Parameters Of Brain Development Research Articles

Influence of Litter Reduction in the Neonatal Period at Different Times after Birth on the Parameters of Brain Development in Rats.

We studied the brain of 5- and 14-day-old intact (control group) rats and rats of the same age from litters experimentally reduced on days 1 and 5 after birth (experimental groups). In animals of both experimental subgroups, the brain had morphological signs of advanced development: greater weight of the brain and hemisphere, greater thickness of the cortex, its molecular layer, lower numerical density of neurons in the anterior parietal and proper parietal lobes, greater sizes of neurons, their nuclei, and nucleoli in the neocortex of these zones, and increased concentration of RNA in the cytoplasm of neurons. These data suggest that the rate of brain development in rats can be accelerated under the influence of environmental changes that occur after litter reduction during the neonatal period at different times after birth.

Effect of Experimental Litters Reduction during the Neonatal and Suckling? Periods of Ontogeny on Some Parameters of Brain Development in 30-Day-Old Rats.

We compared the effect of litter reduction on day 1 (series I) and day 14 after birth (series II) on the weight of the brain and right hemisphere and on the morphometric indicators of the development of the anteroparietal lobe in rats. Animals from both experimental series showed signs of acceleration (higher body weight and weights of the testes and ovaries). In series I, the weight of the brain and hemisphere and the thickness of the cortex surpassed the control values; the numerical density of neurons in layers II and V was lower and the numerical density of gliocytes was higher than in the control. The size of the neuronal nuclei of these layers as well as the size of perikaryons of layer V neurons also surpassed the control. These differences can be considered as evidence of advanced brain development in experimental animals. In contrast, gravimetric and morphometric parameters in series II did not differ significantly from the control values. Thus, the factors that determine accelerated development of the brain after reduction of litter size in the neonatal period produced no similar effect after litter reduction on day 14 after birth.

Immediate and Delayed Effects of Food Restriction on Some Parameters of Brain Development in Rats.

The effects of 15-day restriction diet (from 1 to 1.5 months of age) on some parameters of brain development were studied in rats. The immediate and delayed (15 days after transfer to normal ration) effects were evaluated. The immediate effects included a significant decrease of the absolute weights of the brain and hemispheres. The relative weight of the brain was significantly higher. The thickness of the cortex of the parietal lobe proper and its layer I decreased. The absolute weights of the brain and hemispheres were less than in the control 15 days after the rats were transferred to ad libitum feeding, while the relative weight of the brain was higher than in controls. The thickness of the parietal and anterior parietal cortex and the numerical density of neurons in layers II and V did not differ from the control. In the neurons of layers II and V of the anterior parietal and parietal lobe proper the nuclei were larger, while the nucleoli were enlarged in the neurons of these locations and the hippocampus, the shifts being significant in the anterior parietal layer V. The concentrations of RNA in the parietal, anterior parietal, and hippocampal lobe neurons in different groups were similar directly and 15 days after the diet. Changes in the gravimetric and morphometric parameters of the brain were paralleled by the development of oxidative stress.

The influence of supplemental docosahexaenoic and arachidonic acids during pregnancy and lactation on neurodevelopment at eighteen months

Docosahexaenoic acid (DHA) and arachidonic acid (AA) are important for neurodevelopment. The effects of DHA (220mg/day, n=41), DHA+AA (220mg/day, n=39) or placebo (n=34) during pregnancy and lactation on neurodevelopment at 18 months, and the relations between umbilical cord DHA, AA and Mead acid and neurodevelopment were studied. An age-specific, standardized neurological assessment for the evaluation of minor neurological dysfunction (MND), and the Bayley Scales of Infant Development (BSID) were used. The intervention did not influence any of the outcomes. Umbilical venous (UV) Mead acid was negatively and n-6 fatty acids were weakly positively associated to the BSID mental developmental index. Children with simple MND had lower UV DHA compared to normally classified children. We conclude that relatively short-term maternal DHA or DHA+AA supplementation does not influence neurodevelopment at toddler age, although some parameters of brain development are related to perinatal DHA and AA status.

Effect of Long-Term Constant Illumination of Female Rats on the Parameters of Brain Development in Their 40-Day-Old Progeny

We studied the progeny from female rats exposed to constant illumination for 1 month and mated with intact males 14 days after this exposure. At the age of 40 days, the progeny from experimental rats differed from the control by lower body weight, thickness of the adrenal cortex, and diameter of convoluted seminal tubules. The weight of the brain was similar in both groups. The thickness of the cortex in the parietal lobe, and especially, in the frontoparietal lobe was decreased; the neuronal density in these lobes (layers II and V) was reduced. In layer II and V neurons of the parietal lobe, the size of neuronal nuclei reduced, the concentration of RNA and activities of NADH and NADPH dehydrogenases in the cytoplasm were considerably increased. Elevated concentration of lipids was found in layer I of cerebral and cerebellar cortex and in the white matter, which attests to higher myelinization degree compared to the control.

Effect of experimental litter reduction in female rats on parameters of brain and endocrine gland development in the progeny

We studied the relationship between parameters of brain development, elevated plus-maze behavior, and the status of the endocrine glands in the progeny of 4.5-5- and 8-9-month-old females after litter reduction by removal of one uterine tube. The progeny of young experimental females differed from the progeny of control animals by brain weight (at the age of 1 day), morphometrical characteristics of the cortex and its neurons, activity of 3beta-hydroxysteroid dehydrogenase in the adrenal cortex (at the age of 1 and 40 days), and behavioral reactions in the elevated plus-maze (at the age of 30 days). The differences in these parameters between the progeny from old females with experimentally reduced litter size and control females were significantly less pronounced.

Morphometric and statistical analysis of macro-and microscopic characteristics of the brain and their relationships with adrenocortical histophysiology in newborn rats

A direct relationship between the weights of the brain and hemisphere and parameters characterizing the development of the cortex and its neurons in intact newborn rats was revealed. Parameters of brain development in newborn rats correlate with 3beta-hydroxysteroid dehydrogenase activity in the adrenal zona glomerulosa.

Differences in critical cerebral blood flow with age in swine

Normal cerebral blood flow (CBF), critical CBF at a flat reading of the electroencephalogram (EEG), and reversibility of the flat EEG after reperfusion were investigated in a total of 59 pigs, including seven newborns (1 to 3 days of age), 38 juveniles (1 month old), and 14 adults (7 months old). The CBF was determined by the hydrogen clearance method; the EEG was recorded continuously and a power spectrum analysis was performed. Cerebral ischemia was produced by occlusion of both common carotid arteries and induction of hypotension (approximately 50 mm Hg). The flat EEG reversibility was investigated for 3 hours after reperfusion. As parameters of brain development, the neuronal density and the time at which the S-100 protein appeared in the brain were examined. Normal CBF was highest in neonatal pigs and decreased with age. The critical CBF at a flat EEG was lowest in newborn pigs and was elevated with development of the brain. Tolerance against cerebral ischemia was greatest in newborn pigs.

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.

Changes in brain components during the development of mice homozygous for the locus ?dwarf? (dw)1,5

Brain composition and developmental changes were investigated in mice homozygous for the locus "dwarf," and characterized by a reduced level of growth hormone, thyroid stimulating hormone, and prolactin, and by secondary hypothyroidism. The difference in adult brain weight (-32%) between the dwarf and the normal mice was not found to parallel the difference in body weight (-71%), whereas the differences in the weight of the liver (-79%) and that of the kidney (-75%) did. Several biochemical parameters of brain development were assayed in dwarf and normal mice between the ages of 15 and 210 days. Levels of cerebrosides, sulfatides, gangliosides, phospholipids, cholesterol, protein, and RNA (per gram wet weight) were the same for the dwarf and the controls, but the net difference in total brain DNA was less than the net total brain RNA difference (-11% vs. -27%). Total brain lipids (absolute quantities) were the same at 15 days. The difference was -37% by the 50th day, and remained constant thereafter. No change in the specific activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase or 3'-phosphoadenosine-5'-phosphosulfate: galactocerebroside sulfotransferase was observed. These data suggest that the regulation of the development of brain structures is maintained, but the level of the synthesis of the various brain constituents is reduced in proportion to the brain weight. The development of the dwarf brain seems to proceed harmoniously.