Search

Background: Some reports demonstrated vascular alterations in brain magnetic resonance imaging (MRI) in migraineurs and a relationship between circle of Willis (Circle) variants and lacunar brain infarcts. We examined anomalies of the whole circle of Willis and their relationship with vascular brain lesions in migraineurs, to identify any possible vascular mechanism in migraine., Methods: We studied, with a cohort controlled study, the circle of Willis in migraineurs seen consecutively in our Headache Center, and in non-headache controls, using angio-MRI of the brain. Statistical analysis used ANOVA, Scheffè's criterion, t-student test., Results: We recruited 270 migraineurs (204 without aura (MWOA), 66 with aura (MWA) and 159 controls. Migraineurs presented an anatomical variant in 108 (40%) cases with 34 controls (21.4%) presenting a variant. We found a significant association between MWOA and variants (OR=2.4 CI95% [1.5 to 3.9]) and between MWA and variants (OR=3.2 CI95% [1.6 to 4.1]). Unilateral posterior variants with basilar hypoplasia are statistically associated only with MWA compared to controls (OR=9.2, CI95% [2.3 to 37.2]). Thirty-three percent of MWOA and 24% of MWA sufferers present some kind of brain lesion, included 2% of infra-tentorial lesions. We did not find any statistical association between the presence of Circle variants and ischemic lesions on MRI (OR=1.5 CI95% [0.68; 1.94]), or with infratentorial lacunar lesions (OR=1.58 CI95% [0.48 to 5.24])., Conclusions: Anatomical variants of the Circle of Willis are significantly more frequent in migraineurs; posterior anomalies are more frequent in MWA, suggesting a vascular mechanism provoking changes in cerebral blood flow, thereby stimulating cortical spreading depression.

We have studied the impact of short-term treatment with interferon (IFN)-beta1b of relapsing remitting (RR) multiple sclerosis (MS) patients' blood levels of type 1 and type 2 cytokines such as IFN-gamma, interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-10 and tumour necrosis factor (TNF)-alpha. These cytokines were measured by solid-phase ELISA. Serum samples were obtained prior to, and 2 and 12 hours after beginning of the treatment and 48 h after the last of 5 s.c. injections with 8 million IU IFN-beta1b given on alternate days for 10 days. The treatment was found to increase the circulating levels of IL-2, IL-6, IL-10 and IFN-gamma at some of the time points considered, with the effect acquiring statistical significance for IL-6, IL-10 and IFN-gamma. The blood levels of IL-1beta, IL-4 and TNF-alpha remained below the limit of sensitivity of the assays at any of the time points considered. If this in vivo study mirrors the impact of IFN-beta1b on MS patients' immune cells, these data demonstrate an activation of the immune system upon early treatment with the drug that does not lead to either type 1 or type 2 cytokine prevalence., (Copyright 2000 Academic Press.)

Objectives: To evaluate clinical and MRI effects of natural interferon beta treatment in both relapsing-remitting (RR) and secondary-progressive (SP) multiple sclerosis patients., Material and Methods: A double-blind, randomized trial of natural interferon beta (nIFN-beta) in 58 ambulatory patients with RR and 40 with SP multiple sclerosis. Forty-nine patients (29 RR and 20 SP) were treated with intramuscular nIFN-beta6 MIU three times a week for 24 months and 49 control patients were treated with placebo., Results: Primary clinical endpoints were differences in exacerbation rates and proportion of patients remaining exacerbation-free. There were no significant baseline differences between the treated and placebo groups. In the treated RR group a significant reduction in exacerbation rate, an increase in the probability of remaining exacerbation-free, and an improvement in mean EDSS were found at 24 months. MRI activity and total lesion burden were significantly reduced in treated RR patients. In the SP group, nIFN-beta produced a significant reduction in EDSS score, a significant reduction in active lesion number, a marginally significant favourable difference in total lesion burden but no significant effect on the number of gadolinium-enhancing lesions. Side effects were transient and mild in treated patients., Conclusions: These observations confirm that nIFN-beta is a promising and well-tolerated treatment for either RR or SP MS patients.

Cyclic adenosine diphosphate-ribose (cADPR) and ADPR were separated by high-performance liquid chromatography (HPLC) on a CarboPac PA-1 column at strong basic pH and quantitated by a pulsed amperometric detector. Although this HPLC method was quite sensitive and highly reproducible, it did not allow the separation of cADPR from guanosine monophosphate (GMP) which, when present, could be removed by ion-affinity chromatography, using gel-immobilized Fe3+ columns. Crude synaptic membranes from rat hippocampi were incubated with nicotinamide adenine dinucleotide (NAD) and acidic extracts were subject to HPLC analysis after neutralization. Incubation led to a time-dependent formation of ADPR, which was amplified when membranes were incubated in the presence of guanosine trisphosphate (GTP), guanosine-5'-0-(3-thiotrisphosphate) (GTP-gamma-S) or AlF3. cADPR did not accumulate in detectable amounts and only a minimal proportion (< 5%) of radioactivity originating from [3H]NAD co-eluted with authentic cADPR in extracts from hippocampal membranes. The simultaneous detection of cADPR and ADPR we have described may help the search for inhibitors of cADPR metabolism, which will allow to measure the cADPR that accumulates under basal conditions or in response to extracellular signals.

[3H]Aniracetam bound to specific and saturable recognition sites in membranes prepared from discrete regions of rat brain. In crude membrane preparation from rat cerebral cortex, specific binding was Na+ independent, was still largely detectable at low temperature (4 degrees C), and underwent rapid dissociation. Scatchard analysis of [3H]aniracetam binding revealed a single population of sites with an apparent KD value of approximately 70 nM and a maximal density of 3.5 pmol/mg of protein. Specifically bound [3H]aniracetam was not displaced by various metabolites of aniracetam, nor by other pyrrolidinone-containing nootropic drugs such as piracetam or oxiracetam. Subcellular distribution studies showed that a high percentage of specific [3H]aniracetam binding was present in purified synaptosomes or mitochondria, whereas specific binding was low in the myelin fraction. The possibility that at least some [3H]aniracetam binding sites are associated with glutamate receptors is supported by the evidence that specific binding was abolished when membranes were preincubated at 37 degrees C under fast shaking (a procedure that substantially reduced the amount of glutamate trapped in the membranes) and could be restored after addition of either glutamate or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) but not kainate. The action of AMPA was antagonized by DNQX, which also reduced specific [3H]aniracetam binding in unwashed membranes. High levels of [3H]aniracetam binding were detected in hippocampal, cortical, or cerebellar membranes, which contain a high density of excitatory amino acid receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

In rat hippocampal slices, the novel metabotropic glutamate receptor (mGluR) ligand, (1S,1'R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)glycine (DCG-IV) enhanced the stimulation of polyphosphoinositide (PPI) hydrolysis elicited by quisqualate or by submaximal concentrations of ibotenate or (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD). The enhancing effect of DCG-IV was (i) specific for mGluR agonists, (ii) restricted to hippocampal slice preparation, (iii) reversible, and (iv) not subject to homologous desensitization, in addition, DCG-IV did not interact with L-2-amino-4-phosphonobutanoate (AP4), a noncompetitive antagonist of mGluRs coupled to PPI hydrolysis in brain slices [32]. The action of DCG-IV on quisqualate-stimulated PPI hydrolysis was insensitive to antagonists of ionotropic glutamate receptors and did not appear to be a consequence of a reduction in the intracellular levels of cAMP [14]. When the stimulation of PPI hydrolysis was measured as a function of the incubation time, DCG-IV potentiated quisqualate-stimulated PPI hydrolysis after 60 min of incubation, when quisqualate had already reached its maximal effect. Knowing that activation of protein kinase C (PKC) limits the extent of mGluR agonist-stimulated PPI hydrolysis over time, we have studied the enhancing effect of DCG-IV in the presence of the PKC activator, 12-O-tetradecanoylphorbol-13-acetate (TPA). As expected [9], TPA reduced quisqualate-stimulated PPI hydrolysis in control slices, but was inactive in slices incubated in the presence of DCG-IV. Taken collectively, these results suggest that DCG-IV positively modulates the activity of mGluRs coupled to PPI hydrolysis through a mechanism, which involves PKC-mediated phosphorylation processes.

Inhibition of forskolin-stimulated cAMP formation by (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD) in rat hippocampal slices was partially obliterated by the adenosine-depleting enzyme, adenosine deaminase, or by the adenosine receptor agonist, 5'-(N-ethylcarboxamido)-adenosine, suggesting that activation of metabotropic glutamate receptors (mGluRs) modulates the release of endogenous adenosine. Consistent with this hypothesis, forskolin stimulated the release of purines from rat hippocampal slices, and this effect was reduced by 1S,3R-ACPD. To establish which transduction pathway is involved in the modulation of forskolin-stimulated purine release, we have tested the novel mGluR2 agonist, (2S,1'R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)glycine (DCG-IV), which reduced forskolin-stimulated cAMP formation but, as opposed to 1S,3R-ACPD, did not stimulate polyphosphoinositide hydrolysis. DCG-IV was highly potent and more efficacious than 1S,3R-ACPD in inhibiting forskolin-stimulated purine release. Neither DCG-IV nor 1S,3R-ACPD reduced the release of purines stimulated by depolarizing concentrations of K+, suggesting that their effect was stimulus-specific. These results indicate that, in rat hippocampal slices, activation of mGluR2 receptors attenuates the release of purines induced by forskolin, a process that amplifies the final effect of forskolin on cAMP formation as a result of A2 purinergic receptor activation. Thus, the final effect of mGluR agonists on forskolin-stimulated cAMP formation in hippocampal slices depends on both a direct inhibition of adenylyl cyclase and the inhibition of adenosine release.

We have characterized the pharmacological profile of activation of metabotropic glutamate receptors negatively linked to adenylyl cyclase (mGluR decreases cAMP) in brain slices. Among the putative mGluR agonists, (2S,1'R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)glycine (DCG-IV) and (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD), were the most potent inhibitors of forskolin-stimulated cAMP formation in hippocampal slices, followed by ibotenate, L-2-amino-3-phosphonopropionate (AP3), quisqualate, L-glutamate and beta-N-methylamino-L-alanine (BMAA). Inhibition of forskolin-stimulated cAMP formation by DL-2-amino-4-phosphonobutanoate (AP4) was biphasic, suggesting that the drug interacts with more than one mGluR decreases cAMP subtype. Both L-AP4 and L-serine-O-phosphate (a restricted analogue of AP4) were much more effective in inhibiting forskolin-stimulated cAMP formation than their D-isomers, indicating that interaction of these drugs with the mGluR decreases cAMP is stereoselective. Despite the fact that DCG-IV and ibotenate behave as NMDA receptor agonists, their effect was insensitive to MK-801. The regional pattern of expression of mGluR decreases cAMPS, as estimated by using 1S,3R-ACPD as an agonist, did not correlate with the steady-state levels of mGluR2 mRNA. Thus, 1S,3R-ACPD inhibited forskolin-stimulated cAMP in slices from hippocampus, cerebral cortex, corpus striatum, olfactory tubercle or hypothalamus, but not in slices from olfactory bulb or cerebellum; in contrast, mGluR2 mRNA levels were high in the olfactory bulb and very low in the corpus striatum. 1S,3R-ACPD also inhibited forskolin-stimulated cAMP formation in cortical membranes, excluding the involvement of trans-synaptic mechanisms in the activity of mGluR decreases cAMPS.(ABSTRACT TRUNCATED AT 250 WORDS)

In adult rat hippocampal slices, (2S,1'R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)glycine (DCG-IV) did not affect the basal hydrolysis of polyphosphoinositides but dramatically enhanced (EC50 value = 30 nM) the stimulation of [3H]inositol monophosphate (InsP) formation by quisqualate, without substantially affecting the stimulation produced by maximal concentrations of 1S,3R-amino-cyclopentane-1,3-dicarboxylic acid (ACPD) or carbamylcholine. alpha-Amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) was virtually devoid of activity on [3H]InsP formation, either in the absence or presence of DCG-IV. These results suggest that DCG-IV acts, directly or indirectly, as a positive modulator of metabotropic glutamate receptors in the rat hippocampus.