Glycine activated channels and glycinergic synapses

Dr Marco Beato
Research Fellow
Tel: +44 (0) 20 7679 3767
Email: m.beato@ucl.ac.uk

Lab Members:

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Dr Marco Beato graduated in 1995 with a degree in theoretical physics from the University “La Sapienza” in Rome. He obtained a PhD in Biophysics from the International School for Advanced Studies (SISSA/ISAS, Trieste-Italy) in 1999. He started his post-doctoral work at the School of Pharmacy in the lab of Dr Lucia Sivilotti and moved to UCL in 2001 with a MRC Training Research Fellowship. In 2005 he was awarded a Wellcome Trust Career Development Award and a Royal Society University Research Fellowship for continuing his studies on glycinergic transmission in the spinal cord.

Research

My research is focussed on the properties of glycine activated channels and glycinergic synapses in the ventral horn of the spinal cord. Glycinergic inhibition is involved in all motor circuits and is responsible for recurrent inhibition of motoneurones (through Renshaw cells) or stretch reflex control (through Ia inhibitory interneurones) and left-right alternation during locomotion (through commissural inhibitory interneurones whose axons cross the midline of the spinal cord).

My main aim is to understand how the kinetic properties of post-synaptic receptors and the time course of transmitter release influence the shape and strength of the synaptic response.

I have studied the kinetic of glycine receptors using single channel recordings and fast concentration jumps techniques, combined with mathematical modeling and kinetic analysis. Now I am using the whole cell patch clamp configuration to record from single cells or from synaptically connected inhibitory interneurone-motoneurone pairs in slices or in the en bloc spinal cord.

In collaboration with Professors Andrew Todd and David Maxwell (University of Glasgow) I am also studying the electrophysiological and neurochemical properties of glycinergic interneurones in the ventral horn using a mouse model in which all glycinergic neurones are labeled with EGFP. Quantal analysis methods and kinetic modeling are used to characterize the properties of glycinergic synapses.

My work is funded by a Royal Society University Research Fellowship and by a Wellcome Trust project grant (joint with the University of Glasgow)

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Figure 1 legend: Left, low power confocal stack of a spinal cord slice from GlyT-1-EGFP mice. All glycinergic neurones strongly express EGFP (green). Two recorded neurones have been filled with biocytin and reacted with avidin-rhodamine (red, middle panel). The larger cell is the motoneurone and the smaller one is the interneurone. The insets at the upper left of the middle panel show EGFP (green) in the soma and proximal dendrites of the recorded interneurone. The inset to the lower right shows a region where the axon of the interneurone (arrow) came into contact with a dendrite (arrowhead) belonging to the motoneurone. Although both structures are labelled with avidin rhodamine, they were readily distinguished, as the axon could be followed from its origin from the interneurone soma. The location of the motoneurone dendrite shown in this inset is identified with an asterisk in the main confocal image. Examination of this region at high magnification revealed a contact between a bouton belonging to the interneurone axon and the motoneurone dendrite. Scale bars: 50 µm (main image, upper insets) and 5 µm (lower inset). Right panel: simultaneous current clamp and voltage clamp recordings from the interneurone-motoneurone pair shown on the left, with amplitude and latency distribution of the post-synaptic response.

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Figure 2 legend: These confocal images show the expression of EGFP in the ventral horn of a P14 GlyT2-EGFP mouse. Motoneurons have been revealed by immunostaining for choline acetyltransferase (ChAT, red). EGFP, which is present in glycinergic interneurons appears green. In the low-magnification view to the left, MNs are clustered in the lateral motor nucleus and surrounded by groups of GFP-positive cells. At higher magnification (right) individual MNs can be seen to receive contacts from C boutons (bright red structures) and glycinergic boutons (green profiles that partially surround the motoneurone cell bodies). Scale bars = 50 µm (left) and 20 µm (right).

Bayesian Quantal Analysis Python code download 

We are currently tidying up the Python code for Bayesian Quantal Analysis (BQA) and compiling a list of instructions for its use.

In the meantime the code is available on request. Please e-mail Gary Bhumbra (g.bhumbra@ucl.ac.uk) or Marco Beato (m.beato@ucl.ac.uk).

The code is described in: Bhumbra, G. S., & Beato, M. Reliable evaluation of the quantal determinants of synaptic efficacy using Bayesian analysis. 

Journal of Neurophysiology (innovative methodology section In press. doi:10.1152/jn.00528.2012

Publications