Hava Golan

Specific neurodevelopmental damage in mice offspring following maternal inflammation during pregnancy.

Intrauterine inflammation is a major risk for offspring neurodevelopmental brain damage and may result in cognitive limitations and poor cognitive and perceptual outcomes. Pro-inflammatory cytokines, stimulated during inflammatory response, have a pleotrophic effect on neurons and glia cells. They act in a dose-dependent manner, activate cell-death pathways and also act as trophic factors. In the present study, we have examined in mice the effect of short, systemic maternal inflammation on fetal brain development. Maternal inflammation, induced by lipopolysaccharide (LPS) at gestation day 17, did not affect morphogenic parameters and reflex development during the first month of life. However, maternal inflammation specifically increased the number of pyramidal and granular cells in the hippocampus, as well as the shrinkage of pyramidal cells, but not of the granular cells. No additional major morphological differences were observed in the cerebral cortex or cerebellum. In accordance with the morphological effects, maternal inflammation specifically impaired distinct forms of learning and memory, but not motor function or exploration in the adult offspring. The specific deficiency observed, following maternal inflammation, may suggest particular sensitivity of the hippocampus and other associated brain regions to inflammatory factors during late embryonic development.

Pre-pubertal stress exposure affects adult behavioral response in association with changes in circulating corticosterone and brain-derived neurotrophic factor

Early-life stress produces a cascade of neurobiological events that cause enduring changes in neural plasticity and synaptic efficacy that appear to play pivotal roles in the pathophysiology of post-traumatic stress disorder (PTSD). Brain-derived neurotrophic factor (BDNF) has been implicated in the neurobiological mechanisms of these changes, in interaction with components of the stress response, such as corticosterone. This study examined the consequences of juvenile stress for behavior during adulthood in association with circulating corticosterone levels and BDNF expression. The experiments examined single exposure to predator scent stress (soiled cat litter for 10 min) as compared to repeated exposure, early in life and later on. Behavioral responses were assessed in the elevated plus maze and the acoustic startle response paradigms at 28, 60 and 90 days of age. Plasma corticosterone was measured and brain areas analyzed for BDNF levels. The results show that juvenile stress exposure increased anxiety-like behavior and startle amplitude and decreased plasma corticosterone. This response was seen immediately after exposure and also long term. Adult stress exposure increased anxiety-like behavior, startle amplitude and plasma corticosterone. Exposure to both early and later life trauma elicited reduced levels of corticosterone following the initial exposure, which were not raised by re-exposure, and elicited significant downregulation of BDNF mRNA and protein levels in the hippocampus CA1 subregion. The consequences of adult stress exposure were more severe in rats were exposed to the same stressor as juveniles, indicated increased vulnerability. The results suggest that juvenile stress has resounding effects in adulthood reflected in behavioral responses. The concomitant changes in BDNF and corticosterone levels may mediate the changes in neural plasticity and synaptic functioning underlying clinical manifestations of PTSD.

Intrauterine infection/inflammation during pregnancy and offspring brain damages: Possible mechanisms involved

Intrauterine infection is considered as one of the major maternal insults during pregnancy. Intrauterine infection during pregnancy could lead to brain damage of the developmental fetus and offspring. Effects on the fetal, newborn, and adult central nervous system (CNS) may include signs of neurological problems, developmental abnormalities and delays, and intellectual deficits. However, the mechanisms or pathophysiology that leads to permanent brain damage during development are complex and not fully understood. This damage may affect morphogenic and behavioral phenotypes of the developed offspring, and that mice brain damage could be mediated through a final common pathway, which includes over-stimulation of excitatory amino acid receptor, over-production of vascularization/angiogenesis, pro-inflammatory cytokines, neurotrophic factors and apoptotic-inducing factors.

Maternal hypoxia during pregnancy induces fetal neurodevelopmental brain damage: Partial protection by magnesium sulfate

Fetal low brain oxygenation may be an outcome of maternal complications during pregnancy and is associated with increased risk of cerebral palsy and periventricular leukomalacia in newborns. One treatment used for prevention of fetal brain damage is maternal treatment with MgSO4. Although this treatment is indicated to reduce the risk of cerebral palsy in newborns, its use remains controversial. We have shown previously that pretreatment with MgSO4 in a mouse model of maternal hypoxia prevented a delay in the development of motor reflexes induced by hypoxia. We demonstrate here that pretreatment with MgSO4 reduces hypoxia‐induced motor disabilities in adult offspring. This effect is associated with histologic protection of the Purkinje cells in the cerebellum and stabilization of brain‐derived neurotrophic factor (BDNF) levels in the cerebellum. MgSO4 did not prevent the reduction in cerebral cortex cell density and cell size induced by maternal hypoxia, however, nor did it interfere with the modulation of BDNF and nerve growth factor (NGF) expression in the cerebral cortex. MgSO4 pretreatment also prevented the impairment of short‐term memory (30 min, P < 0.05) but not long‐term memory (7 days). Nevertheless, maternal pretreatment with MgSO4 reduced CA1 cell layer width and induced alterations in both NGF and BDNF in the hippocampus. These results support the prophylactic effect of MgSO4 against motor disabilities; however, they may also indicate possible harmful effects on the cerebral cortex and hippocampus.

Maternal Hypoxia during Pregnancy Delays the Development of Motor Reflexes in Newborn Mice

Prenatal hypoxic-ischemic brain injury is believed to cause permanent neurological deficits in newborns. We investigated the possibility that maternal hypoxia during pregnancy leads to offspring brain damage and its prevention by i.p. administration of MgSO4. Pregnant mice at gestation day 17 were exposed to hypoxia or air following pretreatment with saline or Mg. Newborn mice to mothers exposed to hypoxia demonstrated faster development of morphogenic parameters such as eyelid opening, hair growth and teeth eruption. In addition, hypoxia delayed the development of motor reflexes. Pretreatment with Mg compensates for hypoxia-induced impairment and in some cases accelerates the development of these functions. In conclusion, maternal hypoxia significantly modifies the developmental process of newborn mice. In our study, pretreatment with Mg showed significant prophylactic action against motor impairments.

Normal aging of offspring mice of mothers with induced inflammation during pregnancy

Intrauterine inflammation is a major risk for offspring neurodevelopmental brain damage and may result in cognitive limitations and poor cognitive and perceptual outcomes. In the present study we tested the possibility that prenatal exposure to a high level of inflammatory factors may increase the risk for neurodegeneration in aging. The effect of systemic maternal inflammation (MI), induced by lipopolysaccharide (LPS) on offspring brain aging, was examined in 8 month old (adult) and 20 month old (aged) offspring mice. A significant effect of age was found in the distance and velocity of exploration in the open field in both groups. In addition, MI aged offspring covered longer distances and enter frequently to the center of the field compared with the aged control group. Although only little difference was found in the aged MI offspring compared with the control offspring, the overall profile of behavior of these mice differs from that of the control group, as detected by clustering analysis. The expression of the death-associated protein FAS-ligand and the amount of apoptotic cell death were examined in the brains of aged offspring. Similar levels of FAS-ligand expression and parallel density of apoptotic cells were detected in the brains of aged mice of control and MI groups. Altogether, moderate systemic MI was not found to increase the risk for cell death in the aged offspring; limited effect was found in mice profile of behavior.

Remodeling of hippocampal GABAergic system in adult offspring after maternal hypoxia and magnesium sulfate load : Immunohistochemical study

A strong relationship between hypoxia and fetal brain damage has been described. Specific susceptibility of the GABAergic neurons to these conditions may be crucial to the damage induced. We have previously shown, in a mouse model, that maternal pretreatment with magnesium sulfate (Mg) partially prevented the behavioral consequences of maternal hypoxia in the adult offspring. Here, we tested the effect of maternal hypoxia and maternal Mg load on the GABAergic system of 8-month-old offspring. The immunoreactivity (IR) of several proteins expressed in GABAergic neurons and inhibitory synapses was analyzed in the following regions of the adult offspring brain: hippocampus, cortical M1, caudate putamen, and lateral globus pallidus. Maternal hypoxia reduced the density of parvalbumin (PV)-IR neurons in the hippocampus. The density of PV-IR and calbindin (CB)-IR neurons was also reduced in the deep and superficial layers of the M1. Maternal pretreatment with Mg had a prophylactic action in the superficial, but not the deep, layers of M1. Also, in offspring from the maternal hypoxia group, the vesicular GABA transporter (VGAT)-IR was enhanced in the hippocampal CA1 and hilus regions. No effect of maternal hypoxia on VGAT-IR was observed in the M1. However, maternal pretreatment with Mg enhanced VGAT-IR and glutamate decarboxylase-IR in the deep layers of the M1. In the globus pallidus, maternal hypoxia enhanced CB-IR, which was prevented by maternal pretreatment with Mg. In conclusion, maternal hypoxia induced a loss of PV-IR and CB-IR neurons; maternal pretreatment with Mg partially protected these neuron populations. An increase in proteins of inhibitory synapses, observed under hypoxic conditions in several brain regions, may be a result of some compensatory mechanism.

GABA metabolism controls inhibition efficacy in the mammalian CNS

The effects of changes in gamma-aminobutyric acid (GABA) metabolism or inhibitory processes was studied in the perforant path-dentate gyrus synapses in rat cortico-hippocampal slices, and in the monosynaptic-reflex circuit in isolated newborn, rat spinal cord. GABA metabolism was modulated by pharmacological block of either the anabolic enzyme glutamate decarboxylase (GAD) or the catabolic enzyme GABA transaminase (GABA-T). The results support the notion that GABA concentration determines the efficacy of inhibition in these regions of the central nervous system (CNS).

Synaptic transmission at high pressure: Effects of [Ca2+]o

1. The effects of pressure on synaptic currents were examined in crayfish abdominal muscles. 2. Helium pressure (10.1 MPa) considerably decreased extracellularly-recorded excitatory junctional potentials associated with increased short-term facilitation. 3. These effects could be mimicked by a reduction of [Ca2+]o, and partially compensated by an increase in [Ca2+]o. 4. Pressure also reduced the amplitude of the extracellular nerve terminal potentials (ENTP) by up to 25%, and significantly increased synaptic delay in a [Ca2+]o-dependent manner. 5. The interaction between compression and various [Ca2+]o were analysed in terms of an existing model of transmitter release. The results were consistent with the hypothesis that high pressure decreases the maximal Ca2+ influx into nerve terminals. 6. The decreased ENTP and increased synaptic delay suggest that additional processes may be involved in pressure effects on synaptic transmission.

Sex-dependent behavioral effects of Mthfr deficiency and neonatal GABA potentiation in mice.

The methylenetetrahydrofolate reductase (Mthfr) gene and/or abnormal homocysteine-folate metabolism are associated with increased risk for birth defects and neuropsychiatric diseases. In addition, disturbances of the GABAergic system in the brain as well as Mthfr polymorphism are associated with neurodevelopmental disorders such as schizophrenia and autism. In the present study we performed behavioral phenotyping of male and female Mthfr mice (wild type and their heterozygous littermates). The present study addresses two main questions: (1) genetic susceptibility, as examined by effects of Mthfr deficiency on behavior (Experiment 1) and (2) possible gene-drug interactions as expressed by behavioral phenotyping of Mthfr-deficient mice neonatally exposed to the GABA potentiating drug GVG (Experiment 2). Newborn development was slightly influenced by Mthfr genotype per se (Experiment 1); however the gene-drug interaction similarly affected reflex development in both male and female offspring (Experiment 2). Hyperactivity was demonstrated in Mthfr heterozygous male mice (Experiment 1) and due to GVG treatment in both Wt and Mthfr+/- male and female mice (Experiment 2). The gene-environment interaction did not affect anxiety-related behavior of male mice (Experiment 2). In female mice, gene-treatment interactions abolished the reduced anxiety observed due to GVG treatment and Mthfr genotype (Experiment 2). Finally, recognition memory of adult mice was impaired due to genotype, treatment and the gene-treatment combination in a sex-independent manner (Experiment 2). Overall, Mthfr deficiency and/or GABA potentiation differentially affect a spectrum of behaviors in male and female mice. This study is the first to describe behavioral phenotypes due to Mthfr genotype, GVG treatment and the interaction between these two factors. The behavioral outcomes suggest that Mthfr deficiency modulates the effects of GABA potentiating drugs. These findings suggest that future treatment strategies should consider a combination of genotyping with drug regimens.