[Effect of stimulation of the facial nucleus on discharge of respiratory neurons in the pre-Bözinger complex and its neurotransmitter mechanism in rats].

The experiments were carried out on adult Sprague-Dawley rats. We investigated the discharge response of respiratory neurons (RNs) in the pre-Bözinger complex (PBC) to electrical stimulation of the facial nucleus in which the motor neurons were retrogradely degenerated and the antagonistic effects of microiontophoresis of CNQX, bicuculline (BIC), strychnine (Stry) and atropine on the discharge responses of the neurons. In 12 rats with retrograde degeneration of the facial motor neurons, 116 RNs in the PBC ipsilateral to the facial nerve sectioned were extracellularly recorded. The response of pre-inspiratory (Pre-I) (24 / 26) and inspiratory (I) (30 / 35) neurons to the electrical stimulation of the facial nucleus was mainly excitatory, and the response of expiratory (E) (20 / 22) and inspiratory-expiratory phase-spanning (I-E) (28 / 33) neurons was mainly inhibitory. CNQX partially or completely block the excitatory effect of the stimulation on Pre-I (18 / 24) and I (23 / 27) neurons. Stry could partially or completely block the immediate transient inhibition on Pre-I (12 / 18) and I (14 / 23) neurons and the inhibitory effect on I-E (20 / 28) and E (9 / 16) neurons induced by the stimulation. BIC partially or completely blocked the inhibitory effect on I-E (22 / 25) and E (9 / 9) neurons induced by the stimulation. Atropine did not have obvious influence on the response of RNs to the stimulation. These results suggest that non-motoneurons in the facial nucleus may participate in the modulation of respiration by affecting the activities of RNs in the PBC and that Glu, GABA and Gly serve as neurotransmitters or modulators to regulate the activities of the RNs in the PBC and hence the rhythmic respiratory movement.