglia were essentially normal throughout the brain, although some reductions of 5 to 6 percent were observed. Areas of brain structures in cross section were essentially unchanged. We have previously hypothesized that nutritionally induced brain hypomyelination results from a reduction in the specific numbers of oligodendroglia and consequently a lasting reduction in the brain myelin concentration. The present results are inconsistent with this hypothesis, as both the density of oligodendroglia and sizes of brain regions are essentially normal. We know from prior work using the same model of nutritional deprivation that myelin synthesis is greatly reduced. Consequently an important depressant effect of undernourishment on oligodendroglia in the developing brain involves either the communication between axons and oligodendroglia leading to myelin induction or the synthetic capacity to make myelin.

The influence of protein restriction, rehabilitation and changing nutritional status on synaptic development: a quantitative study in rat brain

Quantitative ultrastructural technique were employed to compare the development and maturation of cortical synapses in rats subjected to protein deprivation, control diet, nutritional rehabilitation and a normal-low crossover diet. Osmicated preparations of the molecular layer of occipital cortex were prepared at 15, 20, 28, 75 and 224 days postnatal in male rats. At 15 and 30 days the values for mitochondrial and synaptic densities, vesicle number and packing per terminal, synaptic length, terminal area and brain weight were lower in the protein-deprived than in the control animals. These initial deficits were progressively transformed to excesses, with the most marked crossover period occurring between 20 and 28 days. By 224 days only brain weight and presynaptic terminal area were lower in the protein-deprived material. A further parameter, synaptic curvature, showed a decrease in negativity in protein-deficient junctions between 15 days (64%) and 224 days (41%). Well-nourished tissue had fewer negatively-curved synapses during early development. These data suggest that the morphological development of the presynaptic terminals is not simply delayed, but is ultimately different in the protein-deprived animals. The nature of these changes may facilitate an adaptation to provide more efficient functioning in the adverse condition. Nutritionally rehabilitated tissue ultimately approaches the control, although significant differences occur in synaptic and mitochondrial densities and in brain weight. The normal--low crossover procedure intensities the differences noted in animals subjected to continuous deprivation.

Implications of malnutrition in chemical carcinogenesis

Epidemiological data indicate that life style, including dietary "imbalances", play a major role in etiology of human cancers. Although two thirds of the world population suffer from varying grades of protein-caloric malnutrition (PCM) today, no consistent pattern is found to be associated wih PCM both in man and laboratory animals. At the tissue level, depression of cellular proliferation by prolongation of DNA-synthetic phase is a characteristic lesion of PCM. Due to changes in liver mixed function oxidases, metabolism of drugs is affected. The cell-mediated immunity is depressed and there is a defective mobilisation of macrophages. These alterations would modulate carcinogenesis; some tend to enhance, while others inhibit tumorigenesis. The balance of evidence suggest that PCM is unlikely to have dominant modulating influence on carcinogenesis.

Effect of chlorpromazine on cell proliferation in the developing rat brain. A combined biochemical and morphological study

Chlorpromazine, a widely used drug in current clinical practice, produced a severe reduction of the rate of [3H]thymidine incorporation into brain DNA of 11-day-old rats. The depression of in vivo synthesis rate was detectable by 6 h after chlorpromazine administration (50 mg/kg, s.c.) and the rate was less than 40% and 60% of controls during period 14-30 h in forebrain and 6-30 h in cerebellum respectively. The depression was dose-dependent and half maximal effect was produced with about 10 mg/kg chlorpromazine. The drug caused some retardation in the rate of conversion of [3H]thymidine to [3H]thymine nucleotides in the brain, but the severe depression in DNA labelling was also evident after correcting the values on the basis of [3H]thymine nucleotides concentration. Mitotic activity was significantly reduced in the cerebellar external granular layer. Increased numbers of cell degenerations, shown by Feulgen cytophotometry to be postmitotic, were seen in both layers 12 and 32 h after chlorpromazine. Analysis of cell cycle parameters showed no significant changes. However, the labelling index in subependymal cells was reduced, indicating an increase in turnover time of about 40%. The results are consistent with an action of chlorpromazine on cell proliferation, either by direct effects on the generation and survival of cells, or via its major pharmacological actions on neurotransmitter balance. These effects are potentially of functional and clinical significance.

Effects of undernutrition on myelination in rat corpus callosum

Rats were undernourished by halving the mother's food intake from the sixth day of pregnancy onwards and through lactation. Subsequently, the young animals were maintained up to 48 days on half the normal diet. The effects of this regime of treatment on myelination in the corpus callosum were investigated by light and electron microscopy. In comparison with controls, the percentage of axons myelinated at 15, 21, and 48 days was reduced in undernourished rats. The number of lamellae constituting the myelin sheath was also reduced at 15 and 21 days, but at 48 days no difference was seen between control and treated rats, suggesting that a catch-up in myelination had occurred. A linear relationship between myelin sheath thickness and axonal diameter was observed in both groups of animals. However, a long-term effect on axonal growth was suggested by findings in the 48-day undernourished animals; in comparison with controls, axonal diameter was reduced, relative to myelin sheath thickness.

Changes in RNA synthesis and messenger RNA content in the cerebellum of rats with graft versus host disease

Cerebellar RNA accumulation, synthesis, and functional capacity was studied in 14-day-old F1 hybrid rats subjected to neonatally induced graft versus host disease (GVHD). There was a decrease in RNA synthetic rate as measured by the uptake of labeled precursors into RNA. The decrease in total cerebellar RNA synthesis was reflected both in a reduced amount of Nissl substance, visible in cresyl violet-stained 10-micron-thick sections of cerebella, and in the total amount of cytoplasmic RNA isolated from individual cerebella from diseased animals compared with control littermates. Analysis of the RNA translational capacity in wheat germ protein synthesizing systems showed that RNA from experimental animals was also biologically less active. Qualitative differences between protein populations in control and diseased animals were analyzed by two-dimensional gel electrophoresis. There were few alterations in the steady state levels of cerebellar protein. However, two-dimensional gel electrophoresis of the peptides synthesized in vitro by RNA from control and diseased animals showed that there were several changes in the relative abundance of some mRNAs between the two RNA populations. These data show that the cerebellar RNA from rats with GVHD differs both qualitatively and quantitatively from that of controls.

Effect of cycloheximide administered to rats in early postnatal life: prolonged inhibition of DNA synthesis in the developing brain

Administration of cycloheximide in a single dose of 0.6 mg/kg to 7-day-old rats was used to induce short-term inhibition of protein synthesis at the period of brain 'growth spurt'. Measurement of the rate of [14C]lysine incorporation indicated that the initial inhibition of protein synthesis in the brain (by 75%) was released within about 12 h. The normal rate of protein synthesis was attained by 48 h after cycloheximide administration; there was no sign of protein synthesis stimulation. The estimation of [14C]thymidine incorporation into brain DNA showed that inhibition of DNA synthesis was greater and longer lasting in the forebrain and olfactory bulbs (by about 80%) than in the cerebellum (by about 40%). Similar differential inhibition of thymidine kinase activity was observed in the olfactory bulbs (by 75%) and cerebellum (by 30%) at 24 h after cycloheximide, suggesting that the formation of [14C]thymidine nucleotides may have been impaired. However, a retardation of DNA accumulation was found in the forebrain and cerebellum at 72 h after cycloheximide. Thus, the short-term inhibition of protein synthesis produced prolonged inhibition of DNA synthesis and altered cell proliferation in the developing brain.

Thyroid deficiency and cell death in the rat cerebellum during development

The [3H]-DNA content of the cerebellum remained constant during a period from 4 h to 8--9 days after the administration of [3H]-thymidine both to normal rats at 6 and 12 days of age and to thyroid deficient rats at 6 days. On the other hand, when [3H]-thymidine was given to 12-day-old thyroid deficient rats, a progressive decrease in the cerebellar content of [3H]-DNA was observed during the first 4 days after the injection. These findings, together with previous results showing a markedly elevated pyknotic index in the internal granular layer of the 12-day-old hypothyroid cerebellum, are consistent with there being an increased death of newly formed and differentiating granule cells in thyroid deficiency towards the end of the second week of postnatal life.

DNA and DNases in normal and undernourished rat brain

Earlier studies from our laboratory [Shrivastaw and Subba Rao, 1975; Subba Rao and Shrivastaw, 1976] have indicated a positive correlation between cell proliferation, as indicated by DNA synthesis, and the levels of DNases in developing chick brain. Since undernutrition is known to affect cell proliferation in developing brain, those studies are now extended to see the effect of early undernutrition on the levels of DNA and DNases along with RNA and protein in developing rat brain. Early nutritional deprivation resulted in lesser amounts of DNA, but the concentration of DNA per gram of brain did not alter. DNA, RNA, and protein values in brains of those rats undernourished from birth to 14 days but subsequently rehabilitated up to 130 days, exhibited complete recovery, while rehabilitation up to 50 days did not show full recovery in the case of DNA. Both the specific activity and total activity of acid and alkaline DNases showed significant reduction in 14-day-old undernourished brain. However, with continued nutritional restriction up to 24 days, the specific activity of these enzymes returned to normal, although the total activity was still in deficit. These results, coupled with those on DNA levels, indicate that a compensatory mechanism may come into play when developing brain is exposed to caloric restriction.

Impeded cerebellar development and reduced serum thyroxine levels associated with fetal alcohol intoxication

Pregnant albino rats were placed on a complete liquid diet (Ensure) containing either 9% ethanol or an isocaloric amount of sucrose between the third and twentieth day of gestation. The pups born to these rats were sacrificed either day 11 or day 14 postnatum and morphometrical, histological and biochemical analyses were done on their cerebellums and cerebrums. Pups that were exposed to ethanol in utero had significantly smaller body weights, cerebrums and cerebellums than pair-fed controls. The cerebellar mass was reduced by 10% and the cerebral weight by 3% in the pups exposed to alcohol when body weights were normalized to that of pair-fed controls. Cerebellar aspartyl aminotransferase (EC 2.6.1.1) activity was reduced at day 11 and 14 in ethanol treated pups compared with controls. Serum T4 levels were also reduced in the ethanol treated group. Histological analyses revealed that the external granule cell (EGC) layer of ethanol treated pups was significantly thicker at 11 and 14 days postnatum than that of pair-fed control pups. Cerebellar ornithine decarboxylase (ODC, EC 4.1.1.17) activity was higher at day 11 in the ethanol treated pups than in controls. The reduced mass, AAT activity, T4 serum levels and the increased thickness of the ECG layer indicate a delayed or impeded maturation of cerebellum in ethanol treated pups. These data are considered from the viewpoint that ethanol, other drugs such as methadone and prenatal stress (malnutrition) may cause delayed cerebellar maturation by reducing serum T4 levels in the early postnatal period (day 5-14).