Fig. 5: Chemogenetic manipulation of NAc D1-MSNs blunts fentanyl seeking in wildtype mice but does not alter seeking in Drd1-cre^120Mxu mice.

A Experimental timeline for IVSA experiments. Following jugular vein catheter surgery mice underwent 10 days of fentanyl self-administration training. Mice then underwent surgery to express DREADDs in NAc core D1-MSNs, using Cre-dependent DREADDs in NAc core of Drd1-cre^120Mxu mice, or retrograde Cre in ventral mesencephalon and Cre-dependent DREADDs in NAc core of wildtype mice. Following 14 d abstinence and viral expression, mice were given 0.1 mg/kg DCZ i.p. 20 min prior to a 1h seeking test. B Infusions earned during fentanyl self-administration in male and female Drd1-cre^120Mxu mice. C Active and inactive responses during the fentanyl seeking test in Drd1-cre^120Mxu mice expressing mCherry control (n = 5♀, 7♂), inhibitory hM4Di (n = 7♀, 7♂), or stimulatory hM3Dq (n = 8♀, 6♂) in NAc core D1-MSNs. D Image demonstrating DREADDs expression in Drd1-cre^120Mxu mice is restricted to the NAc core (ac, anterior commissure). E Fentanyl infusions earned during self-administration in male and female wildtype mice. F Active and inactive responses during the fentanyl seeking test in wildtype mice (mCherry, n = 7♀, 6♂; hM4Di, n = 7♀, 5♂; hM3Dq, n = 7♀, 8♂). Active responses: ****p < 0.0001, hM3Dq vs. mCherry females; *p = 0.024, hM3Dq vs. mCherry males, Sidak’s. Inactive responses: #p = 0.024, female hM3Dq vs. mCherry. G Image demonstrating DREADDs expression in wildtype mice is restricted to the NAc core H Experimental timeline for CPP experiments. Drd1-cre^120Mxu mice underwent surgery for Cre-dependent DREADDs in NAc. Mice freely explored the apparatus during the pre-test day. For the following three days, mice received saline (10 mL/kg i.p.) in one compartment, followed 4 h later by fentanyl (0.2 mg/kg i.p.) in the other. On the fifth day, mice received saline (or DCZ) 20 min prior to the first post-test. Then, 4 h later, mice received 0.1 mg/kg DCZ (or saline) 20 min prior to the second post-test. Tissue was collected immediately following the second post-test to capture immediate early gene expression. I CPP score during the post-test under saline and DCZ conditions (mCherry, n = 12♀, 13♂; hM4Di, n = 12♀, 7♂; hM3Dq, n = 10♀, 6♂). J In mice receiving DCZ just prior to tissue collection, immediate early gene cfos is upregulated in NAc of Drd1-cre^120Mxu mice expressing hM3Dq relative to mCherry, **p = 0.007, Dunnet’s T3 (mCherry, n = 5♀, 4♂; hM4Di, n = 7♀, 6♂; hM3Dq, n = 8♀, 4♂). K In downstream VTA, cfos is downregulated in hM3Dq relative to mCherry, *p = 0.049, Dunnet’s T3. Data are presented as mean ± SEM with individual mice overlaid.