Research: Neuroglial Interactions
Glial cells are the most abundant cell type in the mammal brain. For a long time these cells have been thought to only ensure metabolic and scaffolding functions. However, several studies have revealed that glial cells, and in particular astrocytes, were playing an active role in neurohistogenesis, ionic homeostasis and neurotransmission. Furthermore, anatomical relations between glia and neurons are not fixed but can undergo plastic changes as it is the case during development, learning and under various physiological conditions. Our work is aimed at understanding the influence of the astrocytic environment of neurons on synaptic and extrasynaptic (volume) transmission as well as on glial and neuronal intrinsic electrical properties. Glial cells are not only responsible for clearing and producing numerous transmitters but also represent a barrier to diffusion in the extracellular space. By controlling the concentrations and the range of action of active substances, astrocytes are likely to play a key role in the transfer and processing of information in the brain. To investigate this issue, we are using the hypothalamo-neurohypophysial system that comprises magnocellular neurons located in the paraventricular and supraoptic nuclei of the hypothalamus. These neurons project their axons into the neurohypophysis where their secretory products, oxytocin and vasopressin, are released in the blood stream. Oxytocin is involved in reproductive functions such as parturition and lactation whereas vasopressin is essential to body fluid homeostasis. This system can undergo a striking anatomical neuroglial remodeling under conditions of intense stimulation (lactation, chronic dehydration). This morphological reorganization is characterized by a dramatic reduction in astrocytic coverage of magnocellular neurons. We are taking advantage of this anatomical plasticity to provide important information regarding functional neuroglial interactions in the brain.
Our research includes:
-Astrocytic regulation of synaptic and extrasynaptic transmission
-Neuronal regulation of glial activity
-Cellular basis for the anatomical plasticity of the supraoptic nucleus
Our experiments involve whole-cell patch-clamp recordings from acute brain slices combined with immunohistochemistry, confocal and electron microscopy.
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Contribution of astrocytes to NMDA receptor activity
Regulation of GABA spillover by glia
Synaptogenesis in the adult brain
Characterization of mGluRs regulating transmitter release in the supraoptic nucleus
Localization of membrane and vesicular glutamate transporters