Neuroprotective and Anti-Inflammatory Effects of Pinus densiflora Bark Extract in Gerbil Hippocampus Following Transient Forebrain Ischemia.

Korean red pine (Pinus densiflora) belongs to the Genus Pinus, and its bark contains a great amount of naturally occurring phenolic compounds. Until now, few studies have been conducted to assess the neuroprotective effects of Pinus densiflora bark extract against brain ischemic injury. The aim of this study was to investigate the neuroprotective effects of pre-treatment with the extract in the hippocampus following 5-min transient forebrain ischemia in gerbils. Furthermore, this study examined the anti-inflammatory effect as a neuroprotective mechanism of the extract. Pinus densiflora bark was extracted by pure water (100 °C), and this extract was quantitatively analyzed and contained abundant polyphenols, flavonoids, and proanthocyanidins. The extract (25, 50, and 100 mg/kg) was orally administered once a day for seven days before the ischemia. In the gerbil hippocampus, death of the pyramidal neurons was found in the subfield cornu ammonis 1 (CA1) five days after the ischemia. This death was significantly attenuated by pre-treatment with 100 mg/kg, not 25 or 50 mg/kg, of the extract. The treatment with 100 mg/kg of the extract markedly inhibited the activation of microglia (microgliosis) and significantly decreased the expression of pro-inflammatory cytokines (interleukin 1ß and tumor necrosis factor α). In addition, the treatment significantly increased anti-inflammatory cytokines (interleukin 4 and interleukin 13). Taken together, this study clearly indicates that pre-treatment with 100 mg/kg of Pinus densiflora bark extract in gerbils can exert neuroprotection against brain ischemic injury by the attenuation of neuroinflammatory responses.

Transient forebrain ischemia under hyperthermic condition accelerates memory impairment and neuronal death in the gerbil hippocampus by increasing NMDAR1 expression.

Altered expression levels of N­methyl­D­aspartate receptor (NMDAR), a ligand­gated ion channel, have a harmful effect on cellular survival. Hyperthermia is a proven risk factor of transient forebrain ischemia (tFI) and can cause extensive and severe brain damage associated with mortality. The objective of the present study was to investigate whether hyperthermic preconditioning affected NMDAR1 immunoreactivity associated with deterioration of neuronal function in the gerbil hippocampal CA1 region following tFI via histological and western blot analyses. Hyperthermic preconditioning was performed for 1 h before tFI, which was developed by ligating common carotid arteries for 5 min. tFI­induced cognitive impairment under hyperthermia was worse compared with that under normothermia. Loss (death) of pyramidal neurons in the CA1 region occurred fast and was more severe under hyperthermia compared with that under normothermia. NMDAR1 immunoreactivity was not observed in the somata of pyramidal neurons of sham gerbils with normothermia. However, its immunoreactivity was strong in the somata and processes at 12 h post­tFI. Thereafter, NMDAR1 immunoreactivity decreased with time after tFI. On the other hand, NMDAR1 immunoreactivity under hyperthermia was significantly increased in the somata and processes at 6 h post­tFI. The change pattern of NMDAR1 immunoreactivity under hyperthermia was different from that under normothermia. Overall, accelerated tFI­induced neuronal death under hyperthermia may be closely associated with altered NMDAR1 expression compared with that under normothermia.

Chemogenetics-mediated acute inhibition of excitatory neuronal activity improves stroke outcome.

BACKGROUND AND PURPOSE: Ischemic stroke significantly perturbs neuronal homeostasis leading to a cascade of pathologic events causing brain damage. In this study, we assessed acute stroke outcome after chemogenetic inhibition of forebrain excitatory neuronal activity. METHODS: We generated hM4Di-TG transgenic mice expressing the inhibitory hM4Di, a Designer Receptors Exclusively Activated by Designer Drugs (DREADD)-based chemogenetic receptor, in forebrain excitatory neurons. Clozapine-N-oxide (CNO) was used to activate hM4Di DREADD. Ischemic stroke was induced by transient occlusion of the middle cerebral artery. Neurologic function and infarct volumes were evaluated. Excitatory neuronal suppression in the hM4Di-TG mouse forebrain was assessed electrophysiologically in vitro and in vivo, based on evoked synaptic responses, and in vivo based on occurrence of potassium-induced cortical spreading depolarizations. RESULTS: Detailed characterization of hM4Di-TG mice confirmed that evoked synaptic responses in both in vitro hippocampal slices and in vivo motor cortex were significantly reduced after CNO-mediated activation of the inhibitory hM4Di DREADD. Further, CNO treatment had no obvious effects on physiology and motor function in either control or hM4Di-TG mice. Importantly, hM4Di-TG mice treated with CNO at either 10 min before ischemia or 30 min after reperfusion exhibited significantly improved neurologic function and smaller infarct volumes compared to CNO-treated control mice. Mechanistically, we showed that potassium-induced cortical spreading depression episodes were inhibited, including frequency and duration of DC shift, in CNO-treated hM4Di-TG mice. CONCLUSIONS: Our data demonstrate that acute inhibition of a subset of excitatory neurons after ischemic stroke can prevent brain injury and improve functional outcome. This study, together with the previous work in optogenetic neuronal modulation during the chronic phase of stroke, supports the notion that targeting neuronal activity is a promising strategy in stroke therapy.

Oxidative stress and Na,K-ATPase activity differential regulation in brainstem and forebrain of Wistar Audiogenic rats may lead to increased seizure susceptibility.

The Wistar Audiogenic Rat (WAR) is a well-characterized seizure-prone, inbred rodent strain that, when acutely stimulated with high-intensity sounds, develops brainstem-dependent tonic-clonic seizures that can evolve to limbic-like, myoclonic (forebrain) seizures when the acoustic stimuli are presented chronically (audiogenic kindling). In order to investigate possible mechanisms underlying WAR susceptibility to seizures, we evaluated Na,K-ATPase activity, Ca-ATPase activity, Mg-ATPase activity, lipid membrane composition and oxidative stress markers in whole forebrain and whole brainstem samples of naïve WAR, as compared to samples from control Wistar rats. We also evaluated the expression levels of α1 and α3 isoforms of Na,K-ATPase in forebrain samples. We observed increased Na,K-ATPase activity in forebrain samples and increased oxidative stress markers (lipid peroxidation, glutathione peroxidase and superoxide dismutase) in brainstem samples of WAR. The Ca-ATPase activity, Mg-ATPase activity, lipid membrane composition and expression levels of α1 and α3 isoforms of Na,K-ATPase were unaltered. In view of previous data showing that the membrane potentials from naïve WAR's neurons are less negative than that from neurons from Wistar rats, we suggest that Na,K-ATPase increased activity might be involved in a compensatory mechanism necessary to maintain WAR's brains normal activity. Additionally, ongoing oxidative stress in the brainstem could bring Na,K-ATPase activity back to normal levels, which may explain why WAR's present increased susceptibility to seizures triggered by high-intensity sound stimulation.

IL-6 Improves Energy and Glucose Homeostasis in Obesity via Enhanced Central IL-6 trans-Signaling.

Interleukin (IL)-6 engages similar signaling mechanisms to leptin. Here, we find that central application of IL-6 in mice suppresses feeding and improves glucose tolerance. In contrast to leptin, whose action is attenuated in obesity, the ability of IL-6 to suppress feeding is enhanced in obese mice. IL-6 suppresses feeding in the absence of neuronal IL-6-receptor (IL-6R) expression in hypothalamic or all forebrain neurons of mice. Conversely, obese mice exhibit increased soluble IL-6R levels in the cerebrospinal fluid. Blocking IL-6 trans-signaling in the CNS abrogates the ability of IL-6 to suppress feeding. Furthermore, gp130 expression is enhanced in the paraventricular nucleus of the hypothalamus (PVH) of obese mice, and deletion of gp130 in the PVH attenuates the beneficial central IL-6 effects on metabolism. Collectively, these experiments indicate that IL-6 trans-signaling is enhanced in the CNS of obese mice, allowing IL-6 to exert its beneficial metabolic effects even under conditions of leptin resistance.

Targeted Antioxidant, Catalase-SKL, Reduces Beta-Amyloid Toxicity in the Rat Brain.

Accumulation of beta-amyloid (Aß) in the brain has been implicated as a major contributor to the cellular pathology and cognitive impairment observed in Alzheimer's disease. Beta-amyloid may exert its toxic effects by increasing reactive oxygen species and neuroinflammation in the brain. This study set out to investigate whether a genetically engineered derivative of the peroxisomal antioxidant enzyme catalase (CAT-SKL), is able to reduce the toxicity induced by intracerebroventricular injection of Aß25-35 in the mature rat brain. Histopathological and immunohistochemical analyses were used to evaluate neuroinflammation, and neuronal loss. Spatial learning and reference memory was assessed using the Morris water maze. CAT-SKL treatment was able to reduce the pathology induced by Aß25-35 toxicity by significantly decreasing microglia activation in the basal forebrain and thalamus, and reducing cholinergic loss in the basal forebrain. Aß25-35 animals showed deficits in long-term reference memory in the Morris water maze, while Aß25-35 animals treated with CAT-SKL did not demonstrate long-term memory impairments. This preclinical data provides support for the use of CAT-SKL in reducing neuroinflammation and long-term reference memory deficits induced by Aß25-35.

Is Chronic Curcumin Supplementation Neuroprotective Against Ischemia for Antioxidant Activity, Neurological Deficit, or Neuronal Apoptosis in an Experimental Stroke Model?

AIM: To investigate the neuroprotective effect of chronic curcumin supplementation on the rat forebrain prior to ischemia and reperfusion. MATERIAL AND METHODS: Forebrain ischemia was induced by bilateral common carotid artery occlusion for 1/2 hour, followed by reperfusion for 72 hours. Older rats were divided into five groups: Group I received 300 mg/kg oral curcumin for 21 days before ischemia and 300 mg/kg intraperitoneal curcumin after ischemia; Group II received 300 mg/kg intraperitoneal curcumin after ischemia; Group III received 300 mg/kg oral curcumin for 21 days before ischemia; Group IV had only ischemia; Group V was the sham-operated group. The forebrain was rapidly dissected for biochemical parameter assessment and histopathological examination. RESULTS: In forebrain tissue, enzyme activities of superoxide dismutase, glutathione peroxidase, and catalase were significantly higher in Group I than Groups II or III (p < 0.05) while xanthine dehydrogenase and malondialdehyde enzyme activities and concentrations of interleukin-6 and TNF-alpha were significantly lower in Group I when compared to Groups II and III (p < 0.05). A significant reduction in neurological score was observed after 24 and 72 hours in the curcumin-treated groups compared with the ischemic group. We also found a marked reduction in apoptotic index after 72 hours in the groups receiving curcumin. Significantly more TUNEL-positive cells were observed in the ischemic group compared to those treated with curcumin. CONCLUSION: We demonstrated the neuroprotective effect of chronic curcumin supplement on biochemical parameters, neurological scores and apoptosis following ischemia and reperfusion injury in rats.

Deletion of Suppressor of Cytokine Signaling 3 from Forebrain Neurons Delays Infertility and Onset of Hypothalamic Leptin Resistance in Response to a High Caloric Diet.

UNLABELLED: The cellular processes that cause high caloric diet (HCD)-induced infertility are poorly understood but may involve upregulation of suppressor of cytokine signaling (SOCS-3) proteins that are associated with hypothalamic leptin resistance. Deletion of SOCS-3 from brain cells is known to protect mice from diet-induced obesity, but the effects on HCD-induced infertility are unknown. We used neuron-specific SOCS3 knock-out mice to elucidate this and the effects on regional hypothalamic leptin resistance. As expected, male and female neuron-specific SOCS3 knock-out mice were protected from HCD-induced obesity. While female wild-type mice became infertile after 4 months of HCD feeding, infertility onset in knock-out females was delayed by 4 weeks. Similarly, knock-out mice had delayed leptin resistance development in the medial preoptic area and anteroventral periventricular nucleus, regions important for generation of the surge of GnRH and LH that induces ovulation. We therefore tested whether the suppressive effects of HCD on the estradiol-induced GnRH/LH surge were overcome by neuron-specific SOCS3 knock-out. Although only 20% of control HCD-mice experienced a preovulatory-like LH surge, LH surges could be induced in almost all neuron-specific SOCS3 knock-out mice on this diet. In contrast to females, HCD-fed male mice did not exhibit any fertility decline compared with low caloric diet-fed males despite their resistance to the satiety effects of leptin. These data show that deletion of SOCS3 delays the onset of leptin resistance and infertility in HCD-fed female mice, but given continued HCD feeding this state does eventually occur, presumably in response to other mechanisms inhibiting leptin signal transduction. SIGNIFICANCE STATEMENT: Obesity is commonly associated with infertility in humans and other animals. Treatments for human infertility show a decreased success rate with increasing body mass index. A hallmark of obesity is an increase in circulating leptin levels; despite this, the brain responds as if there were low levels of leptin, leading to increased appetite and suppressed fertility. Here we show that leptin resistant infertility is caused in part by the leptin signaling molecule SOCS3. Deletion of SOCS3 from brain neurons delays the onset of diet-induced infertility.

Lifetime methamphetamine dependence is associated with cerebral microgliosis in HIV-1-infected adults.

Methamphetamine (Meth) use is common among HIV-infected persons. It remains unclear whether Meth dependence is associated with long-lasting degenerative changes in the brain parenchyma and microvasculature of HIV-infected individuals. We examined the postmortem brains of 78 HIV-infected adults, twenty of whom were diagnosed with lifetime Meth dependence (18 past and two current at the final follow-up visit). Using logistic regression models, we analyzed associations of Meth with cerebral gliosis (immunohistochemistry for ionized calcium-binding adapter molecule-1 (Iba1) and glial fibrillary acidic protein (GFAP) in frontal, temporo-parietal, and putamen-internal capsule regions), synaptodendritic loss (confocal microscopy for synaptophysin (SYP) and microtubule-associated protein-2 (MAP2) in frontal cortex), ß-amyloid plaque deposition (immunohistochemistry in frontal and temporo-parietal cortex and putamen), and arteriolosclerosis (histopathology in forebrain white matter). We found that Meth was associated with marked Iba1 gliosis in the temporo-parietal region (odds ratio, 4.42 (95 % confidence interval, 1.36, 14.39), p = 0.014, n = 62), which remained statistically significant after adjusting for HIV encephalitis, white matter lesions, and opportunistic diseases (n = 61); hepatitis C virus seropositivity (n = 54); and lifetime dependence on alcohol, opiates, and cannabis (n = 62). There was no significant association of Meth with GFAP gliosis, SYP or MAP2 loss, ß-amyloid plaque deposition, or arteriolosclerosis. In conclusion, we found lifetime Meth dependence to be associated with focal cerebral microgliosis among HIV-infected adults, but not with other brain degenerative changes examined. Some of the changes in select brain regions might be reversible following extended Meth abstinence or, alternatively, might have not been induced by Meth initially.

Homeostatic changes in neuronal network oscillations in response to continuous hypoperfusion in the mouse forebrain.

Neuronal activity is highly sensitive to changes in oxygen tension. In this study, we examined the impact of hypoxic/ischemic conditions on neuronal ensemble activity patterns in the mouse brain using in vivo extracellular electrophysiological recordings from up to 8 sites in the thalamus, dorsal hippocampus, and neocortex, while cerebral hypoperfusion was induced by unilateral carotid artery occlusion. After a few minutes, the occlusion triggered a rapid change in the power of the local field oscillations. In the hippocampus, but not in the neocortex, the absolute power changes at all frequency ranges (relative to the baseline) became less pronounced with time, and no significant changes were observed 30min after the occlusion-induced hypoperfusion. We also tested whether continuous hypoperfusion induced by the occlusion for up to 1 week alters neuronal activity. In the hippocampus and the thalamus, the chronic occlusion did not lead to a reduction in the power of the local field oscillations. These results indicate that certain neuronal populations have the ability to maintain internal neurophysiological homeostasis against continuous hypoperfusion.

Obesity Weighs down Memory through a Mechanism Involving the Neuroepigenetic Dysregulation of Sirt1.

Aberrant gene expression within the hippocampus has recently been implicated in the pathogenesis of obesity-induced memory impairment. Whether a dysregulation of epigenetic modifications mediates this disruption in gene transcription has yet to be established. Here we report evidence of obesity-induced alterations in DNA methylation of memory-associated genes, including Sirtuin 1 (Sirt1), within the hippocampus, and thus offer a novel mechanism by which SIRT1 expression within the hippocampus is suppressed during obesity. Forebrain neuron-specific Sirt1 knock-out closely recapitulated the memory deficits exhibited by obese mice, consistent with the hypothesis that the high-fat diet-mediated reduction of hippocampal SIRT1 could be responsible for obesity-linked memory impairment. Obese mice fed a diet supplemented with the SIRT1-activating molecule resveratrol exhibited increased hippocampal SIRT1 activity and preserved hippocampus-dependent memory, further strengthening this conclusion. Thus, our findings suggest that the memory-impairing effects of diet-induced obesity may potentially be mediated by neuroepigenetic dysregulation of SIRT1 within the hippocampus. SIGNIFICANCE STATEMENT: Previous studies have implicated transcriptional dysregulation within the hippocampus as being a relevant pathological concomitant of obesity-induced memory impairment, yet a deeper understanding of the basis for, and etiological significance of, transcriptional dysregulation in this context is lacking. Here we present the first evidence of epigenetic dysregulation (i.e., altered DNA methylation and hydroxymethylation) of memory-related genes, including Sirt1, within the hippocampus of obese mice. Furthermore, experiments using transgenic and pharmacological approaches strongly implicate reduced hippocampal SIRT1 as being a principal pathogenic mediator of obesity-induced memory impairment. This paper offers a novel working model that may serve as a conceptual basis for the development of therapeutic interventions for obesity-induced memory impairment.

Neurodegeneration Triggers Peripheral Immune Cell Recruitment into the Forebrain.

Brain-intrinsic degenerative cascades have been proposed to be an initial factor driving lesion formation in multiple sclerosis (MS). Here, we identify neurodegeneration as a potent trigger for peripheral immune cell recruitment into the mouse forebrain. Female C57BL/6 mice were fed cuprizone for 3 weeks, followed by a period of 2 weeks on normal chow to induce the formation of lesion foci in the forebrain. Subsequent immunization with myelin oligodendrocyte glycoprotein 35-55 peptide, which induces myelin autoreactive T cells in the periphery, resulted in massive immune cell recruitment into the affected forebrain. Additional adoptive transfer experiments together with flow cytometry analysis underline the importance of brain-derived signals for immune cell recruitment. This study clearly illustrates the significance of brain-intrinsic degenerative cascades for immune cell recruitment and MS lesion formation. Additional studies have to address the signaling cascades and mechanistic processes that form the top-down communication between the affected brain area, neurovascular unit, and peripheral immune cells. SIGNIFICANCE STATEMENT: We identify neurodegeneration as a potent trigger for peripheral immune cell recruitment into the forebrain. Thus, immune cell recruitment might be a second step during the formation of new inflammatory lesions in multiple sclerosis. A better understanding of factors regulating neurodegeneration-induced immune cell recruitment will pave the way for the development of novel therapeutic treatment strategies.

Relationship between the anterior forebrain mesocircuit and the default mode network in the structural bases of disorders of consciousness.

The specific neural bases of disorders of consciousness (DOC) are still not well understood. Some studies have suggested that functional and structural impairments in the default mode network may play a role in explaining these disorders. In contrast, others have proposed that dysfunctions in the anterior forebrain mesocircuit involving striatum, globus pallidus, and thalamus may be the main underlying mechanism. Here, we provide the first report of structural integrity of fiber tracts connecting the nodes of the mesocircuit and the default mode network in 8 patients with DOC. We found evidence of significant damage to subcortico-cortical and cortico-cortical fibers, which were more severe in vegetative state patients and correlated with clinical severity as determined by Coma Recovery Scale-Revised (CRS-R) scores. In contrast, fiber tracts interconnecting subcortical nodes were not significantly impaired. Lastly, we found significant damage in all fiber tracts connecting the precuneus with cortical and subcortical areas. Our results suggest a strong relationship between the default mode network - and most importantly the precuneus - and the anterior forebrain mesocircuit in the neural basis of the DOC.

Carbon monoxide modulates cytochrome oxidase activity and oxidative stress in the developing murine brain during isoflurane exposure.

Commonly used anesthetics induce widespread neuronal degeneration in the developing mammalian brain via the oxidative-stress-associated mitochondrial apoptosis pathway. Dysregulation of cytochrome oxidase (CcOX), the terminal oxidase of the electron transport chain, can result in reactive oxygen species (ROS) formation. Isoflurane has previously been shown to activate this enzyme. Carbon monoxide (CO), as a modulator of CcOX, is of interest because infants and children are routinely exposed to CO during low-flow anesthesia. We have recently demonstrated that low concentrations of CO limit and prevent isoflurane-induced neurotoxicity in the forebrains of newborn mice in a dose-dependent manner. However, the effect of CO on CcOX in the context of anesthetic-induced oxidative stress is unknown. Seven-day-old male CD-1 mice underwent 1h exposure to 0 (air), 5, or 100ppm CO in air with or without isoflurane. Exposure to isoflurane or CO independently increased CcOX kinetic activity and increased ROS within forebrain mitochondria. However, exposure to CO combined with isoflurane paradoxically limited CcOX activation and oxidative stress. There were no changes seen in steady-state levels of CcOX I protein, indicating post-translational modification of CcOX as an etiology for changes in enzyme activity. CO exposure led to differential effects on CcOX subunit I tyrosine phosphorylation depending on concentration, while combined exposure to isoflurane with CO markedly increased the enzyme phosphorylation state. Phosphorylation of tyrosine 304 of CcOX subunit I has been shown to result in strong enzyme inhibition, and the relative reduction in CcOX kinetics following exposure to CO combined with isoflurane may have been due, in part, to such phosphorylation. Taken together, the data suggest that CO modulates CcOX in the developing brain during isoflurane exposure, thereby limiting oxidative stress. These CO-mediated effects could have implications for the development of low-flow anesthesia in infants and children to prevent anesthesia-induced oxidative stress.

Neuroprotective effects of Z-ajoene, an organosulfur compound derived from oil-macerated garlic, in the gerbil hippocampal CA1 region after transient forebrain ischemia.

The neuroprotective effects of two isomers (Z- and E-) of ajoene, a major compound in oil-macerated garlic products, against ischemic damage were investigated in the gerbil hippocampus. Vehicle (corn oil), Z- or E-ajoenes (25 mg/kg) was orally administered 30 min prior to the induction of transient forebrain ischemia by occlusion of the common carotid arteries for 5 min. One day after ischemia/reperfusion (I/R), I/R-induced hyperactivity significantly reduced in the E- and Z-ajoene-treated groups, compared to that in the vehicle-treated group 5 days after I/R, the number of cresyl violet-positive neurons in the E- and Z-ajoene-treated groups increased, compared to that in the vehicle-treated group. Reactive gliosis in the CA1 region of E- and Z-ajoene-treated groups reduced, compared to that in the vehicle-treated group. These neuroprotective effects were more prominent in animals treated with Z-ajoene, than in those treated with E-ajoene. In addition, Z-ajoene significantly decreased lipid peroxidation, as indicated by 4-hydroxy-2-nonenal levels in hippocampal homogenates, compared to that observed in the vehicle-treated group at a range of time points after I/R. These results suggested that Z-ajoene protected against I/R-induced delayed neuronal death and gliosis by reducing lipid peroxidation in the gerbil hippocampal CA1 region.

Maternal choline supplementation differentially alters the basal forebrain cholinergic system of young-adult Ts65Dn and disomic mice.

Down syndrome (DS), trisomy 21, is a multifaceted condition marked by intellectual disability and early presentation of Alzheimer's disease (AD) neuropathological lesions including degeneration of the basal forebrain cholinergic neuron (BFCN) system. Although DS is diagnosable during gestation, there is no treatment option for expectant mothers or DS individuals. Using the Ts65Dn mouse model of DS that displays age-related degeneration of the BFCN system, we investigated the effects of maternal choline supplementation on the BFCN system in adult Ts65Dn mice and disomic (2N) littermates at 4.3-7.5 months of age. Ts65Dn dams were maintained on a choline-supplemented diet (5.1 g/kg choline chloride) or a control, unsupplemented diet with adequate amounts of choline (1 g/kg choline chloride) from conception until weaning of offspring; post weaning, offspring were fed the control diet. Mice were transcardially perfused with paraformaldehyde, and brains were sectioned and immunolabeled for choline acetyltransferase (ChAT) or p75-neurotrophin receptor (p75(NTR) ). BFCN number and size, the area of the regions, and the intensity of hippocampal labeling were determined. Ts65Dn-unsupplemented mice displayed region- and immunolabel-dependent increased BFCN number, larger areas, smaller BFCNs, and overall increased hippocampal ChAT intensity compared with 2N unsupplemented mice. These effects were partially normalized by maternal choline supplementation. Taken together, the results suggest a developmental imbalance in the Ts65Dn BFCN system. Early maternal-diet choline supplementation attenuates some of the genotype-dependent alterations in the BFCN system, suggesting this naturally occurring nutrient as a treatment option for pregnant mothers with knowledge that their offspring is trisomy 21.

Neonatal hypoxia-ischaemia disrupts descending neural inputs to dorsal raphé nuclei.

Neuronal losses have been shown to occur in the brainstem following a neonatal hypoxic-ischaemic (HI) insult. In particular serotonergic neurons, situated in the dorsal raphé nuclei, appear to be vulnerable to HI injury. Nonetheless the mechanisms contributing to losses of serotonergic neurons in the brainstem remain to be elucidated. One possible mechanism is that disruption of neural projections from damaged forebrain areas to dorsal raphé nuclei may play a role in the demise of serotonergic neurons. To test this, postnatal day 3 (P3) rat pups underwent unilateral common carotid artery ligation followed by hypoxia (6% O2 for 30 min). On P38 a retrograde tracer, fluorescent-coupled choleratoxin b, was deposited in the dorsal raphé dorsal (DR dorsal) nucleus or the dorsal raphé ventral (DR ventral) nucleus. Compared to control animals, P3 HI animals had significant losses of retrogradely labelled neurons in the medial prefrontal cortex, preoptic area and lateral habenula after tracer deposit in the DR dorsal nucleus. On the other hand, after tracer deposit in the DR ventral nucleus, we found significant reductions in numbers of retrogradely labelled neurons in the hypothalamus, preoptic area and medial amygdala in P3 HI animals compared to controls. Since losses of descending inputs are associated with decreases in serotonergic neurons in the brainstem raphé nuclei, we propose that disruption of certain descending neural inputs from the forebrain to the DR dorsal and the DR ventral nuclei may contribute to losses of serotonergic neurons after P3 HI. It is important to delineate the phenotypes of different neuronal networks affected by neonatal HI, and the mechanisms underpinning this damage, so that interventions can be devised to target and protect axons from the harmful effects of neonatal HI.

Effects of Lactobacillus helveticus on murine behavior are dependent on diet and genotype and correlate with alterations in the gut microbiome.

Modulation of the gut microbiota with diet and probiotic bacteria can restore intestinal homeostasis in inflammatory conditions and alter behavior via the gut-brain axis. The purpose of this study was to determine whether the modulatory effects of probiotics differ depending on diet and mouse genotype. At weaning, wild type (WT) and IL-10 deficient (IL-10(-/-)) 129/SvEv mice were placed on a standard mouse chow or a Western-style diet (fat 33%, refined carbohydrate 49%)±Lactobacillus helveticus ROO52 (10(9)cfu/d) for 21 days. Animal weight and food eaten were monitored weekly. Intestinal immune function was analysed for cytokine expression using the Meso Scale Discovery platform. Spatial memory and anxiety-like behavior was assessed in a Barnes maze. Terminal restriction fragment length polymorphism (TRFLP) was used to analyze the fecal microbiota. Both WT and IL-10(-/-) mice on a Western diet had increased weight gain along with changes in gut microbiota and cytokine expression and altered anxiety-like behavior. The ability of L. helveticus to modulate these factors was genotype- and diet-dependent. Anxiety-like behavior and memory were negatively affected by Western-style diet depending on inflammatory state, but this change was prevented with L. helveticus administration. However, probiotics alone decreased anxiety-like behavior in WT mice on a chow diet. Mice on the Western diet had decreased inflammation and fecal corticosterone, but these markers did not correlate with changes in behavior. Analysis of bacterial phyla from WT and IL-10(-/-)mice showed discrete clustering of the groups to be associated with both diet and probiotic supplementation, with the diet-induced shift normalized to some degree by L. helveticus. These findings suggest that the type of diet consumed by the host and the presence or absence of active inflammation may significantly alter the ability of probiotics to modulate host physiological function.

Hyperbaric oxygen and hyperbaric air treatment result in comparable neuronal death reduction and improved behavioral outcome after transient forebrain ischemia in the gerbil.

Anoxic brain injury resulting from cardiac arrest is responsible for approximately two-thirds of deaths. Recent evidence suggests that increased oxygen delivered to the brain after cardiac arrest may be an important factor in preventing neuronal damage, resulting in an interest in hyperbaric oxygen (HBO) therapy. Interestingly, increased oxygen supply may be also reached by application of normobaric oxygen (NBO) or hyperbaric air (HBA). However, previous research also showed that the beneficial effect of hyperbaric treatment may not directly result from increased oxygen supply, leading to the conclusion that the mechanism of hyperbaric prevention of brain damage is not well understood. The aim of our study was to compare the effects of HBO, HBA and NBO treatment on gerbil brain condition after transient forebrain ischemia, serving as a model of cardiac arrest. Thereby, we investigated the effects of repetitive HBO, HBA and NBO treatment on hippocampal CA1 neuronal survival, brain temperature and gerbils behavior (the nest building), depending on the time of initiation of the therapy (1, 3 and 6 h after ischemia). HBO and HBA applied 1, 3 and 6 h after ischemia significantly increased neuronal survival and behavioral performance and abolished the ischemia-evoked brain temperature increase. NBO treatment was most effective when applied 1 h after ischemia; later application had a weak or no protective effect. The results show that HBO and HBA applied between 1 and 6 h after ischemia prevent ischemia-evoked neuronal damage, which may be due to the inhibition of brain temperature increase, as a result of the applied rise in ambient pressure, and just not due to the oxygen per se. This perspective is supported by the finding that NBO treatment was less effective than HBO or HBA therapy. The results presented in this paper may pave the way for future experimental studies dealing with pressure and temperature regulation.

Characterization of a rat model of Huntington's disease based on targeted expression of mutant huntingtin in the forebrain using adeno-associated viral vectors.

Huntington's disease (HD) is a fatal neurodegenerative disorder caused by an expanded CAG repeat in the huntingtin (htt) gene. Neuropathology is most severe in the striatum and cerebral cortex. As mutant htt is ubiquitously expressed, it has not been possible to establish clear structure-to-function relationships for the clinical aspects. In the present study, we have injected recombinant adeno-associated viral vectors of serotype 5 (rAAV5) expressing an 853-amino-acid fragment of htt with either 79 (mutant) or 18 (wild-type) glutamines (Q) in the dorsal striatum of neonatal rats to achieve expression of htt in the forebrain. Rats were followed for 6 months and compared with control rats. Neuropathological assessment showed long-term expression of the green fluorescent protein (GFP) transgene (used as a marker protein) and accumulation of htt inclusions in the cerebral cortex with the rAAV5-htt-79Q vectors. We estimated that around 10% of NeuN-positive cells in the cerebral cortex and 2% of DARPP-32 neurons in the striatum were targeted with the GFP-expressing vector. Formation of intracellular htt inclusions was not associated with neuronal loss, gliosis or microglia activation and did not lead to altered motor activity or changes in body weight. However, the same mutant htt vector caused orexin loss in the hypothalamus - another area known to be affected in HD. In conclusion, our results demonstrate that widespread forebrain expression of mutant htt can be achieved using rAAV5-vectors and suggest that this technique can be further explored to study region-specific effects of mutant htt or other disease-causing genes in the brain.