Figure 1.
(A) Body weight gain after s.c. implantation of placebo or morphine (75 mg) pellets.
(B) Rats were injected with Tween 80 (Tw) or CP-154,526 (20 or 30 mg/kg, i.p., CP) 30 min before saline (Sal) or naloxone (1 mg/kg, s.c., Nx) to evaluate body weight loss. Data are the mean±SEM (n = 5–28). ###p<0.001 versus placebo; ***p<0.001 versus morphine+Tw+Sal; +++ p<0.001 versus placebo+Tw+Nx; &&&p<0.001 versus morphine+Tw+Nx.
Table 1.
Behavioural profiles after morphine withdrawal precipitated by naloxone (nx) in animals chronically administered with vehicle (tween80) or CP-154,526 (CP).
Figure 2.
Plasma adrenocorticotropic hormone (ACTH) (A) and corticosterone (B) concentrations 60 min after saline (Sal) or naloxone (Nx) administration to placebo or morphine dependent rats pretreated with Tween 80 (Tw) or CP-154,526 (20 mg/kg, i.p., CP).
Data are the mean±SEM (n = 6–9). ***p<0.001 versus the morphine dependent group receiving saline instead of naloxone; +++p<0.001 versus the placebo group injected with Tw+Nx; &&p<0.01 versus morphine+Tw+Nx; ###p<0.001 versus morphine+CP+Sal; $$$p<0.001 versus placebo+CP+Nx.
Figure 3.
DOPAC/DA (A) and MHPG/NA (B) ratio in the nucleus accumbens (NAc) 60 min after saline (Sal) or naloxone (Nx) administration to placebo or morphine dependent rats pretreated with Tween 80 (Tw) or CP-154,526 (20 or 30 mg/kg, i.p., CP) (A, B, C,).
Data are the mean±SEM (n = 5). ***p<0.001, versus the morphine dependent group receiving saline instead of naloxone; +++p<0.001 versus the placebo group injected with Tw+Nx; &&p<0.01 versus morphine+Tw+Nx; ###p<0.001 versus morphine+CP20+Sal; $$$p<0.001 versus placebo+CP20+Nx; ΩΩΩp<0.001 versus morphine+CP30+Sal; σσσp<0.001 versus placebo+CP30+Nx.
Figure 4.
Western-blotting analysis of TH phosphorylated (p) at Ser 31 (A) or Ser40 (B)/total (t)TH ratio in the nucleus accumbens (NAc) 60 min after saline (Sal, S) or naloxone (Nx, N) administration to placebo (P) or morphine (M) dependent rats pretreated with Tween 80 (Tw, V) or CP-154,526 (20 mg/kg, i.p., CP) (A, B).
The immunoreactivity corresponding to TH phospho-Ser31 or TH phospho-Ser40 is expressed as a percentage of that in the control group defined as 100% value. Data are the mean±SEM (n = 6). **p<0.01, versus the morphine dependent group receiving saline instead of naloxone; ++p<0.01 versus the placebo group injected with Tw+Nx; &&&p<0.001 versus morphine+Tw+Nx.
Figure 5.
Photographs (A,B,C,D,E,F) represent TH positive neurons coexpressing c-Fos in the ventral tegmental area (VTA) 60 min after naloxone (Nx, N) administration to placebo (P) or morphine (M) dependent rats pretreated with Tween 80 (Tw) or CP-154,526 (20 mg/kg, i.p., CP).
Black arrows: c-Fos+/TH+ neurons; white arrows: c-Fos-/TH+ neurons (E,F). Quantitative analysis of the number c-Fos+, TH+ or c-Fos +/TH+ neurons (G,H,I). Data are expressed as the mean ± SEM (n = 6–7). +++p<0.001 versus the placebo group injected with Tw+Nx; &p<0.05, &&&p<0.001 versus morphine+Tw+Nx.
Figure 6.
Six days after placebo or morphine pellets, rats were treated with CP or vehicle 30 min before saline or naloxone injection and 60 min after the injection, rats were decapitated or perfused transcardiacally for biochemical assays (as described under Material and Methods).