Abstract
The aim of this study was to test whether GABAergic receptors on neurons in dorsal nucleus of the lateral lemniscus (LLD) contribute to the control of swallowing. In acutely decerebrated cats (n=12), swallowing was induced by electrical stimulation (30–80 μA at 10Hz for 10–20 seconds with rectangular pulses of 0.2 ms duration) applied to the superior laryngeal nerve (SLN). Repetitive electrical stimulation (30–50 μA at 50Hz for 10–20 seconds) applied to the LLD facilitated the SLN-induced swallowing. Muscimol, a GABAA receptor agonist, bicuculline, a GABAA receptor antagonist, and baclofen, a GABAB receptor agonist, were microinjected (0.10–0.15 μl, 5 mM) into the LLD through a stereotaxically placed glass micropipette. We observed that an injection of muscimol suppressed the SLN-induced swallowing. However, an injection of bicuculline facilitated the swallowing. An injection of baclofen did not alter the swallowing. Moreover, electrical stimulation applied to the substantia nigra pars reticulata (SNr), a basal ganglia output nucleus, suppressed the SLN-induced swallowing. The SNr-effect was further prevented by injection of bicuculline into the LLD. These results suggest that GABAergic projections from the basal ganglia to the brainstem modulate swallowing through the activation of GABAA receptors on LLD neurons. [J Physiol Sci. 2008;58 Suppl:S196]
