Influence of parafascicular thalamic input on neuronal activity within the nucleus accumbens is mediated by nitric oxide — An in vivo study

Abstract

AimsThalamostriatal fibers are involved in cognitive tasks such as acquisition, learning, processing of sensory events, and behavioral flexibility and might play a role in Parkinson's disease. The aim of the present study was the in vivo electrochemical characterization of the projection from the lateral aspect of the parafascicular thalamus (Pfl) to the dorsolateral aspect of the nucleus accumbens (dNAc). Since nitric oxide (NO) plays a crucial role in striatal synaptic transmission, its implication in Pfl-evoked signaling within the dNAc was investigated. Main methodsThe Pfl was electrically stimulated utilizing paired pulses and extracellular potentials were recorded within the dNAc. Simultaneously, the dNAc was superfused using the push–pull superfusion technique for local application of compounds and for assessing the influence of NO on release of glutamate, aspartate and GABA. Key findingsStimulation of the Pfl evoked a negative-going component at 9–14ms followed by a positive-going component at 39–48ms. The early response was current-dependent and diminished by superfusion of the dNAc with tetrodotoxin, kynurenic acid or NG-nitro-l-arginine methyl ester (L-NAME), while 3-(2-hydroxy-2-nitroso-1-propylhydrazino)-1-propanamine (PAPA/NO) increased this evoked potential. Transmitter release was inhibited by L-NAME and facilitated by PAPA/NO. SignificanceThis study describes for the first time in vivo extracellular electrical responses of the dNAc on stimulation of the Pfl. Synaptic transmission within the dNAc on stimulation of the Pfl seems to be facilitated by NO.