Pregabalin effect on transmitter release at the mouse neuromuscular junction

LÓPEZ ME; PERISSINOTTI PP; DI GUILMI MN; UCHITEL OD

Cordoba

Congreso; IRCN First Joint Meeting of the Argentine Society for Neurosciences (SAN) and the Argentine Workshop in Neurosciences (TAN); 2009

Pregabalin (PGB) is an anticonvulsant and analgesic medication which was initially synthesized as a GABA analogous but strikingly had no effect on its receptors. The primary high-affinity binding site for PGB is the alpha2-delta auxiliary subunit of voltage-gated calcium channels but the cellular and molecular details of its action are completely unknown. The main objective of this work is to understand the effect of PGB at the mouse neuromuscular junction and to characterize its modulation on vesicular release and recycling. Experiments were performed on the levator auris muscle of Swiss mice and fluorescence microscopy of FM2-10 labeled synaptic vesicles were used to reach our aim. We studied the effect of PGB at two different concentrations on the distaining of a full neuromuscular terminal FM2-10 loaded. Results showed that PGB 1mM treatment held up the kinetic decay significantly. The fluorescence distaining was fitted to a biexponential function that models first-order release processes when two different time constants are involved. These time constants are associated to different vesicle pools of different size. Both time constants augmented with the presence of the drug and the size of the fast pool increased versus the control at 1mM concentration. PGB 100 µM had no effect on the distaining decay suggesting dose response behaviour. To study whether PGB is altering both P/Q and L channels, we performed experiments with the L channel blocker nitrendipine. In addition, electrophysiological experiments will be done to contrast the results obtained with imaging technique. All this evidence suggests that PGB acts presynaptically reducing neurotransmitter release