Lesion of the amygdala on the right and left side suppresses testosterone secretion but only left-sided intervention decreases serum luteinizing hormone level.

The effect of right- and left-sided intra-amygdaloid injection of kainic acid on the hypothalamo-hypophyseal-testicular axis was studied in rats. Both right- and left-sided injection of the neurotoxin into the amygdala resulted in a significant decrease in basal testosterone secretion in vitro of both testes and in serum testosterone concentration. In addition, left-sided administration of kainic acid significantly suppressed serum luteinizing hormone level, while right-sided intervention did not alter this parameter. The results of the present study provide further evidence on the involvement of the amygdala in the control of testicular steroidogenesis. Furthermore, the observations suggest functional asymmetry of the amygdala concerning the mechanism of suppressed testosterone secretion.