The influences of sex, rearing environment, and neonatal choline dietary supplementation on spatial and nonspatial learning and memory in adult rats

The potential facilitative effects of early environmental enrichment and perinatal choline chloride dietary supplementation on male and female adult rats' learning and memory were examined using a “stimulus‐elicited investigative,” and a social/observational learning‐cued spatial memory paradigm. Male and female animals were either maintained in a standard lighted colony (SC) or were given supplementary exposure to a complex environment (EC) for 2 hr daily from 24–90 days of age. In each case, half of the animals were exposed to the choline supplementation both prenatally and postnatally for 24 days. In one paradigm, the 90‐day‐old EC rats were found to be significantly more responsive than SC rats to each change in the spatial relationships of objects contained in an open field. Neither sex nor early diet of the animals were much of a factor in the investigative behavior observed. In the second paradigm, the effects of the perinatal choline diet did interact with those of sex and postnatal environment to alter the impact of social/observational experience on the acquisition and memory of place in the water maze. The choline‐treated EC males were the most influenced by their experience seeing a demonstrator swim to a platform location. The present study provides some further insight into the scope of the long‐term functional enhancements produced by perinatal choline supplementation and EC in male and female animals and relates these effects to common modifications to targets of cholinergic basal forebrain systems. © 1999 John Wiley & Sons, Inc. Dev Psychobiol 35: 328–342, 1999