PMC

(A) Total distance traveled (cm) in the 60 minutes prior to morphine administration (Baseline, White bars) and in the 60 minutes following 10 mg/kg morphine injection (Morphine, Gray bars). (§) indicates a significant difference from baseline (p<0.001); (*) indicates a significant difference from saline only mice (p<0.01); (b) indicates a significant difference between the morphine cage-mates (of saline) and morphine only mice (p<0.01). (B) Total distance traveled (cm) during the entire 120 minute test, segmented into 5 minute intervals. Arrow indicates time of morphine administration. (*) indicates a significant difference from saline only mice (p<0.05); (#) indicates a significant difference from saline only mice (p<0.001); (a) indicates a significant difference between the morphine cage-mates (of saline) and morphine only mice (p<0.05); (b) indicates a significant difference between the morphine cage-mates (of saline) and morphine only mice (p<0.01); (c) indicates a significant difference between the morphine cage-mates (of saline) and morphine only mice (p<0.001). Results are presented as mean ± SEM.

This figure shows the reduction of tendency to use morphine in rats which were treated with mPFC lesion, morphine and exercise with morphine + exercise group (#P < 0.05, n = 10 in each groups) and morphine + mPFC lesion (*P < 0.05). Results are presented as mean ± S.E.M.

(A) Effect of morphine on spontaneous firing of VTA-DA neurons. Left panel: representative spontaneous firing traces before and after morphine (10 μM). Middle panel: time course of spontaneous firing before and after morphine (10 μM) (n = 6 cells from five rats). Right panel: average frequency of spontaneous firing before and after morphine (n = 6 cells from five rats, p < 0.05, compared to control before morphine). (B) Influence of the NMDA receptor antagonist APV and the AMPA receptor antagonist DNQX on the effect of morphine on spontaneous firing in VTA-DA neurons. Left panel: representative spontaneous firing traces before and after morphine (10 μM) in the presence of APV (50 μM) and DNQX (10 μM). Middle panel: time course of spontaneous firing before and after morphine in the presence of APV (50 μM) and DNQX (10 μM) (n = 6 cells from five rats). Right panel: average frequency of spontaneous firing before and after morphine in the presence of APV (50 μM) and DNQX (10 μM) (n = 6 cells from five rats, p = 0.34). Data are shown as the mean ±s.e.m. *p < 0.05.
DOI: http://dx.doi.org/10.7554/eLife.09275.004

(a) Experimental design. Mice were intraperitoneally injected with saline or morphine 1x per day for 7 consecutive days. 1 week following the final injection P1 fractions were derived from NAc lysates.
(b and c) Western blots and quantification indicate that 1 week of morphine withdrawal does not affect PDZ-RhoGEF (t=0.3266, p>0.05), RhoA (t=0.1282, p>0.05), or Rock1 (t=0.02593, p>0.05) levels in NAc P1 fractions relative to saline-treated mice. n=12 saline mice, 11 morphine mice.
(d and e) Western blots and quantification indicate that 1 week of morphine withdrawal did not alter the expression of MAL (t=0.1606, p>0.05) or SRF (t=0.2064, p>0.05) in NAc P1 fractions. n=12 saline mice, 11 morphine mice
(f) Experimental design. Mice were intraperitoneally injected with saline or morphine 1x per day for 7 consecutive days. 1 week following the final injection S2 fractions were derived from NAc lysates.
(g and h) Western blots and quantification indicate that 1 week of morphine withdrawal did not affect the levels of PDZ-RhoGEF (t=1.991, p>0.05), RhoA (t=0.8842, p>0.05), or Rock1 (t=0.4595, p>0.05) in NAc S2 fractions. n=12 saline mice, 11 morphine mice.
(i and j) Western blots and quantification indicate that 1 week of morphine withdrawal did not alter the expression of MAL (t=0.4299, p>0.05) or SRF (t=1.918, p>0.05) in NAc S2 fractions. n=12 saline mice, 11 morphine mice.
(k) Experimental design. Mice were intraperitoneally injected with saline or morphine 1x per day for 7 consecutive days. 1 week following the final injection P2 fractions were derived from NAc lysates.
(l and m) Western blots and quantification indicate that 1 week of morphine withdrawal did not affect the levels of PDZ-RhoGEF (t=0.4244, p>0.05), RhoA (t=0.3352, p>0.05), or Rock1 (t=0.07281, p>0.05) in NAc P2 fractions. n=12 saline mice, 11 morphine mice.
All summary data are the mean + SEM.