Miguel Ángel de Pablo Hernández

Cyclosporin A targets involved in protection against glutamate excitotoxicity

The toxicity of glutamate in neuronal cultures has been attributed in part to a mitochondrial dysfunction involving the permeability transition pore. The participation of the permeability transition pore in this process has been pharmacologically demonstrated by the use of cyclosporin A, which inhibits pore opening by interaction with mitochondrial cyclophilin and, thus, prevents cell death and upstream events. Since cyclosporin A also acts on calcineurin, we have investigated which of the targets of cyclosporin A was responsible for the inhibition of glutamate-excitotoxicity in cerebrocortical primary neuronal cultures. Reactive oxygen species production and early (30 min to 2 h) drop in ATP levels are initial events in glutamate excitotoxicity taking place before neuronal death. Cyclosporin A did not inhibit reactive oxygen species production, but reduced the drop in ATP levels and subsequent neuronal death. However, cyclosporin derivatives that do not bind to calcineurin had smaller effect on survival than cyclosporin A, (regardless of whether they were able to bind cyclophilin), indicating that cyclosporin A protects against glutamate toxicity also through calcineurin-related mechanisms. Consistent with this view, ATP loss appears to result from nitric oxide synthase (NOS) activation (including calcineurin-dependent dephosphorylation) and nitric oxide (NO)/peroxinitrite-dependent increase in poly (ADP-ribose) polymerase activity, since it was reduced by inhibitors of these activities. Collectively, these results suggest that cyclosporin A exerts its protective effects through calcineurin-dependent and independent mechanisms.

Quality of life in multiple sclerosis patients in Spain

Objective: The cross-sectional study evaluated the psychometric properties of the Functional Assessment of Multiple Sclerosis (FAMS) Spanish version and its use in measuring quality of life (QOL) of multiple sclerosis (MS) patients in Spain. Methods: The FAMS is a factorially derived self-report scale designed to assess six primary aspects of QOL of patients with MS: Mobility, Symptoms, Emotional Well-Being, General Contentment, Thinking and Fatigue, and Family/Social Well-Being. Its Spanish translated version was used to assess QOL of 625 MS patients recruited in an outpatient clinic setting from 58 hospitals in Spain. Internal consistency of the Spanish FAMS was evaluated. Multiple regression analyses were performed to identify significant predictors from demographic, clinical and treatment characteristics, and Kurtzke Expanded Disability Status Scale (EDSS) scores in predicting FAMS scale scores. Results: Most of the patients are females (66%), and 74% were of the relapsing-remitting (RR) clinical subtype. Cronbach’s alpha coefficients were high (range=0.78-0.96), indicating subscale homogeneity comparable to that of the original English version. Linear multivariate regression analyses revealed that the EDSS is a dominant variable in predicting all the FAMS subscales, especially mobility (R2=0.51) and the total scores. Conclusions: The Spanish FAMS is a psychometrically valid instrument that allows clinicians and clinical researchers the ability to measure the QOL concerns of MS patients in Spain.

Effects of chronic nimodipine on working memory of old rats in relation to defects in synaptosomal calcium homeostasis

The present study was designed to investigate whether chronic (from 12 to 23 months of age) dietary treatment with the L-type Ca2+ channel blocker nimodipine (30 mg/kg body weight) enhances the cognitive behavior of aged animals and whether such a treatment would have long-term effects on the mechanisms of Ca2+ regulation in synaptic terminals from the aged rat brain. Cognitive behavior was evaluated in an 8-arm radial maze in 6 test series comprising a total of 105 test sessions, with intervals of no training between series. Nimodipine-treated rats performed better than vehicle-treated, aged-matched controls in all the test series, making more correct choices every time a new series was initiated. However, differences between nimodipine- and vehicle-treated rats were most remarkable in the last three test series, when the rats were 19 to 22 months. In these series 74% of the nimodipine-treated rats were able to perform the task in 4 to 9 test sessions whereas only 12%, 14% or none of the control rats learned the task. To study Ca2+ regulation in synaptosomes derived from cerebral cortex and hippocampus, we analyzed 45Ca2+ accumulation as well as the levels of the Ca2+-binding proteins calbindin-D28K and calreticulin by Western blotting. Nimodipine administration had no effect on hippocampal synaptosomes but increased the levels of calbindin-D28K and calreticulin in cerebral cortex preparations. These results indicate that chronic nimodipine treatment from 12 to 23 months of age prevents age-induced learning deficits without showing any signs of toxicity, and that these effects are associated with a small increase in the levels of synaptosomal Ca2+-binding proteins from cerebral cortex. The up-regulation of these proteins might provide a link between the long-term effects of nimodipine on gene expression and learning ability in old rats.