Glial cell-derived neurotrophic factor decrease may mediate learning, memory and behavior impairments in rats after neonatal surgery

Patients who have surgery during the first few years of their lives may have an increased risk of behavioral abnormality. Our previous study has shown a role of glial cell-derived neurotrophic factor (GDNF) in neonatal surgery-induced learning and memory impairment in rats. This study was designed to determine whether neonatal surgery induced hyperactive behavior in addition to learning and memory impairment and whether GDNF played a role in these changes. Postnatal day 7 male and female Sprague-Dawley rats were subjected to right common carotid arterial exposure under sevoflurane anesthesia. Their learning, memory and behavior were tested from 23 days after the surgery. GDNF was injected intracerebroventricularly at the end of surgery. Surgery reduced GDNF expression in the hippocampus. Surgery impaired learning and memory and induced a hyperactive behavior as assessed by Barnes maze, fear conditioning and open field tests. In addition, surgery reduced dendritic arborization and spine density. The effects were attenuated by GDNF injection. These results suggest that surgery induces a hyperactive behavior pattern, impairment of learning and memory, and neuronal microstructural damage later in the lives in rats. GDNF reduction may mediate these surgical effects.