Acetyl-L-carnitine induces a sustained potentiation of the afterhyperpolarization

Neuroscience. 2004;128(2):293-303. doi: 10.1016/j.neuroscience.2004.06.028.


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 afterhyperpolarization, 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 arborized, 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.

MeSH terms

  • Acetylcarnitine / administration & dosage
  • Acetylcarnitine / pharmacology*
  • Animals
  • Electrophysiology
  • Ganglia / cytology
  • Ganglia / drug effects
  • Injections
  • Leeches
  • Models, Neurological
  • Neuronal Plasticity
  • Neurons, Afferent / drug effects*
  • Neurons, Afferent / enzymology
  • Neurons, Afferent / physiology*
  • Sodium-Potassium-Exchanging ATPase / physiology
  • Synapses / physiology
  • Touch / physiology*


  • Acetylcarnitine
  • Sodium-Potassium-Exchanging ATPase