Images in electroconvulsive therapy: Pilot impressions suggesting that ECT reduces excitatory synapses in the basolateral amygdala.

Background: In animal models, stress and depression are associated with excitatory changes in the amygdala; this aberrant neuroplasticity may represent increased fear learning, explaining the anxiety, fear, and related symptoms that characterize clinical depression.

Materials And Methods: In a pilot investigation, we treated adult, male, Wistar rats with sham electroconvulsive shocks (ECS; n=3), low-dose ECS (10 mC; n=3), and high-dose ECS (60 mC; n=3). The rats were sacrificed 1 month after the last of 6 once-daily ECS and, after dissection, sections of the basolateral amygdala were examined using transmission electron microscopy under low (×11,000) and high (×30,000) magnification.

Results: In each group, 4 fields were examined under low magnification and 6 fields under high magnification. The number of excitatory synapses and the ratio of excitatory to inhibitory synapses were both numerically lower with ECS than with sham ECS, and the effect was stronger in the high-dose ECS group (statistical analyses were not performed because this was a pilot study).

Conclusions: By reducing the number of excitatory synapses and the ratio of excitatory to inhibitory synapses, ECT (especially high-dose ECT) may reduce stress-induced excitatory changes in the amygdala. These changes may help explain a part of the benefits observed with ECT in conditions such as depression and post-traumatic stress disorder.