Curcumin Prevents Cerebellar Hypoplasia and Restores the Behavior in Hyperbilirubinemic Gunn Rat by a Pleiotropic Effect on the Molecular Effectors of Brain Damage.

Bilirubin toxicity to the central nervous system (CNS) is responsible for severe and permanent neurologic damage, resulting in hearing loss, cognitive, and movement impairment. Timely and effective management of severe neonatal hyperbilirubinemia by phototherapy or exchange transfusion is crucial for avoiding permanent neurological consequences, but these therapies are not always possible, particularly in low-income countries. To explore alternative options, we investigated a pharmaceutical approach focused on protecting the CNS from pigment toxicity, independently from serum bilirubin level. To this goal, we tested the ability of curcumin, a nutraceutical already used with relevant results in animal models as well as in clinics in other diseases, in the Gunn rat, the spontaneous model of neonatal hyperbilirubinemia. Curcumin treatment fully abolished the landmark cerebellar hypoplasia of Gunn rat, restoring the histological features, and reverting the behavioral abnormalities present in the hyperbilirubinemic rat. The protection was mediated by a multi-target action on the main bilirubin-induced pathological mechanism ongoing CNS damage (inflammation, redox imbalance, and glutamate neurotoxicity). If confirmed by independent studies, the result suggests the potential of curcumin as an alternative/complementary approach to bilirubin-induced brain damage in the clinical scenario.

WNT1-associated osteogenesis imperfecta with atrophic frontal lobes and arachnoid cysts.

A rare form of osteogenesis imperfecta (OI) caused by Wingless-type MMTV integration site family 1 (WNT1) mutations combines central nervous system (CNS) anomalies with the characteristic increased susceptibility to fractures. We report an additional case where arachnoid cysts extend the phenotype, and that also confirms the association of intellectual disabilities with asymmetric cerebellar hypoplasia here. Interestingly, if the cerebellum is normal in this disorder, intelligence is as well, analogous to an association with similar delays in a subset of patients with sporadic unilateral cerebellar hypoplasia. Those cases typically appear to represent vascular disruptions, and we suggest that most brain anomalies in WNT1-associated OI have vascular origins related to a role for WNT1 in CNS angiogenesis. This unusual combination of benign cerebellar findings with effects on higher functions in these two situations raises the possibility that WNT1 is involved in the pathogenesis of the associated sporadic cases as well. Finally, our patient reacted poorly to pamidronate, which appears ineffective with this form of OI, so that a lack of improvement is an indication for molecular testing that includes WNT1.

MRI analysis of cerebellar and vestibular developmental phenotypes in Gbx2 conditional knockout mice.

PURPOSE: Our aim in this study was to apply three-dimensional MRI methods to analyze early postnatal morphological phenotypes in a Gbx2 conditional knockout (Gbx2-CKO) mouse that has variable midline deletions in the central cerebellum, reminiscent of many human cerebellar hypoplasia syndromes. METHODS: In vivo three-dimensional manganese-enhanced MRI at 100-µm isotropic resolution was used to visualize mouse brains between postnatal days 3 and 11, when cerebellum morphology undergoes dramatic changes. Deformation-based morphometry and volumetric analysis of manganese-enhanced MRI images were used to, respectively, detect and quantify morphological phenotypes in Gbx2-CKO mice. Ex vivo micro-MRI was performed after perfusion-fixation with supplemented gadolinium for higher resolution (50-µm) analysis. RESULTS: In vivo manganese-enhanced MRI and deformation-based morphometry correctly identified known cerebellar defects in Gbx2-CKO mice, and novel phenotypes were discovered in the deep cerebellar nuclei and the vestibulo-cerebellum, both validated using histology. Ex vivo micro-MRI revealed subtle phenotypes in both the vestibulo-cerebellum and the vestibulo-cochlear organ, providing an interesting example of complementary phenotypes in a sensory organ and its associated brain region. CONCLUSION: These results show the potential of three-dimensional MRI for detecting and analyzing developmental defects in mouse models of neurodevelopmental diseases.

Antenatal taurine supplementation for improving brain ultrastructure in fetal rats with intrauterine growth restriction.

Changes in brain ultrastructure of fetal rats with intrauterine growth restriction (IUGR) were explored and the effects of antenatal taurine supplementation on their brain ultrastructure were determined. Fifteen pregnant rats were randomly divided into three groups: control group, IUGR model group and IUGR group given antenatal taurine supplements. Taurine was added to the diet of the taurine group at a dose of 300 mg/kg/d from 12 days after conception until natural delivery. Transmission electron microscopy was used to observe ultrastructural changes in the brains of the newborn rats. At the same time, brain cellular apoptosis was detected using TUNEL, and the changes in protein expression of neuron specific enolase and glial fibrillary acidic protein were analyzed using immunohistochemistry. The results showed that: 1) The average body weight and cerebral weight were significantly lower in the IUGR group than in the control group (p<0.01) and both of them were less so after taurine was supplemented (p<0.01). 2) Transmission electron microscopy revealed that brain cortex structures were sparse IUGR rats, showing many scattered apoptotic cells, decreased numbers of synapses, lower glial cell proliferation, and fewer neurons, more sparsely arranged, while these factors were significantly improved with taurine supplementation. 3) The results of TUNEL showed that the counts of apoptotic brain cells in IUGR groups were significantly increased from those in control groups and that taurine could significantly decrease brain cell apoptosis (p<0.001). 4) The results of immunohistochemistry showed that antenatal taurine-supplementation could significantly increase the counts of neuron specific enolase and glial fibrillary acidic protein immunoreactive cells in fetal rats with IUGR (p<0.001). It can be concluded that it IUGR has a significant detrimental influence on the development of fetal rat brains, and antenatal supplement of taurine can significantly improve the IUGR fetal brain development.

Astrocyte-mediated hepatocyte growth factor/scatter factor supplementation restores GABAergic interneurons and corrects reversal learning deficits in mice.

Many psychiatric and neurological disorders present persistent neuroanatomical abnormalities in multiple brain regions that may reflect a common origin for a developmental disturbance. In mammals, many of the local GABAergic inhibitory interneurons arise from a single subcortical source. Perturbations in the ontogeny of the GABAergic interneurons may be reflected in the adult by interneuron deficits in both frontal cerebral cortical and striatal regions. Disrupted GABAergic circuitry has been reported in patients with schizophrenia and frontal lobe epilepsy and may contribute to their associated impairments in behavioral flexibility. The present study demonstrates that one type of behavioral flexibility, reversal learning, is dependent upon proper numbers of GABAergic interneurons. Mice with abnormal interneuron ontogeny have reduced numbers of parvalbumin-expressing GABAergic local interneurons in the orbitofrontal cortical and striatal regions and impaired reversal leaning. Using a genetic approach, both the anatomical and functional deficiencies are restored with exogenous postnatal growth factor supplementation. These results show that GABAergic local circuitry is critical for modulating behavioral flexibility and that birth defects can be corrected by replenishing crucial growth factors.

Prenatal exposure to bisphenol A affects adult murine neocortical structure.

Prenatal exposure to low-doses of bisphenol A (BPA) has been shown to affect murine neocortical development by accelerating neuronal differentiation/migration through disrupting thyroid hormone function. We therefore studied whether prenatal exposure to low-doses of BPA affected organization of adult neocortical structures. Pregnant mice were injected with 20 microg/kg of BPA daily from embryonic day 0.5 (E0.5) and bromodeoxyuridine (BrdU) was injected at E12.5, E14.5 and at E16.5, and the fetal brains were analyzed after birth. The BrdU-positive cells labeled at E14.5 were significantly increased in the Vth and VIth cortical layers of BPA-treated mice at postnatal 3 weeks (P3W), whereas they were confined to the IVth layer of control mice, though such differences disappeared at P12W. The thalamocortical projections demonstrated by DiI-labeling were abnormal at P3W and P12W in BPA-treated mice. These results indicate that BPA might affect not only neocortical development but also thalamocortical connections.

Inherited tertiary hypothyroidism in Sprague-Dawley rats.

Thyroid hormones (THs) are important in the development and maturation of the central nervous system (CNS). The significant actions of THs during CNS development occur at the time when TH levels are lower than those in the mother and the hypothalamic-thyroid (HPT) axis is not fully functional. In the developing rat nervous system, primarily the cerebellum, the first three postnatal weeks represent a period of significant sensitivity to thyroid hormones. This study presents a spontaneous, inherited recessive hypothyroidism in Sprague-Dawley rats with devastating functional consequences to the development of the CNS. The clinical signs develop around 14 day's postnatal (dpn) and are characterized by ataxia, spasticity, weight loss and hypercholesterolemia. The afflicted rats died at 30 days due to severe neurological deficits. The deterioration affects the entire CNS and is characterized by progressive neuronal morphological and biochemical changes, demyelination and astrogliosis. The cerebellum, brain stem, neocortex, hippocampus and adrenal gland medulla appear to be most affected. Thyroid Stimulating Hormone (TSH), T3 and T4 levels were significantly lower in hypothyroid rats than control. Immunohistochemistry and RT-PCR demonstrated a reduction of Thyrotropin Releasing Hormone (TRH) in the hypothalamus of hypothyroid rats. The weight of both thyroid and pituitary glands were significantly less in hypothyroid rats than the corresponding normal littermate controls. Transmission electron microscopy demonstrates consistent postsynaptic dendritic, synaptic and spine alterative changes in the brain of hypothyroid rats. These data suggest that we discovered a tertiary form of inherited hypothyroidism involving the hypothalamus.

Developmental timeframes for induction of microgyria and rapid auditory processing deficits in the rat.

Induction of a focal freeze lesion to the skullcap of a 1-day-old rat pup leads to the formation of microgyria similar to those identified postmortem in human dyslexics. Rats with microgyria exhibit rapid auditory processing deficits similar to those seen in language-impaired (LI) children, and infants at risk for LI and these effects are particularly marked in juvenile as compared to adult subjects. In the current study, a startle response paradigm was used to investigate gap detection in juvenile and adult rats that received bilateral freezing lesions or sham surgery on postnatal day (P) 1, 3 or 5. Microgyria were confirmed in P1 and 3 lesion rats, but not in the P5 lesion group. We found a significant reduction in brain weight and neocortical volume in P1 and 3 lesioned brains relative to shams. Juvenile (P27-39) behavioral data indicated significant rapid auditory processing deficits in all three lesion groups as compared to sham subjects, while adult (P60+) data revealed a persistent disparity only between P1-lesioned rats and shams. Combined results suggest that generalized pathology affecting neocortical development is responsible for the presence of rapid auditory processing deficits, rather than factors specific to the formation of microgyria per se. Finally, results show that the window for the induction of rapid auditory processing deficits through disruption of neurodevelopment appears to extend beyond the endpoint for cortical neuronal migration, although, the persistent deficits exhibited by P1 lesion subjects suggest a secondary neurodevelopmental window at the time of cortical neuromigration representing a peak period of vulnerability.

Auditory event-related responses in children with semi-lobar holoprosencephaly.

The purpose of this study was to evaluate auditory sensory and discrimination responses in children with semi-lobar holoprosencephaly (HPE). Event-related potential (ERP) signals were recorded to tone pair stimuli at 62 electrode sites from the scalp using an oddball paradigm (a two-block design, inter-stimulus interval=70 or 300 ms; frequency of tone pair=100 vs. 100 Hz for the frequent and 100 vs. 300 Hz for the infrequent). Latencies and amplitudes of P150, N250, and mismatch negativity (MMN)-like components were compared between children with HPE and controls. Our results revealed less organized ERP waveforms to both stimuli in children with HPE, with diminished P150 and N250 components across brain area. Robust and delayed MMN-like responses were elicited from the children with HPE, with decreased MMN amplitudes in the central, parietal, occipital, and posterior temporal areas. Our results suggest that while brain sensory responses to auditory tones may be impaired in children with semi-lobar HPE, subcomponents of auditory discrimination processes remain functional.

Cortical/subcortical BOLD changes associated with epileptic discharges: an EEG-fMRI study at 3 T.

BACKGROUND: Malformations of cortical development have characteristic interictal discharges, yet the mechanisms of generation of these discharges are not known in humans. Interictal discharges in malformations of cortical development were studied with EEG-fMRI. METHODS: Six subjects with malformations of cortical development and seizures were studied using spike-triggered fMRI at 3 T. The blood oxygen level-dependent (BOLD) signal changes associated with interictal discharges were measured. RESULTS: All subjects showed spike-related BOLD signal changes. In four subjects, the signal increases were seen in the lesion, and in four subjects, decreases were seen surrounding the lesion. Five subjects had BOLD signal changes at distant cortical sites and three had subcortical changes (basal ganglia, reticular formation, or thalamic). CONCLUSION: BOLD signal changes may be directly correlated with overall synaptic activity. Changes were found in and around the lesion of malformations of cortical development and in distant cortical and subcortical structures. The results suggest that EEG-fMRI studies might help elucidate the mechanisms of epileptic discharges in humans.

Impaired gap detection in juvenile microgyric rats.

Previous research with adult animal models links the presence of cortical neuromigrational anomalies (i.e., microgyria similar to that found in brains of dyslexics) with rapid auditory processing (RAP) impairments. RAP impairments are in turn found in children with specific language impairment (SLI) and also in individuals with dyslexia. Gap detection, a simple measure of auditory temporal acuity, appears to be impaired in children with SLI but not in dyslexic adults, even though both groups exhibit impaired processing on more complex, rapid auditory tasks. In the current study, juvenile rats with bilateral microgyria, but not their adult counterparts, exhibited impaired detection of short duration silent gaps in white noise when compared to age-matched sham littermates. Results lend further support to: (1) an association between neuromigrational anomalies and RAP impairments; and (2) the validity of an animal model of RAP impairments associated with language disturbances in humans. Current results also support the view that auditory processing disturbances associated with cortical malformations may be evident early in development at a relatively "low" level (e.g., simple gap detection), but may require "higher-order" auditory discrimination tasks (e.g., tone sequences, phonemic discriminations) to be elicited later in life.

Epilepsy.

PURPOSE OF REVIEW: The purpose of this review is to consider the current and potential role of neuroimaging from an epilepsy perspective, and to illustrate that by combining appropriate imaging techniques, neuroimaging can contribute greatly to elucidating the basic mechanisms of the various forms of epileptic disorders. RECENT FINDINGS: New magnetic resonance imaging sequences (magnetization transfer imaging) and positron emission tomography ligands (serotonergic system) were biologically validated in large groups of patients with localization-related epilepsies. Investigations in genetically determined homogenous patient populations (PAX6, juvenile myoclonic epilepsy) have strengthened the link between genetic defects and neuropathological targets (anterior commissure, thalamus). Magnetic resonance spectroscopy and electroencephalogram-triggered functional magnetic resonance imaging provided converging evidence for a key role of the thalamus in the generation of generalized seizures. The role of functional magnetic resonance imaging in identifying eloquent areas of cortex and its relationship to structural lesions, in particular malformations of cortical development, has been further elucidated. Longitudinal magnetic resonance imaging studies reported progressive volume loss after febrile convulsions and in active epilepsy. SUMMARY: Neuroimaging is essential for improving the efficacy and safety of therapeutic, in particular, surgical procedures. Investigations of larger, more homogenous genetic disorders and longitudinal rather than cross-sectional neuroimaging studies have advanced our knowledge about the cause and effect of epileptic disorders, and will ultimately link defects in molecular genetics with specific neuropathological targets.

Freeze lesion-induced focal cortical dysplasia predisposes to atypical hyperthermic seizures in the immature rat.

PURPOSE: To determine the effects of focal cortical dysplasia on the behavioral and electrographic features of hyperthermia-induced seizures (HSs) in rats. METHODS: A right sensorimotor cortex freeze lesion was induced in postnatal day 1 (P1) rat pups, and HSs were provoked at P10 under continuous monitoring of core temperature; EEGs were recorded from the right amygdala during and after hyperthermia. Controls included both sham-operated at P1 and naïve rats. RESULTS: HSs began with jaw myoclonus, followed by hindlimb clonus and generalized convulsions (GCs), and terminated by a period of posthyperthermia depression. The threshold temperature and latency of jaw myoclonus were similar across the groups. However, both the threshold temperature and latency of GCs were significantly lower in lesioned pups than in controls (40.5 +/- 0.5 degrees C, n = 24, vs. 42.0 +/- 0.2 degrees C, n = 21; p < 0.001; 6.7 +/- 0.6 min, n = 20, vs. 8.4 +/- 0.6 min, n = 22; p < 0.05). In lesioned pups, the threshold and latencies for jaw myoclonus and hindlimb clonus were similar, whereas in controls, the progression from one to the other was marked by significant differences in both parameters. Posthyperthermia depression was longer in lesioned (13.3 +/- 1.2 min, n = 21) than in control (8.0 +/- 0.8 min, n = 20; p < 0.0001) pups. Ictal EEG activity was recorded during both behavioral seizures and posthyperthermia depression. CONCLUSIONS: An HS in rats with a localized freeze lesion results in lower threshold GC and prolonged ictal manifestations, thus supporting a pathophysiologic link between focal cortical dysplasia and atypical febrile seizures, conditions that have a high prevalence in children with mesial temporal lobe epilepsy.

Concurrent generation of subplate and cortical plate neurons in developing trisomy 16 mouse cortex.

During embryonic development of the mammalian cerebral cortex, the generation of the marginal zone (MZ) and subplate (SP) precedes that of the cortical plate (CP). MZ and SP neurons are believed to play a 'pioneering' role in directing the organization of the CP and the specificity of connections between the CP and other brain regions. Here we report that this sequential order of neurogenesis is disrupted in the trisomy 16 (Ts16) mouse, a potential animal model of Down syndrome. Bromodeoxyuridine labeling was used to establish the date of generation of postmitotic SP and CP neurons in the somatosensory cortex. As has been previously reported, most SP neurons in euploid (control) cortex were generated on embryonic day 12.5 (E12.5), and production of CP neurons began a day later. In contrast, in the Ts16 cortex, few SP neurons were born on E12.5 and most were generated on E13.5 and E14.5 when CP neurons were also being produced. Thus, in the Ts16 cortex, many CP neurons are born and arrive at their destinations before the normal complement of SP neurons is present. This disruption of the temporal sequence of SP and CP generation may, therefore, interfere with the pioneering functions of the SP during cortical neurogenesis and may alter the connectivity of the cortex. Indeed, using lipophilic membrane tracers to label axonal projections, we found very little thalamocortical innervation of the Ts16 SP at an age when there is extensive innervation of the euploid SP.

Abnormal distributions of callosal commissural and corticothalamic neurons in the cerebral neocortex of Shaking Rat Kawasaki.

Shaking Rat Kawasaki (SRK) is an autosomal recessive mutant rat recognized by unstable gait and tremor and by early death around the time of weaning. We previously reported that corticospinal tract neurons are malpositioned in the motor cortex of the SRK rat [Ikeda and Terashima (1997) J. Comp. Neurol. 383, 370-380]. In the present study, we examined the distribution pattern of callosal commissural (CC) and corticothalamic (CT) neurons of SRK and normal rats with the injection of horseradish peroxidase (HRP) into the contralateral hemisphere or wheat germ agglutinin-conjugated HRP into the ventral lateral thalamic nucleus. The intracortical distribution pattern of retrogradely labeled CC and CT neurons in the motor cortex of SRK rat was abnormal: CC neurons were more deeply situated and CT neurons were more superficially situated in the SRK cortex than the corresponding components in the normal cortex. Most of labeled CC and CT neurons had abnormal dendritic configurations. Statistical analysis revealed that the difference of the mean intracortical position of CC and CT neurons of the SRK was significantly different from the normal counterparts (Student's t-test, P<0.01). Taken together with previous findings, our data demonstrate that the abnormal cytoarchitecture of SRK cortex resembles the reeler cortex.

GABAergic neuronal subtypes in the human frontal cortex--development and deficits in schizophrenia.

Recent studies have provided evidence for a deficit of GABA-containing interneurons in the frontal cortex in schizophrenia. That this deficit might be brought about during early foetal or neonatal life is a hypothesis consistent with the substantial indications for a neurodevelopmental aetiology of the disease. GABAergic neurons can be defined by the presence of one of three types of calcium binding proteins, which are thought to have neuroprotective properties. We have undertaken an investigation into the postnatal ontology of these neuronal subtypes and find that calretinin expression is relatively constant and present from before birth, calbindin expression is also present early but redistributes in the cortex over the first months of life, while parvalbumin-immunoreactivity is not observed until between 3 and 6 months of age. Investigation of frontal cortical tissue taken post mortem from a series of schizophrenic patients and matched control subjects revealed that parvalbumin-, but not calretinin-immunoreactive cells are significantly diminished in schizophrenia. These observations support the hypothesis that GABAergic deficits in schizophrenia may stem from toxic events occurring during cortical development which selectively target immature neurons before protection by parvalbumin is conferred.