Motor impairments and increased GFAP expression in different stages of a progressive model of parkinsonism induced by reserpine.

Neuroinflammation plays a pivotal role in the progression of Parkinson's disease, involving the activation of microglia and astrocytes. Astrocytes are essential for the development and maintenance of neural tissue, but can shift to a pro-inflammatory phenotype in response to factors such as oxidative stress and excitotoxicity. Here, we aimed to evaluate the astroglial response in a rodent model of parkinsonism induced by chronic low-dose reserpine administration. Adult male Wistar rats received reserpine (0.1 mg/kg, i.p.) every other day for 30 days (RES group), while control animals (CTL group) received the same number of vehicle injections. Motor impairment was assessed via catalepsy and tape tests after the 4th, 8th, 12th, and 15th injections. Subsets of animals were perfused 48 h after the 4th, 10th, and 15th injections for immunohistochemical analysis of glial fibrillary acidic protein (GFAP) and tyrosine hydroxylase (TH). We found increased GFAP cell density in the dorsal striatum at all time points, indicating early astrocyte activation. However, reductions in astrocytic arborization after the 10th and 15th injections suggested a phenotypic shift toward a reactive, pro-inflammatory state. Concurrently, TH cell counts declined in the substantia nigra pars compacta after the 10th and 15th injections, and in the ventral tegmental area after the 15th, paralleling the onset of motor deficits. Behavioral tests showed increased latency to movement from the 4th injection onward, suggesting that initial astrocyte activation may confer neuroprotection, which wanes as reserpine-induced tissue damage progresses.