Lack of combined effect of continuous exposure to α-glycosyl isoquercitrin from fetal stages to adulthood and voluntary exercise or environmental enrichment on learning and behaviors in rats

Abstract

We previously reported that continuous exposure to α-glycosyl isoquercitrin (AGIQ) from the fetal stage to adulthood facilitates fear-extinction learning in rats. The present study investigated the combined effect of continuous exposure to AGIQ with voluntary exercise or environmental enrichment on learning and behaviors in rats. For this purpose, maternal Long-Evans rats were either untreated or treated with 0.5% AGIQ in basal diet from gestational day 6 to day 21 post-delivery. Offspring in both groups were weaned on postnatal day 21 and reared thereafter either in a standard cage, a wheel cage or an environmental enrichment cage until the end of the experiment with or without exposure to AGIQ. Fear memory, locomotor activity and anxiety-like behavior in open field test, spatial memory and nonspatial memory were assessed in adulthood. Environmental enrichment without AGIQ exposure, as well as AGIQ exposure in standard cage, showed a tendency for facilitation of fear-extinction learning. However, exposure to AGIQ and environmental enrichment did not act synergistically. Voluntary exercise only decreased the total distance traveled in the open field test in the condition with or without AGIQ exposure, suggesting induction of anxiety-like behavior. Body weight from lactation period to adulthood, body and brain weights at the end of the experiment did not change by exposure to AGIQ under any cage condition. Therefore, there was no beneficial or detrimental effect of voluntary exercise and environment enrichment on the outcome of behavior or general conditions by continuous AGIQ exposure from the fetal stage.