LPA1 receptor and chronic stress: Effects on behaviour and the genes involved in the hippocampal excitatory/inhibitory balance.

The LPA1 receptor, one of the six characterized G protein-coupled receptors (LPA1-6) through which lysophosphatidic acid acts, is likely involved in promoting normal emotional behaviours. Current data suggest that the LPA-LPA1-receptor pathway may be involved in mediating the negative consequences of stress on hippocampal function. However, to date, there is no available information regarding the mechanisms whereby the LPA1 receptor mediates this adaptation. To gain further insight into how the LPA-LPA1 pathway may prevent the negative consequences of chronic stress, we assessed the effects of the continuous delivery of LPA on depressive-like behaviours induced by a chronic restraint stress protocol. Because a proper excitatory/inhibitory balance seems to be key for controlling the stress response system, the gene expression of molecular markers of excitatory and inhibitory neurotransmission was also determined. In addition, the hippocampal expression of mineralocorticoid receptor genes and glucocorticoid receptor genes and proteins as well as plasma corticosterone levels were determined. Contrary to our expectations, the continuous delivery of LPA in chronically stressed animals potentiated rather than inhibited some (e.g., anhedonia, reduced latency to the first immobility period), though not all, behavioural effects of stress. Furthermore, this treatment led to an alteration in the genes coding for proteins involved in the excitatory/inhibitory balance in the ventral hippocampus and to changes in corticosterone levels. In conclusion, the results of this study reinforce the assumption that LPA is involved in emotional regulation, mainly through the LPA1 receptor, and regulates the effects of stress on hippocampal gene expression and hippocampus-dependent behaviour.This study was supported by FEDER/Ministerio de Ciencia, Innovación y Universidades – Agencia Estatal de Investigación/__(PSI2017-83408-P) to C.P., Consejería de Economía, Innovación, Ciencia y Empleo, Junta de Andalucía (SEJ1863 to C.P. and CTS-643 to G.E.-T), Consejería de Salud, Junta de Andalucía, (NICOLÁS MONARDE to G.E-T). Ministerio de Educación, Cultura y Deporte (FPU14/01610 to R.D.M.-F. and intramural funding from the EPFL to C.S

Electrical and geometrical tuning of MoS2 field effect transistors:Via direct nanopatterning

Mechanically exfoliated van der Waals materials can be used to prepare proof-of-concept electronic devices. Their optoelectronic properties strongly depend on the geometry and number of layers present in the exfoliated flake. Once the device fabrication steps have been completed, tuning the device response is complex, since the geometry and number of layers cannot be easily modified. In this work, we employ Pulsed Focused Electron Beam Induced Etching (PFEBIE) to tailor the geometry and electronic properties of field effect transistors based on mechanically exfoliated Molybdenum Disulfide (MoS2) flakes. First, MoS2 field effect transistors are fabricated via optical lithography and conventional methods. Then, the geometry of the MoS2 source-drain conduction channel is modified employing a Xenon difluoride (XeF2) gas injection nozzle combined with a pulsed electron beam pattern-generation system. Electrical characterization of devices carried out before and after the nanopatterning step via PFEBIE reveals a shift in the doping from N-type towards P-type. We attribute this change to sulfur vacancies induced during the direct nanopatterning step. This is confirmed by micro-Raman and micro-Photoluminescence spectroscopy experiments. The direct nanopatterning method allows us to fine-tune the geometry and thus the electronic properties of the devices, once the conventional fabrication steps have been completed. The success rate of our tailoring method exceeds 85% when tuning the geometry of the flake into a 250 nm wide and straight conduction channel between source and drain