[ effects of CCK-8 and CCK2 receptor antagonists on naloxone-induced jumping in morphine dependent mice]

Opioids are an important group of analgesics that are used extensively to control sever pains. Physical dependence to these drugs is a major problem. There are a few studies regarding the involvement of cholecyctokinin [CCK] in the withdrawal syndromes of opioids. In the present study, the effects of CCK agonist and antagonist on the number of jumping of morphine dependent mice were evaluated. In this experimental study, the effects of CCK-8 and LY225910 [selective CCK2 receptor antagonist] on jumpings of mice after morphine dependence were evaluated. Mice were injected with morphine three times a day [50, 50 and 75 mg/kg] for three days; at the forth day they received 50 mg/kg morphine. Injection of naloxone [5 mg/kg] induced withdrawal signs such as jumping. The experimental groups received different doses of CCK-8 [0.1, 0.3 and 0.6 mg/kg] and LY225910 [0.01, 0.5 and 1 mg/kg] with each injection of morphine. Injection of CCK-8 significantly decreased the naloxone-induced jumpings, while LY225910 did not have any significant effects on these jumpings. Based on the results of the present study, activation of CCK1 receptors probably is involved in morphine dependence. The results also confirm that injection of CCK but not CCK2 selective antagonist probably decreases the jumpings of mice following withdrawal syndrome of morphine

[ effect of intracerebroventricular injection of GABAc selective agonist and antagonist on anxiety-like behaviors in male rats]

The Gamma amino Butyric Acid [GABA], has three receptors: A, B and C in the body. GABAc receptors play an important role in process of vision, however, their role in other physiological processes yet to be identified. The aim of this study was to evaluate the effect of specific drugs for GABAc agonist and antagonist on anxiety, in male rats. In the present experimental study, the effects of intracerebroventricular [i.c.v] administration of two drugs knows as CACA and TPMPA [as the GABAc specific agonist and antagonist, respectively] on anxiety-like behavior in male Wistar rats were determined using elevated plus-maze test model of anxiety. The collected data was analyzed statistically by two and one way ANOVA analysis. Intracerebroventricular administration of CACA with the doses of 0.5, 1, 2 and 4 micro g/ rat induced anxiogenic effects whereas the i.c.v administration of TPMPA with the doses of 4 and 6 micro g/rat induced anxiolytic effects. Moreover, pretreatment of rats with 3 micro g/rat of TPMPA before injection of either 0.25, 0.5 or 1 micro g/rat of CACA have inhibited the anxiogenic effect of CACA at the dose of 1 micro g/rat. The present study showed that, stimulation of GABAc receptors can induce anxiogenic responses contrary to stimulation of A and B receptors. Nevertheless blocking the GABAc receptors can induce anxiogenic responses contrary to stimulation of A and B receptors. Nevertheless blocking the GABAc receptors contrary to blocking off the other two receptors can induce anxiolytic responses; therefore, it may possibly concluded that GABA can induce various effects on anxiety-related behaviors through its receptors. Our results also showed that the anxiogenic effects of CACA was selectively mediated by GABAc receptors