The effects of adenosine receptor agonists and antagonists on morphine state-dependent memory of passive avoidance.

Pretraining administration of morphine (5 mg/kg, intraperitonically) in a step-down passive avoidance task led to state-dependent learning with impaired retrieval on the test day that was dose-dependently restored by pretest administration of morphine (0.5, 1, 3, and 5 mg/kg). This restoration was reversible by pretest naloxone administration.

Effects of lithium carbonate on apomorphine-induced sniffing behaviour in rats.

Effects of lithium carbonate (Li2CO3) on sniffing induced by apomorphine have been tested in rats. Intraperitoneal administration of different doses of apomorphine (0.25, 0.

Effects of alpha-adrenoceptor agonists and antagonists on histamine-induced impairment of memory retention of passive avoidance learning in rats.

The effect of alpha-adrenoceptor agents on the impairment induced by histamine was measured for memory retention of passive avoidance learning in rats. Post-training intracerebroventricular (i.c.

Influence of nitric oxide on morphine-induced conditioned place preference in the rat central amygdala.

Effects of intra-central amygdala injections of L-arginine, a nitric oxide (NO) precursor, and N(G)-nitro-L-arginine methyl ester (L-NAME), a NO synthase (NOS) inhibitor, on morphine-induced conditioned place preference in rats were investigated by using an unbiased 3-day schedule of place conditioning design. Animals receiving once daily injections of morphine (0.5-7.

Involvement of dopamine D2 receptors of the central amygdala on the acquisition and expression of morphine-induced place preference in rat.

In the present study, the effects of intra-central amygdala (CeA) injections of dopamine (DA) D2-like receptor agonist and antagonist on the acquisition and expression of morphine-induced place preference in male Wistar rats have been investigated. Subcutaneous administration of different doses of morphine sulphate (0.5-10 mg/kg) produced a dose-dependent conditioned place preference (CPP).

The role of alpha-adrenoceptors in the amnestic effect of intracerebroventricular dexamethasone.

Corticosteroids exert dual enhancing or impairing effects on cognitive functions. While their memory-enhancing effects have been well investigated, the mechanisms involved in their amnestic effects are not completely understood. Thus, we examined the role of alpha-adrenoceptors on dexamethasone-induced amnesia using step-through passive avoidance test in rat.

Effects of histamine and opioid systems on memory retention of passive avoidance learning in rats.

The present study investigated the effect of interactions between histamine receptor agents and the opioid peptidergic system on memory retention of passive avoidance learning in rats. Post-training intracerebroventricular (i.c.

The effects of dopamine receptor agents on naloxone-induced jumping behaviour in morphine-dependent mice.

In the present study, the effects of dopamine receptor agonists and antagonists on naloxone-induced jumping in morphine-dependent mice were examined. Mice were rendered dependent as described in the methods section. Naloxone was injected to elicit jumping (as withdrawal sign).

Dopamine receptor mechanism(s) and morphine tolerance in mice.

Based on our previous demonstration of the involvement of dopamine-2 (D2) dopamine receptors in morphine antinociception, we examined the role of D2 dopamine receptors in the expression and development of tolerance to morphine antinociception in mice. Tolerance to morphine antinociception was assessed by the tail-flick response after the administration of morphine (50 mg/kg) once daily for 3 days. The D2 dopamine receptor agonist, quinpirole (0.

Role of nitric oxide in systemic effect of theophylline on mouse body temperature.

In the present study, the interaction of nitric oxide synthase (NOS) inhibitors, L-NAME (N(G)-nitro-L-arginine methyl ester HCl) and L-NA (N(omega)-nitro-L-arginine), and its precursor, L-arginine (2-(S)-2-amino-5-[(aminoiminomethyl)amino] pentatonic acid), with theophylline on mouse body temperature was studied. Intraperitoneal (i.p.

Effect of imipramine on the expression and acquisition of morphine-induced conditioned place preference in mice.

The effect of imipramine and alpha-adrenoceptor agonists and antagonists on the acquisition or expression of morphine-induced conditioned place preference (CPP) was studied in mice. An unbiased CPP paradigm was used to study the effect of the agents. In the first set of experiments, the drugs were used during the development of CPP by morphine or they were used alone in order to see if they induce CPP or conditioned place aversion (CPA).

Nitric oxide mediation of morphine-induced place preference in the nucleus accumbens of rat.

In the present study, the effects of intra-nucleus accumbens injection of L-arginine, a nitric oxide (NO) precursor, and N(G)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase (NOS) inhibitor, on morphine-induced conditioned place preference in male Wistar rats were investigated. Our data showed that subcutaneous (s.c.

Role of nitric oxide in the rat hippocampal CA1 area on morphine-induced conditioned place preference.

Effects of intrahippocampal CA1 injections of L-arginine, a nitric oxide (NO) precursor, and N(G)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, on morphine-induced conditioned place preference in male Wistar rats were investigated. Animals received subcutaneous (s.c.

The effects of simultaneous administration of alpha(2) -adrenergic agents with L-NAME or L-arginine on the development and expression of morphine dependence in mice.

Both alpha(2)-adrenoceptors and the L-arginine/nitric oxide (NO) pathway have been implicated in the modulation of morphine dependence. This study examined the effects of simultaneous administration of the alpha(2)-adrenoceptor agonist clonidine or the antagonist yohimbine together with the NO precursor L-arginine or the NO synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME) on the induction and expression of morphine dependence as assessed by naloxone-precipitated withdrawal jumping and diarrhoea. Male NMRI mice weighing 20-30 g were used.

Effect of intracerebroventricular injection of GABA receptor agents on morphine-induced antinociception in the formalin test.

In the present study, the effects of gamma-aminobutyric acid (GABA) receptor agonists and antagonists on antinociception induced by morphine in the formalin test were investigated in rats. Intraperitoneal (i.p.

Effects of adrenoceptor agonists and antagonists on morphine-induced Straub tail in mice.

Straub-tail behavior was induced by subcutaneous injection of different doses (10-60 mg/kg) of morphine to mice. The maximum response was obtained with 20-40 mg/kg of the drug. The response induced by morphine (40 mg/kg) was decreased by intraperitoneal administration of different doses of clonidine (0.

Nicotine potentiation of morphine-induced catalepsy in mice.

In the present study, effects of nicotine on catalepsy induced by morphine in mice have been investigated. Morphine but not nicotine induced a dose-dependent catalepsy. The response of morphine was potentiated by nicotine.

Effect of alpha-adrenoceptor agonists and antagonists on imipramine-induced antinociception in the rat formalin test.

In this study, the effect of central administration of the alpha-adrenoceptor agents on the antinociception induced by imipramine in the formalin test has been investigated. Intraperitoneal (IP) administration of different doses of imipramine (10-80 mg/kg) and intracerebroventricular (ICV) administration of the alpha(2)-adrenoceptor agonist clonidine (0.05-0.

Modified synthesis of 11-[14C]-clozapine.

The reported synthetic pathway of 8-chloro-11-(4-methyl-1-piperazinyl)-11-[14C]-5H-dibenzo[b,e][1,4]diazapine (clozapine) was modified in several steps. The synthetic pathway was shortened by 60% and the total yield was increased from 6% to 23%.

Effects of adenosine receptor agonists and antagonists on pentylenetetrazole-induced amnesia.

The effect of adenosine agents on amnesia induced by pentylenetetrazole was examined in mice. Post-training administration of pentylenetetrazole (50 and 60 mg/kg) disrupted 24-h retention of a single-trial passive avoidance task. The adenosine receptor antagonists, theophylline (2.

GABA mechanisms and antinociception in mice with ligated sciatic nerve.

In the present study, the effects of GABA (gamma-aminobutyric acid) receptor agonists and antagonists on hyperalgesia induced by sciatic nerve ligation was investigated in mice. The response to morphine or GABA receptor agonists was examined 14 days after unilateral nerve ligation by hot-plate test. Intraperitoneal injection of different doses of morphine (3, 6 and 9 mg/kg), muscimol (0.

On the mechanism of tolerance to morphine-induced Straub tail reaction in mice.

The effect of 5-HT and opioid receptor antagonists on morphine-induced Straub tail was studied in mice. Straub tail behavior was induced by subcutaneous administration of different doses (20, 30, and 40 mg/kg) of morphine hydrochloride to mice. The effect of morphine was dose-dependent.

GABA(A) but not GABA(B) receptor stimulation induces antianxiety profile in rats.

The effect of GABA receptor agonists and antagonists on anxiety behavior in rats in the elevated-plus-maze has been investigated. The increase in two parameters of %open arm entries (%OAE) and %time spent in the open arms (%OAT) and decrease in the %time spent in closed arm (%CAT) was considered as antianxiety effects. Intracerebroventricular (i.

Effect of alpha-adrenoceptor agents on imipramine-induced antinociception in nerve-ligated mice.

In this study, the effects of adrenoceptor agonists and antagonists on antinociception induced by imipramine in sciatic-nerve-ligated mice were investigated. The response of different doses of morphine, imipramine and adrenoceptor agonists and antagonists was examined 14 days after unilateral nerve-ligation in the hot-plate test. Intraperitoneal injection of different doses of morphine (3, 6 and 9 mg/kg), imipramine (10, 20 and 40 mg/kg), the alpha(2)-adrenoceptor agonist, clonidine (0.

The possible cross-tolerance between morphine- and nicotine-induced hypothermia in mice.

In the present study, cross-tolerance between hypothermia induced by morphine and nicotine in mice has been investigated. Different doses of morphine or nicotine induced dose-dependent hypothermia. The sub-maximal doses of both drugs were used for interaction studies.