Electroconvulsive shock and the estrous cycle in the rat

The effects of electroconvulsive shock on the estrous cycle in the rat were investigated. Sixty animals, chosen on the basis of stability of estrus, were assigned randomly to one of four treatment conditions with the restriction that each condition contain 15 subjects. Treatment conditions were as follows: one electroconvulsive shock; five electroconvulsive shocks; one sham electroconvulsive shock; and five sham electroconvulsive shocks. Results indicated that one electroconvulsive shock did not affect estrus, while five electroconvulsive shocks produced a significant delay in the onset of estrus. Once estrus began following a course of five shocks, no additional delays were observed.