Abstract
We investigated the influence of environmental enrichment on newly born cells after 6-hydroxydopamine (6-OHDA) injection into the striatum. Male Wistar rats (P25) were housed in normal cages (18x23x40cm, 2-3 rats per cage) or environmental enrichment cages (81x51x53cm, with enriched apparatus, 6-7 rats per cage) for 1 week. Then 6-OHDA (20μg) was injected into the left striatum, and then rats were kept under each circumstance to the end of experiment. To label proliferating cells, the animals were received BrdU (daily, 50mg/kg body weight, i.p.) for 3 days just before fixation at 1 or 2 weeks after 6-OHDA injection. Coronal sections (40μm) were counted (n=7-10) for BrdU-positive (BrdU+) cells in the subventricular zone (SVZ) and the striatum near SVZ (STR). In the SVZ, the number of BrdU+ cells significantly decreased 2 weeks after the lesion in both groups (63.7±7.3 to 45.5±5.4 in normal condition-groups, 76.0±6.8 to 51.3±4.4 in enriched groups). In the STR, BrdU+ cells increased 1 week after the lesion in both groups (12.1±1.5 in control, 18.9±1.9 for lesions in normal condition-groups, 16.7±2.73 for lesions in enriched groups). Although BrdU+ cells significantly decreased to control level 2 weeks after the lesion in normal condition-groups (9.7±1.34), the number of BrdU+ cells remained high in enriched groups (14.4±3.0). Data suggest that the production of BrdU+ cells, 2 weeks after 6-OHDA injection into the striatum, remained in the STR but not in the SVZ under environmental enrichment. [Jpn J Physiol 54 Suppl:S242 (2004)]
