Kindling of the lateral septum and the amygdala: Effects on anxiety in rats

Long-term kindling of limbic system structures may produce substantial changes in emotional behavior in rats. This study examined long-term changes in two kindled structures that have opposite effects on anxiety, the lateral septum and the central nucleus of the amygdala. The purpose of the experiment was to examine the specificity of the emotional effects of kindling by employing a double dissociation design. Animals were tested in two common animal models of anxiety, the water-lick conflict test and the elevated plus-maze. In the conflict test amygdala-kindled animals demonstrated a significant anxiolytic effect when compared with sham-kindled animals. This effect was potentiated by chlordiazepoxide. Septally-kindled animals exhibited a significant anticonflict effect when compared to sham-kindled animals in the first session. Septally-kindled animals spent significantly more time on the open arms of the elevated plus-maze than did sham-kindled animals. Observed changes persisted 6 weeks after the termination of 150 kindling sessions. The effects of long-term kindling were highly consistent with those of disruption rather than facilitation.

► Kindling of the amygdala has an anti-conflict effect in a water-lick conflict test. ► Kindling of the amygdala potentiates the anxiolytic effect of chlordiazepoxide. ► Kindling of the lateral septum has a small temporary anti-conflict effect. ► Septal kindling increases open arm entries in the elevated plus-maze. ► The results are consistent with a disruptive effect of kindling.