Role of olfactory bulbectomy and DSP4 treatment in avoidance learning in the rat.
Olfactory bulbectomized rats and DSP4-treated rats were studied on a two-way active avoidance task as well as on step-down passive avoidance and fear conditioning and retention tasks in three experiments. The DSP4-treated, but not olfactory bulbectomized, rats were impaired in acquiring two-way avoidance; bulbectomized, but not DSP4-treated, rats were found to show notable passive avoidance and fear retention deficits. Bulbectomized rats treated with DSP4 did not show passive avoidance and fear retention deficits, nor did these animals evidence the two-way avoidance impairment of the DSP4-treated rats. No alteration of dopamine-beta-hydroxylase activity in the frontal cortex and hippocampus as a result of the bulbectomy operation was indicated. The double dissociation between bulbectomized and DSP4-treated rats is discussed in terms of opponent behavioral processes, influenced by olfactory bulbectomy and DSP4, which may permit insights into experimental investigations of stress, anxiety, and depression.