Overcrowding; induces anxiety and causes loss of serotonin 5HT-1a receptors in rats

Unfavorable conditions under which children grow up may contribute signific antly to the development of psychiatric abnormalities in adult life. We stu died the effects of overcrowding at an early age and how it may result in a nxiety later in life. Sprague-Dawley rats were housed 10 animals per cage, from birth until 4 weeks post-weaning. Rats housed 3 per cage served as con trols. The Elevated Plus maze was used to determine their anxious behavior. Thereafter. the serotonergic system in the hippocampus was investigated. O vercrowded rats were significantly more anxious than controls. The number o f 5HT-1a receptors in the hippocampus decreased significantly and their aff inity for the ligand, OH-DPAT, increased significantly. There was no signif icant difference in the hippocampal levels of serotonin between overcrowded rats and controls. Our study shows that overcrowding during childhood can result in anxious behavior and that the serotonergic system appears to play a role in its manifestation.