Methamphetamine augment HIV-1 Tat mediated memory deficits by altering the expression of synaptic proteins and neurotrophic factors.

Methamphetamine (METH) abuse is common among individuals infected with HIV-1 and has been shown to affect HIV replication and pathogenesis. These HIV-1 infected individuals also exhibit greater neuronal injury and higher cognitive decline. HIV-1 proteins, specifically gp120 and HIV-1 Tat, have been earlier shown to affect neurocognition. HIV-1 Tat, a viral protein released early during HIV-1 replication, contributes to HIV-associated neurotoxicity through various mechanisms including production of pro-inflammatory cytokines, reactive oxygen species and dysregulation of neuroplasticity. However, the combined effect of METH and HIV-1 Tat on neurocognition and its potential effect on neuroplasticity mechanisms remains largely unknown. Therefore, the present study was undertaken to investigate the combined effect of METH and HIV-1 Tat on behavior and on the expression of neuroplasticity markers by utilizing Doxycycline (DOX)-inducible HIV-1 Tat (1-86) transgenic mice. Expression of Tat in various brain regions of these mice was confirmed by RT-PCR. The mice were administered with an escalating dose of METH (0.1 mg/kg to 6 mg/kg, i.p) over a 7-day period, followed by 6 mg/kg, i.p METH twice a day for four weeks. After three weeks of METH administration, Y maze and Morris water maze assays were performed to determine the effect of Tat and METH on working and spatial memory, respectively. Compared with controls, working memory was significantly decreased in Tat mice that were administered METH. Moreover, significant deficits in spatial memory were also observed in Tat-Tg mice that were administered METH. A significant reduction in the protein expressions of synapsin 1, synaptophysin, Arg3.1, PSD-95, and BDNF in different brain regions were also observed. Expression levels of Calmodulin kinase II (CaMKII), a marker of synaptodendritic integrity, were also significantly decreased in HIV-1 Tat mice that were treated with METH. Together, this data suggests that METH enhances HIV-1 Tat-induced memory deficits by reducing the expression of pre- and postsynaptic proteins and neuroplasticity markers, thus providing novel insights into the molecular mechanisms behind neurocognitive impairments in HIV-infected amphetamine users.

Pathogenic implications of iron accumulation in multiple sclerosis.

Iron, an essential element used for a multitude of biochemical reactions, abnormally accumulates in the CNS of patients with multiple sclerosis (MS). The mechanisms of abnormal iron deposition in MS are not fully understood, nor do we know whether these deposits have adverse consequences, that is, contribute to pathogenesis. With some exceptions, excess levels of iron are represented concomitantly in multiple deep gray matter structures often with bilateral representation, whereas in white matter, pathological iron deposits are usually located at sites of inflammation that are associated with veins. These distinct spatial patterns suggest disparate mechanisms of iron accumulation between these regions. Iron has been postulated to promote disease activity in MS by various means: (i) iron can amplify the activated state of microglia resulting in the increased production of proinflammatory mediators; (ii) excess intracellular iron deposits could promote mitochondria dysfunction; and (iii) improperly managed iron could catalyze the production of damaging reactive oxygen species (ROS). The pathological consequences of abnormal iron deposits may be dependent on the affected brain region and/or accumulation process. Here, we review putative mechanisms of enhanced iron uptake in MS and address the likely roles of iron in the pathogenesis of this disease.

Iron deposition is independent of cellular inflammation in a cerebral model of multiple sclerosis.

BACKGROUND: Perivenular inflammation is a common early pathological feature in multiple sclerosis (MS). A recent hypothesis stated that CNS inflammation is induced by perivenular iron deposits that occur in response to altered blood flow in MS subjects. In order to evaluate this hypothesis, an animal model was developed, called cerebral experimental autoimmune encephalomyelitis (cEAE), which presents with CNS perivascular iron deposits. This model was used to investigate the relationship of iron deposition to inflammation. METHODS: In order to generate cEAE, mice were given an encephalitogen injection followed by a stereotactic intracerebral injection of TNF-α and IFN-γ. Control animals received encephalitogen followed by an intracerebral injection of saline, or no encephalitogen plus an intracerebral injection of saline or cytokines. Laser Doppler was used to measure cerebral blood flow. MRI and iron histochemistry were used to localize iron deposits. Additional histological procedures were used to localize inflammatory cell infiltrates, microgliosis and astrogliosis. RESULTS: Doppler analysis revealed that cEAE mice had a reduction in cerebral blood flow compared to controls. MRI revealed T2 hypointense areas in cEAE animals that spatially correlated with iron deposition around vessels and at some sites of inflammation as detected by iron histochemistry. Vessels with associated iron deposits were distributed across both hemispheres. Mice with cEAE had more iron-labeled vessels compared to controls, but these vessels were not commonly associated with inflammatory cell infiltrates. Some iron-laden vessels had associated microgliosis that was above the background microglial response, and iron deposits were observed within reactive microglia. Vessels with associated astrogliosis were more commonly observed without colocalization of iron deposits. CONCLUSION: The findings indicate that iron deposition around vessels can occur independently of inflammation providing evidence against the hypothesis that iron deposits account for inflammatory cell infiltrates observed in MS.

Upregulation of inflammatory mediators in a model of chronic pain after spinal cord injury.

Chronic neuropathic pain is a disabling condition observed in large number of individuals following spinal cord injury (SCI). Recent progress points to an important role of neuroinflammation in the pathogenesis of central neuropathic pain. The focus of the present study is to investigate the role of proinflammatory molecules IL-1ß, TNF-α, MCP-1, MMP-9 and TIMP-1 in chronic neuropathic pain in a rodent model of SCI. Rats were subjected to spinal cord contusion using a controlled linear motor device with an injury epicenter at T10. The SCI rats had severe impairment in locomotor function at 7 days post-injury as assessed by the BBB score. The locomotor scores showed significant improvement starting at day 14 and thereafter showed no further improvement. The Hargreaves' test was used to assess thermal hyperalgesia for hindpaw, forepaw and tail. A significant reduction in withdrawal latency was observed for forepaw and tail of SCI rats at days 21 and 28, indicating the appearance of thermal hyperalgesia. Changes in expression of mRNAs for IL-1ß, TNF-α, MCP-1, MMP-9 and TIMP-1 were assessed using real-time polymerase chain reaction in spinal cord including the injury epicenter along with regions above and below the level of lesion at day 28 post-injury. A significant increase was observed in the expression of MCP-1, TNF-α, TIMP-1 and IL-1ß in the injury epicenter, whereas only TIMP-1 was upregulated in the area below the injury epicenter. The results of the study suggest that prolonged upregulation of inflammatory mediators might be involved in chronic neuropathic pain in SCI, and that TIMP-1 may play a role in maintenance of chronic below level pain.

Sex-related differences in animal models of migraine headache.

Trigeminal nerve-mediated pain disorders such as migraine, temporomandibular joint disorder, and classical trigeminal neuralgia are more prevalent in women than in men. Female laboratory animals also show greater responses to various nociceptive stimuli than male animals. However, current knowledge of migraine pathogenesis is based primarily on experimental studies conducted in male animals and lack of migraine research with female animals limits clinical relevance. Migraine is triggered by any alteration in the intrinsic or extrinsic milieu and women at reproductive age are continuously prone to waxing and waning effects of female sex hormones. The experimental approach to this problem is complex because the rodent estrous cycle differs from the human cycle, and because exogenous hormone replacement in ovariectomized females has its limitations. The existence of multiple estrogen receptors in the trigeminal system also presents a challenge. Estrogens do not seem to directly affect calcitonin gene-related peptide or 5-HT(1D) receptors in the trigeminal system. Nonetheless, 2 estrogen receptors activate MAPK/ERK signaling pathway that mediates nociceptive processing in trigeminal nucleus caudalis. In addition, estrogen enhances susceptibility to cortical spreading depression, the neurobiological event underlying migraine aura, which may be independent of the estrous cycle. Further studies in female animals are required to clarify mechanisms underlying sex differences with respect to fluctuating sex hormones, cortical spreading depression, and excitability of the trigeminovascular system.

Mechanisms of pain modulation by sex hormones in migraine.

A number of pain conditions, acute as well as chronic, are much more prevalent in women, such as temporomandibular disorder (TMD), irritable bowel syndrome, fibromyalgia, and migraine. The association of female sex steroids with these nociceptive conditions is well known, but the mechanisms of their effects on pain signaling are yet to be deciphered. We reviewed the mechanisms through which female sex steroids might influence the trigeminal nociceptive pathways with a focus on migraine. Sex steroid receptors are located in trigeminal circuits, providing the molecular substrate for direct effects. In addition to classical genomic effects, sex steroids exert rapid nongenomic actions to modulate nociceptive signaling. Although there are only a handful of studies that have directly addressed the effect of sex hormones in animal models of migraine, the putative mechanisms can be extrapolated from observations in animal models of other trigeminal pain disorders, like TMD. Sex hormones may regulate sensitization of trigeminal neurons by modulating expression of nociceptive mediator such as calcitonin gene-related peptide. Its expression is mostly positively regulated by estrogen, although a few studies also report an inverse relationship. Serotonin (5-Hydroxytryptamine [5-HT]) is a neurotransmitter implicated in migraine; its synthesis is enhanced in most parts of brain by estrogen, which increases expression of the rate-limiting enzyme tryptophan hydroxylase and decreases expression of the serotonin re-uptake transporter. Downstream signaling, including extracellular signal-regulated kinase activation, calcium-dependent mechanisms, and cAMP response element-binding activation, are thought to be the major signaling events affected by sex hormones. These findings need to be confirmed in migraine-specific animal models that may also provide clues to additional ion channels, neuropeptides, and intracellular signaling cascades that contribute to the increased prevalence of migraine in women.

Sex differences in behavior and expression of CGRP-related genes in a rodent model of chronic migraine.

OBJECTIVE: The objectives of this study were to develop a preclinical rodent model that produces migraine-like behaviors based on International Headache Society diagnostic criteria, to determine whether sex differences are present, and to determine whether expression of calcitonin gene-related peptide (CGRP) and the genes encoding its receptor in trigeminal ganglion or medulla correlates with those behaviors. BACKGROUND: Few animal studies of migraine have tested behaviors associated with migraine diagnostic criteria. In this study, changes in activity and in mechanical sensitivity of facial regions following application of inflammatory soup (IS) or vehicle (phosphate-buffered saline [PBS]) to the dura were measured to model changes in routine activity and allodynia. CGRP, an important mediator of migraine pathogenesis, and the 3 components of its receptor, calcitonin-like receptor (CLR), receptor activity-modifying protein 1 (RAMP1), and receptor component protein (RCP) mRNAs were quantified in the trigeminal ganglion and medulla to identify baseline sex differences and changes associated with application of IS or PBS to the dura. METHODS: Male and female Sprague-Dawley rats were implanted with a dural cannula. Groups of rats were treated with 10 or 20 µL volumes of IS or PBS. Baseline behavioral testing was conducted prior to surgery and again at 7 days postsurgery, and dural application of IS or PBS was performed repeatedly for a total of 8 applications. Locomotor activity was assessed using force plate actimetry during and following application to provide information on distance traveled, bouts of low mobility, spatial confinement, and focused energy. Periorbital and perimasseter sensory testing was performed 20 minutes post-application to measure allodynia. The rats were sacrificed 30 minutes following the final dural treatment, tissue was dissected and total RNAs were isolated from ipsilateral trigeminal ganglia and ipsilateral medulla. Quantitative real-time polymerase chain reactions were used to measure the expression of amplified constructs using gene-specific primers for CGRP, RAMP1, CLR, and RCP. RESULTS: Both males and females showed behavioral effects of IS application, but there were pronounced sex differences. Females showed effects at the lower dose, and activity changes were present for a longer duration, but males required fewer applications of IS to exhibit behavioral changes. Females showed increased withdrawal responses for periorbital and perimasseter mechanical testing (10 µL IS groups), and males showed increased perimasseter withdrawal responses (20 µL IS group). In the trigeminal ganglion, there were no baseline sex differences in CGRP-encoding mRNA, but females had lower baseline expression of RAMP1, CLR, and RCP-encoding mRNAs. In the medulla, females had higher baseline levels of CGRP-encoding mRNAs and lower baseline levels of RAMP1, CLR, and RCP-encoding mRNAs than males. Both IS and PBS increased expression of mRNAs encoding CGRP, RAMP1, RCP, and CLR in the trigeminal ganglion in males, but in females, only CLR and RCP were increased. In the medulla both IS and PBS increased expression of CGRP, CLR in males and CLR and RCP in females. Thus, expression of CGRP-related genes did not mirror the behavioral differences between IS and PBS groups. Instead, CGRP-related genes were upregulated by both IS and PBS applications. CONCLUSIONS: This study demonstrates significant changes in locomotor activity and facial allodynia associated with application of IS to the dura as well as significant sex differences, demonstrating that International Headache Society diagnostic criteria can be used to design a rodent behavioral model of migraine. In addition, there were prominent baseline sex differences in expression of CGRP and its receptor in both the trigeminal ganglion and medulla, but the majority of changes in expression of CGRP and its receptor were present in both the IS and PBS treated rats. This suggests that the CGRP pathway responds to changes in intracranial pressure or meningeal stretch, while migraine-like behaviors occur after meningeal inflammation.

Post-acute pathological changes in the thalamus and internal capsule in aged mice following controlled cortical impact injury: a magnetic resonance imaging, iron histochemical, and glial immunohistochemical study.

Traumatic brain injury (TBI) is a major cause of neurological disability across all ages, but the elderly are particularly vulnerable and have a worse prognosis than younger individuals. To advance the understanding of long-term pathogenesis induced by TBI in the elderly, aged mice (21 -- 24 months) were given a controlled cortical impact (CCI) injury to the sensorimotor cortex, and their brains were analyzed by MRI and histopathology at 1 and 2 months after CCI injury, a post-acute period. A T2 hypointensity was observed in the ipsilateral thalamus but not in the contralateral thalamus or in the thalamus of sham operated, control mice. The hypointensity was co-localized with increased histochemical staining of iron, a paramagnetic substance that causes a shortening of the T2 relaxation time. Since iron catalyzes reactions that lead to toxic free radicals, the deposition of iron in the thalamus raises the possibility that it promotes pathogenesis following TBI. Astrocyte gliosis and microgliosis were also observed in the ipsilateral thalamus in the post-acute period. The ipsilateral internal capsule displayed a trend for a T2 hypointensity, however, unlike the thalamus it did not have an increase of iron or GFAP staining, but it did have evidence of microgliosis. In summary, areas of T2 hypointensity were revealed in both the thalamus and internal capsule during the post-acute period following CCI injury, but the underlying pathology appeared to be distinct between these regions.

Detrimental effects of aging on outcome from traumatic brain injury: a behavioral, magnetic resonance imaging, and histological study in mice.

Considerable evidence indicates that outcomes from traumatic brain injury (TBI) are worse in the elderly, but there has been little preclinical research to explore potential mechanisms. In this study, we examined the age-related effects on outcome in a mouse model of controlled cortical impact (CCI) injury. We compared the responses of adult (5-6 months old) and aged (21-24 months old) male mice following a moderate lateral CCI injury to the sensorimotor cortex. Sensorimotor function was evaluated with the rotarod, gridwalk and spontaneous forelimb behavioral tests. Acute edema was assessed from hyperintensity on T2-weighted magnetic resonance images. Blood-brain barrier opening was measured using anti-mouse immunoglobulin G (IgG) immunohistochemistry. Neurodegeneration was assessed by amino-cupric silver staining, and lesion cavity volumes were measured from histological images. Indicators of injury were generally worse in the aged than the adult mice. Acute edema, measured at 24 and 48 h post-injury, resolved more slowly in the aged mice (p < 0.01). Rotarod recovery (p < 0.05) and gridwalk deficits (p < 0.01) were significantly worse in aged mice. There was greater (p < 0.01 at 3 days) and more prolonged post-acute opening of the blood-brain barrier in the aged mice. Neurodegeneration was greater in the aged mice (p < 0.01 at 3 days). In contrast, lesion cavity volumes, measured at 3 days post-injury, were not different between injured groups. These results suggest that following moderate controlled cortical impact injury, the aged brain is more vulnerable than the adult brain to neurodegeneration, resulting in greater loss of function. Tissue loss at the impact site does not explain the increased functional deficits seen in the aged animals. Prolonged acute edema, increased opening of the blood-brain barrier and increased neurodegeneration found in the aged animals implicate secondary processes in age-related differences in outcome.

APOBEC3G expression is restricted to epithelial cells of the proximal convoluted tubules and is not expressed in the glomeruli of macaques.

The Vif protein of human immunodeficiency virus-1 (HIV-1) interacts with members of the APOBEC family of cytidine deaminases. In this study, we isolated RNA from renal cortex as well as from isolated glomeruli and tubulointerstitial fractions from two pigtailed macaques that were exsanguinated and perfused with saline. RT-PCR results indicate that APOBEC3G was detected in the tubule fractions but not in the glomerular fractions. Immunoblot analysis using lysates prepared from these same fractions and a monoclonal antibody to APOBEC3G confirmed the RT-PCR findings. To determine which cell types express APOBEC3G, immunohistochemical studies were performed using this monoclonal antibody on renal cortical sections. Our results clearly show that the glomeruli do not express APOBEC3G but that select tubules within the cortex express APOBEC3G at high levels. To further differentiate the distribution of APOBEC3G expression, serial sections were stained with the lectins Dolichos biflorus agglutinin (DBA) and Phaseolus vulgaris erythroagglutinin (PHA-E), which differentially bind to epithelial cells of the tubules and glomeruli. Our results indicate that APOBEC3G expression was restricted to PHA-E-staining tubules and not DBA-staining tubules, suggesting that APOBEC3G expression was restricted to proximal convoluted tubules. These findings suggest that infection of epithelial cells of proximal renal tubules could suppress Vif-defective HIV-1 replication, whereas infection of cells of the glomeruli, a major target of HIV-associated nephropathy, could act as a reservoir for the replication of Vif-defective HIV-1.

A mouse model of sensorimotor controlled cortical impact: characterization using longitudinal magnetic resonance imaging, behavioral assessments and histology.

The present study establishes a new mouse model for traumatic brain injury (TBI), using an electromechanically driven linear motor impactor device to deliver a lateral controlled cortical impact (CCI) injury to the sensorimotor cortex. Lesion cavity size was measured, and inter-animal consistency demonstrated, at 14 days post injury. Qualitative information regarding damage progression over time was obtained by scanning with high field magnetic resonance imaging (MRI) at five time points following injury. Functional impairment and recovery were measured with the Rotarod, gridwalk and cylinder tests, and lesion cavity volume was measured post mortem with thionin-stained tissue sections. The study establishes the reliability of a linear-motor based device for producing repeatable damage in a CCI model, demonstrates the power of longitudinal MRI in studying damage evolution, and confirms that a simple battery of functional tests record sensorimotor impairment and recovery.

APOBEC3G expression is restricted to neurons in the brains of pigtailed macaques.

The Vif protein of human immunodeficiency virus-1 (HIV-1) has been shown to interact with members of the APOBEC family of cytidine deaminases, particularly APOBEC3G/F. In this study, we isolated RNA from 12 regions of the brain from two pigtailed macaques that were exsanguinated and perfused with saline. Our results indicate that APOBEC3G was detected in all regions of the brain analyzed. Immunoblot analysis using lysates prepared from these same regions of the brain and a monoclonal antibody to APOBEC3G confirmed the RT-PCR findings. To determine which cell types express APOBEC3G, immunohistochemical studies were performed using this monoclonal antibody on whole brain sections. Our results clearly show that the pyramidal neurons within the gray matter of cerebral and cerebellar cortices express APOBEC3G. However, APOBEC3G expression in the pyramidal neurons appeared to be nuclear or associated with nuclei. In contrast to our findings in the cerebral cortex, immunohistochemical analysis of the spleen and kidney tissues revealed that APOBEC3G expression in the cells of these tissues was predominantly cytoplasmic. We further investigated the expression of APOBEC3G in astrocytes. Immunohistochemical staining of serial sections was performed using antibodies to glial fibrillary acidic protein (GFAP) and APOBEC3G. As expected, the cortical and cerebellar white matter showed extensive immunostaining of astrocytes with the antibody against GFAP but a lack of reactivity to the antibody to APOBEC3G. Additionally, Immunoblot analysis of lysates prepared from primary human fetal astrocytes revealed a lack of APOBEC3G expression. Taken together, these results indicate that APOBEC3G expression is restricted to neurons in the brain and that astrocytes and microglia probably do not express this protein or express it at levels undetectable by immunohistochemistry. These finding have implications for the brain as a potential reservoir for Vif-defective viruses.

Ghrelin is expressed in trigeminal neurons of female mice in phase with the estrous cycle.

Several disorders mediated by the trigeminal nerve including migraine and temporomandibular disorder (TMD) are more common in women than in men, and painful attacks are often linked to the menstrual cycle. Estrogen receptors in trigeminal neurons may be involved in regulating neuronal function, causing changes in sensitivity that contribute to these attacks. In a previous study, we demonstrated that expression of specific neuropeptides including galanin and neuropeptide Y in trigeminal ganglia of female rodents varies with the estrous cycle. In this study, we examined expression of the orexigenic peptide ghrelin in trigeminal ganglia of cycling female mice. RT-PCR studies demonstrated that ghrelin mRNA is upregulated by over 5-fold at the high estrogen stages of the cycle, proestrus and early estrus over the levels expressed at the low estrogen stage of the cycle, diestrus. Double-labeling immunohistochemical studies and cell size measurements were conducted to identify the phenotype of neurons in trigeminal ganglia containing ghrelin. Ghrelin was present in trigeminal neurons containing peripherin, a marker of neurons with unmyelinated axons, in trigeminal neurons binding IB4, a marker of nonpeptidergic nociceptors, in trigeminal neurons containing neurofilament H, a marker of neurons with myelinated axons, and in trigeminal neurons containing the neuropeptide calcitonin gene-related peptide (CGRP). Ghrelin-positive neurons averaged 25.6 microm in diameter, but included neurons in all the size ranges except the smallest peripherin-positive neurons. Thus, nearly all of the major populations of trigeminal neurons including peptidergic and nonpeptidergic nociceptors contain ghrelin. These studies suggest that ghrelin, a multifunctional peptide, may contribute to the mechanism linking orofacial pain syndromes in females, including temporomandibular disorder and migraine, to cyclical hormonal changes.

Early dysregulation of cripto-1 and immunomodulatory genes in the cerebral cortex in a macaque model of neuroAIDS.

Human immunodeficiency virus type 1 (HIV-1) and related primate lentiviruses are known to enter the central nervous system (CNS) during the primary phase of infection. Neuroinvasion by simian immunodeficiency virus and simian human immunodeficiency virus (SHIV) is characterized by transient meningitis and astrocytosis. In this report, we used targeted cytokine cDNA arrays to analyze cortical brain tissue from four pig-tailed macaques inoculated for 2 weeks with pathogenic SHIV(50OLNV) and a normal age-matched pig-tailed macaque. Our results revealed that eight genes were significantly upregulated in all four macaques. These included: leukocyte interferon inducible peptide, corticotrophin releasing factor receptor 1, interleukin 6, CDW40 antigen, cysteine-rich fibroblast growth factor, neurotrophin 3, ciliary neurotrophin factor receptor and cripto-1. The upregulation of three of these genes was confirmed by reverse transcriptase PCR (RT-PCR). Since cripto-1 had not been previously identified within specific cell types within the primate central nervous system, we performed immunohistochemical studies, which revealed the presence of cripto-1 in neurons. RT-PCR studies demonstrated that cripto-1 mRNA was widely expressed in the CNS. These results indicate that immunomodulatory genes are upregulated during the primary phase of infection of the central nervous system. Cripto-1, which acts as a survival factor in tumor cells and may be neuroprotective, is expressed in neurons within the CNS and is upregulated during viral invasion.

Altered expression of pro-inflammatory and developmental genes in the fetal brain in a mouse model of maternal infection.

Human studies of unexplained cerebral palsy (CP) suggest an association with maternal infection. We used an established model of maternal infection, lipopolysaccharide (LPS) administration, to investigate the molecular changes in the fetal brain that may link maternal infection and CP. We compared gene expression in brains from mouse pups exposed to LPS in utero to those from saline-treated controls. Dams were injected with 50 microg LPS or saline on E18 with surgical delivery from 0.5 to 6h later. Differential gene expression was analyzed in the whole mouse brain using RT-PCR. When compared to control mice, pups exposed to LPS showed increased expression of pro-inflammatory genes monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6), and interleukin-1beta (IL-1beta), as well as VEGF, a regulator of vascular development and permeability, the anti-apoptotic protein Y-box-binding protein-1 (YB-1), and the neuronal differentiation factor necdin. LPS-exposed mice also showed downregulation of semaphorin 5b and groucho, involved in axon guidance and neurogenesis, respectively, providing evidence that LPS may disrupt normal developmental pathways. These data suggest possible mechanisms for adverse neurological outcomes following maternal infection involving elevated cytokine levels and altered expression of developmental genes in the fetal brain.

Ovarian steroids regulate neuropeptides in the trigeminal ganglion.

Women are more than three times as likely as men to experience migraine headaches and temporomandibular joint pain, and painful episodes are often linked to the menstrual cycle. To understand how hormone levels may influence head and face pain, we assessed expression of pain-associated neuropeptides and estrogen receptor alpha (ERalpha) during the natural estrous cycle in mice. Gene expression was analyzed in the trigeminal ganglia of cycling female mice at proestrus, estrus and diestrus using RT-PCR. Peptide/protein expression in trigeminal neurons was analyzed using immunohistochemistry. ERalpha mRNA was present at all stages and highest at estrus. ERalpha protein was present in the cytoplasm of medium-sized and small trigeminal neurons. ERalpha immunoreactive neurons were most common at diestrus. CGRP and ANP mRNAs did not change across the estrous cycle, while expression of galanin and NPY mRNAs were strongly linked to the estrous cycle. Galanin mRNA levels peaked at proestrus, when expression was 8.7-fold higher than the diestrus levels. Galanin immunoreactivity also peaked at proestrus. At proestrus, 7.5% of trigeminal neurons contained galanin, while at estrus, 6.2% of trigeminal neurons contained galanin, and at diestrus, 4.9% of trigeminal neurons contained galanin. NPY mRNA peaked at estrus, when levels were 4.7-fold higher than at diestrus. Our findings suggest that estrogen receptors in trigeminal neurons modulate nociceptive responses through effects on galanin and NPY. Variations in neuropeptide content in trigeminal neurons across the natural estrous cycle may contribute to increases in painful episodes at particular phases of the menstrual cycle.

Exercise preconditioning improves traumatic brain injury outcomes.

PURPOSE: To determine whether 6 weeks of exercise performed prior to traumatic brain injury (TBI) could improve post-TBI behavioral outcomes in mice, and if exercise increases neuroprotective molecules (vascular endothelial growth factor-A [VEGF-A], erythropoietin [EPO], and heme oxygenase-1 [HO-1]) in brain regions responsible for movement (sensorimotor cortex) and memory (hippocampus). METHODS: 120 mice were randomly assigned to one of four groups: (1) no exercise+no TBI (NOEX-NOTBI [n=30]), (2) no exercise+TBI (NOEX-TBI [n=30]), (3) exercise+no TBI (EX-NOTBI [n=30]), and (4) exercise+TBI (EX-TBI [n=30]). The gridwalk task and radial arm water maze were used to evaluate sensorimotor and cognitive function, respectively. Quantitative real time polymerase chain reaction and immunostaining were performed to investigate VEGF-A, EPO, and HO-1 mRNA and protein expression in the right cerebral cortex and ipsilateral hippocampus. RESULTS: EX-TBI mice displayed reduced post-TBI sensorimotor and cognitive deficits when compared to NOEX-TBI mice. EX-NOTBI and EX-TBI mice showed elevated VEGF-A and EPO mRNA in the cortex and hippocampus, and increased VEGF-A and EPO staining of sensorimotor cortex neurons 1 day post-TBI and/or post-exercise. EX-TBI mice also exhibited increased VEGF-A staining of hippocampal neurons 1 day post-TBI/post-exercise. NOEX-TBI mice demonstrated increased HO-1 mRNA in the cortex (3 days post-TBI) and hippocampus (3 and 7 days post-TBI), but HO-1 was not increased in mice that exercised. CONCLUSIONS: Improved TBI outcomes following exercise preconditioning are associated with increased expression of specific neuroprotective genes and proteins (VEGF-A and EPO, but not HO-1) in the brain.

Behavioral effects and mechanisms of migraine pathogenesis following estradiol exposure in a multibehavioral model of migraine in rat.

Migraine is one of the most common neurological disorders, leading to more than 1% of total disability reported and over 68 million visits to emergency rooms or physician's offices each year in the United States. Three times as many women as men have migraine, and while the mechanism behind this is not well understood, 17ß-estradiol (estradiol) has been implicated to play a role. Studies have demonstrated that exposure to estrogen can lead to activation of inflammatory pathways, changes in sodium gated channel activity, as well as enhanced vasodilation and allodynia. Estradiol receptors are found in trigeminal nociceptors, which are involved in signaling during a migraine attack. The purpose of this study was to investigate the role of estradiol in migraine pathogenesis utilizing a multibehavioral model of migraine in rat. Animals were surgically implanted with a cannula system to induce migraine and behavior was assessed following exposure to a proestrus level of estradiol for total locomotor activity, light and noise sensitivity, evoked grooming patterns, and enhanced acoustic startle response. Results demonstrated decreased locomotor activity, increased light and noise sensitivity, altered facial grooming indicative of allodynia and enhanced acoustic startle. Further examination of tissue samples revealed increased expression of genes associated with inflammation and vasodilation. Overall, this study demonstrates exacerbation of migraine-like behaviors following exposure to estradiol and helps further explain the underlying mechanisms behind sex differences found in this common neurological disorder.

Overexpression of monocyte chemoattractant protein 1 in the brain exacerbates ischemic brain injury and is associated with recruitment of inflammatory cells.

Brain cells produce cytokines and chemokines during the inflammatory process after stroke both in animal models and in patients. Monocyte chemoattractant protein 1 (MCP-1), one of the proinflammatory chemokines, can attract monocytes to the tissue where MCP-1 is overexpressed. However, the role of MCP-1 elevation in stroke has not been explored in detail. The authors hypothesized that elevated MCP-1 levels would lead to increased influx of monocytes and increased brain infarction size in stroke induced by middle cerebral artery occlusion with partial reperfusion. There were no differences in blood pressure, blood flow, or vascular architecture between wild-type mice and transgenic MBP-JE mice. Twenty-four to 48 hours after middle cerebral artery occlusion, brain infarction volumes after ischemia were significantly larger in MBP-JE mice than in wild-type controls and were accompanied by increased local transmigration and perivascular accumulation of macrophages and neutrophils. These results indicate that MCP-1 can contribute to inflammatory injury in stroke.

The primary phase of infection by pathogenic simian-human immunodeficiency virus results in disruption of the blood-brain barrier.

Using the simian-human immunodeficiency virus (SHIV), we have investigated whether the blood-brain barrier (BBB) is compromised during the early stages of infection. Five macaques were inoculated with pathogenic SHIV(50OLNV) for 2 weeks at which time macaques were anesthetized, perfused with saline, and sacrificed. The brains were removed and examined for the disruption of the blood-brain barrier by immunohistochemical staining for the plasma protein fibrinogen in the neural parenchyma. Our results indicate a disruption of the BBB in the five of five macaques inoculated with SHIV(50OLNV) for 2 weeks. Zonula occludens 1 (ZO-1), which is a marker for the tight junctions formed by brain vascular endothelial cells, was largely absent in areas that showed fibrinogen deposition in all five macaques. To determine if the BBB integrity correlated with the initial stages of infection, the brains from two macaques were analyzed that had progressed to end-stage disease following inoculation with pathogenic SHIV(50OLNV) but developed no neuropathology and from two macaques that were inoculated with a gene-deleted, nonpathogenic virus (novpuSHIV(KU-1bMC33)) for over 1 year. Our results indicate that unlike the macaques sacrificed during the acute phase of infection, immunohistochemical staining for fibrinogen in the neural parenchyma was negative and ZO-1 staining was readily detected in the endothelial cells of the blood vessels. The results of this study indicate that the transient loss of BBB integrity is a function of the high level of virus replication that occurs during the acute phase of infection and provides important information on the early stages of lentivirus neuroinvasion.