Forebrain ischemia triggers GABAergic system degeneration in substantia nigra at chronic stages in rats

Abstract

The long-term consequences of forebrain ischemia include delayed Parkinson's syndrome. This study revealed delayed neurodegeneration in the substantia nigra 8 weeks after 12.5 minutes of global ischemia in rat brain. Following neuronal loss of 30-40 in central and dorsolateral striatum at day 3, neuronal damage in the substantia nigra (SN) was assessed at 4-8 weeks using immunohistochemistry for glutamate decarboxylase 67 (GAD67), vesicular GABA transporter (VGAT), and calretinin (CR). At day 56, the optical density of GAD67-, but not VGAT-, immunoreactivity in substantia nigra pars reticulata (SNR)significantly decreased. CR-neurons concentrated in substantia nigra pars compacta (SNC) were reduced by 27 from day 3 (n = 5) to day 56 (n = 7, ANOVA, p