Morphine hydrochloride (First Pharmaceutical Factory of Shenyang, Shenyang, China) was dissolved in 0.9% saline to a final concentration of 1.0 mg/mL. ACPC and L-701,324 (Sigma-Aldrich, St. Louis, MO) were suspended in a 1% aqueous solution of Tween-80 to obtain concentrations of 20 mg/mL and 5 mg/mL, respectively. All drugs were injected i.p. at a volume of 10 mL/kg. Drug doses were chosen based on previous works (T. Li et al., 2010 (link); Y. P. Wang et al., 2015c (link)), pilot experiments, and other behavioral studies (Poleszak et al., 2007 (link); Labrie et al., 2008 (link); Skolnick et al., 2015 (link)). Rabbit polyclonal antibodies against phospho-NR1 (Ser890), phospho-CaMKII (Thr286), phospho-CREB (Ser133), and their total proteins were purchased from Cell Signaling Technology (Danvers, MA). Mouse monoclonal antibodies against GAPDH and the horseradish peroxidase-conjugated anti-rabbit and anti-mouse secondary antibodies were purchased from Santa Cruz Technology (Santa Cruz, CA).