Cerebellar Weight Research Articles

Elephant brain: Part I: Gross morphology, functions, comparative anatomy, and evolution

We report morphological data on brains of four African, Loxodonta africana, and three Asian elephants, Elephas maximus, and compare findings to literature. Brains exhibit a gyral pattern more complex and with more numerous gyri than in primates, humans included, and in carnivores, but less complex than in cetaceans. Cerebral frontal, parietal, temporal, limbic, and insular lobes are well developed, whereas the occipital lobe is relatively small. The insula is not as opercularized as in man. The temporal lobe is disproportionately large and expands laterally. Humans and elephants have three parallel temporal gyri: superior, middle, and inferior. Hippocampal sizes in elephants and humans are comparable, but proportionally smaller in elephant. A possible carotid rete was observed at the base of the brain. Brain size appears to be related to body size, ecology, sociality, and longevity. Elephant adult brain averages 4783 g, the largest among living and extinct terrestrial mammals; elephant neonate brain averages 50% of its adult brain weight (25% in humans). Cerebellar weight averages 18.6% of brain (1.8 times larger than in humans). During evolution, encephalization quotient has increased by 10-fold (0.2 for extinct Moeritherium, ∼2.0 for extant elephants). We present 20 figures of the elephant brain, 16 of which contain new material. Similarities between human and elephant brains could be due to convergent evolution; both display mosaic characters and are highly derived mammals. Humans and elephants use and make tools and show a range of complex learning skills and behaviors. In elephants, the large amount of cerebral cortex, especially in the temporal lobe, and the well-developed olfactory system, structures associated with complex learning and behavioral functions in humans, may provide the substrate for such complex skills and behavior.

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.

A Novel Mutant Mouse, joggle, with Inherited Ataxia

While establishing a new mouse strain, we discovered a novel mutant mouse that exhibited ataxia. Mating experiments showed that the mutant phenotype was due to a single autosomal recessive gene, which we have termed joggle (gene symbol: jog). The ataxia becomes apparent around postnatal day 12, when the mice first attempt to walk, and worsens thereafter. The life span of the mutant mouse is comparable to that of the wild-type mouse. After 21 days of age, the cerebellum weights of the jog/jog mice are significantly lower than those of the wild-type mice. These observations indicate that jog/jog mutant mice could be useful models for biomedical research.

Cerebellar vermis morphology in children with spina bifida and Chiari type II malformation

Posterior fossa size and cerebellar weight and volume are reduced in Chiari type II malformation (CII). This is assumed to affect the cerebellum uniformly. We quantified the presumed reduction in vermis size on magnetic resonance imaging (MRI). A midsagittal brain MRI slice was selected from each of 68 participants with CII (mean age 13 years). Control participants were 28 typically developing children (mean age 14.1 years). Midsagittal surface areas occupied by the intracranial fossa, posterior fossa, vermis, and its lobules were measured. Mean posterior fossa area was significantly smaller (P<0.003), although mean vermis area was significantly larger (P<0.0001), in participants with CII than in control participants. This expansion involved vermis lobules I-V and VI-VII areas (P<0.0001). The midsagittal vermis was expanded and not reduced in size in participants with CII. This is attributed to compressive displacement of midline structures within the confines of a small posterior fossa.

A High Inorganic Phosphate Diet Perturbs Brain Growth, Alters Akt-ERK Signaling, and Results in Changes in Cap-Dependent Translation

Inorganic phosphate (Pi) plays a key role in diverse physiological functions. Recently, considerable progress has been made in our understanding of the function and regulation of the brain-specific sodium-dependent inorganic phosphate transporter 1 (NPT1), which is found to exist principally in cerebrum and cerebellum. The potential importance of Pi as a novel signaling molecule and the poor prognosis of diverse neurodegenerative diseases that involve brain-specific NPT1 have prompted us to define the pathways by which Pi affects mouse brain growth. A high phosphate diet caused an increase in serum Pi accompanied by a decrease in calcium, and a decrease in body weight coupled with a decreased relative weight of cerebellum. A high phosphate diet caused a significant increase in protein expression of NPT1, both in cerebrum and cerebellum. Additionally, the high phosphate diet increased Homo sapiens v-akt murine thymoma viral oncogene homolog 1 (Akt) phosphorylation at Ser473 in cerebrum and cerebellum, whereas suppression of Akt phosphorylation at Thr308 was observed only in cerebellum. Selective suppression of eukaryotic translation initiation factor-binding protein (eIF4E-BP1) in cerebrum was induced by high levels of Pi, which induced cap-dependent and cap-independent protein translation in cerebrum and cerebellum, respectively. Phosphorylation of extracellular regulated kinase 1 (ERK1) in comparison with that of ERK2 was significantly reduced in both cerebrum and cerebellum. High levels of Pi reduced protein expressions of proliferating cell nuclear antigen (PCNA) and cyclin D1 in cerebrum and cerebellum. In conclusion, the results indicate that high dietary Pi can perturb normal brain growth, possibly through Akt-ERK signaling in developing mice.

Deficits in the Brain Growth in Rats Induced by Methylmercury Treatment during the Brain Growth Spurt

This paper describes the deficits in brain regional growth of rats treated with methylmercury (MeHg) among the postnatal developing phases. Rats were orally administered 10 mg/kg/day of methylmercury chloride (MMC) for 10 consecutive days from postnatal days 1 (PD-1), -14 and -35, which corresponded to the early-, late- and post-brain growth spurt, respectively. Weight-matched control rats were periodically isolated from their mother or diet and placed in an incubator for intervals of 4 to 10 hr in order to adjust the body weight to MMC-treated rats. The earlier the postnatal phase the higher the resistance to body weight loss induced by MMC. The rats were dissected on the day after final MMC treatment and the weight of organs and their mercury (Hg) concentrations were measured. Hg accumulation in the brain on the day after final treatment with 10 mg/kg/day of MMC was highest in the rats treated during the late-brain growth spurt. On the other hand, Hg accumulations in the liver and kidney increased rapidly with development of postnatal phases. Then, the brain/kidney and brain/liver ratio of Hg concentration were much higher in early postnatal rats than in later one. The weight of brain regions in MMC-treated rats was compared with those in weight-matched control rats. The significantly lower weight of the cerebrum, cerebellum and midbrain + diencephalon were confirmed in rats treated with MMC during the early-brain growth spurt. The significantly lower cerebellum weight was confirmed in rats treated with MMC during the late-brain growth spurt. The Significant differences were not observed in the brain regions in rats treated during post-brain growth spurt. In the case of human, a similar reduction of the brain weight occurred in the fetal and non-fetal infantile Minamata disease patients. The experiment using postnatal rats succeeded to reproduce the deficit in the brain growth during the early- and late brain growth spurt by MMC treatment.

Purkinje cell loss in the cerebellum of ataxic mutant mouse, dilute‐lethal: A fractionator study

This study estimated total number of Purkinje cells in the cerebellum of an ataxic mutant mouse, dilute-lethal (DL), with reference to severe ataxic symptoms of this mutant. On postnatal day (PD) 21, the cerebellar weight is significantly lower in DL than in non-ataxic littermates (control mice). Total number of Purkinje cells is also significantly lower in DL than in the controls; approximately 25% less in DL than in the controls. Furthermore, we performed in situ nick end labeling (TUNEL) -staining in the cerebellum of DL during prenatal and postnatal periods in order to examine the cause of the reduced Purkinje cell number. For analyzes of the mutant fetuses, it is necessary to identify the homozygous mutant. We succeeded in identifying the homozygous DL fetuses from the control fetuses (wild-type or heterozygous fetuses) by the hair color of the grafted skin pieces on nude mice. The histological features of the cerebellar primordium did not differ between the DL and controls on embryonic and postnatal ages examined. In DL, a significantly greater number of TUNEL-positive Purkinje cells was detected on embryonic day (ED) 12, but not throughout ED 14 to PD 21. The results suggest that the Purkinje cell loss in the DL cerebellum is attributed to increased apoptotic cell death of the progenitors. This may be involved in the development of severe ataxic symptoms of DL.

Effects of Undernutrition on Glycine Metabolism in the Cerebellum of Rats

Undernutrition is a worldwide problem affecting millions of unborn and young children during the most vulnerable stages of brain development. Total restriction of protein during the perinatal period of life can alter the development of the mammalian fetus and have marked repercussions on development of the central nervous system (CNS). The brain is vulnerable to undernutrition with altered morphologic and biochemical maturation, leading to impaired functions. The focus of this study is to investigate [U-¹⁴C]glycine metabolism in undernourished rats submitted to pre- and postnatal protein deprivation (diet: 8% protein with and without addition of L-methionine; control group: 25% protein). Although undernutrition produced a reduction in cerebellar weight and alterations in the DNA concentration, the present study shows that glycine metabolism in this structure is partially protected because the undernourished group with L-methionine did not show modifications in glycine metabolism at all ages studied. However, L-methionine deficiency alters glycine metabolism at 7 and 21 days, but in the adult age both undernourished groups presented no differences in oxidation to CO₂, conversion to lipids and incorporation into protein from glycine, compared to the control group.

Effects of Caffeine on the Saturated and Monounsaturated Fatty Acids of the Newborn Rat Cerebellum

Caffeine (1,3,7-trimethylxanthine) is one of the most commonly consumed drugs in our daily life, and its use is increasing. However, very little attention has been paid to its potential effects on early growth and development. Because of the steady increase in breast feeding of infants and because caffeine diffuses readily into breast milk, the present study examined if caffeine intake by newborn rats during lactation would affect the saturated and monounsaturated fatty acids in the growing cerebellum. A total of 10 timed pregnant rats were purchased from the breeder. At birth litters were combined, and 8 pups were randomly assigned to each dam without regard to the sex of the pups. Dams with litters were divided into 2 groups. Dams of group 1 received a 20% protein diet as a control, and dams of group 2 received a 20% protein diet plus caffeine (4 mg/100 g BW). Pups were killed at day 10. The cerebellums were removed, weighed and homogenized. Gas chromatograph-mass spectrometry was used to identify and quantify free fatty acids. Chronic caffeine exposure from birth to day 10 in pups through the maternal milk resulted in a decrease in cerebellum weight, a significant increase in the saturated fatty acids, and a tendency toward an increase of monounsaturated fatty acids. In addition, there was a slight increase of some of the polyunsaturated fatty acids. However, there was no difference in food intake of the lactating dams and weight gain of the pups between the groups. These data indicate that early caffeine intake by the suckling pups alters the composition of fatty acids of the cerebellum; thus, avoidance of caffeine during lactation is critical. The risks and benefits of caffeine administration in premature infants must be carefully evaluated during this rapid period of brain growth.

Developmental treatment with difluoromethylornithine has few effects on behavior or body weight in Sprague–Dawley rats

Developmental difluoromethylornithine (DFMO) treatment reduces cerebellar weight [Neuroscience 17 (1986) 399, Neurotoxicol. Teratol. 22 (2000) 415, Behav. Brain Res. 126 (2001) 135], but the functional alterations resulting from this have been little investigated. Here, Sprague–Dawley rats were subcutaneously injected with 500 mg/kg DFMO on postnatal days (PNDs) 5–12 and a comprehensive set of behavioral assessments measured early developmental behaviors (righting reflex, negative geotaxis), motor coordination, acoustic startle, short- and long-term activity, social behaviors, anxiety, and spatial learning and memory. DFMO treatment appeared to cause a decreased latency to perform the negative geotaxis behavior on PNDs 8–10 and increased latency to hang by the forelimbs on PNDs 12–14. Our previous study did not indicate similar effects, but age at testing differed between the two studies. DFMO treatment caused a decreased latency to maximum acoustic startle response in both the acoustic startle paradigm and in the pulse-alone trials of the prepulse inhibition test. This DFMO treatment paradigm induced a 10% decrease in adult cerebellar weight [Behav. Brain Res. 126 (2001) 135], but the results here imply that such developmental stunting has few functional alterations.

Chronic prenatal ethanol exposure-induced decrease of guinea pig hippocampal CA1 pyramidal cell and cerebellar Purkinje cell density.

The brain is a key target of ethanol teratogenicity, in which ethanol can produce neurodegeneration in selected areas, including the hippocampus and cerebellum. The research objective was to test the hypothesis that chronic prenatal ethanol exposure, via maternal ethanol administration, produces differential time course of decreased linear density of hippocampal CA1 pyramidal cells and cerebellar Purkinje cells. Timed pregnant guinea pigs received chronic oral administration of ethanol, isocaloric-sucrose/pair-feeding, or water throughout gestation (term, about gestational day (GD) 68), and the offspring were studied at GD 62 (near-term fetus), postnatal day (PD) 1 (neonate), PD 5, and PD 12 (early postnatal life). Ethanol treatment, compared with isocaloric-sucrose/pair-feeding and water treatments, decreased brain, hippocampal, and cerebellar weights at GD 62, PD 1, PD 5, and PD 12. Hippocampal CA1 pyramidal cell linear density and cerebellar Purkinje cell linear density were unaffected at GD 62. Ethanol treatment produced 25, 30, and 30% decreases in linear density of hippocampal CA1 pyramidal cells at PD 1, PD 5, and PD 12, respectively, and a 30% decrease in linear density of cerebellar Purkinje cells at PD 12 only. At PD 5, Purkinje cell profile linear density remained unaffected; however, ethanol treatment appeared to increase linear density of apoptotic Purkinje cell nuclei, as determined by a modified TUNEL method. The data demonstrate that chronic prenatal ethanol exposure produces apparent differential time course of decreased linear density of hippocampal CA1 pyramidal cells and cerebellar Purkinje cells in the developing guinea pig.

Long-term nicotine exposure reduces Purkinje cell number in the adult rat cerebellar vermis

Nicotine affects functions of the central nervous system. A previous study showed that developing cerebellar Purkinje cells are targets for early postnatal nicotine exposure. In this study, we assessed the effects of long-term nicotine exposure on mature cerebellar Purkinje cells. This is particularly relevant since the majority of smokers are exposed to nicotine over a long period. Female adult Sprague–Dawley rats received three doses of nicotine (0.01%, 0.03%, or 0.06%) through their sole water source. After 8 weeks of nicotine exposure, the cerebellar vermis was removed and processed for stereological cell counting. The results showed that this long-term nicotine treatment did not change the cerebellum weight or the size (volume) of the cerebellar vermis. The long-term nicotine treatment regimen did result in a significant loss of mature Purkinje cells in the cerebellum, however, such a loss of Purkinje cells was not nicotine dose-related. These findings indicated that the mature adult cerebellum is susceptible to the damaging effects of nicotine in depleting Purkinje cells in the cerebellum.

The effect of the timing of prenatal X-irradiation on Purkinje cell numbers in rat cerebellum

Exposure of the developing brain to X-irradiation in utero is known to cause various deleterious consequences. We have previously reported the effects of prenatal X-irradiation on the development of the cerebral cortex in rats. We have now extended this study to examine the effects of such X-irradiation on the development of the cerebellum. Wistar rats were exposed to 1.5 Gy X-irradiation either on days 14, 15 or 16 of gestation (E14, E15, E16). Sham-irradiated animals were used as controls. At seven postnatal weeks of age, male rats from each group were deeply anesthetized and killed by intracardiac perfusion with 2.5% glutaraldehyde in 0.1 M phosphate buffer. The unbiased stereological procedure known as the fractionator method was used to estimate the total number of Purkinje cells in the cerebellum of each animal. Body and cerebellar weights from E14 and E15, but not E16 irradiated rats showed significant deficits compared to control animals. Rats irradiated on E16 and control rats had about 285 100–304 800 Purkinje cells in the cerebellum. There was no significant difference between these values. However, E14 and E15 irradiated animals had about 117 500 and 196 300 Purkinje cells, respectively. These estimates were significantly different from those observed in both control and E16 irradiated rats. Given that the phase of division of Purkinje cell progenitors is mainly between E14–E15 and the phase of differentiation and migration is between E16–E20, it is concluded that the vulnerable period of the Purkinje cells to X-irradiation closely overlaps the phase of division of progenitors.

Deficiency of neuronal nitric oxide synthase (nNOS) worsens alcohol-induced microencephaly and neuronal loss in developing mice

Previous work conducted in vitro suggests that nitric oxide (NO) protects developing neurons against the toxic effects of alcohol. We tested the hypothesis that neonatal mice carrying a null mutation for neuronal nitric oxide synthase (nNOS), the enzyme which synthesizes NO in neurons, have increased vulnerability to alcohol-induced microencephaly and neuronal loss. Wild-type mice and mutant (nNOS −/−) mice received a single intraperitoneal injection of ethanol (0.0, 2.2, 3.3, or 4.4 g/kg) daily over postnatal days (PD) 4–9 and were sacrificed on PD10. Peak blood alcohol concentrations were approximately 170, 280, and 385 mg/dl for the 2.2, 3.3 and 4.4 g/kg/day treatment groups, respectively, and did not differ significantly between wild-type and nNOS −/− strains. Exposure to alcohol induced dose-dependent reductions in total brain weight, forebrain weight and cerebellum weight in both strains of mice. However, the reductions in brain weight were significantly more severe in the nNOS −/− mice than in wild type. Quantification of cerebellar neurons revealed that alcohol-induced losses of Purkinje cells and granule cells were both significantly greater in the nNOS −/− mice than in wild type. The increased vulnerability of nNOS-deficient neurons to alcohol-induced cell death was confirmed in vitro. Cerebellar granule cell cultures derived from nNOS −/− and wild-type mice were exposed for 24 h to 0, 100, 200 or 400 mg/dl ethanol. At each alcohol concentration, the nNOS −/− neurons had a significantly greater cell loss than did the wild-type neurons. The results demonstrate that deficiency of nNOS decreases the ability of developing neurons to survive the toxic effects of alcohol. Because NO upregulates intracellular cGMP, which can activate cGMP-dependent protein kinase (PKG), we hypothesize that the NO–cGMP–PKG pathway has a neuroprotective role against alcohol toxicity within the developing brain.

Neonatal exposure of newborn mice to pyrethroid (permethrin) represses activity-dependent c-fos mRNA expression in cerebellum.

In a previous report, we demonstrated that the exposure of cultured mouse cerebellar granule cells to permethrin, a type I pyrethroid insecticide, repressed the induction of activity-dependent c- fos and brain-derived neurotrophic factor (BDNF) gene expression, accompanying a decrease in Ca(2+) influx into neurons. In addition, it has been suggested that some pyrethroids, including permethrin, are endocrine-modulating chemicals and accumulate in human breast milk. In this study, therefore, we investigated whether lactational exposure of newborn mice to permethrin influenced c- fos, BDNF and beta-actin gene expression in the developing neonatal cerebellum. In the cerebella of control neonates, c- fos mRNA expression was characterized by a significant increase in postnatal weeks 2 and 3, followed by a marked decrease. In the cerebella of permethrin-treated neonates, the expression of c- fos mRNA was dose-dependently repressed by cis-permethrin more effectively than by trans-permethrin at postnatal week 3, without alterations in the body or cerebellum weights of neonates. In the fourth and fifth week, however, c- fos mRNA expression had decreased to the same level as that in the control and permethrin-treated neonates. A decrease in BDNF mRNA expression tended to be observed in the cerebella of newborn mice on exposure to permethrin. Thus, our results indicate that the activity-dependent gene expressions in cerebellar neuronal cells can be repressed by permethrin both in vitro and in vivo, and suggest that lactational exposure to pyrethroids might affect the postnatal development of the mammalian brain.

Ganglioside alterations in the central nervous system of rats chronically injected with methylmalonic and propionic acids.

Neurological dysfunction and structural cerebral abnormalities are commonly found in patients with methylmalonic and propionic acidemia. However, the mechanisms underlying the neuropathology of these disorders are poorly understood. We have previously demonstrated that methylmalonic and propionic acids induce a significant reduction of ganglioside N-acetylneuraminic acid in the brain of rats subjected to chronic administration of these metabolites. In the present study, we investigated the in vivo effects of chronic administration of methylmalonic (MMA) and propionic (PA) acids (from the 6th to the 28th day of life) on the distribution and composition of gangliosides in the cerebellum and cerebral cortex of rats. Control rats were treated with the same volumes of saline. It was first verified that MMA and PA treatment did not modify body, cerebellum, or cortical weight, nor the ganglioside concentration in the cerebral cortex of the animals. In contrast, a significant reduction in total ganglioside content in the cerebellum of approximately 20-30% and 50% of control levels occurred in rats injected with MMA and PA, respectively. Moreover, chronic MMA and PA administration did not interfere with the ganglioside pattern in the cerebral cortex, whereas the distribution of individual gangliosides was altered in the cerebellum of MMA- and PA-treated animals. Rats injected with MMA demonstrated a marked decrease in GM1 and GD3, whereas chronic PA treatment provoked a significant reduction of all ganglioside species, with the exception of an increase in GM2. Since gangliosides are closely related to the dendritic surface and other neural membranes, indirectly reflecting synaptogenesis, these ganglioside abnormalities may be associated with the brain damage found in methylmalonic and propionic acidemias.

No alterations in the performance of two interval timing operant tasks after α-difluoromethylornithine (DFMO)-induced cerebellar stunting

The cerebellum is critically involved in temporal processes in the millisecond range and may be involved in longer time estimations (i.e. in the seconds range). Estimates in the millisecond range are impaired after developmentally induced cerebellar alterations, however, little is known about the effects of similar alterations on longer timing performance. Appropriately timed DFMO treatment reliably causes cerebellar stunting in rats, however, its effects on temporal estimation performance are unknown. Here, male and female Sprague–Dawley rats were treated with subcutaneous injections of 500 mg/kg DFMO on postnatal days 5–12, causing a 10% cerebellar weight reduction at adulthood. As adults, subjects were tested under one of two paradigms — a differential reinforcement of low response rate (DRL) task requiring that subjects withhold a lever press response for 10–14 s or a temporal response differentiation (TRD) task requiring that subjects maintain a lever press response for 10–14 s. Training and steady-state performance of the DRL and TRD tasks were not significantly altered by DFMO treatment. Performance after acute challenges with two dopaminergic agonists (2.00–7.50 mg/kg methylphenidate and 0.10–1.00 mg/kg d-amphetamine) was measured after which all subjects underwent behavioral extinction. Generally, performance after methylphenidate and d-amphetamine was similar in control and DFMO-treated rats and DFMO treatment had no differential effects on performance during extinction. These results support findings from an earlier study [Ferguson SA, Paule MG, Holson RR. Neonatal dexamethasoneon day 7 in rats causes behavioral alterations reflective of hippocampal, but not cerebellar, deficits. Neurotoxicol Teratol, 2001; 23:57–69] indicating that developmental cerebellar stunting has few effects on time estimation within the range of seconds.

Alcohol‐Mediated Purkinje Cell Loss in the Absence of Hypoxemia During the Third Trimester in an Ovine Model System

Although the mechanisms that underlie fetal alcohol-induced neuronal loss have not been determined, hypoxia/hypoxemia has been considered a leading candidate. This study was designed to test the hypothesis that neuronal loss could occur in the developing brain in the absence of fetal hypoxemia. Three groups of pregnant sheep were used: a control group, a binge-drinking group, and a pair-fed group. The alcohol and pair-fed animals were anesthetized on day 113 of pregnancy, and the mothers and fetuses were instrumented with arterial and venous catheters. All animals were killed on day 133. Stereological cell counting techniques were used to estimate the total number of Purkinje cells in the fetal cerebellum. Peak maternal and fetal blood alcohol concentrations did not produce fetal hypoxemia. Nevertheless, there was a 25% loss of Purkinje cells of the cerebellum in the alcohol-exposed fetuses compared with that in the pair-fed controls. The loss of neurons was not accompanied by microencephaly or a concomitant decrease in either cerebellar weight or volume of the fetal cerebellum. Neuronal loss can be observed after alcohol exposure during the third trimester equivalent in fetal sheep in the absence of alcohol-induced hypoxemia. Furthermore, cell loss in the absence of deficits in gross brain weight or regional brain volume indicates that the lack of gross brain volume deficits from magnetic resonance imaging techniques is not a reliable indication that the brain is unaffected by the alcohol exposure.

Effect of prenatal ethanol exposure during the brain growth spurt of the guinea pig

This study tested the hypothesis that prenatal ethanol exposure during the last third of gestation, including the brain growth spurt (BGS), in the guinea pig produces neurobehavioural teratogenicity, manifesting as brain growth restriction and hyperactivity. Pregnant guinea pigs (term, about gestational day (GD) 68) received oral administration of ethanol (2 g/kg maternal body weight per day on GD 43 and/or GD 44 and then 4 g/kg maternal body weight per day from GD 45 to GD 62), isocaloric-sucrose/pair-feeding, or water. Maternal blood ethanol concentration (BEC) on GD 57 or 58, at 1 h after the daily dose, was 340±76 mg/dl ( n=8). Ethanol treatment decreased brain, cerebral cortical, hippocampal, and cerebellar weights at GD 63 ( P<0.05), and decreased brain and cerebral cortical weights at postnatal day 10 ( P<0.05), with no effect on body weight and no apparent effect on spontaneous locomotor activity. The data demonstrate that, in the guinea pig, prenatal ethanol exposure during the last third of gestation, including the BGS, decreases brain weight that persists into postnatal life, which is associated with growth restriction of the cerebral cortex. However, this prenatal ethanol exposure regimen, including the BGS, does not increase spontaneous locomotor activity in contrast to the persistent hyperactivity that occurs after chronic ethanol exposure throughout gestation.

Effect of Chemically Induced Propionic Acidemia on Neurobehavioral Development of Rats

High levels of propionic acid (PPA) comparable to those of human propionic acidemia were achieved in blood (1–5 mmol/l) and brain (1 μmol/g) of rats by administering saline-buffered propionate (pH 7.4) subcutaneously twice a day from the 6th to the 28th day of life. PPA doses ranged from 1.44 to 1.92 μmol/g body weight as a function of animal age. Control rats were treated with saline in the same volumes. Growth and development of physical landmarks were assessed by monitoring the following parameters daily: body weight, upper incisor eruption, eye opening, and hair coat. Development of some reflexes was also monitored, and a specific subset of motor skills was evaluated at days 14 and 21 of life by the free-fall righting test and the spontaneous alternation test. Chronic PPA administration had no effect on body weight, cerebral cortex weight, or cerebellum weight, but caused slight but significant delays in the day of appearance of hair coat and eye opening, indicating an effect of PPA on the development of physical parameters. Free-fall righting was impaired in PPA-treated animals. On the other hand, PPA administration had no effect on the performance of the animals in the spontaneous alternation tests. Long-term effects of early PPA administration were investigated by assessing animal performance in an aversive task (two-way shuttle avoidance task) and in a nonaversive (open-field task) behavioral task at 60 days of age. PPA-treated rats did not habituate to the open field, and presented a lack of retention of the shuttle-avoidance task. Our results suggest that early postnatal PPA administration to rats alters normal development and induces long-term behavioral deficits in aversive and nonaversive tasks.