Constitutively active microglial populations limit anorexia induced by the food contaminant deoxynivalenol.

Microglia are involved in neuroinflammatory processes during diverse pathophysiological conditions. To date, the possible contribution of these cells to deoxynivalenol (DON)-induced brain inflammation and anorexia has not yet been evaluated. DON, one of the most abundant trichothecenes found in cereals, has been implicated in mycotoxicosis in both humans and farm animals. DON-induced toxicity is characterized by reduced food intake, weight gain, and immunological effects. We previously showed that exposure to DON induces an inflammatory response within the hypothalamus and dorsal vagal complex (DVC) which contributes to DON-induced anorexia. Here, in response to anorectic DON doses, we reported microglial activation within two circumventricular organs (CVOs), the area postrema (AP) and median eminence (ME) located in the DVC and the hypothalamus, respectively. Interestingly, this microglial activation was observed while DON-induced anorexia was ongoing (i.e., 3 and 6 h after DON administration). Next, we took advantage of pharmacological microglia deletion using PLX3397, a colony-stimulating factor 1 receptor (CSF1R)-inhibitor. Surprisingly, microglia-depleted mice exhibited an increased sensitivity to DON since non-anorectic DON doses reduced food intake in PLX3397-treated mice. Moreover, low DON doses induced c-Fos expression within feeding behavior-associated structures in PLX3397-treated mice but not in control mice. In parallel, we have highlighted heterogeneity in the phenotype of microglial cells present in and around the AP and ME of control animals. In these areas, microglial subpopulations expressed IBA1, TMEM119, CD11b and CD68 to varying degrees. In addition, a CD68 positive subpopulation showed, under resting conditions, a noticeable phagocytotic/endocytotic activity. We observed that DON strongly reduced CD68 in the hypothalamus and DVC. Finally, inactivation of constitutively active microglia by intraperitoneal administration of minocycline resulted in anorexia with a DON dose ineffective in control mice. Taken together, these results strongly suggest that various populations of microglial cells residing in and around the CVOs are maintained in a functionally active state even under physiological conditions. We propose that these microglial cell populations are attempting to protect the brain parenchyma from hazardous molecules coming from the blood. This study could contribute to a better understanding of how microglia respond to environmental contaminants.

Mass Spectrometric and Synchrotron Radiation based techniques for the identification and distribution of painting materials in samples from paints of Josep Maria Sert.

BACKGROUND: Establishing the distribution of materials in paintings and that of their degradation products by imaging techniques is fundamental to understand the painting technique and can improve our knowledge on the conservation status of the painting. The combined use of chromatographic-mass spectrometric techniques, such as GC/MS or Py/GC/MS, and the chemical mapping of functional groups by imaging SR FTIR in transmission mode on thin sections and SR XRD line scans will be presented as a suitable approach to have a detailed characterisation of the materials in a paint sample, assuring their localisation in the sample build-up. This analytical approach has been used to study samples from Catalan paintings by Josep Maria Sert y Badía (20th century), a muralist achieving international recognition whose canvases adorned international buildings. RESULTS: The pigments used by the painter as well as the organic materials used as binders and varnishes could be identified by means of conventional techniques. The distribution of these materials by means of Synchrotron Radiation based techniques allowed to establish the mixtures used by the painter depending on the purpose. CONCLUSIONS: Results show the suitability of the combined use of SR µFTIR and SR µXRD mapping and conventional techniques to unequivocally identify all the materials present in the sample and their localization in the sample build-up. This kind of approach becomes indispensable to solve the challenge of micro heterogeneous samples. The complementary interpretation of the data obtained with all the different techniques allowed the characterization of both organic and inorganic materials in the samples layer by layer as well as to establish the painting techniques used by Sert in the works-of-art under study.