Modulation of firing activity by endogenous GABAA receptors in the globus pallidus of MPTP-treated parkinsonian mice

The globus pallidus in rodents, equivalent to the external segment of the globus pallidus in primates, plays an important role in movement regulation. Previous studies have shown abundant γ-aminobutyric acid (GABA)ergic innervation and GABA_A receptors in the globus pallidus. In this study, we investigated the effects of endogenous GABA_A receptors on the spontaneous firing activity of pallidal neurons in both normal and MPTP-treated mice using multi-barrel electrodes extracellular recordings in vivo. We found that in normal mice, pressure ejection of 0.1 mmol/L gabazine, a specific GABA_A receptor antagonist, increased the spontaneous firing rate of globus pallidus neurons by 27.6 ± 5.6%. Furthermore, in MPTP mice (14 days after MPTP treatment), 0.1 mmol/L gabazine increased the firing rates by 51.0 ± 7.9%, significantly greater than in normal mice. These results suggest that endogenous GABA_A receptors modulate the activity of globus pallidus neurons. The present findings may provide a rationale for investigations into the potential role of GABA_A receptors in Parkinson’s disease.