Fig. 10.

Diagram of the proposed model of neurotensin inhibition of G-coupled inward rectifying potassium (GIRK) currents activated by D2 and GABA_B receptors. Activation of NTS1 with neurotensin in VTA DA neurons causes robust inhibition of D2R and GABA_B GIRK currents when the relative levels of free intracellular Ca²⁺ are low due to strong Ca²⁺ buffering, while neurotensin-induced inhibition of D2R and GABA_B GIRK currents is significantly attenuated when relative levels of free intracellular Ca²⁺ are higher due to weak Ca buffering.