Choline supplementation attenuates learning deficits associated with neonatal alcohol exposure in the rat: effects of varying the timing of choline administration

Abstract

Despite the harmful effects of fetal alcohol exposure, some pregnant women continue to drink alcohol. Thus, it is imperative to pursue safe, effective treatments for children with fetal alcohol spectrum disorders. Using an animal model, our laboratory has demonstrated that choline, an essential nutrient, effectively reduces the severity of some fetal alcohol effects, even when administered after the ethanol insult is complete. The present study investigated whether there is a critical developmental period when choline is most effective in attenuating ethanol's teratogenic effects. Sprague-Dawley rats were exposed to 5.25 g/kg/day ethanol during the third trimester equivalent brain growth spurt (postnatal days (PD) 4-9) via intubation. A non-intubation control group and a sham intubation control group were included. Following ethanol exposure, pups received subcutaneous injections of saline vehicle or choline chloride (100 mg/kg/day) from PD 11-20, PD 21-30, or PD 11-30. Beginning on PD 45, subjects were tested on a Morris water maze spatial learning task. Performance of both the ethanol-exposed group that did not receive choline and the ethanol-exposed group treated with choline from PD 21-30 was significantly impaired compared to controls during acquisition of the Morris water maze task. Performance of ethanol-exposed groups treated with choline from PD 11-20 or PD 11-30 was intermediate, not differing significantly from any other groups. However, during the probe trial, ethanol exposure produced significant deficits in spatial memory which were mitigated by all choline treatments, regardless of the timing of administration. These findings suggest that choline's therapeutic window may be very large, or spans across the two developmental periods examined in this study. Importantly, these findings indicate that choline supplementation may effectively reduce some alcohol-related learning impairments, even when administered in later childhood.

Figure 1

Body weights for males and females over treatment days. Panels A and C show growth during the ethanol treatment period, whereas Panels B and D show growth during the choline treatment period. Ethanol-exposed subjects lagged in growth compared to controls (NC s/s and SHAM s/s) beginning on PD 5, but caught up by PD 30. There were no significant effects of choline on body growth. EtOH s/s = ethanol-exposed, saline treated; EtOH c/s = ethanol-exposed, choline from PD 11–20, saline from PD 21–30; EtOH s/c = ethanol-exposed, saline from PD 11–20, choline from PD 21–30; EtOH c/c = ethanol-exposed, choline from PD 11–30, SHAM s/s = sham control; NC s/s = nonintubated control.

Figure 2

Path length (A) and latency (B) to find the hidden platform during Morris maze acquisition. Performance of all groups improved over days. When collapsed across days (C), EtOH s/s and EtOH s/c subjects took significantly longer path lengths to find the platform compared to controls, whereas performance of EtOH c/s and EtOH c/c subjects was intermediate, not differing significantly from controls or other ethanol-exposed groups. Treatment effects were not significant on the latency to find the hidden platform (panel D shows group effects collapsed across days). ** = significantly different from SHAM s/s and NC s/s control groups

Figure 3

The heading angles of the EtOH s/s and EtOH s/c groups were significantly greater than those of NC s/s and SHAM s/s controls, indicating that ethanol-exposed subjects that did not get choline during the early period (PD 11–20) were less accurate in their spatial navigation.

Figure 4

Time spent in the target quadrant (A) and target area (B) during the probe trial. EtOH s/s subjects were significantly impaired in spatial memory compared to all other groups. ** = significantly different from all groups except EtOH c/s; *** = significantly different from all other groups

Figure 5

Ethanol exposure did not significantly influence the number of target passes (A), but did significantly reduce the ratio of passes through the target compared to other quadrant targets (B). Choline administration during any of the time periods significantly mitigated ethanol’s effects. *** = significantly different from all other groups