Do Aging Changes in the Preoptic Area Contribute to Loss of Cyclic Endocrine Function?

Two-year-old Wistar rats showing repeated periods of pseudopregnancy were compared with young rats that had electrolytic lesions placed in the medial preoptic area. Electrolytic lesions in the medial preoptic area in young rats induced repeated pseudopregnancies what were similar to those seen in the old pseudopregnant rats. Serum prolactin levels were elevated in both groups of rats. Administration of lergotrile mesylate (an ergot-dervied dopamine agonist and prolactin inhibitor) resulted in a reduction in serum prolactin levels and in the appearance of normal consecutive 4- or 5-day estrous cycles in the old rats and in the young rats with brain lesions. These results suggest that the repeated periods of pseudopregnancy in the aged rats may result from a deficiency in dopamine or from an abnormality in dopamine metabolism in neurons arising or passing through the medial preoptic area.