Acetyl-L-carnitine is known to improve many aspects of the neural activity even if its exact role in neurotransmission is still unknown. This study investigates the effects of acetyl-L-carnitine in T segmental sensory neurons of the leech Hirudo medicinalis. These neurons are involved in some forms of neural plasticity associated with learning processes. Their physiological ﬁring is accompanied by a large afterhyperpolarization that is mainly due to the Na+/K+ ATPase activity and partially to a Ca2+-dependent K+ current. A clear-cut hyperpolarization and a signiﬁcant increase of the afterhyperpolarization have been recorded in T neurons of leeches injected with 2 mM acetyl-L-carnitine some days before. Acute treatments of 50 microM acetyl-L-carnitine induced similar effects in T cells of naive animals. In the presence of apamin, a pharmacological blocker of Ca2+-dependent K+ channel, acetyl-L-carnitine still enhanced the residual after-hyperpolarization, suggesting an effect of the drug on the Na+/K+ATPase. Acetyl-L-carnitine also increased the hyperpolarization induced by intracellular injection of Na+ ions. Therefore, acetyl-L-carnitine seems to be able to exert a positive sustained effect on the Na+/K+ ATPase activity in leech T sensory neurons. Moreover, in these cells, widely ar- borized, the afterhyperpolarization seems to play an important role in determining the action potential transmission at neuritic bifurcations. A computational model of a T cell has been previously developed considering detailed data for geometry and the modulation of the pump current. Herein, we showed that to a larger afterhyperpolarization, due to the acetyl-L-carnitine-induced effects, corresponds a decrement in the number of action potentials reaching synaptic terminals.
|Autori:||P. LOMBARDO; R. SCURI; E. CATALDO; M. CALVANI; R. NICCOLAI; BRUNELLI M|
|Titolo:||ACETYL-L-CARNITINE INDUCES A SUSTAINED POTENTIATION OF THE AFTERHYPERPOLARIZATION|
|Anno del prodotto:||2004|
|Digital Object Identifier (DOI):||10.1016/j.neuroscience.2004.06.028|
|Appare nelle tipologie:||1.1 Articolo in rivista|