Abstract
There are many studies reporting that enriched rearing environment has the advantages in promoting brain plasticity and learning. In the present study, we examined the effects of environmental enrichment during rearing on sexual and social behavior after maturation in male Wistar rats. Following weaning on day 25, 7 males were housed together in a large cage with several objects and equipments, and other 7 males were kept in conventional cages without objects (2 or 3 males / cage). When tested in a narrow cylinder (20 cm diameter) or in a round open field (60 cm diameter), males reared in enriched environment showed increased immobility (decrease in locomotor activity) than males reared in conventional cages. Following the activity tests, 3 successive sexual behavior tests were weekly carried out with receptive females that were ovariectomized and primed with estrogen and progesterone. The rearing environment had no effects on male sexual behavior, locomotion and anogenital investigation were significantly decreased in males reared in enriched environment. The decrease in these social activities culminated in diminished soliciting behavior (hopping and darting) shown by stimulus females. Current data suggest in combination with our earlier result that motivational states in social behavior regulated by dopamine may be affected by enriched environment in early life. [J Physiol Sci. 2007;57 Suppl:S193]
