Propagation of spreading depression inversely correlates with cortical myelin content

The acute effects of hemorrhagic shock on cerebral blood flow, brain tissue oxygen tension, and spreading depolarization following penetrating ballistic-like brain injury

Traumatic brain injury (TBI) often occurs in conjunction with additional trauma, resulting in secondary complications, such as hypotension as a result of blood loss. This study investigated the combined effects of penetrating ballistic-like brain injury (PBBI) and hemorrhagic shock (HS) on physiological parameters, including acute changes in regional cerebral blood flow (rCBF), brain tissue oxygen tension (P(bt)O₂), and cortical spreading depolarizations (CSDs). All recordings were initiated before injury (PBBI/HS/both) and maintained for 2.5 h. Results showed that PBBI alone and combined PBBI and HS produced a sustained impairment of ipsilateral rCBF that decreased by 70% from baseline (p<0.05). Significant and sustained reductions in P(bt)O₂ (50% baseline; p<0.05) were also observed in the injured hemisphere of the animals subjected to both PBBI and HS (PBBI+HS). In contrast, PBBI alone produced smaller, more transient reductions in P(bt)O₂ levels. The lower limit of cerebral autoregulation was significantly higher in the PBBI+HS group (p<0.05, compared to HS alone). Critically, combined injury resulted in twice the number of spontaneous CSDs as in PBBI alone (p<0.05). It also lowered the propagation speed of CSD and the threshold of CSD occurrence [induced CSD at higher mean arterial pressure (MAP)]. However, rCBF and P(bt)O₂ were not responsive to the depolarizations. Our data suggest that PBBI together with HS causes persistent impairment of CBF and brain tissue oxygen tension, increasing the probability of CSDs that likely contribute to secondary neuropathology and compromise neurological recovery.

Meta-analysis of the relationship between multiple sclerosis and migraine

Background

Studies investigating a proposed association between multiple sclerosis (MS) and migraine have produced conflicting results and a great range in the prevalence rate of migraine in MS patients. By meta-analysing all available data we aimed to establish an overall estimate of any association in order to more accurately inform clinicians and care-givers about a potential association between MS and migraine.

Methods

Pubmed and EMBASE were searched to identify suitable studies. Studies were included if they were a case-control study or cohort study in which controls were not reported to have another neurological condition, were available in English, and specified migraine as a headache sub-type. The odds ratio (OR) of migraine in MS patients vs. controls was calculated using the inverse variance with random effects model in Review Manager 5.1.

Results

Eight studies were selected for inclusion, yielding a total of 1864 MS patients and 261563 control subjects. We found a significant association between migraine and MS (OR = 2.60, 95% CI 1.12–6.04), although there was significant heterogeneity. Sensitivity analysis showed that migraine without aura was associated with MS OR = 2.29 (95% CI 1.14–4.58), with no significant heterogeneity.

Conclusions

MS patients are more than twice as likely to report migraine as controls. Care providers should be alerted to ask MS patients about migraine in order to treat it and potentially improve quality of life. Future work should further investigate the temporal relationship of this association and relationship to the clinical characteristics of MS.

The use of cortical spreading depression for studying the brain actions of antioxidants

OBJECTIVES

We review the main adverse effects of reactive oxygen species (ROS) in the mammalian organism, introducing the reader on the worldwide problem of the ROS neurophysiological impact on the developing and the adult brain, and discussing the neuroprotective action of antioxidant molecules.

METHODS

We briefly present the electrophysiological phenomenon designated as 'cortical spreading depression' (CSD), as a parameter of normal brain functioning. We highlight recent electrophysiological advances obtained in experimental studies from our laboratory and from others, showing how to investigate the ROS effects on the brain by using the CSD phenomenon.

RESULTS

Under conditions such as aging, ROS production by photo-activation of dye molecules and ethanol consumption, we describe the effects, on CSD, of treating animals with (1) antioxidants and (2) with antioxidant-deficient diets.

DISCUSSION

The current understanding of how ROS affect brain electrophysiological activity and the possible interaction between these ROS effects and those effects of altered nutritional status of the organism are discussed.

The impairing effect of acute ethanol on spreading depression is antagonized by astaxanthin in rats of 2 young-adult ages

BACKGROUND

Ethanol (EtOH) abuse and insufficient ingestion of antioxidants are external factors that can alter brain electrophysiology. Our previous studies have demonstrated that the excitability-related brain electrophysiological phenomenon known as cortical spreading depression (CSD) was facilitated by chronic EtOH intake, and chronic treatment with carotenoids attenuated this effect. Here, we investigated the acute effect of a single EtOH administration on CSD in young and adult rats previously (1 hour) treated with 10 μg/kg of astaxanthin.

METHODS

Male Wistar rats (5 young- and 5 adult groups, 60 to 80 and 150 to 180 days of age, respectively) were treated by 2 gavage procedures at 1-hour interval as follows: groups 1 and 2 received astaxanthin in gavage I combined with EtOH (group 1) or water (group 2) in gavage II; groups 3 and 4 received olive oil (the vehicle in which astaxanthin was dissolved) in gavage I combined with EtOH (group 3) or water (group 4) in gavage II; group 5 received water in gavage I combined with EtOH in gavage II. CSD was recorded on the cortical surface for 4 hours.

RESULTS

Compared to the respective water and oil controls (groups 2 and 4; CSD velocities: 3.73 ± 0.09 and 3.78 ± 0.07 mm/min in the young groups; 2.99 ± 0.10 and 3.05 ± 0.19 mm/min in the adult groups), a single dose of EtOH (groups 3 and 5) decreased CSD propagation velocities (3.29 ± 0.23 and 3.16 ± 0.10 mm/min in the young groups; 2.71 ± 0.27 and 2.75 ± 0.31 mm/min in the adult groups). Astaxanthin antagonized the impairing effect of acute EtOH on CSD (group 1; mean velocity: 3.70 ± 0.19 and 3.13 ± 0.16 mm/min for the young and adult groups, respectively).

CONCLUSIONS

The results showed an antagonistic effect of acute EtOH treatment on CSD propagation that was reverted by astaxanthin. The EtOH-astaxanthin interaction was not influenced by the age, as it was found in both young and adult animals.

Differential effects of physical exercise and L-arginine on cortical spreading depression in developing rats

OBJECTIVE

We investigated the effect of early-in-life administration of L-arginine, combined with physical exercise, on cortical spreading depression (CSD) in young and adult rats.

METHODS

L-arginine (300 mg/kg/day, n = 40) or distilled water (vehicle, n = 40) was given to the rats during postnatal days 7-35 by gavage. Physical exercise (treadmill) was carried out during postnatal days 15-35 in half of the animals in each gavage condition described above. The other half (non-exercised) was used for comparison. When the animals reached 35-45 days (young groups) or 90-120 days of age (adult) CSD was recorded on two cortical points during 4 hours and CSD propagation velocity was calculated.

RESULTS

L-arginine-treated + exercised rats had increased body weight, but not brain weight, in adult age compared to L-arginine + non-exercised ones (P < 0.05). In both young and adult animals, L-arginine increased, whereas exercise decreased the CSD propagation velocity. Analysis of variance revealed a significant interaction between gavage treatment and age (P < 0.001), and also between gavage treatment and exercise (P = 0.004), but not between age and exercise. An additional control group of young rats, treated with 300 mg/kg of L-histidine, presented CSD velocities comparable to the corresponding water-treated controls, suggesting that the CSD acceleration seen in the L-arginine group was an L-arginine-specific effect, rather than an effect due to a non-specific amino acid imbalance.

DISCUSSION

L-arginine and exercise affect CSD differentially (L-arginine accelerated, while exercise decelerated CSD), and both effects did interact. Probably, they depend on developmental plasticity changes associated with the treatments.

Potentiation of spontaneous and evoked cortical electrical activity after spreading depression: in vivo analysis in well-nourished and malnourished rats

Cortical spreading depression (CSD) is influenced by brain excitability and is related to neurological diseases, such as epilepsy. In vitro evidence indicates that neuronal electrical activity is potentiated after CSD. Malnutrition can cause electrophysiological changes in the brain, both in animals and in humans. Here, we investigated in vivo whether CSD potentiates the amplitude of electrocorticogram (ECoG) and of transcallosal evoked responses in adult well-nourished (W), early-malnourished (M), and food-restricted rats. ECoG amplitudes were compared before and after CSD, at two parietal regions (designated the anterior and posterior regions). In the anterior region, post-CSD amplitudes of the ECoG waves were 13-23% higher (P < 0.05) than the pre-CSD values in all groups. In the posterior region, amplitudes increased 22% in the M group only (P < 0.05). In a fourth CSD-free group, ECoG amplitude did not change during the four recording hours. Transcallosal electrically evoked cortical responses also increased 21.5 ± 9.6% and 41.8 ± 28.5%, after CSD, in the W and M conditions, respectively, as compared to pre-CSD values. The data support the hypothesis of an in vivo CSD potentiation on cortical excitability as recorded by spontaneous and evoked electrical activity and modulation by nutritional status.

Enhanced subcortical spreading depression in familial hemiplegic migraine type 1 mutant mice

Familial hemiplegic migraine type 1, a monogenic migraine variant with aura, is linked to gain-of-function mutations in the CACNA1A gene encoding Ca(V)2.1 channels. The S218L mutation causes severe channel dysfunction, and paroxysmal migraine attacks can be accompanied by seizures, coma, and hemiplegia; patients expressing the R192Q mutation exhibit hemiplegia only. Familial hemiplegic migraine knock-in mice expressing the S218L or R192Q mutation are highly susceptible to cortical spreading depression, the electrophysiological surrogate for migraine aura, and develop severe and prolonged motor deficits after spreading depression. The S218L mutants also develop coma and seizures and sometimes die. To investigate underlying mechanisms for these symptoms, we used multielectrode electrophysiological recordings, diffusion-weighted magnetic resonance imaging, and c-fos immunohistochemistry to trace spreading depression propagation into subcortical structures. We showed that unlike the wild type, cortical spreading depression readily propagated into subcortical structures in both familial hemiplegic migraine type 1 mutants. Whereas the facilitated subcortical spread appeared limited to the striatum in R192Q, hippocampal and thalamic spread was detected in the S218L mutants with an allele-dosage effect. Both strains exhibited increased susceptibility to subcortical spreading depression and reverberating spreading depression waves. Altogether, these data show that spreading depression propagates between cortex, basal ganglia, diencephalon, and hippocampus in genetically susceptible brains, which could explain the prolonged hemiplegia, coma, and seizure phenotype in this variant of migraine with aura.

Caffeine/nutrition interaction in the rat brain: Influence on latent inhibition and cortical spreading depression

Caffeine, like malnutrition, can produce behavioral and electrophysiological alterations. However, the interaction of both factors remains unclear. Here this interaction has been studied in male Wistar rats previously malnourished during the lactation period by feeding their dams the "regional basic diet" of Northeast Brazil, containing about 8% protein, predominantly from vegetable sources (RBD(8)). At 70-75days of life, a subset of the pups was treated intraperitoneally with 30mg/kg caffeine for 4days while being tested according to the behavioral model of latent inhibition. Another group was subjected to an electrophysiological recording of the phenomenon known as cortical spreading depression, and the effects of caffeine injected during the recording session were evaluated. Caffeine did not affect cortical spreading depression, but antagonized latent inhibition in both the RBD(8)-malnourished rats and in the well-nourished control group fed a chow diet with 22% protein. This effect of caffeine was not seen in malnourished rats fed a protein-supplemented RBD (protein increased to 22% by increasing the proportion of foodstuffs from vegetable origin; RBD(22) group), suggesting that the amino acid imbalance of this diet may modulate the caffeine effects on latent inhibition. The results indicate a differential effect of caffeine in the latent inhibition behavioral model, as compared to the cortical spreading depression phenomenon, and this effect is influenced by the early nutritional status of the animal. We suggest that caffeine may modulate dopaminergic subcortical receptors participating in attention processes, but does not interact at the cortical level, in a way that would affect cortical spreading depression.