Locomotor development in undernourished rats

Maternal nutrient restriction during late gestation reduces vigor and alters blood chemistry and hematology in neonatal beef calves

Fall-calving primiparous beef females [body weight: 451 ± 28 (SD) kg; body condition score: 5.4 ± 0.7] were individually-fed either 100% (control; CON; n = 13) or 70% (nutrient restricted; NR; n = 13) of metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth from day 160 of gestation to parturition. Calves were reared naturally by their dams and monitored for latency times from birth to first sternal recumbency, attempt to stand, and stand; vigor scores were assigned at 2, 5, 10, and 20 min of age. Rectal temperatures and jugular blood were obtained at 0 (pre-suckling), 6, 12, 24, and 48 h of age, and blood chemistry, hematology, cortisol, and insulin were determined. Data were analyzed with fixed effects of late gestational nutritional plane (single data point) or nutritional plane, hour, and their interaction (data over time, repeated measures). Calving date was a fixed effect; calf sex was included when P < 0.25. We previously reported that late gestational nutritional plane did not affect gestation length or calf size at birth, but calving assistance and fetal malpresentation occurred more often in NR. Nutritional plane did not affect (P = 0.65) duration of parturition, but calves born to NR dams had slower times to attempt to stand (P = 0.09), slower times to stand (P = 0.02), and poorer 20 min vigor scores (P = 0.05). Serum immunoglobulin G and A concentrations at 48 h were greater (P ≤ 0.03) for NR calves. Rectal temperature of NR calves was less (P = 0.02) at 0 h, but greater (P = 0.04) at 24 h compared with CON. Circulating glucose, non-esterified fatty acids, triglycerides, cortisol, and insulin were not affected by nutritional plane (P ≥ 0.18). Total protein and globulin from 6 to 48 h were greater (P ≤ 0.02) in NR calves. Calves from NR dams had greater (P ≤ 0.08) gamma-glutamyl transferase at 6, 12, and 48 h. Serum aspartate aminotransferase was greater (P ≤ 0.07) from 0 to 24 h and creatine kinase was greater (P ≤ 0.04) from 6 to 24 h in NR calves. At 0 h, potassium was greater (P = 0.03) in NR calves. Calves born to CON had greater chloride (P = 0.08; main effect), sodium (P ≤ 0.09) from 0 to 48 h, and anion gap (P = 0.02) at 6 h. Hematocrit from 6 to 24 h and red blood cells and hemoglobin at 6 and 12 h were greater (P ≤ 0.09) in CON calves. These data indicate that nutrient restriction during late gestation resulted in less vigorous calves with more indicators of trauma in early life.

Motor skill learning in children with Developmental Coordination Disorder

Children with Developmental Coordination Disorder (DCD) are characterized as having motor difficulties and learning impairment that may last well into adolescence and adulthood. Although behavioral deficits have been identified in many domains such as visuo-spatial processing, kinesthetic perception, and cross-modal sensory integration, recent studies suggested that the functional impairment of certain brain areas, such as cerebellum and basal ganglia, are the underlying causes of DCD. This review focuses on the "motor learning deficits" in DCD and their possible neural correlates. It presents recent evidence from both behavioral and neuroimaging studies and discusses dominant neural hypotheses in DCD. Given the heterogeneity of this disorder, a successful intervention program should target the specific deficits on an individual basis. Future neuroimaging studies are critical steps in enhancing our understanding of learning deficits in DCD.

Early development influences ontogeny of personality types in young laboratory rats

Features of an individual's early development are frequently reported to alter the postnatal ontogeny in litter-bearing mammals with respect to various physiological parameters. We hypothesized that such effects might also apply to the ontogeny of personality types. On the one hand, litter size effects by means of more contacts with littermates, might lead to the development of more offensive types. On the other hand, smaller and less developed young from larger litters might be less offensive due to their lower physical capabilities to deal with challenging situations. We studied these contrasting hypotheses in young rats, which we tested in a battery of emotionality tests. There were clear indications for the existence of distinct behavioral types by means of consistencies in behavioral responses within and across contexts. Based on these responses, we calculated three new variables by PCA, which we interpreted to mainly reflect boldness, exploration, and anxiety. Overall, our results strongly suggest that the early development alters the ontogeny of personality types, with heavier individuals being bolder and more explorative. Furthermore, body mass and litter size influenced the changes in the behavioral responses in successive tests, further supporting the importance of the litter size-dependent body mass for the ontogeny of personalities. Anxiety also depended on litter size, however, in a nonlinear way. Animals born to litters of small or large sizes had higher scores, whereas individuals from medium-sized litters were less anxious. This optimum curve indicates that opposing effects of litter size are involved in shaping personalities in young rats.

Different effects of anoxia and hind-limb immobilization on sensorimotor development and cell numbers in the somatosensory cortex in rats

Cerebral palsy (CP) is a group of movement and posture disorders attributed to insults in the developing brain. In rats, CP-like motor deficits can be induced by early hind-limb sensorimotor restriction (SR; from postnatal days P2 to P28), associated or otherwise with perinatal anoxia (PA; on P0 and P1). In this study, we address the question of whether PA, early SR or a combination of both produces alterations to sensorimotor development. Developmental milestones (surface righting, cliff aversion, stability on an inclined surface, proprioceptive placing, auditory startle, eye opening) were assessed daily from P3 to P14. Motor skills (horizontal ladder and beam walking) were evaluated weekly (from P31 to P52). In addition, on P52, the thickness of the somatosensory (S1) and cerebellar cortices, and corpus callosum were measured, and the neuronal and glial cell numbers in S1 were counted. SR (with or without PA) significantly delayed the stability on an inclined surface and hastened the appearance of the placing reflex and impaired motor skills. No significant differences were found in the thickness measurements between the groups. Quantitative histology of S1 showed that PA, either alone or associated with SR, increased the number of glial cells, while SR alone reduced neuronal cell numbers. Finally, the combination of PA and SR increased the size of neuronal somata. We conclude that SR impairs the achievement of developmental milestones and motor skills. Moreover, both SR and PA induce histological alterations in the S1 cortex, which may contribute to sensorimotor deficits.

Development of behavior in the litter huddle in rat pups: within- and between-litter differences

Early postnatal growth in mammals can be considerably influenced by litter size and often differs among littermates in relation to birth mass. In a study of Long Evans laboratory rats we asked whether within- and between-litter differences in body mass and growth are related to behavioral development during early postnatal life. For this, we analyzed the amount of general motor activity and the display of directed, seemingly goal-oriented interactions within the litter huddle in previsual pups. During the study period from postnatal days 2 to 11, we found significant changes in pup behavior, showing a nonlinear, quadratic shape. General motor activity and, more specifically, the display of behaviors apparently directed to reaching central positions in the litter huddle increased during the first postnatal days and then decreased again. However, pups from small litters that grow more rapidly than pups from large litters, showed a faster increase in both behaviors, whereas the young from large litters reached a higher maximum. We also found striking within-litter differences in the amount of directed behavior performed by light and heavy pups, with higher levels in the former group, most probably because light pups that have a less favorable body mass-to-volume ratio and more often occupy peripheral positions in the litter huddle, make a greater effort to reach thermally favorable central positions. In conclusion, our study shows there to be consistent between-litter as well as within-litter differences in behavioral patterns during early life. These differences might have important implications for an individual's long-term behavioral and physiological performance.

Nutrition and neurodevelopment: mechanisms of developmental dysfunction and disease in later life

Nutrition plays a central role in linking the fields of developmental neurobiology and cognitive neuroscience. It has a profound impact on the development of brain structure and function and malnutrition can result in developmental dysfunction and disease in later life. A number of diseases, including schizophrenia, may be related to neurodevelopmental insults such as malnutrition, hypoxia, viruses or in utero drug exposure. Some of the most significant findings on nutrition and neurodevelopment during the last three decades, and especially during the last few years, are discussed in this review. Attention is focused on the underlying cellular and molecular mechanisms by which diet exerts its effects. Randomized intervention studies have revealed important effects of early nutrition on later cognitive development, and recent epidemiological findings show that both genetics and environment are risk factors for schizophrenia. Particularly important is the effect of early nutrition on development of the hippocampus, a brain structure important in establishing learning and memory, and hence for cognitive performance. A major aim of future research should be to elucidate the molecular mechanisms underlying nutritionally-induced impairment of neurodevelopment and specifically to determine the mechanisms by which early nutritional experience affects later cognitive performance. Key research objectives should include: (1) increased understanding of mechanisms underlying the normal processes of ageing and neurodegenerative disorders; (2) assessment of the role of susceptibility genes in modulating the effects of early nutrition on neurodevelopment; and (3) development of nutritional and pharmaceutical strategies for preventing and/or ameliorating the adverse effects of early malnutrition on long-term programming.

Continuous and discontinuous drawing: high temporal variability exists only in discontinuous circling in young children

The authors studied whether the drawing variability in young children is best explicable by (a) demands on the explicit timing system, (b) an underdeveloped ability to control limb dynamics, or (c) both. The explicit timing demands were lower in continuous drawing in comparison with the discontinuous task. The authors manipulated limb dynamics by changing the number of joints involved, with line drawing requiring fewer joints than circle drawing. Results showed that young children had high temporal variability in discontinuous circling but not in other conditions. The authors argue that both explicit timing and dynamic complexity of limb control may be determinants of temporal consistency and may thus play an important role in the development of drawing and writing skills in children.

Soyabean fortification and enrichment of regular and quality protein maize tortillas affects brain development and maze performance of rats

The brain development and performance of rats fed throughout two generations with an indigenous maize tortilla-based diet was studied. The experiment compared casein control with five different diets produced from: regular fresh masa; regular, enriched dry masa flour containing thiamin, riboflavin, niacin, folic acid, Fe and Zn (REDMF); dry masa flour fortified with 60 g/kg defatted soyabean meal and enriched (FEDMF); enriched quality protein maize (QPM) flour (EQPM); QPM flour fortified with 30 g/kg defatted soyabean meal and enriched (FEQPM). In both generations, brain and cerebellum weights and myelin concentration were significantly higher (P < 0.05) in rats fed the FEDMF and FEQPM diets. There was no significant difference (P > 0.05) in brain DNA in first-generation rats; however, second-generation rats fed FEDMF, EQPM and FEQPM tortillas had higher cerebral DNA, neuron size and brain activity as estimated by the RNA:DNA ratio. Short-term and long-term memory performance in the Morris maze improved (P < 0.05) among rats fed the FEDMF, FEQPM and EQPM diets. Second-generation rats fed the FEDMF and FEQPM diets had a superior (P < 0.05) working memory and learning performance. The utilisation of regular or QPM tortillas enriched with selected micronutrients and fortified with soyabean is highly recommended to assure adequate brain development. The high lysine-tryptophan QPM made it possible to save half of the soyabean flour without sacrificing the nutritional value of soyabean-fortified tortillas.

Neonatal food restriction and binaural ear occlusion interfere with the maturation of cortical motor pyramids in the rat

Golgi-Cox-impregnated pyramidal neurons of layer five motor cortical area were investigated in control, binaural ear-occluded control, undernourished and binaural ear-occluded undernourished Wistar rats of 12, 20 and 30 days of age. In neonatally undernourished, binaural ear-occluded-undernourished and partly in ear-occluded-control subjects, there were significant reductions in both the number and extent of the distal part of the dendritic branches of motor pyramids compared to their controls. Moreover, minimal effects on perikarya measurements were observed. These findings suggest that neonatal undernutrition and the concurrent reduction of auditory cues affect dendritic arbor development and possibly the convergence of the auditory experience upon motor pyramids and may interfere with the neocortical modulation of postural and movements activities.

Breed, litter and parity effects on placental weight and placentome number, and consequences for the neonatal behaviour of the lamb

Lamb survival is impaired in low birth weight lambs, and those that are slow to stand and suck. Many of the factors that influence lamb vigour, such as parity, litter size, and breed, may exert their effects, at least partially, before birth by influencing placenta development. Our hypothesis was that retarded lamb behavioural development was due to differences in placentation in these animals. Data were collected from Blackface and Suffolk lambs in the first 2 h after birth and placentas were collected when delivered. Suffolk lambs, which were behaviourally slower and had lower rectal temperatures than Blackface lambs, were associated with larger but less efficient placentas (placental efficiency defined as foetal weight supported per g placenta) with fewer foetal cotyledons than Blackface placentas. Triplet lambs were significantly slower than twin or single lambs to suck and had lower rectal temperatures. Although placenta efficiency increased with litter size, placenta and cotyledon weight, and cotyledon number increased with twinning but not thereafter. It seemed likely that triplet lambs suffered some placental insufficiency in comparison to other litter sizes. Lambs born to first parity mothers were slower to stand and reach the udder than lambs of more experienced ewes, and first parity ewes also had smaller and less efficient placentas although cotyledon number was not affected. Male lambs tended to be slower than female lambs for most behaviours, although rectal temperatures were not affected. The sire of the lamb also influenced lamb behaviour and rectal temperature. Both lamb sex and lamb sire influenced the average weight of placental cotyledons, thus some of the sire effect on the behaviour and birth weight of his progeny might be mediated through placental development. Lamb neonatal vigour was correlated with placental efficiency suggesting that lamb behaviour immediately after birth is related to placental development and function.

Effects of sensorimotor restriction and anoxia on gait and motor cortex organization: implications for a rodent model of cerebral palsy

Chronic or acute perinatal asphyxia (PA) has been correlated with the subsequent development of cerebral palsy (CP), a developmental neurological disorder characterized by spasticity and motor abnormalities often associated with cognitive deficits. Despite the prevalence of CP, an animal model that mimics the lifetime hypertonic motor deficits is still not available. In the present study, the consequences of PA on motor behavior, gait and organization of the primary motor cortex were examined in rats, and compared with the behavioral and neurological consequences of early postnatal movement-restriction with or without oxygen deprivation. Rats subjected to PA had mild increases in muscular tone accompanied by subtle differences in walking patterns, paralleled by significantly altered but relatively modest disorganization of their primary motor cortices. Movement-restricted rats, suffering PA or not, had reduced body growth rate, markedly increased muscular tone at rest and with active flexion and extension around movement-restricted joints that resulted in abnormal walking patterns and in a profoundly distorted representation of the hind limbs in the primary motor cortex. Within the sensorimotor-restricted groups, non-anoxic rats presented the most abnormal pattern and the greatest cortical representational degradation. This outcome further supports the argument that PA per se may represent a substrate for subtle altered motor behaviors, and that PA alone is sufficient to alter the organization of the primary motor cortex. At the same time, they also show that early experience-dependent movements play a crucial role in shaping normal behavioral motor abilities, and can make a powerful contribution to the genesis of aberrant movement abilities.

Postnatal weight gain inhibition does not account for neurobehavioral consequences of neonatal Borna disease virus infection

Neonatal Borna disease virus (BDV) infection of the rat's brain produces neurodevelopmental damage similar to some pathological and clinical features of human developmental disorders, e.g., autism and schizophrenia. Since BDV-infected rats exhibited an inhibition of postnatal weight gain, the present study sought to evaluate a contribution of nutritional status to virus-induced neurodevelopmental injury. We compared neuroanatomical, neurochemical, and behavioral alterations following neonatal BDV infection and rearing in the oversized litters in Fischer344 rats on postnatal day (PND) 26. Despite a comparable weight gain inhibition, different patterns of brain pathology, alterations in brain monoamine systems, and behavioral deficits were observed in the BDV-infected rats compared to the malnourished rats. While no appreciable cell injury was noted in the brains of the malnourished rats, a significant loss of Purkinje cells (PC) and early signs of degeneration of the hippocampal dentate gyrus were found in the BDV-infected rats. Both neonatal BDV infection and postnatal malnourishment increased tissue concentrations of serotonin [5-hydroxytryptamine (5-HT)] in the hippocampus. In contrast, increased turnover of 5-HT in the cortex and hippocampus and elevated turnover of dopamine (DA) in the striatum were found in the malnourished rats only, suggesting that different pathogenic mechanisms might underlie monoamine disturbances in virus-infected and malnourished rats. The observed dissimilar neuroanatomical and neurochemical abnormalities might explain the different responses to novelty in the BDV-infected and malnourished rats. Compared to the control rats, the BDV-infected rats exhibited novelty-induced hyperactivity, while no differences in locomotion were noted between the control and malnourished rats. Taken together, the present data indicate that virus-associated inhibition of postnatal weight gain is unlikely to account for the major BDV-associated neurodevelopmental alterations that seem to be due to specific effects of neonatal BDV infection.

Ewe-lamb bonding behaviours at birth are affected by maternal undernutrition in pregnancy

Maternal undernutrition in pregnancy results in low birth-weights and impaired postnatal survival in sheep. Largely anecdotal evidence suggests that the expression of appropriate maternal and neonate behaviours may also be disrupted by undernutrition. In the present study, we investigated the effect of a moderate (35 %) reduction in ewe nutritional intake in pregnancy on the expression of ewe-lamb bonding behaviours in primiparous Scottish Blackface ewes. Low-intake (L) ewes had significantly higher plasma progesterone than high-intake (H) ewes from mid-gestation onwards (e.g. plasma progesterone at 20 weeks (ng/ml): H 15.72, L 22.38, sed 1.80, P<0.001), and a lower oestradiol: progesterone value than H ewes at delivery (H 0.46, L 0.35, sed 0.05, P<0.05). Lamb birth-weight was reduced in the L lambs compared with H lambs (mean body weight (kg): H 3.31, L 3.00, sed 0.14, P<0.05), but the incidence of malpresentation at delivery was greater in L lambs. L ewes spent significantly less time licking their lambs than H ewes after delivery (time grooming in 2 h after birth (%): H 56.12, L 48.17, sed 2.639, P<0.01) and were more aggressive towards the lambs. Lamb behaviours were not directly affected by maternal nutritional treatment, but lamb birth-weight had a significant effect on neonatal developmental progress. Low-birth-weight lambs were slower than heavier lambs to stand and sucked less frequently. In tests of maternal attachment to the lamb, H ewes received higher scores than L ewes at both 24 h after birth (ewes receiving high scores (%): H 41.3, L 21.4, P<0.05) and at 3 d postnatal. We conclude that even a moderate level of undernutrition impairs the attachment between ewes and lambs by affecting maternal behaviours expressed at birth. In addition, the results suggest that levels of nutrition resulting in a decrease in birth weight will affect neonatal lamb behavioural progress.

Effect of chronic protein restriction on motor co-ordination and brain neurotransmitters in albino rats

In this study we evaluated the motor co-ordination in Wistar strain albino rats that were maintained on a protein-restricted diet for a period of 1 year immediately after the weaning period, by substituting 75% of the normal diet with a carbohydrate-rich diet deficient in protein, for a period of 1 year immediately after the weaning period. This type of chronic protein restriction caused disturbances in motor co-ordination. It also caused a significant reduction in the basal levels of dopamine, norepinephrine, epinephrine and serotonin along with their metabolites homovanillic acid (HVA), vanillyl mandelic acid (VMA) and 5-hydroxy indoleacetic acid (5HIAA) and precursor L-dopa in the corpus striatum and cerebellum. Changes in these neurotransmitters could have caused altered co-ordination in the protein-restricted animals.

Development of play behavior in neonatally undernourished rats

The effects of neonatal food and sensory deprivation on play social behavior (boxing, wrestling, and pinning) were studied in male and female Wistar strain rats from 20 to 60 days of age. Data showed that the mean frequency of total play was markedly increased in neonatally underfed subjects. Play did also increase in the females and during the interaction in pairs and in the play that occurred during the prepuberal period. These findings suggest that early food restriction and the unavoidable sensory deprivation associated to the undernourishing procedure, interfere with the neuroendocrine maturational processes of central and peripheral modulatory mechanisms underlying play behavior.

Early malnutrition followed by nutritional restoration lowers the conduction velocity and excitability of the corticospinal tract

The physiological sequelae of undernutrition were investigated in rats that were undernourished from day 1-21 and subsequently free-fed to 75 days of age. Population responses were recorded in the corticospinal tract following surface stimulation of the motor cortex, which activates corticospinal cells directly, and also indirectly via cortical synapses. The conduction velocity of the fastest corticospinal fibers in 15 malnourished rats was 16.9 m/s, significantly slower (P < 0.001) than the 20.0 m/s observed in 26 controls. In addition, the excitability of corticospinal neurons to direct stimulation was reduced as much as 67% in malnourished rats, while no effect on synaptic activation was observed. Our findings suggest that early malnutrition reduces the number of large fibers in the adult corticospinal tract. These results are discussed with respect to known morphological and behavioral effects of malnutrition in rats and their relevance to humans.