The content of gonadotropin-releasing hormone (GnRH), kisspeptin, and estrogen receptors (ERα/ERß) in the anteromedial hypothalamus displays daily variations throughout the rat estrous cycle.

The content of gonadotropin-releasing hormone (GnRH), its mRNA, and estrogen receptor alpha (ERα) and beta (ERß) in the hypothalamus varies throughout the estrous cycle. Furthermore, the abundance of these molecules displays asymmetry between the right and left side. In the present study, we investigated the changes in the content of ERα, ERß, kisspeptin, and GnRH by western blot in the left and right anteromedial hypothalamus, at four different times during each stage of the rat estrous cycle. The serum levels of the follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were also measured. ERα and ERß levels changed depending on the stage of the estrous cycle, meanwhile that of kisspeptin was modified according to both the hour of the day and the stage of the cycle. Except in estrus day, ERß was higher in the right hypothalamus, while ERα was similar in both sides. During both proestrus and estrus, the content of kisspeptin and GnRH was higher in the right hypothalamus. The highest levels of FSH and LH occurred at 17:00 h of proestrus. But at estrus, the highest FSH levels were observed at 08:00 h and the lowest at 17:00 h. Thus, the current results show that the content of ERα, ERß, kisspeptin, and GnRH in the anteromedial hypothalamus are regulated as a function of the stage of the estrous cycle and the hour of the day. Furthermore, the content of these proteins is regularly higher in the right anteromedial hypothalamus, regardless of the stage of the cycle or time of the day.

Chemoinformatic Analysis of Selected Cacalolides from Psacalium decompositum (A. Gray) H. Rob. & Brettell and Psacalium peltatum (Kunth) Cass. and Their Effects on FcεRI-Dependent Degranulation in Mast Cells.

Cacalolides are a kind of sesquiterpenoids natural compounds synthesized by Psacalium decompositum (A. Gray) H. Rob. & Brettell or Psacalium peltatum (Kunth) Cass. Antioxidant and hypoglycemic effects have been found for cacalolides such as cacalol, cacalone or maturine, however, their effects on inflammatory processes are still largely unclear. The main aim of this study was to investigate the biological activities of secondary metabolites from P. decompositum and P. peltatum through two approaches: (1) chemoinformatic and toxicoinformatic analysis based on ethnopharmacologic background; and (2) the evaluation of their potential anti-inflammatory/anti-allergic effects in bone marrow-derived mast cells by IgE/antigen complexes. The bioinformatics properties of the compounds: cacalol; cacalone; cacalol acetate and maturin acetate were evaluated through Osiris DataWarrior software and Molinspiration and PROTOX server. In vitro studies were performed to test the ability of these four compounds to inhibit antigen-dependent degranulation and intracellular calcium mobilization, as well as the production of reactive oxygen species in bone marrow-derived mast cells. Our findings showed that cacalol displayed better bioinformatics properties, also exhibited a potent inhibitory activity on IgE/antigen-dependent degranulation and significantly reduced the intracellular calcium mobilization on mast cells. These data suggested that cacalol could reduce the negative effects of the mast cell-dependent inflammatory process.

The Role of Neuroinflammation in Age-Related Dementias.

The most common dementias such as Alzheimer's disease, vascular dementia, Lewy body dementia, and frontotemporal dementia are associated with a decline in cognitive and social abilities. Although the molecular mechanisms of tissue damage in these dementias are not completely understood, these neurodegenerative illnesses share certain alterations such as neuroinflammation and gliosis. Increasing evidence suggests that microgliosis and astrogliosis play a key role in neuroinflammation observed in these dementias. Here we provide an overview of the participation of microglia and astrocytes in the neuroinflammatory response in common dementias.

Memantine enhances recovery from stroke.

BACKGROUND AND PURPOSE: Stroke treatment is constrained by limited treatment windows and the clinical inefficacy of agents that showed preclinical promise. Yet animal and clinical data suggest considerable poststroke plasticity, which could allow treatment with recovery-modulating agents. Memantine is a well-tolerated N-methyl-D-aspartate glutamate receptor antagonist in common use for Alzheimer disease. METHODS: Memantine, 30 mg/kg per day, or vehicle, was delivered chronically in drinking water beginning >2 hours after photothrombotic stroke. RESULTS: Although there was no difference in infarct size, behavior, or optical intrinsic signal maps in the first 7 days after stroke, mice treated chronically with memantine showed significant improvements in motor control, measured by cylinder test and grid-walking performance, compared with vehicle-treated animals. Optical intrinsic signal revealed an increased area of forepaw sensory maps at 28 days after stroke. There was decreased reactive astrogliosis and increased vascular density around the infarcted cortex. Peri-infarct Western blots revealed increased brain-derived neurotrophic factor and phosphorylated-tropomyosin-related kinase-B receptor expression. CONCLUSIONS: Our results suggest that memantine improves stroke outcomes in an apparently non-neuroprotective manner involving increased brain-derived neurotrophic factor signaling, reduced reactive astrogliosis, and improved vascularization, associated with improved recovery of sensory and motor cortical function. The clinical availability and tolerability of memantine make it an attractive candidate for clinical translation.

Minimum conditions for the induction of cortical spreading depression in brain slices.

Cortical spreading depression (CSD) occurs during various forms of brain injury such as stroke, subarachnoid hemorrhage, and brain trauma, but it is also thought to be the mechanism of the migraine aura. It is therefore expected to occur over a range of conditions including the awake behaving state. Yet it is unclear how such a massive depolarization could occur under relatively benign conditions. Using a microfluidic device with focal stimulation capability in a mouse brain slice model, we varied extracellular potassium concentration as well as the area exposed to increased extracellular potassium to determine the minimum conditions necessary to elicit CSD. Importantly, we focused on potassium levels that are physiologically plausible (≤145 mM; the intracellular potassium concentration). We found a strong correlation between the threshold concentration and the slice area exposed to increased extracellular potassium: minimum area of exposure was needed with the highest potassium concentration, while larger areas were needed at lower concentrations. We also found that moderate elevations of extracellular potassium were able to elicit CSD in relatively small estimated tissue volumes that might be activated under noninjury conditions. Our results thus show that CSD may be inducible under the conditions that expected in migraine aura as well as those related to brain trauma.

Dihydromyricetin ameliorates behavioral deficits and reverses neuropathology of transgenic mouse models of Alzheimer's disease.

Alzheimer's disease (AD) is the leading progressive neurodegenerative disorder afflicting 35.6 million people worldwide. There is no therapeutic agent that can slow or stop the progression of AD. Human studies show that besides loss of cognition/learning ability, neuropsychological symptoms such as anxiety and seizures are seen as high as 70 and 17 % respectively in AD patients, suggesting dysfunction of GABAergic neurotransmission contributes to pathogenesis of AD. Dihydromyricetin (DHM) is a plant flavonoid and a positive allosteric modulator of GABAARs we developed recently (Shen et al. in J Neurosci 32(1):390-401, 2012 [1]). In this study, transgenic (TG2576) and Swedish transgenic (TG-SwDI) mice with AD-like pathology were treated with DHM (2 mg/kg) for 3 months. Behaviorally, DHM-treated mice show improved cognition, reduced anxiety level and seizure susceptibility. Pathologically, DHM has high efficacy to reduce amyloid-ß (Aß) peptides in TG-SwDI brain. Further, patch-clamp recordings from dentate gyrus neurons in hippocampal slices from TG-SwDI mice showed reduced frequency and amplitude of GABAAR-mediated miniature inhibitory postsynaptic currents, and decreased extrasynaptic tonic inhibitory current, while DHM restored these GABAAR-mediated currents in TG-SwDI. We found that gephyrin, a postsynaptic GABAAR anchor protein that regulates the formation and plasticity of GABAergic synapses, decreased in hippocampus and cortex in TG-SwDI. DHM treatment restored gephyrin levels. These results suggest that DHM treatment not only improves symptoms, but also reverses progressive neuropathology of mouse models of AD including reducing Aß peptides, while restoring gephyrin levels, GABAergic transmission and functional synapses. Therefore DHM is a promising candidate medication for AD. We propose a novel target, gephyrin, for treatment of AD.

Morin improves learning and memory in healthy adult mice.

BACKGROUND: Morin is a flavonoid found in many edible fruits. The hippocampus and entorhinal cortex play crucial roles in memory formation and consolidation. This study aimed to characterize the effect of morin on recognition and space memory in healthy C57BL/6 adult mice and explore the underlying molecular mechanism. METHODS: Morin was administered i.p. at 1, 2.5, and 5 mg/kg/24 h for 10 days. The Morris water maze (MWM), novel object recognition, novel context recognition, and tasks were conducted 1 day after the last administration. The mice's brains underwent histological characterization, and their protein expression was examined using immunohistochemistry and Western blot techniques. RESULTS: In the MWM and novel object recognition tests, mice treated with 1 mg/kg of morin exhibited a significant recognition index increase compared to the control group. Besides, they demonstrated faster memory acquisition during MWM training. Additionally, the expression of pro-brain-derived neurotrophic factor (BDNF), BDNF, and postsynaptic density protein 95 proteins in the hippocampus of treated mice showed a significant increase. In the entorhinal cortex, only the pro-BDNF increased. Morin-treated mice exhibited a significant increase in the hippocampus's number and length of dendrites. CONCLUSION: This study shows that morin improves recognition memory and spatial memory in healthy adult mice.

Physiopathology of ischemic stroke and its modulation using memantine: evidence from preclinical stroke.

Ischemic stroke is the most common type of cerebrovascular disease and is caused by an interruption of blood flow in the brain. In this disease, two different damage areas are identifying: the lesion core, in which cells quickly die; and the penumbra (surrounding the lesion core), in which cells are functionally weakened but may recover and restore their functions. The currently approved treatments for ischemic stroke are the recombinant tissue plasminogen activator and endovascular thrombectomy, but they have a short therapeutic window (4.5 and 6 hours after stroke onset, respectively) and a low percentage of stroke patients actually receive these treatments. Memantine is an approved drug for the treatment of Alzheimer's disease. Memantine is a noncompetitive, low affinity and use-dependent antagonist of N-methyl-D-aspartate glutamate receptor. Memantine has several advantages over developing a new drug to treat focal ischemic stroke, but the most important is that it has sufficient safe probes in preclinical models and humans, and if the preclinical studies provide more evidence about pharmacological actions in tissue protection and repair, this could help to increase the number of clinical trials. The present review summarizes the physiopathology of isquemic stroke and the pharmacological actions in neuroprotection and neuroplasticity of memantine in the post stroke stage of preclinical stroke models, to illustrate their potential to improve functional recovery in human patients.

Bradykinin increases resensitization of purinergic receptor signaling in glioma cells.

BACKGROUND: Purinergic receptor-mediated signaling plays an important role in the function of glial cells, including glial tumor cells. Bradykinin is also an important paracrine mediator which is highly expressed in brain tumors and may correlate with their pathological grade. Interaction between bradykinin and purinergic signaling may therefore be involved in the regulation of glial tumor cells. RESULTS: We examined the effect of bradykinin on glial purinergic signaling in an immortalized glioma cell line. Confocal calcium imaging revealed that ATP evokes an increase in [Ca2+]i in the U87 human astrocytoma cell line. This response was reduced with repetitive application of ATP, likely due to receptor desensitization. However exposure to bradykinin increased the Ca2+ response to a second application of ATP, consistent with increased resensitization. The bradykinin effect on resensitization was similar in the absence of extracellular Ca2+ or in the presence of the PKC activator PMA, but was inhibited by the protein phosphatase inhibitor okadaic acid and the PI3K inhibitor LY294002. CONCLUSIONS: Modulation of protein phosphatases and the PI3K pathway may represent a mechanism by which bradykinin potentiates purinergic signaling in glial cells.

Preclinical Research of Dihydromyricetin for Brain Aging and Neurodegenerative Diseases.

Brain aging and neurodegenerative diseases share the hallmarks of slow and progressive loss of neuronal cells. Flavonoids, a subgroup of polyphenols, are broadly present in food and beverage and numerous studies have suggested that it could be useful for preventing or treating neurodegenerative diseases in humans. Dihydromyricetin (DHM) is one of the main flavonoids of some Asian medicinal plants that are used to treat diverse illness. The effects of DHM have been studied in different in vitro systems of oxidative damage and neuroinflammation, as well as in animal models of several neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and Huntington's disease. Here we analyzed the most important effects of DHM, including its antioxidant, anti-inflammatory, and neuroprotective effects, as well as its ability to restore GABA neurotransmission and improve motor and cognitive behavior. We propose new areas of research that might contribute to a better understanding of the mechanism of action of this flavonoid, which could help develop a new therapy for aging and age-related brain diseases.

Inhaled nicotine equivalent to cigarette smoking disrupts systemic and uterine hemodynamics and induces cardiac arrhythmia in pregnant rats.

Maternal smoking with obligatory nicotine inhalation is associated with preterm delivery, low birth weight, fetal growth retardation and developmental defects. We tested the hypothesis that cigarette smoking-relevant nicotine inhalation during pregnancy impairs cardiovascular function and uterine hemodynamics with consequential fetal ischemia. Pregnant rats exposed to episodic inhaled nicotine via a novel lung alveolar region-targeted aerosol method produced nicotine pharmacokinetics resembling cigarette smoking in humans. This clinically relevant nicotine aerosol inhalation (NAI) induced transient reduction and irregular fluctuations in uterine artery blood flow associated with cardiac arrhythmia and high magnitude irregular fluctuations of systemic blood pressure. The arrhythmia included sinoatrial (SA) block, sinus arrest, 2° and 3° atrioventricular (A-V) block and supraventricular escape rhythm. These effects were blocked by the nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine. Resection of the ovarian nerve, which innervates uterine blood vessels, counteracted the NAI-induced reduction in uterine blood flow. We suggest that the rapid rise pattern of arterial blood nicotine concentration stimulates and then desensitizes autonomic nAChRs leading to disruptions of cardiac function as well as systemic and uterine hemodynamics that reduces uteroplacental blood flow, a mechanism underlying maternal smoking-associated pregnancy complications and developmental disorders. These findings challenge the safety of pure nicotine inhalation, i.e., E-cigarettes.

Effects of clomipramine on neuronal nicotinic acetylcholine receptors.

The action of the tricyclic antidepressant clomipramine on membrane currents elicited by acetylcholine was studied in Xenopus oocytes expressing neuronal alpha2beta4 nicotinic acetylcholine receptors. Clomipramine inhibited the acetylcholine responses rapidly and reversibly, with a similar IC(50) when the oocytes were preincubated with clomipramine (1.3+/-0.2 microM) or when they were exposed simultaneously with acetylcholine and clomipramine (1.5+/-0.3 microM). The EC(50) was 39.9+/-2.1 microM for acetylcholine alone and 65.7+/-3.6 microM for acetylcholine in the presence of 2 microM clomipramine. The inhibitory effect of clomipramine was weakly voltage-dependent, with an electric distance of approximately 0.14. Moreover, clomipramine increased the rate of decay of currents elicited by acetylcholine. From all of these, we conclude that clomipramine reversibly and noncompetitively regulates neuronal alpha2beta4 nicotinic acetylcholine receptors by blocking the open receptor-channel complex at a site close to the extracellular vestibule of the channel. The actions of clomipramine on neuronal nicotinic acetylcholine receptors may play an important role in the treatment of mental depression and other mood disorders.

Isolation and properties of a Kunitz-type protein inhibitor obtained from Pithecellobium dulce seeds.

We report for the first time the isolation and characterization of a protease inhibitor from the seeds of Pithecellobium dulce, which is a Leguminosae tree native to Mexico. The purification of the P. dulce trypsin inhibitor (PDTI) was a direct process. After its extraction (pH 8.0) and precipitation (80% (NH(4))(2)SO(4)), the pH was adjusted to 4.0, the supernatant was loaded onto a CM-Sepharose column, and a single peak of trypsin inhibitory activity was eluted (CM-TIA). The main component of CM-TIA was PDTI, a protein composed of two polypeptide chains joined by disulfide bridge(s), with a pI of 4.95 and a molecular weight determined by electrospray mass spectrometry of 19 614 Da. The N-terminal sequence of PDTI has the highest similarity with the seed inhibitor of Acacia confusa. PDTI lacks chymotrypsin inhibitory activity. A low rate of cytotoxicity of CM-TIA toward RINm5F cells contrasted with a high rate of the active fraction G75-TIA (gel filtration chromatography; LC(50) of 0.04 mg/mL).

Multimodal examination of structural and functional remapping in the mouse photothrombotic stroke model.

Recent studies show a limited capacity for neural repair after stroke, which includes remapping of sensorimotor functions and sprouting of new connections. However, physiologic and connectional plasticity of sensory maps during long-term functional recovery in the mouse have not been determined. Using a photothrombotic stroke model, we targeted the motor cortex, which we show results in lasting behavioral deficits on the grid-walking and in the cylinder tasks out to 8 weeks after stroke. Mice recovered performance in a skilled reaching task, showing no deficit from week 2 after stroke. Long-term optical intrinsic signal imaging revealed functional reorganization of sensory cortical maps for both forelimb and hindlimb, with more diffuse sensory physiologic maps. There was a small but significant increase in motor neuron projections within the areas of functional cortical reorganization as assessed using the neuroanatomic tracer biotinylated dextran amine. These findings show that the sensorimotor cortex undergoes remapping of cortical functions and axonal sprouting within the same regions during recovery after stroke. This suggests a linked structural and physiologic plasticity underlying recovery. Combined long-term structural and functional mapping after stroke in the mouse is practical and provides a rich data set for mechanistic analysis of stroke recovery.

Development and characterization of a microfluidic chamber incorporating fluid ports with active suction for localized chemical stimulation of brain slices.

We report a novel microfluidic chamber incorporating fluid ports with active suction to achieve localized chemical stimulation of brain slices. A two-level soft-lithography process is used to fabricate fluid ports with integrated injection and suction holes that are connected to underlying microchannels. Fluorescence imaging, particle tracking velocimetry, and cell staining are used to characterize flows around a fluid port with or without active suction to validate effective localization of injected chemicals. To demonstrate biological applicability of the chamber, we show an induction of cortical spreading depression (CSD) waves in mouse brain slices through controlled focal delivery of potassium chloride solution.

Lethal iron deprivation induced by non-neutralizing antibodies targeting transferrin receptor 1 in malignant B cells.

A number of antibodies have been developed that induce lethal iron deprivation (LID) by targeting the transferrin receptor 1 (TfR1/CD71) and either neutralizing transferrin (Tf) binding, blocking internalization of the receptor and/or inducing its degradation. We have developed recombinant antibodies targeting human TfR1 (ch128.1 and ch128.1Av), which induce receptor degradation and are cytotoxic to certain malignant B-cells. We now show that internalization of TfR1 bound to these antibodies can lead to its sequestration and degradation, as well as reduced Tf uptake, and the induction of a transcriptional response consistent with iron deprivation, which is mediated in part by downstream targets of p53. Cells resistant to these antibodies do not sequester and degrade TfR1 after internalization of the antibody/receptor complex, and accordingly maintain their ability to internalize Tf. These findings are expected to facilitate the rational design and clinical use of therapeutic agents targeting iron import via TfR1 in hematopoietic malignancies.

Bidirectional alterations of hippocampal cannabinoid 1 receptors and their endogenous ligands in a rat model of alcohol withdrawal and dependence.

BACKGROUND: The hippocampus is strongly implicated in memory processes and contains high concentrations of both cannabinoid receptors and their endogenous ligands. Chronic alcohol consumption impairs a variety of cognitive and performance tasks, including memory and learning. As the activation of cannabinoid receptors by their endogenous ligands modulates hippocampal neurotransmission, we hypothesized that the impaired memory and learning in alcoholism may be due to alterations in the hippocampal endocannabinoid system. METHODS: We used the rat chronic intermittent ethanol (CIE) model for alcohol withdrawal and dependence which involves intermittent episodes of ethanol intoxication (60 doses) and withdrawal (approximating binge drinking episodes in humans). We measured the levels of cannabinoid 1 receptor (CB1R) protein (Western blot using a C-terminal-directed antibody), CB1R mRNA (real-time RT-PCR), CB1R localization (immunocytochemistry), tissue levels of the endocannabinoids N-arachidonoylethanolamine/anandamide (AEA) and 2-arachidonoylglycerol (2-AG), and function (patch-clamp recordings of depolarization-induced suppression of inhibition (DSI), as well as effects of CB1R agonist WIN 55,212-2 on inhibitory currents) in the hippocampus of CIE rats and their saline-treated controls. RESULTS: Results were obtained in saline and CIE-treated rats after 2 and 40 days of withdrawal (DW) from their respective treatments. In 2 DW CIE rats, CB1R mRNA and protein levels were decreased by 27% (p<0.05) compared with saline controls. Surprisingly, in 40 DW CIE rats, CB1R mRNA increased by 100% and protein increased by 21%, confirmed by immunohistochemistry. Hippocampal [2-AG] increased in both 2 and 40 DW CIE rats; [AEA] increased only at 40 DW. Hippocampal DSI of CIE rats was significantly reduced at 2 DW but not at 40 DW. The CB1R agonist WIN 55,212-2 (0.5 microM) produced a significantly greater decrease in the frequency of spontaneous inhibitory currents from saline-treated rats compared with CIE rats at 2 DW, but not at 40 DW. CONCLUSIONS: These data demonstrate that CIE treatment and withdrawal transiently down-regulates hippocampal CB1 Rs followed by a long-term up-regulation, including increased levels of endogenous cannabinoids. These findings are consistent with our hypothesis and suggest that long-term up-regulation of hippocampal CB1Rs may contribute to the long-term cognitive impairments in alcoholism. The data further suggest that the effectiveness of CB1R blockade in decreasing alcohol consumption may be greater after protracted abstinence from alcohol.

Binding specificity and internalization properties of an antibody-avidin fusion protein targeting the human transferrin receptor.

The human transferrin receptor (hTfR1) is a membrane-bound protein involved in transferrin (Tf)-mediated iron uptake and is highly expressed on malignant cells. A second version of the receptor (hTfR2) also mediates Tf-dependent iron import. We previously developed a protein composed of avidin fused to a mouse/human chimeric IgG3 specific for hTfR (anti-hTfR IgG3-Av) that was originally designed to deliver biotinylated drugs into cancer cells. We have now found that anti-hTfR IgG3-Av does not cross-react with hTfR2 and binds hTfR1 expressed on the surface of cells, attached to a solid surface, and in solution. We also found that the hemochromatosis protein (HFE), another ligand of the TfR, does not inhibit the binding of anti-hTfR IgG3-Av to the receptor. In addition, using live cell laser scanning confocal microscopy (LCLSCM) we demonstrated that anti-hTfR IgG3-Av and anti-hTfR IgG3 are internalized into cells expressing hTfR1 at a similar rate. Furthermore, our proliferation and morphological studies demonstrated the effective cytotoxicity of a biotinylated toxin delivered by anti-hTfR IgG3-Av only into cells expressing hTfR1. Our results better define the properties of anti-hTfR IgG3-Av and pave the way for the rational design of future in vitro and in vivo studies for the treatment of human malignancies.

Distinct vascular conduction with cortical spreading depression.

Cortical spreading depression (CSD) is associated with significant vasodilatation and vasoconstriction, but the relationship between the cortical parenchymal and vascular phenomena remains poorly understood. We used optical intrinsic signal (OIS) imaging and electrophysiology to simultaneously examine the vascular and parenchymal changes that occur with CSD in anesthetized mice and rats. CSD was associated with a propagated multiphasic change in optical reflectance, with correlated negative DC shift in field potential. Dilatation of cortical surface arterioles propagated with a significantly greater intrinsic velocity than the parenchymal CSD wavefront measured by OIS and electrophysiology. Dilatation traveled in a circuitous pattern along individual arterioles, indicating specific vascular conduction as opposed to concentric propagation of a parenchymal signal. Arteriolar dilatation propagated into areas beyond the spread of parenchymal OIS and electrophysiological changes of CSD. Conversely, vasomotor activity could be experimentally dissociated from the parenchymal CSD wave. Frequent repetitive CSD evoked by continuous stimulation was associated with a reduced or absent arteriolar response despite preserved parenchymal OIS and electrophysiological changes. Similarly, dimethylsulfoxide at high concentrations (10%) inhibited arteriolar reactivity despite preserved parenchymal OIS and electrophysiological changes. These results suggest a mechanism, intrinsic to the vasculature, for propagation of vasodilatation associated with CSD. Distinct vascular conduction could be important for the pathogenesis of conditions that involve CSD, including migraine, stroke, and traumatic brain injury.

Reduced threshold for cortical spreading depression in female mice.

The prevalence of migraine is much greater in female than male individuals. Cortical spreading depression (CSD) is thought to be a fundamental mechanism of migraine, and CSD in rodents is used as a model for migraine. We used optical intrinsic signal imaging and electrophysiological techniques to investigate CSD in C57Bl/6 mice. Using two different methods for induction of CSD, we found that female mice had a significantly reduced threshold for induction of CSD compared with male mice. These results suggest an increased cortical excitability in female mice that may be independent of the estrous cycle.