Resumen Debido a las restricciones sanitarias secundarias a la pandemia de COVID-19, diversas interacciones entre la industria farmacéutica y los médicos cambiaron. Una de ellas ha sido el método promocional de medicamentos a través de reuniones académicas en torno a padecimientos de interés financiero. Una modalidad reciente ha sido la promoción unilateral de un fármaco determinado por parte de la industria farmacéutica por medio de eventos académicos con la invitación de aparentes “expertos”. Estas reuniones frecuentemente están sesgadas no hacia la atención óptima de un padecimiento, sino a la promoción comercial de un medicamento específico que pudiera o no ser la mejor opción o sin la consideración de alternativas terapéuticas asociadas. El Comité de Ética y Transparencia en la Relación Médico-Industria, de la Academia Nacional de Medicina de México, analiza esta nueva circunstancia y propone algunas consideraciones a la comunidad médica.

Abstract Due to sanitary restrictions secondary to the COVID-19 pandemic, various interactions between the pharmaceutical industry and physicians have changed. One of them has been the method for promoting medicinal products through academic meetings around diseases of financial interest. A recent modality has been unilateral promotion by the pharmaceutical industry through academic events with the invitation of so-called “experts” for the promotion of a specific drug; these meetings are often biased not towards optimal care of a disease, but rather towards commercial promotion of a specific drug, which may or may not be the best option, without considering associated therapeutic alternatives. The Committee of Ethics and Transparency in the Physician-Industry Relationship, of the National Academy of Medicine, analyzes this new circumstance and proposes some considerations to the medical community.

Abstract Autism spectrum disorder is associated with alterations in GABAergic and glutamatergic neurotransmission. Here, we aimed to determine the concentration of GABA, glutamate, glutamine, aspartate, taurine, and glycine in brain tissue and plasma of rats prenatally exposed to valproic acid (VPA), a well-characterized experimental model of autism. Pregnant rats were injected with VPA (600mg/Kg) during the twelfth-embryonic-day. Control rats were injected with saline. On the fourteen-postnatal-day, rats from both groups (males and females) were anesthetized, euthanized by decapitation and their brain dissected out. The frontal cortex, hippocampus, amygdala, brain stem and cerebellum were dissected and homogenized. Homogenates were centrifuged and supernatants were used to quantify amino acid concentrations by HPLC coupled with fluorometric detection. Blood samples were obtained by a cardiac puncture; plasma was separated and deproteinized to quantify amino acid concentration by HPLC. We found that, in VPA rats, glutamate and glutamine concentrations were increased in hippocampus and glycine concentration was increased in cortex. We did not find changes in other regions or in plasma amino acid concentration in the VPA group with respect to control group. Our results suggest that VPA exposure in utero may impair inhibitory and excitatory amino acid transmission in the infant brain.

Epilepsy is a recurrent, often progressive neurological disorder with a chronic evolution, affecting 1 to 2 % of the world population. Research with experimental models and imaging analysis of diseased patients have been used to show that recurrent episodes produce oxidative stress, most of which is related to neuronal excitability phenomena. It is known that the excessive stimulation of glutamate receptors results in neurotoxicity; a process that, under the denomination of excitotoxicity, is thought to constitute the principal cellular death mechanism behind different disorders of the central nervous system, including epilepsy. Paradoxically, although the signaling pathways, molecular mechanisms and sites of action of excitotoxicity have received considerable attention since the 1970s, little is known about their relevance to CNS disorders. Further detail is necessary about the fundamental role of neuronal death and the mechanisms, particularly those relevant to neurological pathogenesis, that are engaged whenever glutamate receptors are excessively stimulated, as the results would aid considerably the development of timely clinical interventions delaying the evolution of these disorders. We review clinical and experimental data on the relevant alterations of the glutamatergic system, cell death pathways, and the activation of caspases and members of the Bcl-2 gene family involved in the process as modulators of cell death during epilepsy. The findings support the hypothesis that excitotoxic processes as well as both apoptotic and necrotic neuronal cell death phenomena converge in drug-resistant epilepsy.

La epilepsia es una afección neurológica de evolución crónica, recurrente, casi siempre progresiva, que afecta del 1 al 2 % de la población mundial. Modelos experimentales y estudios de imágenes neurológicas de pacientes con este padecimiento muestran que las crisis recurrentes provocan estrés oxidativo, relacionado fundamentalmente con la excitabilidad neuronal. La estimulación excesiva de los receptores de glutamato induce neurotoxicidad, un proceso que se ha definido como excitotoxicidad. Se considera que este puede ser el principal mecanismo de muerte celular en numerosas afecciones del sistema nervioso central, incluida la epilepsia. Desde los años 70 se han estudiado con profundidad las vías de señalización, los mecanismos moleculares y los sitios de acción relacionados con la excitotoxicidad; aunque de forma muy limitada en las enfermedades del sistema nervioso central. En particular, deberán evaluarse con especial cuidado la función crucial de la muerte neuronal y los mecanismos que se potencian con la sobreactivación de los receptores de glutamato, principalmente los relativos a las enfermedades neurológicas, con el fin de intervenir de manera oportuna para retardar el desarrollo de estas afecciones neurológicas. Se repasan las evidencias clínicas y experimentales sobre las alteraciones del sistema glutamatérgico, las vías de muerte celular, la activación de las caspasas y de la familia de genes Bcl-2 involucrados, como moduladores de la muerte celular en la epilepsia. Tales hallazgos sustentan que en la epilepsia farmacorresistente convergen procesos excitotóxicos y de muerte neuronal apoptótica y necrótica.

Objetivo: El incremento en el contenido de GABA cerebral o la administración de un agente GABA-mimético se emplea como un tratamiento antiepiléptico eficaz. Sin embargo, se sugiere que el empleo de fármacos que alteran continuamente la transmisión sináptica puede afectar al sistema nervioso. En el presente estudio se evaluaron los efectos del pretratamiento agudo (una administración) y subcrónico (administraciones diarias por 7 días) de diazepam (DZP; 10 mg/kg, ip), gabapentina (GBP, 100 mg/kg, vo) y vigabatrina (VGB, 500 mg/kg, vo) en las crisis generalizadas inducidas por pentilenetetrazol (PTZ, 80 mg/kg ip). Materiales y métodos: Ratones macho de la cepa taconic (20-25 g) recibieron tratamiento agudo y subcrónico de DZP, GBP o VGB y 24 h después de la última administración se aplicó PTZ. Se evaluaron las latencias a la primera crisis clónica, a la fase tónica así como la incidencia de muerte. Resultados: El pretratamiento agudo con DZP protegió 100% a los animales de los efectos del PTZ, mientras que su administración subcrónica redujo la latencia a la crisis clónica (21%; p<0.05), la fase tónica (27%, p<0.05) y muerte (37%, p<0.05). La aplicación aguda de VGB protegió 100% a los animales de los efectos del PTZ, mientras que su aplicación subcrónica aumentó la latencia a las crisis clónicas (32%, p<0.05), aunque facilitó la aparición de la crisis tónica (55%, p<0.05) y la muerte (58%, p<0.05). La administración aguda de GBP elevó la latencia a la crisis clónica (52%, p<0.05), mientras que su administración subcrónica no modificó el efecto producido por PTZ. Conclusiones: Estos resultados sugieren que el pretratamiento agudo y subcrónico de fármacos que incrementan la transmisión GABAérgica modifican diferencialmente la susceptibilidad a las crisis por PTZ y que su administración repetida puede facilitar la producción de crisis convulsivas.

Objetives: The increased GABA content or administration of a centrally active GABA-mimetic agent have been used as a efficacious anticonvulsant therapeutic approach. However, it has been suggested that the use of drugs that continually and noncontingently alter synaptic transmission could alter at the nervous system. The present study was carried out to investigate the effects of acute (one administration) and subchronic (7 daily administrations) treatments with Diazepam (DZP; 10 mg/kg, ip), Gabapentin (GBP, 100 mg/kg. vo) and Vigabatrin (VGB, 500 mg/kg, vo) on pentylenetetrazol-induced generalized seizures (PTZ, 80 mg/kg, ip). Materials and methods: Male Taconic mice (20-25 g) received acute or subchronic treatment with DZP, VGB or GBP and 24 h after the last administration, the effects of PTZ (latency to the clonus, forelimb extension and death incidence) were evaluated. Results: Acute DZP protected all animals (100%) to the convulsant effects of PTZ, whereas subchronic DZP decreased the latency to the clonic (21%; p<0.05), tonic (27%, p<0.05) and death (37%, p<0.05). The acute treatment with VGB protect all animals (100%) to the effects of PTZ, whereas its subcronic administration enhanced the latency to clonus (32%, p<0.05), but facilitated the appearance of tonic seizures (55%, p<0.05) and death (58%, p<0.05). The acute administration of GPB increased the latency to clonus (52%, p<0.05), whereas its subchronic treatment did not modify the PTZ-induced effects Conclusions: The present results indicate that the acute pretreatment with drugs enhancing GABAergic transmission differently modifies the seizure susceptibility, and that the subchronic administration may facilitate the seizure activity.