Effects of Postnatal Choline Supplementation on Open Field Behavior in Developing Rats

Abstract

<p>Choline is an essential biological nutrient and precursor to acetylcholine, a major neurotransmitter in the limbic system and in learning & memory processes. Recent work in our lab using classical eye-blink conditioning procedures demonstrated that postnatal choline may improve hippocampal-dependent learning and memory in normal adolescent rats. The present study examined whether choline's effects on eye-blink conditioning could be mediated by increased exploratory behavior or reduced fear of novelty, as tested in an open field paradigm. Thirty-one LongEvans rats (16 female, 15 male) received daily subcutaneous injections of either choline or saline on postnatal days 15 -22 and open field testing on day 23. Open field testing consisted of 10 minutes in a novel environment. Observed exploratory behaviors included rearing (raising front paws off the ground), number of entries, and time spent in the center or periphery of the field. The frequency of exploratory behaviors decreased over time, but there were no differences between drug groups. Both choline-and saline-treated animals reared more and crossed into the center more in the early part of the testing period. Time spent rearing decreased while time in the center increased as the novelty wore off. Postnatal choline treatment did not increase activity levels or novelty exploration in young rats. It is unlikely that improvements in learning in our other studies are mediated by changes in general arousal or exploratory tendencies.<p><p>This presentation occurred at the Wright State University Campus-Wide Celebration of Research, Scholarship and Creative Activities on April 8, 2011</p>