Increasing evidence indicates that modulation of Na+⁄K+ ATPase activity is involved in forms of neuronal and synaptic plasticity. In tactile (T) neurons of the leech Hirudo medicinalis, Na+⁄K+ ATPase is the main determinant of the afterhyperpolarization (AHP), which characterizes the ﬁring of these mechanosensory neurons. Previously, it has been reported that cAMP (3',5'-cyclic adenosine monophosphate), which mediates the effects of serotonin (5HT) in some forms of learning in the leech, negatively modulates Na+⁄K+ ATPase activity, thereby reducing the AHP amplitude in T neurons. Here, we show that a transient inhibition of Na+⁄K+ ATPase can affect the synaptic connection between two ipsilateral T neurons. Bath application of 10 nm dihydroouabain (DHO), an ouabain analogue, causes an increase in the amplitude of the synaptic potential (SP) recorded in the postsynaptic element when a test stimulus is applied in the presynaptic neuron. Iontophoretic injection of cAMP into the presynaptic T neuron also produces an increase of SP. Simulations carried out by using a computational model of the T neuron suggest that a reduction of the pump rate and a consequent depression of the AHP might facilitate the conduction of action potentials to the synaptic terminals. Moreover, nearly intact leeches injected with 10 nm DHO respond with a swimming episode more quickly to an electrical stimulation, which selectively activates T neurons exhibiting sensitization of swimming induction. Collectively, our results show that inhibition of Na+⁄K+ ATPase is critical for short-term plasticity.
|Autori:||SCURI R; PAOLA LOMBARDO; ENRICO CATALDO; CHIARA RISTORI; MARCELLO BRUNELLI|
|Titolo:||Inhibition of Na+/K+ ATPase potentiates synaptic transmission in tactile sensory neurons of the leech|
|Anno del prodotto:||2007|
|Digital Object Identifier (DOI):||10.1111/j.1460-9568.2006.05|
|Appare nelle tipologie:||1.1 Articolo in rivista|