On the interactive role of central noradrenaline neurons and corticosterone in two-way active avoidance acquisition in the rat.

The noradrenaline (NA) neurotoxin, DSP4, caused a marked impairment of two-way active avoidance acquisition. Pretreatment with desipramine, which inhibits the degeneration of NA neurons by DSP4, consistently blocked the avoidance deficit. Daily treatment with corticosterone (2 X 1 mg/kg, s.c.) also blocked the impaired acquisition of avoidance induced by DSP4 but failed to affect the increase in cortical beta-noradrenergic receptors induced by DSP4. The present findings give further evidence for the important role interactions between the pituitary-adrenal axis and the locus coeruleus NA system play in aversive learning.