Estrogen facilitates and the kappa and mu opioid receptors mediate antinociception produced by intrathecal (-)-pentazocine in female rats.
Robinson DL, Nag S, Mokha SS. Estrogen facilitates and the kappa and mu opioid receptors mediate antinociception produced by intrathecal (-)-pentazocine in female rats. Behav Brain Res. 2016 10 01; 312:163-8.