Coupling of ORL1 (NOP) receptor to G proteins is decreased in the nucleus accumbens of anxious relative to non-anxious mice

We studied the involvement of endogenous ORL1 (NOP) receptors in the anxiety state. In mice selected as “anxious” and “non-anxious”, ORL1 (NOP) receptor has been analysed by means of two autoradiographic approaches: [3H]nociceptin binding and nociceptin-stimulated [35S]GTPγS binding. We show that differences in anxiety state are associated with differences in G protein coupling efficiency of ORL1 (NOP) receptor in the nucleus accumbens, without any change in the density of the receptors.