Figure 5. SPNs express postsynaptic GABA_B receptors.

Aa, samples of a continuous whole-cell current-clamp recording from an SPN showing bath application of baclofen, induces membrane hyperpolarization associated with a decrease in neuronal input resistance. Subsequent application of 2-hydroxy-saclofen (2-OH-S) reduced the membrane response induced by baclofen. Ab, bath application of baclofen to another SPN induced membrane hyperpolarization corresponding with a decrease in neuronal input resistance. Subsequent bath application of CGP55845 reversibly reduced the magnitude of the membrane response to baclofen. B, summary histogram illustrating the pharmacological profile of GABA_B receptor-mediated responses evoked in SPNs. The peak membrane potential responses (filled columns) and changes in neuronal input resistance (open columns) induced by GABA_B receptor agonists and the effects of antagonists on agonist-induced responses are shown. Error bars represent s.e.m. Numbers above individual bars indicate number of cells tested (n). (*P < 0.01, **P < 0.005, ***P < 0.03.)