228 | ATP-dependent P2X7R activation controls presynaptic homeostatic plasticity

Neural excitability, synaptic transmission and neuron-glia interactions

Author: Alberto Ezequiel Rafael | Email: a.rafael0786@gmail.com

Alberto Rafael , Nathalia Vitureira , Verónica Abudara

1° Departamento de Fisiología/Facultad de Medicina/Universidad de la República

Homeostatic synaptic plasticity (HSP) regulates synaptic strength to stabilize the activity of a neuron or a neuronal circuit. HSP mechanisms can operate on pre and postsynaptic terminals. An increased number of reports indicate that neurotransmission and Hebbian plasticity are modulated by ATP and its P2X and P2Y purinergic receptors. However, very little is known about how ATP modulates synaptic strength in HSP.
We have previously reported that ATP and P2X7 receptors (P2X7Rs) modulate the homeostatic adjustment of synaptic efficiency. Here we investigate the functional changes occurring in the presynaptic terminal by this purinergic signalling pathway. To carry out this work, we use hippocampal dissociated cultures and functional imaging techniques to estimate changes in presynaptic function. Our results show that blocking neuronal activity triggers an increase in extracellular ATP levels and suggest that P2X7Rs activation is necessary to the compensatory increase in presynaptic Ca2+ and vesicular release upon chronic inactivity. The results obtained show the importance of purinergic signalling in the homeostatic adjustment of activity-dependent presynaptic function.

Key words: homeostatic synaptic plasticity, ATP, P2X7