Dopamine-dependent periadolescent maturation of corticostriatal functional connectivity in mouse

Altered corticostriatal information processing associated with early dopamine systems dysfunction may contribute to attention deficit/hyperactivity disorder (ADHD). Mice with neonatal dopamine-depleting lesions exhibit hyperactivity that wanes after puberty and is reduced by psychostimulants, reminiscent of some aspects of ADHD. To assess whether the maturation of corticostriatal functional connectivity is altered by early dopamine depletion, we examined preadolescent and postadolescent urethane-anesthetized mice with or without dopamine-depleting lesions. Specifically, we assessed (1) synchronization between striatal neuron discharges and oscillations in frontal cortex field potentials and (2) striatal neuron responses to frontal cortex stimulation. In adult control mice striatal neurons were less spontaneously active, less responsive to cortical stimulation, and more temporally tuned to cortical rhythms than in infants. Striatal neurons from hyperlocomotor mice required more current to respond to cortical input and were less phase locked to ongoing oscillations, resulting in fewer neurons responding to refined cortical commands. By adulthood some electrophysiological deficits waned together with hyperlocomotion, but striatal spontaneous activity remained substantially elevated. Moreover, dopamine-depleted animals showing normal locomotor scores exhibited normal corticostriatal synchronization, suggesting that the lesion allows, but is not sufficient, for the emergence of corticostriatal changes and hyperactivity. Although amphetamine normalized corticostriatal tuning in hyperlocomotor mice, it reduced horizontal activity in dopamine-depleted animals regardless of their locomotor phenotype, suggesting that amphetamine modified locomotion through a parallel mechanism, rather than that modified by dopamine depletion. In summary, functional maturation of striatal activity continues after infancy, and early dopamine depletion delays the maturation of core functional capacities of the corticostriatal system.Fil: Galiñanes, Gregorio Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Taravini, Irene Rita Eloisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Murer, Mario Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; Argentin

Behavioral sensitization to different dopamine agonists in a parkinsonian rodent model of drug-induced dyskinesias

Repeated treatment with dopamine (DA) receptor agonists strongly potentiates contralateral turning behavior due to selective stimulation of D1 or D2-class receptors in 6-hydroxydopamine (6-OHDA)-lesioned rats. This phenomenon, referred to as sensitization, is believed to be related to the motor response complications (dyskinesias, on-off states) that occur during chronic administration of levodopa in Parkinson’s disease patients. In recent years a new method for the evaluation of abnormal involuntary movements (AIMs) secondary to dopaminergic stimulation in 6-OHDA-lesioned rats was described. These AIMs resemble dyskinesias as seen in parkinsonian patients under levodopa therapy. Our objective was to evaluate the effects of repeated treatment with different regimes of DA agonists on turning behavior and on an AIMs scale in 6-OHDA lesioned rats, with the aim of discriminating between drugs with different dyskinesia-inducing potential. In addition, we explored the effects of a previous exposure to a DA agonist (priming) on the behavioral response to the subsequent administration of a DA agonist with the same or different pharmacologic profile. Our results show that in apomorphine-treated rats, rotational behavior and AIMs run a parallel course of enhancement, while in those receiving quinpirole there is a dissociation, suggesting that they could be mediated by different mechanisms. The finding of a significant priming effect on subsequent testing of 6-OHDA lesioned rats should be borne in mind as the use of these pharmacological tests in the screening of well lesioned animals could lead to an erroneous interpretation of further results on dyskinesias and rotational behavior.Fil: Delfino MA. ININFA; Argentina. ININFA; ArgentinaFil: Stefano AV. ININFA; ArgentinaFil: Ferrario, Juan Esteban. ININFA; ArgentinaFil: Taravini, Irene Rita Eloisa. ININFA; ArgentinaFil: Murer, Mario Gustavo. FACULTAD DE MEDICINA; ArgentinaFil: Gershanik OS. ININFA; Argentin

Sandblasted, acid etched and UV irradiated titanium surface for dental implants: In vitro and in vivo analysis

In the implant dentistry field, rehabilitation through osseointegrated implants have been a huge advance, leading to excellent outcomes. Biomaterial integration to bone tissue determines the implant clinical success and the recovery of lost functionality, depending on clinical and engineering factors and patient whole health. Because of this, it is important the development of new strategies to achieve higher success rates and to decrease the healing period of osseointegrated implants. The present study addresses the UV irradiation effect on superficial characteristics of sandblasted and acid etched titanium discs. Furthermore, the irradiation protocol with the best outcomes was selected and applied to titanium implants placed in vivo in order to study the influence of the UV irradiation over the surrounding tissue. The results showed that UVC, but not UVA, enhanced surface hydrophilicity significantly. After 24 h of exposure to UVC, a superhydrophilic surface was obtained, with higher protein adsorption capability. New bone formation occurred for all the implants considered, with no detriment of surrounding tissue density and removal torque for UVC irradiated group. Further studies are needed to assess whether this improved surface promotes the growth of bone tissue around the implant.Fil: Cura, Andrea Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos. Facultad de Bromatología; ArgentinaFil: Zuchuat, Jésica Itatí. Universidad Nacional de Entre Ríos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tribbia, Liliana Teresita. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos. Facultad de Bromatología; ArgentinaFil: Taravini, Irene Rita Eloisa. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos. Facultad de Bromatología; ArgentinaFil: Decco, Oscar Alfredo. Universidad Nacional de Entre Ríos; Argentin

Loss of homeostasis in the direct pathway in a mouse model of asymptomatic parkinson’s disease

The characteristic slowness of movement in Parkinson's disease relates to an imbalance in the activity of striatal medium spiny neurons (MSNs) of the direct (dMSNs) and indirect (iMSNs) pathways. However, it is still unclear whether this imbalance emerges during the asymptomatic phase of the disease or if it correlates with symptom severity. Here, we have used in vivo juxtacellular recordings and transgenic mice showing MSN-type-specific expression of fluorescent proteins to examine striatal imbalance after lesioning dopaminergic neurons of the substantia nigra. Multivariate clustering analysis of behavioral data discriminated 2 groups of dopamine-lesioned mice: asymptomatic (42 ± 7% dopaminergic neuron loss) and symptomatic (85 ± 5% cell loss). Contrary to the view that both pathways have similar gain in control conditions, dMSNs respond more intensely than iMSNs to cortical inputs in control animals. Importantly, asymptomatic mice show significant functional disconnection of dMSNs from motor cortex without changes in iMSN connectivity. Moreover, not only the gain but also the timing of the pathways is altered in symptomatic parkinsonism, where iMSNs fire significantly more and earlier than dMSNs. Therefore, cortical drive to dMSNs decreases after partial nigrostriatal lesions producing no behavioral impairment, but additional alterations in the gain and timing of iMSNs characterize symptomatic rodent parkinsonism.Fil: Escande, Mariela Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Taravini, Irene Rita Eloisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; Argentina. Universidad Nacional de Entre Ríos; ArgentinaFil: Zold, Camila Lidia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Belforte, Juan Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Murer, Mario Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; Argentin

Cabergoline and pramipexole fail to modify already established dyskinesias in an animal model of parkinsonism

Levodopa-induced dyskinesias are one of the major limiting side effects encountered in the treatment of Parkinson's disease. Dopamine agonists of the D2 family are less prone to induce these abnormal involuntary movements (AIMs), and in some instances it has been proposed that they could counteract them once already established. As differences in the plasma half-life of a given DA agonist could be related with a greater or lesser propensity to induce or to counteract AIMs, we compared the effects of two D2 agonists (cabergoline and pramipexole) with different half-lives, and levodopa, at doses producing similar improvement in purposeful forelimb use, in rats with severe nigrostriatal lesion, previously sensitized to levodopa. The same therapeutic regime was subsequently used in pharmacologically naïve rats. We found that: (i) prior induction of AIMs by levodopa administration primes rats for the occurrence of AIMs during mono-therapy with pramipexole (but not with cabergoline); (ii) an intervening period of D2 agonist mono-therapy does not modify the severity of AIMs induced by subsequent mono-therapy with levodopa; iii. de novo treatment with D2 agonists is associated with a lower risk of AIMs (regardless of the severity of the lesion) and does not modify AIMs during subsequent mono-therapy with levodopa. An unexpected finding was that prior levodopa therapy sensitized rats to the therapeutic effects of D2 agonists given in mono-therapy. In summary, the use of the rat with nigrostriatal lesion to model relevant therapeutic conditions does not support that D2 agonists prevent the development of AIMs during subsequent levodopa mono-therapy or can revert the dysfunction underlying it. © 2008 Elsevier B.V. All rights reserved.Fil: Larramendy, Celia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Taravini, Irene Rita Eloisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Saborido, Mariano Diego. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Ciencias Fisiológicas. Laboratorio de Fisiología de Circuitos Neuronales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ferrario, Juan Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Murer, Mario Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Gershanik, Oscar Samuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; Argentin

Regulation of Pleiotrophin and Fyn in the striatum of rats undergoing L-DOPA-induced dyskinesia

L-DOPA is the gold standard pharmacological therapy for symptomatic treatment of Parkinson´s disease (PD), however, its long-term use is associated with the emergence of L-DOPA-induced dyskinesia (LID). Understanding the underlying molecular mechanisms of LID is crucial for the development of newer and more effective therapeutic approaches. In previous publications, we have shown that Pleiotrophin (PTN), a developmentally regulated trophic factor, is up-regulated by L-DOPA in the striatum of dopamine denervated rats. We have also shown that both mRNA and protein levels of RPTPζ/β, a PTN receptor, were upregulated in the same experimental condition and expressed in striatal medium spiny neurons. The PTN-RPTPζ/β intracellular pathway has not been fully explored and it might be implicated in the striatal plastic changes triggered by L-DOPA treatment. RPTPζ/β is part of the postsynaptic density zone and modulates Fyn, a Src tyrosine kinase that regulates the NR2A and NR2B subunits of the NMDA receptor and has been singled out as a key molecule in the development of LID. In this study, we evaluated the changes in PTN and Fyn protein levels and Fyn phosphorylation status in the 6-OHDA rat model of PD rendered dyskinetic with L-DOPA. We found an increase in the number of PTN immunoreactive neurons, no changes in the amount of total Fyn but a significant increase in Fyn phosphorylation in the dorsolateral striatum of dyskinetic rats. Our results support the idea that both PTN and Fyn may be involved in the development of LID, further contributing to the understanding of its molecular mechanisms.Fil: Gomez, Gimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Saborido, Mariano Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Bernardi, Maria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Gershanik, Oscar Samuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Taravini, Irene Rita Eloisa. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos. Facultad de Bromatología; ArgentinaFil: Ferrario, Juan Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; Argentin

Enfermedad de Parkinson y disquinesias: comprender y disecar los mecanismos moleculares para racionalizar el diseño y uso de fármacos

La administración de levodopa es la terapia de elección para la enfermedad de Parkinson a pesar de que su uso prolongado conlleva la aparición de efectos secundarios incapacitantes llamados disquinesias. El desarrollo de nuevas estrategias terapéuticas para mitigar estos efectos constituye hoy uno de los grandes desafíos en la lucha contra la enfermedad. A nivel estructural, las disquinesias involucran a los ganglios de la base, y derivan de un desbalance neuroquímico en el microcircuito estriatal. En este artículo se describen los principales mecanismos moleculares afectados por el tratamiento crónico con levodopa en las neuronas medianas espinosas del estriado, que correlacionan positivamente con disquinesias. Este conocimiento ha sentado las bases para el diseño y uso racional de fármacos, como por ejemplo amantadina, un bloqueante de la neurotransmisión glutamatérgica mediada por el receptor NMDA. En este sentido, nosotros proponemos interferir la señalización del receptor de NMDA a través del bloqueo específico de Fyn, una proteína responsable de la externalización del receptor de NMDA a la membrana, a fin de complementar el uso de drogas efectivas como la amantadina, y reducir sus efectos adversos. Como corolario, se presentan perspectivas futuras de intervención genómica tales como RNA de interferencia o el sistema CRISPR/Cas9, que aportarán la opción de una herramienta farmacológica racional con precisión quirúrgica molecular.Levodopa is the gold standard treatment for Parkinson’s disease, despite its long-term use leads to disabling side effects known as dyskinesia. The development of new therapeutic approaches to mitigate these effects constitutes a great challenge to control the disease. At structural level, dyskinesia involves basal ganglia, and results from neurochemical imbalance in striatal microcircuit. This article describes the main molecular mechanisms affected by chronic levodopa treatment in striatal medium spiny neurons, which highly correlates with dyskinesia. This knowledge has set the grounds for the rational design and use of drugs, such as amantadine to block NMDA receptor-mediated glutamatergic neurotransmission. In this sense, we propose to interfere the NMDA receptor signaling through the specific blockade of Fyn, a protein that mediates the externalization of NMDA receptor to the membrane, to complement the use of effective drugs such amantadine and to reduce its side effects. Finally, we discuss future perspectives of genomic intervention such as RNA interference technology or CRISPR / Cas9 system, providing powerful molecular tools to use as rationale pharmacological option.Fil: Gomez, Gimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Bernardi, Maria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Sanz Blasco, Sara Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Bordone, Melina Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Taravini, Irene Rita Eloisa. Universidad Nacional de Entre Ríos. Facultad de Bromatología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ferrario, Juan Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; Argentin

Development of extracts obtained from yerba mate leaves with different industrial processing steps: Antimicrobial capacity, antioxidant properties, and induced damage

This study was aimed at developing a yerba mate extract (YME) intended to be used as food additive with antioxidant and antimicrobial capacity. For the extraction, yerba mate (Ilex paraguariensis, St Hill) leaves collected from three industrial processing steps (green, unaged-canchada, and aged-canchada) were used. The aged-canchada YME exhibited higher theobromine, chlorogenic acid, caffeic acid, caffeine, and kaempferol than green YME. It was selected for further analyses as it showed the highest polyphenol content (PC = 3.7 ± 0.3 mg GAE/ml) and total antioxidant activity (TAA) by DDPH (573 ± 4 mg Trolox Eq/ml) while possessed the lowest minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations in culture media against E. coli and S. Enteritidis. Additionally, its MBC value was validated in a green juice. Moreover, aged-canchada YME addition (0.04%wt/vol) doubled PC, TAADPPH, and TAAABTS in the juice blend. Transmission electron microscopy images of E. coli cells exposed to the aged-canchada extract revealed severe cell damage encompassing direct rupture of outer structures with efflux of inner cell content, formation of vacuoles, vesicles, and swollen cell walls. In conclusion, the aged-canchada YME may be used as a food additive with the main purpose of increasing the concentration of bioactive compounds and contributing to the overall antimicrobial activity in the food product. Practical applications: There is an increasing demand for the use of plant-based antimicrobials and/or antioxidant properties as a total or partial replacement of synthetic preservatives which are usually related to the appearance of allergies and other health issues. The present work investigated the potential use of an aged-canchada yerba mate extract, obtained by ultrasound, as a food additive. This extract exhibited the highest antimicrobial activity against relevant bacteria compared to other extracts obtained from different industrial stages. The extract added to a green juice doubled its concentration of antioxidants, thus positively contributing to the daily intake of these health-promoting compounds.Fil: Schenk, Marcela Liliana. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; ArgentinaFil: Ferrario, Mariana Inés. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; ArgentinaFil: Schmalko Radichowski, Miguel Eduardo. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales; ArgentinaFil: Rivero, Roy Cristian. Universidad Nacional de Entre Ríos. Facultad de Bromatología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Taravini, Irene Rita Eloisa. Universidad Nacional de Entre Ríos. Facultad de Bromatología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Guerrero, Sandra N.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; Argentin

L-DOPA treatment selectively restores spine density in dopamine receptor d2-expressing projection neurons in dyskinetic mice

Background: L-3,4-dihydroxyphenylalanine (L-DOPA)–induced dyskinesia is an incapacitating complication of L-DOPA therapy that affects most patients with Parkinson’s disease. Previous work indicating that molecular sensitization to dopamine receptor D1 (D1R) stimulation is involved in dyskinesias prompted us to perform electrophysiological recordings of striatal projection “medium spiny neurons” (MSN). Moreover, because enhanced D1R signaling in drug abuse induces changes in spine density in striatum, we investigated whether the dyskinesia is related to morphological changes in MSNs. Methods: Wild-type and bacterial artificial chromosome transgenic mice (D1R-tomato and D2R–green fluorescent protein) mice were lesioned with 6-hydroxydopamine and subsequently treated with L-DOPA to induce dyskinesia. Functional, molecular, and structural changes were assessed in corticostriatal slices. Individual MSNs injected with Lucifer-Yellow were detected by immunohistochemistry for three-dimensional reconstructions with Neurolucida software. Intracellular current-clamp recordings with high-resistance micropipettes were used to characterize electrophysiological parameters. Results: Both D1R-MSNs and D2R-MSNs showed diminished spine density in totally denervated striatal regions in parkinsonian mice. Chronic L-DOPA treatment, which induced dyskinesia and aberrant FosB expression, restored spine density in D2R-MSNs but not in D1R-MSNs. In basal conditions, MSNs are more excitable in parkinsonian than in sham mice, and excitability decreases toward normal values after L-DOPA treatment. Despite this normalization of basal excitability, in dyskinetic mice, the selective D1R agonist SKF38393 increased the number of evoked action potentials in MSNs, compared with sham animals. Conclusions: Chronic L-DOPA induces abnormal spine re-growth exclusively in D2R-MSNs and robust supersensitization to D1R-activated excitability in denervated striatal MSNs. These changes might constitute the anatomical and electrophysiological substrates of dyskinesia.Fil: Suárez, Luz M.. Consejo Superior de Investigaciones Cientificas; EspañaFil: Solís, Oscar. Consejo Superior de Investigaciones Cientificas; EspañaFil: Caramés, Jose M.. Consejo Superior de Investigaciones Cientificas; EspañaFil: Taravini, Irene Rita Eloisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas (i); ArgentinaFil: Solís, Jose M.. Hospital Universitario Ramón y Cajal; EspañaFil: Murer, Mario Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay; Argentina. Universidad de Buenos Aires. Facultad de Medicina; ArgentinaFil: Moratalla, Rosario. Consejo Superior de Investigaciones Cientificas; Españ

Immunodetection of heparin-binding growth associated molecule (pleiotrophin) in striatal interneurons

Pleiotrophin (PTN), a developmentally-regulated trophic factor, is over-expressed in the striatum of parkinsonian rats. Because striatal PTN can provide trophic support to dopamine neurons, we identified the cellular types containing PTN in the striatum of adult rats. By means of fluorescent double-immunolabeling, we found PTN to co-localize with a neuronal nuclei marker but not with glial fibrillary acidic protein. The number, distribution, and morphology of the PTN-immunolabeled cells suggested that they were interneurons. Further double-immunolabeling studies ruled out PTN localization to calretinin- and parvalbumin-containing interneurons. Instead, ∼40% of the PTN-immunolabeled neurons contained nitric oxide synthase or somatostatin and ∼60% expressed the vesicular acetylcholine transporter, supporting that they were GABAergic nitric oxide synthase/somatostatin-containing and cholinergic interneurons. Further work is necessary to determine if PTN from striatal interneurons can provide trophic support to dopamine neurons.Fil: Taravini, Irene Rita Eloisa.Fil: Ferrario, Juan Esteban.Fil: Jean Delbe.Fil: Laure Ginestet.Fil: Thomas Debeir.Fil: José Courty.Fil: M. Gustavo Murer. FACULTAD DE MEDICINA; ArgentinaFil: Gershanik, Oscar Samuel. ININFA; ArgentinaFil: Rita Raisman-Vozari