Effects of the stimulation of β2-adrenoceptors of the the basolateral amygdala on anxiety-like behaviors following electrical foot-shock stress in male rat

Introduction: The basolateral amygdala (BLA) is a key structure that integrated anxiety information. It is suggested that baso-lateral area of amygdala receives a dense norepinephrine innervation from the locus coeruleus nucleus. Furthermore, stress increased norepinephrine secretion in the BLA. In the present study, we examined the effects of the stimulation of β2-adrenoceptors in the BLA on anxiety-like behaviors following foot-shock stress. Materials and Methods: Foot-shock stress (10 Hz, 40 mV for 60 seconds) for 4 consecutive days applied to animals. Salbutamol (the β2-adrenoreceptor agonist; 4 µg/rat) bilaterally injected into the BLA 5 min before starting foot-shock stress for 4 consecutive days. Anxiety-like behaviors assessed 24h after the last session of stress, using elevated plus-maze (EPM) and open field test (OFT). Results: Foot-shock stress significantly decreased time spent and the number of entries into the open arms of EPM. Similarly, stress significantly decreased the time spent and the number of entries into the center area of OFT. Furthermore, foot-shock stress significantly decreased the number of grooming and rearing behaviors. Additionally, intra-BLA infusions of salbutamol before stress significantly increased time spent and the number of entries into the open arms as compared with stress group. In addition, OFT results showed that salbutamol increased the time spent in the center, number of center entries, the number of rearing and grooming behaviors, line crossing and total distance as compared with the stress group. Conclusion: It is likely that β2- adrenoceptors of the BLA mediate the induced-anxiety-behaviors by foot-shock stress.