Exogenous l-DOPA induce no dopamine immuno-reactivity in striatal astroglias and microglias of adult rats with extensive nigro-striatal dopaminergic denervation

The aim of this study was to determine whether striatal glial cells of adult rats with extensive nigro-striatal dopaminergic denervation are induced to contain dopamine by injection of exogenous l-DOPA. At 2 weeks after injection of 6-hydroxydopamine into the medial forebrain bundle of rats, immuno-reactivity of glial cells was detected with antibodies against glial fibrillary acidic protein (GFAP) or ionized calcium binding adapter molecule 1 (Iba1) in the intact and lesioned striatum. Double-labeling immunofluorescence method was secondly performed. In the lesioned striatum, immuno-reactivity of GFAP was significantly increased, whereas immuno-reactivity of Iba1 was significantly increased except for ventral portion. Exogenous l-DOPA induced DA immuno-reactivity in the striatum, which was independently detected from GFAP immuno-positive astroglial cells or Iba1 immuno-positive microglial cells in the intact side as well as in the lesioned side. These findings suggest that the proliferation of glial cells in the striatum is the response to the loss of dopaminergic terminals but the glial cells do not compensate for the lost dopaminergic terminals.