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Comunicación presentada en el IX Simposi de Neurobiologia Experimental, celebrado los días 22 y 23 de octubre de 2014 en Barcelona y organizado por la Societat Catalana de Biologia del Institut d'Estudis Catalans, Objectives: Enriched environment (EE) promotes functional recovery in animal models of stroke. Here, we used fMRI to assess temporal dynamics of brain recovery after stroke in rats, comparing different housing conditions. Methods: Transient brain ischemia (90 min) was induced in adult male Wistar rats. Groups of shamoperated rats were carried out in parallel for both housing conditions. Three weeks after stroke, animals were randomly distributed in either EE (n=11) or STD (n=12). EE consisted in large cages, with 2 levels, ramps, a running wheel, wooden blocks, among other items that were modified 2 times per week. Rats were studied for 12 weeks. MRI: T2 maps (7T, Bruker) were acquired to measure the lesion size. fMRI was performed every three weeks. Electrical forepaw stimulation was repeated 5 times (15sec each) with resting state periods in between (45sec each). Statistical activation maps were constructed with the software STIMULATE. Behavioral test: Cylinder test for asymmetries and Rotarod test for motor coordination were performed the day before each MRI session. Results None of the rats kept under STD showed signs of behavioural recovery, while EE significantly improved motor coordination and ameliorated motor asymmetries in relation to STD. In fMRI, 42% of the EE rats showed activity recovery (BOLD) between week 9 and 12, whereas this effect was not observed in any of the STD rats. Conclusion fMRI provides useful information of activated areas after forepaw stimulation. EE promotes the functional recovery of the original representation field, as assessed with fMRI and behavioural testing

The motor responses (such as stereotypic behavior or convulsions) induced in rats by N-methyl-D-aspartate (NMDA) administered systemically were followed by a rapid, moderate increase in the putrescine concentration in plasma which preceded an increase in this mine in the brain. This effect was not observed following the convulsions evoked by pentylentetrazol, picrotoxinine, lindane or 4-aminopyridine. However, all the convulsants assayed induced a mild increase in the concentration of putrescine in the frontal cortex and hippocampus. A differential activation of the ornithine decarboxylase (ODC)/polyamine system in both cerebral and peripheral tissues could account for these results.

Trabajo presentado al 8th Forum of Neuroscience (FENS) celebrado en Barcelona del 14 al 18 de julio de 2012., Bilateral common carotid artery occlusion (BCCAO) has been proposed as a model of vascular dementia. The aim of this work was to longitudinally study how vascular remodeling is developed in a chronic hypoperfusion model, and how it correlates with structural cerebral alterations. A multimodal magnetic resonance imaging (MRI) study was performed before and 24h, 7 days, and 3, 7 and 12 weeks after BCCAO, or sham-operation, in Wistar rats. The study comprised: time of flight (TOF) angiography to quantify the alterations of main cerebral arteries and T1 weighted images and T2 relaxometry mapping for evaluation of structural cerebral changes. Cerebral blood flow (CBF) was studied at the last time point by dynamic contrast enhanced MRI, and the basilar artery (BA) was collected to investigate its physical properties. BCCAO progressively increased length, tortuosity and diameter of the BA and the area of the whole cerebral artery network, with significant differences versus sham-operated rats first identified at day 10. At 12 weeks, the BA cross-sectional area and the number of smooth muscle cells per BA ring were significantly increased. Relative CBF values 12 weeks after BCCAO were not reduced versus sham-operated rats, suggesting CBF normalization. In 70% of the cases, BCCAo induced unilateral focal acute damage, mainly in the striatum ranging from 1.7 mm3 to 27.13 mm3. Three weeks after BCCAO high resolution T1 weighted images showed striatal hyperintensities, non observable in T2 relaxometry maps, which were correlated with necrosis and gliosis, as assessed by histological means. The study suggests that outward hypertrophic remodeling of the BA and arteriogenesis can effectively compensate for the reduced blood supply to the brain after BCCAO. In addition, in vivo MRI evidenced alterations in brain microstructure associated to acute focal ischema after BCCAO, suggesting this model is more suitable for the study of subcortical infarcts.

Trabajo presentado al XXVth International Symposium on Cerebral Blood Flow, Metabolism and Function y a la Xth International Conference on Quantification of Brain Function with PET celebrados del 25 al 28 de mayo en Barcelona., [Objectives]: Cerebrovascular diseases are the second leading cause of cognitive decline. Damage of brain white matter induced by cerebral hypoperfusion is the main factor causing vascular dementia. These white matter lesions affect mainly the prefrontal subcortical circuit, which explains most of the cognitive impairments observed in patients. The aim of this work was to longitudinally study how vascular remodeling is developed in a chronic hypoperfusion model in rats, and how it correlates with grey and white matter tissue alterations. [Methods]: Longitudinal MRI scans were performed under isofluorane anaesthesia in a BioSpec 70/30 horizontal animal scanner (Bruker BioSpin, Ettlingen, Germany), equipped with a 12 cm inner diameter actively shielded gradient system (400 mT/m) and a phased array surface coil for rat brain. A multimodal imaging study was performed before and 2h, 24h, 7 days, and 3, 7 and 12 weeks after bilateral carotid artery occlusion (BCCAO), or sham-operation, in male Wistar rats (weighting 280-300 gr). The MRI study comprised: T2 relaxometry for lesion evaluation, time of flight angiography to quantify the alterations of main cerebral arteries and Diffusion Tensor Imaging for assessing grey and white matter microstructural changes. [Results]: As observed in figure 1, BCCAO significantly affected the vertebro-basilar artery system since it increased in length and tortuosity in comparison to pre-occlusion data (p< 0.01) already 10 days following BCCAO. Seven weeks later, these effects were enhanced and significant differences were also demonstrated in comparison to sham-operated animals (p, This work was supported by Instituto de Salud Carlos III(FIS PS09/00527) and the European Union (FP7-ARISE 201024) and CIBER-BBN.

The neurotoxin 2-chloropropionic acid (2CPA, 750 mg/kg, per os) induces ataxia in rats causing neuropathological changes (necrosis and edema) localized mainly in the cerebellum (CB). It has been described that putrescine (PUT) is a good marker of severe brain damage. We measured the concentration of PUT (by HPLC) in ataxic rat brains 3 days after 2CPA dosing. PUT was 9-fold higher than normal values in CB, 5-fold higher in midbrain (MB) and medulla oblongata+pons (MO) and 3-fold higher in the remaining areas studied. Treatment with glycerol, a reducer of brain edema, lowered the concentration of PUT only in CB, MB and MO. Histological damage was found in CB and the spinal trigeminal nucleus (located in the pontomedullar brainstem). We suggest that PUT can act as a marker of both neuronal necrosis and brain edema. © 2004 Elsevier Ireland Ltd. All rights reserved. This work was supported by grant SAF 2001-1643 (CICYT). The Department of Neurochemistry and the Department of Pharmacology and Toxicology are recipients of grants 1999SGR-00210/00212 from the Generalitat of Catalunya. The work was also partially supported by the CIEN network Ministry of Health. The authors thank L. Campa and A. Llobet for their excellent technical assistance.

Putrescine (PUT) increases have been seen in a range of models of neuropathological disturbances. The present study was designed to compare the ability of various types of glutamate receptor agonist to promote excitotoxic brain damage and to examine whether a PUT increase is a general marker of excitotoxic brain damage. To that end, we evaluated features of brain damage associated with the excitotoxicity induced by both ionotropic glutamate receptor (iGluR) and metabotropic glutamate receptor (mGluR) agonists in the conscious rat and the changes produced in the regulation of polyamine metabolism. Intracerebroventricular infusion of N-methyl-Daspartate (NMDA; 80 nmol), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA; 15 nmol), kainic acid (KA; 2.3 nmol), (R,S)-3,5-dihydroxyphenylglycine (3,5-DHPG; 1.5 οmol), and (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD; 2 οmol) produced similar seizure incidences (76-84%) in the rat. The convulsant episodes appeared sooner after iGluR (13-22 min) than after mGluR agonists (50-179 min). Histological analysis of the hippocampus 24 hr after seizures indicated several degrees of excitotoxic injury after equiconvulsive doses of the iGluR and mGluR agonists assayed. The agonists can be placed in the following order, according to the degree of damage they produce: AMPA > 3,5-DHPG ≃ KA > NMDA > 1S,3R-ACPD. In the frontal cortex, moderate to low levels of damage were observed after all GluR agonists. Both iGluR- and mGluR-induced seizures produced an overshoot in the hippocampal and cortical PUT concentration, whereas spermidine and spermine levels were similar to control. Moreover, a concurrence of increased PUT levels and brain damage was observed, indicating that PUT is a general marker of excitotoxic brain damage.

The cerebral ODC/polyamine system is disturbed by brain injury. The main modifications are important increases in ODC activity and putrescine concentration, with minor variations in spermidine and spermine concentrations. A great diversity of stimuli such as cerebral ischemia or overstimulation of the central nervous system by chemical or nonchemical agents can induce polyamine disturbances. Both the contribution of polyamines to the brain damage and their involvement in the repair mechanisms triggered after brain insults have been proposed.

In a previous work we described that after the systemic administration of kainic acid to the rat there was a decrease in the concentrations of spermidine and spermine in the brain in the acute convulsant phase, whereas the concentration of putrescine was not modified. However, the concentration of putrescine increased dramatically in the post-convulsant period, associated to histological damage. The aim of the present work, was to evaluate the sensitivity of the blood polyamine pool to the convulsions induced by kainic acid. The concentration of polyamines was determined by HPLC analysis. Two hours after the injection of the neurotoxin (acute convulsant phase), there was an increase in the concentration of putrescine, spermidine and spermine in plasma and serum (about 100% over controls) of rats displaying convulsions; this increase was still maintained 24 h after kainic acid administration. Putrescine was also increased in red blood cells but only in the acute convulsant phase. In the present work we found changes in brain polyamines similar to those described previously. The time course and concentrations reached by putrescine in both pools do not support a common regulatory mechanism. These results indicate that the increase of putrescine in the blood precedes the increase of this polyamine in the brain. The data reported stimulate the study of polyamines as biochemical markers in models of epilepsy.

Putrescine (PUT) given ip to male rats produced a dose-dependent behavioural response. The observed signs were mainly shaking behaviour and motor disorders. The severity of the motor signs closely correlated with cortical PUT levels. After [14C]-PUT, the levels of related radioactivity ([14C]-PUT(rr)) in frontal cortex paralleled the levels of tracer in blood. Furthermore, the levels of tracer in blood and in frontal cortex were higher in the animals with toxicity signs than in non-affected ones. The frontal cortex levels of polyamines determined by HPLC revealed that only PUT paralleled the severity of the clinical status of the rats. No modifications of spermidine (SD) or spermine (SM) content were detected. Two hours after [14C]-PUT administration, only about 30% of the cortical [14C]-PUT(rr) was analyzed as PUT itself and no radioactivity was detected as SD and SM. Our results suggest that the radioactivity not associated to PUT could be related to more polar metabolites than SD or SM as acetylated derivatives.

Tesis doctoral presentada para lograr el grado de Doctor por la Universidad de Barcelona.--1990, La vincamina se utiliza en la terapéutica de la isquemia cerebral y de la demencia senil. En este trabajo se ha establecido el perfil farmacocinético del medicamento, así como la relación entre niveles plasmáticos de fármaco - efecto farmacológico sobre la presión arterial y la frecuencia cardiaca en humanos. Además, utilizando el medicamento en forma tritiada, se ha definido también el perfil farmacocinetico del medicamento y de sus metabolitos conjuntamente considerados, así como su biodisponibilidad real en el organismo humano. Por otra parte, se ha estudiado el efecto que la vincamina produce sobre el metabolismo energético de distintas regiones cerebrales de rata, valorado como consumo de 2-desoxiglucosa, detectando como áreas mas sensibles a la acción del fármaco zonas corticales y algunas áreas subcorticales relacionadas con los sistemas visual, límbico y extrapiramidal. Además, se ha investigado el efecto que el fármaco produce sobre los sistemas aminergicos de neurotransmisión central, concluyendo que los sistemas dopaminérgico y, fundamentalmente, noradrenérgico son los más afectados por la acción del medicamento, estando estos sistemas posiblemente implicados en su mecanismo de acción farmacológica.

We have developed a model for the treatment of data of concentration of brain neurotransmitters (particularly serotonin and the catecholamines), in which the changes induced by any given treatment on the neurotransmitter (NT) and its main metabolite (ME) are converted into 2 new parameters named S and U, that are related to the modifications in the synthesis (S) and utilization (U) of the neurotransmitter elicited by the treatment. Using this model we have studied the effect of subconvulsant doses of lindane and other hexachlorocyclohexane isomers (α, β and δ) on brain monoaminergic systems. The results obtained indicate that serotonergic activity is increased in cell bodies (dorsal raphe) as well as in regions rich in nerve terminals after treatment with lindane. Also, the activity of dopaminergic neurons is increased in the substantia nigra. These results are in agreement with the proposed role of lindane as a “picrotoxinin-like” substance acting as an antagonist at the GABA-A receptor complex and thus impairing the inhibitory tone exerted by GABA on a variety of neurons (serotonin in raphe nuclei and dopamine in substantia nigra).

Tesis doctoral presentada para optar al grado de Doctor por la Universidad de Barcelona.--1991, • La finalidad de la presente tesis es, por una parte, desarrollar modelos biológicos para el estudio de la acción de xenobióticos neurotóxicos y, por otra, aportar información que pueda ayudar a establecer como el lindano -insecticida organoclorado- ejerce su acción toxica en el sistema nervioso central (snc) de mamíferos. Para ello se plantean los siguientes objetivos: 1) estudiar la distribución intracerebral del lindano en la rata, para ver si existen regiones cerebrales donde este se acumula de manera preferente; 2) conocer la acción del lindano en la actividad funcional del snc de rata, a partir de estudios de consumo de glucosa y flujo sanguíneo regional cerebral, para comprobar si existen regiones cerebrales especialmente sensibles a la acción del toxico; y 3) estudiar el efecto del lindano sobre el receptor gaba a en diferentes regiones y núcleos del cerebro de rata, para ver si puede establecerse una relacion directa entre el efecto del lindano sobre la actividad funcional del snc y un efecto a nivel del receptor gaba a. Para el abordaje de estos objetivos se utilizan distintas metodologías basadas fundamentalmente en la utilización de trazadores radioactivos. Los animales de experimentación son sometidos a distintas pautas de administración del xenobiótico.