Somatic and endocrine consequences of electrolytic lesions in the epi and subthalamus of weanling and mature rats.

Weanling rats received lesions in the zona incerta (ZIN). Sham-operated rats served as controls. Two experiments were performed several months apart. The animals were maintained on lab chow and tap water for 30 days and then sacrificed. Ponderal and linear growth, food and water intake, water/food-intake ratio, and pituitary weights were significantly reduced in rats with ZIN lesions. Plasma, growth hormone, insulin, glucose, and body composition were normal, however. Weanling and mature rats received lesions in the medial habenula (HAB). Sham-operated rats served as controls. The experiment lasted 44 days postoperatively. In the weanling Hab-lesioned rats, body weight changes, body composition pituitary, weight, food and water intake, water/food-intake ratio, and plasma insulin were normal. Linear growth was slightly (p < 0.05) reduced. In the mature HAB-lesioned rats, all the above parameters were normal except for water intake, which was slightly (p < 0.05) reduced. The pathways by which the epi- and subthalamus may influence the observed changes--or the lack thereof--are discussed.