UNASSIGNED: Opioid-conditioned reinforcement is thought to exacerbate @entity4784 and @entity734 . Sex/gender can influence @entity4784 behaviors, but the effects of sex/gender on opioid-conditioned reinforcement, specifically, are unclear. In this study, we compared new-response acquisition with opioid-conditioned reinforcement in male and female @entity35 . First, separate groups received response-independent @entity1937 injections (0.0-32.0    g/kg, intravenous) and presentations of a light-noise stimulus. In the experimental groups, injections and stimulus presentations always co-occurred [paired Pavlovian conditioning (PAV)]; in the control groups, the two occurred independently of each other (random PAV). Next, in the instrumental acquisition (ACQ) sessions, two novel nose-poke manipulanda were introduced. All animals (regardless of sex, dose, and PAV type) could respond in the active nose-poke, which produced the stimulus alone, or in the inactive nose-poke. Both males and females dose-dependently acquired nose-poke responding (active>inactive) after paired PAV, but not after random PAV. Therefore, the stimulus was a conditioned reinforcer. We identified three sex differences. First, only females acquired responding after paired PAV with 32.0    g/kg @entity1937 . Second, using a progressive ratio schedule for ACQ, both sexes acquired responding, but females made significantly more active responses. Third, when a single session of PAV was conducted, only males acquired responding. Thus, @entity35 ' sex interacts with pharmacological and environmental factors to determine opioid-conditioned reinforcement.

Effects of sex and @entity1937 dose on XXXX ' acquisition of responding for a @entity1937 -conditioned reinforcer.

@entity35 :: ('10116', 'Species') :: ['rats'] @entity4784 :: ('MESH:D009293', 'Disease') :: ['opioid abuse'] @entity734 :: ('MESH:D019966', 'Disease') :: ['dependence'] @entity1937 :: ('MESH:C071741', 'Chemical') :: ['remifentanil']
@entity35 :: (10116,Species) :: ['rats']
