A Novel Insular/Orbital-Prelimbic Circuit That Prevents Persistent Avoidance in a Rodent Model of Compulsive Behavior.

BACKGROUND: A common symptom of obsessive-compulsive disorder is the persistent avoidance of cues incorrectly associated with negative outcomes. This maladaptation becomes increasingly evident as subjects fail to respond to extinction-based treatments such as exposure-with-response prevention therapy. While previous studies have highlighted the role of the insular-orbital cortex in fine-tuning avoidance-based decisions, little is known about the projections from this area that might modulate compulsive-like avoidance. METHODS: Here, we used anatomical tract-tracing, single-unit recording, and optogenetics to characterize the projections from the insular-orbital cortex. To model exposure-with-response prevention and persistent avoidance in rats, we used the platform-mediated avoidance task followed by extinction-with-response prevention training. RESULTS: Using tract-tracing and unit recording, we found that projections from the agranular insular/lateral orbital (AI/LO) cortex to the prefrontal cortex predominantly target the rostral portion of the prelimbic (rPL) cortex and excite rPL neurons. Photoinhibiting this projection induced persistent avoidance after extinction-with-response prevention training, an effect that was still present 1 week later. Consistent with this, photoexcitation of this projection prevented persistent avoidance in overtrained rats. This projection to rPL appears to be key for AI/LO's effects, considering that there was no effect of photoinhibiting AI/LO projections to the ventral striatum or basolateral amygdala. CONCLUSIONS: Our findings suggest that projections from the AI/LO to the rPL decreases the likelihood of avoidance behavior following extinction. In humans, this connectivity may share some homology of projections from lateral prefrontal cortices (i.e., ventrolateral prefrontal cortex, orbitofrontal cortex, and insula) to other prefrontal areas and the anterior cingulate cortex, suggesting that reduced activity in these pathways may contribute to obsessive-compulsive disorder.

Incidencia de amibiasis en el aborto / Amibiasis incidence in abortion

En nuestro país la amibiasis tiene una alta incidencia, y se desconoce su relación con el aborto. En el presente estudio se incluyeron 100 pacientes con diagnóstico de aborto en sus diferentes formas clínicas; fueron excluidas las pacientes con causas definidas como: incompetencia ístimico-cervical, toxoplasmosis, aborto séptico o provocado. Se le practicó a cada paciente: prueba serológica de hemaglutinación en búsqueda de anticuerpos antiamiba, coproparasitocópicos en serie de tres, examen en fresco; y el material obtenido al realizar el legrado uterino, fue enviado a estudio histopatológico con búsqueda intencionada de entamoeba histolytica. En 28% de las pacientes se obtuvo positividad a la prueba serológica, en el examen en fresco, así como en la serie coproparasitiscópica, resultaron con 10% de positividad. En el informe histopatológico de las 100 pacientes se encontraron lesiones compatibles con amibiasis en 3% de los casos