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Basolateral Amygdala is an important site of anxiety. Interactions between α-adrenergic and opioidergic systems in Basolateral amygdale were used for investigation anxiety and memory. The elevated plus-maze has been employed. The male wistar rats were used for this test. The site of BLA was cannulated bilaterally. Rats we injected morphine (4, 5.6 mg/kg) intraperitonealy, while clonidine (1, 2, 4 µg/rat) and yohimbin (0.5, 1,2 µg/rat) were injected to BLA. Open arm time percentage (%OAT), open arm entry (%0AE) and locomotor activity were determined by this behavioral test. Retention tested 24 hours later. Administration of morphine (6mg/kg) increased the OAT% in anxiety test, indicating anxiolytic-like effect. Intra Basolateral amygdala infusion of clonidine (4μg/rat) has an anxiolytic-like effect. While co-administration clonidine (4μg/rat) and in effective dose of morphine (4mg/kg) showed significant increase of OAT% in anxiety test; thus presenting anxiolytic response. Intra Basolateral amygdala administration of yohimbine (2μg/rat) decreased OAT% indicating of decrease anxiety-like behavior. While co-administration of intra Basolateral amygdala clonidine (4μg/rat) and effective dose of morphine (6mg/kg) showed a significant increase of OAT%, presenting anxiolytic response; co-administration of ineffective doses of morphine (4mg/kg) and yohimbine (1μg/rat) with the effective dose of clonidine (4μg/rat) showed that yohimbine could reverse the anxiolytic-like effect of morphine and clonidine. It should be noted that there are no significant changes in locomotor activity. The results indicate that morphine creates the compromise changes in adrenergic neurons of Basolateral amygdala by changing the α-adrenergic system on anxiety.                                                                                                                                                                  

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Septohippocampal system plays an important role in regulating fear and anxiety behaviors. In this study, the effects of histamine injected into the dorsal hippocampus and opioidergic agents into medial septum on the anxiety-like behaviors in rats were analyzed, using the Elevated Plus-Maze (EPM) test. Injection of 1 and 5 μg/rat histamine into dorsal hippocampus had no effect on anxiety-like behavior, while injection of 10 μg/rat histamine increased the percentage of open arm time (%OAT) and open arm entry (%OAE), which indicated the anxiolytic effects of histamine. Microinjection of morphine, μ-opioid receptor agonist, into the medial septum (1μg/rat) increased the (%OAT) and (%OAE). Doses of 0.25, 0.5 μg/rat morphine had no effect on anxiety. Co-administration of histamine ineffective dose (1μg/rat) to the dorsal hippocampus and ineffective dose of morphine (0.25µg/rat) to the medial septum increased the (%OAT) and (%OAE). Subsequently, injection of different doses of naloxone (1, 2, 4 µg/rat), as an opioid receptor antagonist, into the medial septum in the presence and absence of an effective dose of histamine (10 µg/rat) in the dorsal hippocampus, was studied. Injection of naloxone (4 µg/rat) into medial septum decreased the (%OAT) and (%OAE), but did not alter the locomotor activity, which indicated the anxiogenic effects of naloxone. Simultaneous injection of histamine (10 µg/rat) into dorsal hippocampus with doses of naloxone (1, 2, 4 µg/rat) into the medial septum, indicate anxiolytic effects and increased %OAT and %OAE in Elevated Plus Maze, although when the dose of naloxone was 4μg/rat, this effect was less observed. The results indicate that hippocampus histaminergic system interact with medial septum opioidergic system and the interaction of these systems modulates anxiety behavior.

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The Basolateral Amygdala (BLA) has modulatory effects on working and reference memory. The aim of this study was the evaluation of effects of dopaminergic system in the BLA of rats on working and reference memory behaviors. The number of working and reference errors and time spent in the arms by rats were measured in the radial arm maze according to DSWS protocol. The animals were cannulated in the BLA bilaterally. The microinjection of low dose (0.005µg/rat) and high dose (0.5 µg/rat) of apomorphine have indicated a significant decrease in number of working memory error. But, there was not any change in the numberof reference memory error that showing the improvement of working memory. While the injection of moderate dose apomorphine (0.05 µg/rat) increased these parameters and also enhanced the spent time in working arm that presenting both memories damage. The chlorpromazine injection (2 µg/rat) decreased the number of working and reference memory errors representing the improvement of these memories. Microinjection of chlorpromazine (2 µg/rat) with different doses of apomorphine had no significant change on the both number of errors and the time spent in comparison with control groups. These findings show that BLA dopaminergic system modulates the working and reference memory through that both of (D1/D2) receptors. Also, the effect of this system in BLA is the resultant function of the both receptor families.
 

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Hippocampus is a key structure in anxiety processing and memory storage. The purpose of this study was to investigate the interaction between GABAergic systems in CA1 area of hippocampus with morphinergic system in modulating of these behaviors. In this study, male wistar rats were cannulated with stereotaxic surgery in CA1 site. After a recovery period, morphine (µ opioid receptor agonist) was injected intraperitoneal, muscimol and bicuculline (GABA_A receptor agonist and antagonist) were injected into the CA1. Parameters such as percentage of Open arms time (%OAT) and entries (%OAE) were calculated by means of an EPM apparatus. One-way ANOVA analysis showed that intraperitoneal administration of morphine increased %OAT and %OAE, indicating the anxiolytic effect of morphine. Based on paired sample T-test, the rate of memory formation improved. Pre-test intra-CA1 infusion of muscimol and bicuculline induced anxiolytic-like and anxiogenic-like behaviors, respectively; meanwhile, both drugs improved memory. Systemic injections of an effective dose of morphine combined with triple doses of muscimol showed a synergistic effect on memory formation and anxiety reduction. Simultaneous injection of morphine and bicuculline altered the negative effects of the latter on anxiety and increased the memory formation. This finding showed that GABAergic and opioidergic systems have similar effects on memory and anxiety in CA1 area.