Supplemental choline during the periweaning period protects against trace conditioning impairments attributable to post-training ethanol exposure in adolescent rats

Abstract

Supplemental choline during early stages of development can result in long-lasting improvements to memory function. In addition, pre- or postnatal choline has been shown to be protective against some of the adverse effects of early alcohol exposure. The present experiment examined whether supplemental choline given to rats would protect against the effects of posttraining alcohol administration on trace fear conditioning. Posttraining alcohol exposure in adolescent rats results in poor performance in this hippocampus-dependent task, although delay conditioning is unaffected. Here, rats were given an s.c. injection of either saline or choline chloride daily on postnatal days (PD) 15-26. On PD 30 subjects were trained in a trace fear conditioning procedure. For the next 3 days animals were administered 2.5 g/kg ethanol or water control, and conditional stimulus (CS)-elicited freezing was measured on PD 34. Results indicated that posttraining alcohol disrupted the expression of trace conditioning and that supplemental choline on PD 15-26 was protective against this effect. That is, choline-treated animals subsequently given posttraining ethanol performed as well as animals not given ethanol. These results indicate that supplemental choline given during the periweaning period protects against ethanol-induced impairments in a hippocampus-dependent learning task. Findings contribute to the growing literature showing improvements in learning and memory in subjects given extra dietary choline during critical periods of brain development.

Figure 1

Mean (+/- SEM) % freezing during a baseline (pre-CS) period and during the light CS. Data are the % of intervals scored as freezing using a time-sampling procedure. Subjects were given s.c. saline or choline injections on postnatal days (PD) 15-26. On PD 30 subjects were trained using a trace fear conditioning procedure and were subsequently given i.g. water or 2.5 g/kg ethanol (EtOH) for three days. Subjects were tested for freezing on PD 34, approximately 24 h after the final ethanol exposure. Pre-CS freezing was equivalent in all groups. Post-training ethanol impaired trace conditioned responding (group Saline-EtOH), and supplemental choline prevented this effect (group Choline-EtOH).