ABSTRACT
Objective To explore the modulatory effect of 5-HT2A receptors on the discharge activities of inspiratory neurons in medial region of nucleus retrofacialis of neonatal rats. Methods Experiments were performed in vitro brainstem slice preparations from neonatal rats. These preparations included the medial region of nucleus retrofacialis with the hypoglossal nerve rootlets retained. The rhythmic discharges of the inspiratory neurons and activities of the hypoglossal nerve rootlets were simultaneously recorded by using microelectrodes and suction electrodes, respectively. Roles of 5-HT2A receptors in modulation of the discharge activities of inspiratory neurons were investigated by administration of the 5-HT2A receptor agonist 1-(2,5-dimethoxy-4-iodopbenyl)-2-aminopropane (DOI), and its specific antagonist ketanserine dissolved in modified Kreb's solution for perfused slices. Results In DOI group, the inspiratory time (TI) was (0.864±0.07)s, expiratory time (TE) was (10.78±1.06)s, respiratory cycle (RC) was (11.79±1.64)s, integral amplitude (IA) was (357.98±37.21)(μV·s) and the peak discharge frequency (PF) was (37.83±3.66)Hz. In control group, they were (0.68±0.06)s, (13.89±2.14)s, (14.77±1.92)s, (273.57±24.39)(μV·s), and (29.92±4.50)Hz, there were significant differences between the 2 groups (Pa<0.01). In ketanserine group, TI was (0.55±0.07)s, TE and RC were (18.43±3.28)s and (20.17+2.91)s respectively, IA and PF were (214.37±33.52)(μV·s) and (22.17±3.92)Hz, there were significant differences between ketanserine group and DOI, control group (Pa<0.01). Conclusion 5-HT2A receptors take part in modulate the discharge activities of inspiratory neurons in neonatal rat brainstem slices.