Sexual receptivity in female rats after lesion or stimulation in different amygdaloid nuclei.

Lesions in the anterior part of the corticomedial amygdaloid nucleus decreased the frequency of lordotic reponses in ovariectomized rats treated with estradiol benzoate and progesterone. Electrochemical stimulation (iron deposition) of the same area had the opposite effect. When lesions were made in the posterior part of the lateral amygdaloid nucleus a highly significant increase in receptivity was observed; on the other hand stimulation in this region depressed the lordosis quotient in receptive animals. Appropriate controls showed that the effects observed after lesioning cannot be attributed to the different estrogen doses used, nor to nonspecific effects of tissue destruction. Similarly, the changes observed after electrochemical stimulation do not depend on the lesion produced by this procedure or the repeated-tests paradigm employed. Electrocorticograms and electroencephalograms of the amygdala showed no apparent alterations after electrochemical stimulations. It is proposed that amygdaloid structures play a modulatory and integrative role on the control of sexual behavior in the female rat: activation of cells in the anterior part of the corticomedial nucleus increases the probability of lordotic responses while excitation of the neurons in the posterior part of the lateral nucleus has the opposite effect.