Effect of BNST lesions on behavioral despair and navigational learning in female wistar rats

Abstract

The bed nucleus of the stria terminalis (BNST) is involved in many motivational processes especially in coping with stressful situations. Previously we reported that in male rats BNST lesions aggravated behavioral despair but did not interfere with navigational learning as tested by performance in the Morris water maze (MWM) task. Since the BNST is a sexually dimorphic structure, in the present study we tested female Wistar rats in both behavioral paradigms after bilateral electrolytic BNST lesions. Two weeks after surgery, lesioned animals (n=8) and sham-operated controls (n=7) underwent two forced swim tests separated by 24 hr to assess behavioral despair. A week later, animals were tested in the MWM with a hidden platform task for 10 days (5 trials per day) followed by a probe trial test with the platform removed. One day after probe trial, the animals were tested in a one day visible platform MWM. To assess locomotor activity, an open field test was administered two weeks after termination of the MWM task. Our results indicated that female rats also showed aggravated behavioral despair after BNST lesions which did not impair acquisition in navigational learning in the MWM task. The BNST lesions did not affect performance in probe trial of MWM or in open field test. Our findings strongly suggest that the BNST modulates depression as measured by behavioral despair in also female rats but does not seem to affect navigational learning.