Serotonin and noradrenaline content and release in the dorsal hippocampus during learning and spatial memory in prenatally stressed rats

Prenatal stress causes learning and spatial memory deficits in adulthood by modifying hippocampal function. The dorsal hippocampus contains serotonergic and noradrenergic neuron terminals, which are related to cognitive processes. It is currently unknown whether prenatal stress modifies serotonin (5-HT) and noradrenaline (NA) content and their release in the hippocampus during cognitive performance. Therefore, we measured these variables in the dorsal hippocampus of prenatally stressed males during spatial learning and memory tests. Cognitive tests were performed in 3-month-old control and prenatally stressed male rats in the Morris Water Maze (MWM). After cognitive tests, the dorsal hippocampus was dissected to quantify 5-HT and NA content. In other males, 5-HT and NA release in the dorsal hippocampus was assessed by microdialysis, before and after cognitive tests. Prenatally stressed males showed longer latencies to reach the platform, compared to control animals. Hippocampal 5-HT content decreased during learning and memory tasks in both groups, while NA content was not modified in prenatally stressed males neither before, nor after learning and memory tests. 5-HT and NA release were significantly lower in prenatally stressed animals during spatial learning and memory tasks. Corticosterone response was greater in prenatally stressed animals compared to controls. These results show that cognitive disruption caused by prenatal stress is related to decreased 5-HT and NA release, and to higher adrenal axis response in prenatally stressed animals.