FIGURE 10.

Model summarizing the effects of nicotine on glutamate terminals in the RMTg nucleus. Scheme illustrating the main inputs to the RMTg and the neurotransmitters involved (top). RMTg nucleus receives glutamate (GLU) inputs from the lateral habenula (LHb) and cholinergic (ACh) inputs from the laterodorsal (LDTg) and pedunculopontine (PPTg) tegmental nuclei. RMTg exerts a GABA-mediated inhibitory effect on the dopaminergic (DA) cells of the ventral tegmental area (VTA). A detailed view of the action mechanisms of nicotine on the LHb glutamate terminals is shown (bottom). Nicotine activates α7 nAChRs. The calcium influx through these nicotinic receptors will, in turn, evoke CICR from the endoplasmic reticulum (ER) through the activation of ryanodine receptors (RyR). This will result in long-lasting synchronized release of glutamate and an increased excitability of the RMTg GABAergic neurons.