Neonatal Novelty Exposure Induced Enhancement of Adult LTP and CORT Modulation Were Late- rialized to Right Hippocampus

It has been reported that neonatal stimulation can cause lateralization in adult rats hemisphere. In our previous studies, we specifically showed that neonatal exposure lead to right side shift of preference in paw reaching test and lateralization of hemisphere thickness in adult rats. Therefore, we postulated that the effect of neonatal novelty exposure may have different effect on long term potentiation (LTP) and conticosterone(CORT) modulation in hippocampus. Using a neonatal novelty procedure (modified from the neonatal handling procedure), we exposed rats (post-natal days 1-21) to a novel non-home environment for 3 min daily. When the animals grew into adult (7-8 months), we examined hippocampal LTP of extracelluar EPSP and population spike keeping track of the left and right side. The results showed that the neonatal novelty exposure enhanced LTP of neonatal novelty exposed rats (Novel) verse the control (Home), but this enhancement was laterialized to the right side of hippocampus ( ). Furthermore, pre-exposure of the slices to corticosterone (CORT) lead to reduction of LTP in Novel group and this reduction was also laterialized to the right side of hippocampus. These results suggested that neonatal novelty stimulation induced brain asymmetry in adulthood might originate at least from limbic system. Classification term: Theme: Development and regeneration Zou-Tang LTP Lateralization September 20, 2001 2 Topic: Hormones and development