Information is transferred from one neuron to another via synapses. This communication is mediated by neurotransmitters packaged into vesicles. These structures seem identical on electron microscopic images. However, recordings of electrical activity between neurons show that synapses operate under multiple modes of neurotransmitter release depending on the level of activity.
How can anatomically identical vesicles possess different functions? How do vesicles fulfill various physiological functions?
A recent study led by Katalin Tóth at the Institut Universitaire en Santé Mentale de Québec (IUSMQ), Université Laval aimed to answer these questions. This article reports that asynchronous neurotransmitter release is preferentially mediated by synaptic vesicles derived via a unique recycling pathway, the AP-3-dependent endocytotic pathway. Asynchronous neurotransmitter release was found to be a key determinant of information transfer between hippocampal granule cells and CA3 pyramidal neurons, a pathway known to play an important role in spatial information processing. Synaptic transfer was impaired during naturally-occurring patterns of activity in animals lacking the AP-3-dependent recycling pathway. These results demonstrate that synaptic terminals contain vesicles that are destined to be released under very different physiological activities.
Original Research Article:
Evstratova A, Chamberland S, Faundez V, Tóth K. Vesicles derived via AP-3 dependent recycling contribute to asynchronous release and influence information transfer. Nature Communications, 2014 November 20 5:5530. doi: 10.1038/ncomms6530.
Picture: Alesya Evstratova, Katalin Tóth, and Simon Chamberland