REACTIVE ASTROCYTES AND THEIR RELATIONSHIP WITH PYROPTOSIS IN A PARKINSON’S DISEASE RAT MODEL INDUCED BY BSSG​

Parkinson’s disease (PD) is a neurodegenerative disorder characterized by progressive loss of dopaminergic neurons in the nigrostriatal pathway, α-synuclein aggregation, motor and non-motor symptoms, and pronounced neuroinflammation. Emerging evidence implicates inflammatory forms of regulated cell death—particularly pyroptosis mediated by caspase-1 and gasdermin-D—together with region-specific astrocyte reactivity in PD progression. To investigate these mechanisms, a toxin-based rodent PD model was used involving unilateral intranigral injection of β-sitosterol β-D-glucoside (BSSG), which reproduces major pathological hallmarks of PD. Male Wistar rats received 6 μg BSSG in 1 μL DMSO; groups included intact controls, mock, and BSSG-lesioned animals examined at early, intermediate, and late stages (15, 30, and 60 days post-lesion). Brains were analyzed by immunohistochemistry and double immunofluorescence. GFAP/C3 labeling identified neurotoxic C3(+) reactive astrocytes, while GFAP/S100A10 labeling identified putative neuroprotective S100A10(+) reactive astrocytes in α-synuclein–affected regions: anterior olfactory nucleus (AON), motor cortex, substantia nigra, striatum, and hippocampus. Caspase-1 and gasdermin-D immunostaining in substantia nigra pars compacta and motor cortex assessed pyroptotic signaling. Quantitative analyses showed significant increases in both C3(+) and S100A10(+) reactive astrocytes in α-synuclein–affected areas, with regional predominance: C3(+) astrocytes dominated in motor cortex and hippocampal CA2, whereas S100A10(+) astrocytes were more abundant in the AON. These astrocytic changes coincided with decreased neuronal density and heightened caspase-1 and gasdermin-D activation, indicating engagement of pyroptosis-associated neurodegenerative mechanisms. Overall, region-specific astrocyte reactivity combined with pyroptotic cell death contributes to neurodegeneration in the BSSG PD model, highlighting neuroinflammatory signaling as a key driver and therapeutic target.