The influence of 5-HT1A receptors in the dorsal raphé nucleus on genioglossus activity

Genioglossus activity maintains the patency of the upper airway. 5-HT neurons in the raphe nucleus regulate genioglossus activity. In order to study the influence of 5-HT1A receptors in dorsal raphé nucleus (DRN) on genioglossus EMG during normoxia, adult male Wistar rats were randomly divided into four groups: the artificial cerebrospinal fluid group (ACSF group), the low-concentration of 5-HT1A receptors agonist 8-OH-DPAT group (0.1 mM group), the mid-concentration 8-OH-DPAT group (0.4 mM group) and the high-concentration 8-OH-DPAT group (1.0 mM group). Rats received 0.1 μl ACSF/8-OH-DPAT microinjections into the DRN. EMG activity of the genioglossus was recorded at 5 min, 15 min and 30 min after microinjection. In three 8-OH-DPAT groups, genioglossus EMG activity significantly decreased at 5 min after microinjection and persisted for 30 min. The significantly decreased EMG activity was more pronounced in the mid- and high-concentration groups than in the low-concentration group, indicating that 5-HT1A receptors in the DRN could rapidly and continuously inhibit genioglossus EMG activity during normoxia.