Effect of unilateral deafferentiation in the medial basal portion of the temporal lobe on the hypophyseo-ovarian axis in rats: an age-dependent lateralized control mechanism.

The possible physiological role of the medial basal portion of the temporal lobe (including the corticomedial amygdaloid nucleus) in the neural control of the hypophyseo-ovarian axis was studied in pre- and postpubertal as well as in adult rats. Unilateral deafferentiation of a small medio-basal portion of the temporal lobe was performed in unilaterally ovariectomized animals, and the rate of compensatory hypertrophy of the remaining ovary was recorded. In adults compensatory ovarian hypertrophy was significantly reduced following right- but not left-sided deafferentiation. Temporal lobe surgery did not significantly influence the usual compensatory ovarian growth in pre- and postpubertal rats. Serum luteinizing hormone levels decreased significantly in adults regardless of the side of brain interventions, while no obvious change in the hormone concentration could be observed in prepubertals. Serum follicle-stimulating hormone concentrations showed no alterations in any experimental group. In postpubertal rats the serum progesterone level was unchanged following brain surgery. The present observations indicate that unilateral deafferentation in the temporal lobe could modify compensatory ovarian hypertrophy by a direct neural mechanism and data further suggest functional laterality of these structures in the control of ovarian functions.