By measuring AMPA/NMDA ratio, we wanted to compare the strength of glutamate synapses of VTA DA cells 24 h after a single in vivo injection of morphine (10 mg/kg) to young GluA1−/−and GluA1+/+ mice. The mouse lines responded differently to the treatment (genotype×drug interaction, F1,27 = 20.32, p<0.001). In GluA1+/+ mice, morphine strongly increased AMPA/NMDA ratio (drug effect, F1,27 = 14.14, p<0.01), as shown in Figure 5. However, no such increase was detected in GluA1−/− mice. However, after saline injection, the baseline AMPA/NMDA ratio was higher in GluA1−/− than in GluA1+/+ mice (p<0.05).
