Impact of the interaction between morphine and α-noradrenergic system of basolateral Amygdala on anxiety-related behavior and memory

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