Abstract
To investigate the effect of environmental enrichment on newly-born cells and migrating cells after 6-hydroxydopamine (6-OHDA) injection into the striatum (STR), male Wistar rats (P25) housed in normal or environmental-enriched cage (large cage with several equipments) for 5 weeks were injected with 6-OHDA (20μg) into the left STR and kept in each environment. Animals were received BrdU (daily, 50mg/kg, i.p.) for 3 days just before fixation at 1 or 2 weeks after 6-OHDA injection, and processed for immunostainings of BrdU and doublecortin (Dcx, a marker of migrating neuroblasts). In the subventricular zone, the number of BrdU(+) cells showed a tendency to decrease in both groups. Dcx(+) cells showed morphologies of non-migrating type (symmetric with several processes) in medial STR and migrating type (elongated and leading processes) in dorsal STR. Number of Dcx(+) cells increased in both medial and dorsal STR by 6-OHDA injection, and it was enhanced in dorsal STR of environmental-enriched group 1 week after the lesion. However, the increase of Dcx(+) cells was not seen in both environmental groups in case that 6-OHDA was injected into substantia nigra. Stronger STR damage by injection of higher dose of 6-OHDA or quinolic acid increased the number of Dcx(+) cells. Data suggest that environmental enrichment enhanced the response to increase Dcx(+) cells that was found in STR with relatively strong damage, indicating that environmental enrichment has, at least in part, effect on cell migration after brain damage. [Jpn J Physiol 55 Suppl:S226 (2005)]
