Background Phosphorylation plays an essential role in regulating the voltage-gated sodium (Nav) channels and excitability. Yet, a surprisingly limited number of kinases have been identified as regulators of Nav channels. Herein, we posited that glycogen synthase kinase 3 (GSK3), a critical kinase found associated with numerous brain disorders, might directly regulate neuronal Nav channels. Methods We used patch-clamp electrophysiology to record sodium currents from Nav1.2 channels stably expressed in HEK-293 cells. mRNA and protein levels were quantified with RT-PCR, Western blot, or confocal microscopy, and in vitro phosphorylation and mass spectrometry to identify phosphorylated residues. Results We found that exposure of cells to GSK3 inhibitor XIII significantly potentiates the peak current density of Nav1.2, a phenotype reproduced by silencing GSK3 with siRNA. Contrarily, overexpression of GSK3β suppressed Nav1.2-encoded currents. Neither mRNA nor total protein expression were changed upon GSK3 inhibition. Cell surface labeling of CD4-chimeric constructs expressing intracellular domains of the Nav1.2 channel indicates that cell surface expression of CD4-Nav1.2-Ctail was up-regulated upon pharmacological inhibition of GSK3, resulting in an increase of surface puncta at the plasma membrane. Finally, using in vitro phosphorylation in combination with high resolution mass spectrometry, we further demonstrate that GSK3β phosphorylates T1966 at the C-terminal tail of Nav1.2. Conclusion These findings provide evidence for a new mechanism by which GSK3 modulate Nav channel function via its C-terminal tail. General Significance These findings provide fundamental knowledge in understanding signaling dysfunction common in several neuropsychiatric disorders.

Chlorpyrifos is a pesticide, member of the organophosphate class, widely used in several countries to manage insect pests on many agricultural crops. Currently, chlorpyrifos health risks are being reevaluated due to possible adverse effects, especially on the central nervous system. The aim of this study was to investigate the possible action of this pesticide on the behaviors related to anxiety and depression of offspring rats exposed during pregnancy. Wistar rats were treated orally with chlorpyrifos (0.01, 0.1, 1 and 10mg/kg/day) on gestational days 14-20. Male offspring behavior was evaluated on post-natal days 21 and 70 by the elevated plus-maze test, open field test and forced swimming test. The results demonstrated that exposure to 0.1, 1 or 10mg/kg/day of chlorpyrifos could induce anxiogenic-like, but not depressive-like behavior at post-natal day 21, without causing fetal toxicity. This effect was reversed on post-natal day 70.

Abstract. We evaluated Trypanosoma cruzi infection in 397 wild Mepraia gajardoi specimens from five coastal localities in northern Chile by detection of minicircle DNA by polymerase chain reaction. The wild capture sites were classified into two ecotopes: a fully wild ecotope (ecotope 1) and a wild ecotope near human dwellings (ecotope 2). Infection rates varied between 11% and 27%. Minicircle hybridization assays showed that T. cruzi lineages Tc II and Tc VI were commonly detected in ecotope 1 and ecotope 2, respectively. These results are discussed in the context of insect proximity to human dwellings, the alimentary profile of Mepraia sp., T. cruzi lineages detected in the past in the same diseaseendemic area circulating in humans, and Triatoma infestans.

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Abstract. We evaluated Trypanosoma cruzi infection rates by means of minicircle DNA-based polymerase chain reactions (PCRs) in 70 starved Mepraia gajardoi from northern Chile and 65 M. spinolai from central Chile after feeding. Immediately after collection in the field, 20% of M. gajardoi were found infected; after feeding, 67% of the uninfected were infected. One group of M. spinolai seemed to be completely uninfected, but after the first and second feedings, 62% and 59% were positive, respectively.The protozoan Trypanosoma cruzi (Kinetoplastida Trypanosomatidae), etiologic agent of Chagas disease, is mainly transmitted to mammals by contamination of the skin lesions with triatomine insect feces with parasites.1 In a regularly fed infected triatomine, T. cruzi amplify as epimastigotes, which later, differentiate to trypomastigotes that are eliminated by the feces. Several biological factors modulate T. cruzi-insect vector interactions, including food supply, intestinal components, gut flora, T. cruzi strain, and insect physiology.2 The Triatominae subfamily is composed of 146 species distributed in 18 genera and grouped into six tribes.3,4 Important vectors rapidly defecate on the host. These vectors urinate/defecate during or after feeding from a rapid to a delayed behavior according the triatomine species.5 Several factors, such as the competition of enterobacteria of the flora and T. cruzi with its vector for nutrients, and thereby, feeding affect not only parasite density and insect molting but also, changes in the epimastigote/trypomastigote ratio in the rectum of Triatoma infestans (Hemiptera, Triatominae). 6 The rectal parasite density increases until several weeks post-infection with regular blood meals, reaching maximal values of several million parasites. The parasite density is only strongly influenced by very long starvation up to 20 weeks. [7][8][9] In the laboratory, the feeding status also modulated the olfactory host search behavior of triatomines.10 In Chile, the wild vector of Chagas disease is Mepraia spp. (Hemiptera, Triatominae), which is composed of three different species: M. gajardoi, M. spinolai, and M. parapatrica.11-13 M. gajardoi and M. spinolai are frequently found in corrals of domestic animals and stony hills and rock crevices of arid zones of the northern and semiarid areas of central Chile, respectively. Between 11% and 27% infections with T. cruzi were found in M. gajardoi.14 Infection rates in M. spinolai range from 46% to 54%. 15 In the national surveillance program of triatomine vectors, 11-47% of these species were infected. 16 Thus, the aim of this study is to determine T. cruzi infection in M. gajardoi and M. spinolai by assessing infection on insects under natural conditions (right after collection) and reassessing after feeding in the laboratory.In the laboratory overall, 70 M. gajardoi nymphs stages III-V from Vitor and 35 and 30 M. spinolai nymphs stages III-V from Illapel and Colina, respectively, were studied. The insects were maintained and fed individually inside ...