Effects of exogenous CCK-8 on the development of naloxone-precipitated withdrawal-induced CPA in morphine dependent rats.

<p><b>A:</b> The induction of CPA by CCK-8 (0.01–1 µg, i.c.v.) itself after morphine pretreatment in rats. Animals were pretreated with morphine, and then microinjected with CCK-8 instead of naloxone for precipitation before conditioning. Data of CPA scores are expressed as means ± S.D. (n = 7, 8, 8, 9). <b>B:</b> Animals were pretreated with either saline or morphine, and then microinjected with CCK-8 (0.01, 0.1 and 1 µg, i.c.v.) 15 min before naloxone precipitation and CPA conditioning. Data of CPA scores are expressed as means ± S.D. (n = 8, 9, 8, 7 and 8, 7, 9, 8 in saline and morphine pretreated rats respectively) **<i>P</i><0.01 compared with the morphine pretreated and saline microinjected group by Bonferroni's post hoc test.