Cell-specific effects of morphine-induced spontaneous acute withdrawal on nucleus accumbens AMPA receptor transmission. A Experimental timeline including five twice-daily injections of escalating morphine administration (i.p.) and 24 hours post final injection behavior assessment. Recordings were performed in coronal slices approximately 2 hours following behavior. B Mean (1) global withdrawal scores and (2) locomotor activity 24 hours following repeated saline (Sal, while; N=7) or morphine (Mor, black; N=12) injections. C Mean mEPSC amplitude (left) and frequency (right) in NAcSh (1) D1-MSNs [Sal (n=6/N=5), Mor- n=11/N=7)] and (2) D2-MSNs [Sal (n=6/N=5). Mor (n=12/N=8)]. D Mean mEPSC amplitude and frequency in NAcC (1) D1-MSNs [Sal (n=8/N=7), Mor (n=12/N=9)] and D2-MSNs [Sal (n=5/N=4), Mor (n=11/N=8). *p<0.05, ***p<0.001 vs Sal.