Basolateral amygdala lesions block glucocorticoid-induced modulation of memory for spatial learning

This study examined the role of the amygdala in mediating the effects of glucocorticoids on spatial memory in rats. Adrenalectomy (ADX) induced 4-5 days prior to training impaired memory in a water-maze spatial task. This effect was reversed by a posttraining injection of dexamethasone (0.3 mg/kg sc) but not by corticosterone (0.3 mg/kg). Lesions of the basolateral (BLA), but not the central (CEA) or the medial (MEA), amygdala blocked the effects of ADX and dexamethasone. ADX also impaired acquisition. CEA, MEA, and BLA lesions blocked the ADX effect on acquisition. In adrenally intact rats, intracerebroventricular posttraining injections of a specific glucocorticoid receptor (GR or Type-II) antagonist impaired retention, and BLA lesions blocked the effect of the GR antagonist. These finding provide evidence that the BLA is involved in mediating glucocorticoid influences on learning and memory.