LBN alters both baseline and morphine-induced glutamate transmission in male rats. (A) LBN exposure reduced sEPSC frequency in male rats regardless of morphine history. *P < 0.05. (B) sEPSC amplitude was lower following morphine exposure, and this effect was driven primarily by the LBN group. *P < 0.05, drug-naïve LBN males vs. morphine LBN males. (C) While no differences were seen in drug-naïve rats, control males exposed to morphine exhibited an increase in the AMPA/NMDA ratio that was not present in the LBN males. ***P < 0.001. (D) Example sEPSC traces from male rats. LBN exposure did not significantly affect sESPC frequency (E), sEPSC amplitude (F), or AMPA/NMDA ratio (G) in females. (H) Example sEPSC traces from female rats.