MA/MSc, PhD Internship for EUGLOH program

Keywords: NMDA receptors, Co-agonists, Prefrontal cortex, inhibitory neurons, fluorescent reporter mice

Internship Duration: 30/11/-1 - 30/11/-1

NMDA glutamate receptors play a central role in many physiological processes such as synaptic plasticity and cognitive processes but are also consistently involved in the etiology of many brain disorders (1). These receptors are particular because their activation requires not only the binding of glutamate but also of a co-agonist, glycine or D-serine (2). The host team is internationally recognized for its work on the exploration of the role of NMDA receptors and their co-agonists in the healthy and pathological brain (3,4). Surprisingly, two decades after the discovery of the NMDA co-agonist role of D-serine (5) and glycine (6), and despite considerable progress in defining their functions at excitatory synapses between glutamatergic neurons in various brain areas (7,8), we still do not know whether and how D-serine and/or glycine regulate NMDA receptors functioning at GABAergic interneurons. Our project aims at exploring this modulation in the dynamics of neural circuits in the prefrontal cortex, a brain area involved in higher cognitive tasks and executive functions whose dysfunction is implicated in the etiology of certain developmental disorders such as schizophrenia or autism spectrum disorders (9).

The general objective of this internship is to explore the respective roles of D-serine and glycine in the control of NMDA receptor activity located on different populations of GABAergic interneurons and their impact on the dynamics of the neuronal network of the prefrontal cortex. It aims in particular to establish the physiological conditions that condition their intervention and to measure their functional impact. The main experimental approach will consist in patch-clamp electrophysiological recordings on acute brain slices of intrinsic activity and inhibitory and excitatory synaptic activities combined with selective pharmacological and genetic manipulations disrupting the action of co-agonists (AAV, CRISPR-cas9, knock-out mice). Particular emphasis will be put on exploring the effect of co-agonist site modulation of NMDA receptors on short and long term synaptic plasticity and on oscillatory rhythms that depend on the proper functioning of GABAergic interneurons.

The answer to these questions is a crucial issue in Neurobiology because of the cardinal functions that NMDA receptors and GABAergic interneurons (11) play in the pathophysiology of the cortical circuit. The hypofunction of NMDA receptors is strongly suspected in many psychiatric diseases such as depression, autism or schizophrenia. We hypothesize that D-serine and glycine modulate specific GABAergic interneurons by acting on specific NMDARs and that specific disruption of thier action would recapitulate the endophenotypes of the diseases. Our project aims at clearly answering this question which will allow the development of more efficient therapies. The hosting team has the necessary expertise, the various equipment and the adequate mouse models to carry out this project

Whole-Cell patch-clamp electrophysiology on acute brain slices
Use of fluoresecent reporter mouse transgenic lines (Ai9-Tdtomato::Cre) where PV+, SST+ and CCK+ interneurons are readily identifiable.
Cre-dependent CRISPR/SaCas9 mediated conditional gene knockout
Pharmacological and genetical manipulations of the co-agonists levels

(1). Paoletti P, et al. (2013). Nat Rev Neurosci.14: 383-400.
(2)*. Le Bail M, et al. (2015) Proc Natl Acad Sci USA. 112(2): E204-13.
(3)*. Papouin, T. et al.(2012) Cell. 150: 633–646.
(4)*. Dallérac G, et al. (2021). Proc Natl Acad Sci USA. 18(23):e2023750118.
(5)*. Mothet, J-P., et al. (2000). Proc Natl Acad Sci USA. 97: 4926-4931.
(6). Johnson, J.W. & Ascher, P. (1987). Nature 325: 529-531.
(7). Li, Y. et al. (2013). Nat Commun. 4: 1760.
(8). Perez EJ, et al. (2017). J Clin Invest. 127: 3114-3125.
(9). Nakazawa et al (2017). NPJ Schizophrenia 3:7
(10).Fishell G., Kepecs A. (2020). Annu. Rev. Neurosci. 43: 1-30.

* articles of the hosting team

• Medicine and health sciences, Veterinary science
• Pharmacy, Biology, Physics and Chemistry