Effects of perinatal dietary choline supplementation on learning and memory in the adult rat

• Main Author: Johnston, Judi L.
• Format: Others
• Language: English
• Published: 2008
• Online Access: http://hdl.handle.net/2429/1933

The effects of perinatal choline supplementation on learning and memory in the adult rat were investigated. Subjects were 36 experimentally naive female and male Long-Evans rats. A .05M/litre solution of saccharin containing either 0or 5m1/litre of 70% choline chloride was administered via drinking water to mature females. Treatment began prior to conception and continued until pups were weaned on postnatal day 31 (P31). One group of dams were switched from the 0 to the 5m1/litre choline solution on P16. Three groups comprised of six males and six females each, designated as pre- and postnatal supplementation (PP), postnatal-only supplementation (PO), and control were evaluated for learning and memory performance on a test battery designed to assess open field behavior and recognition memory (open field arena), nonspatial reference memory (visual discrimination t-maze), nonspatial working memory (delayed nonmatching-to-sample), and spatial working and reference memory (17-arm radial arm maze). Testing began when all subjects had reached at least 70 days of age. Significant differences were found on all tasks except the delayed nonmatching-to-sample assessment of nonspatial working memory. In the habituation phase of the open field testing females were found to exhibit significantly more exploratory rearing behavior than males. PP subjects exhibited significantly more exploratory behavior than PO subjects and PO subjects were found to spent significantly less time in the "home-base" quadrant than the PP or control subjects. In the second phase of the open field, the test of recognition memory, PO males were found to exhibit significantly less exploratory rearing than PP females. In addition, PO females spent significantly more time in the quadrant containing a novel stimulus object than control females and contacted the novel object significantly more times than either control females or PO males. In the nonspatial reference memory task it was found that both PP and PO groups reached final criterion in significantly fewer trials than controls. Males also reached final criterion significantly faster than females. These differences arose from the first two stages of testing, initial acquisition of the discrimination and transfer to a novel cue. By the third stage of training (cue location change), all differences were nonsignificant, as was the case in the final stage where a distractor was added to the cue. On the radial arm maze task it was found that PP subjects required significantly fewer total arm entries to retrieve all rewards than the control group. Both PP and PO groups committed significantly fewer reference memory errors than the controls. PO subjects made significantly more correct choices in the first eight arm entries than controls, however, this group also exhibited significantly more working memory errors than PP subjects at various stages of training, as did control subjects. PO subjects also missed more baited arms than the PP group. These findings are discussed in light of the existing literature regarding choline supplementation. Implications for future directions in research are also addressed. === Arts, Faculty of === Psychology, Department of === Graduate