Hippocampal or pyriform lobe damage in infancy and endocrine development of rats

¹ Department of Anatomy, State University of New York Medical Center, Brooklyn, New York

Lesions were produced in the brains of male and female albino rats at 1 week of age. It was found that bilateral hippocampal damage is associated with diminished gonadal and adrenal development when that development is estimated by morphologic and behavioral indices (running activity). Only those female rats with bilateral degeneration of the dorsal fornix failed to exhibit cyclic running. Both male and female rats with considerable bilateral hippocampal damage showed diminished running, smaller-sized gonads, and larger thymus bodies at 75–80 days of age. On the other hand, male and female rats with bilateral damage to the pyriform lobe developed a precocious spurt in running activity. A spurt is normally associated with puberty. The question of whether the hippocampus and pyriform lobe should be regarded only as "centers" for trophic stimulation or suppression or whether they should be regarded as important links in circuits mediating an endocrine response to environmental conditions is discussed.