Ad. Miller et al., MULTIFUNCTIONAL VENTRAL RESPIRATORY GROUP - BULBOSPINAL EXPIRATORY NEURONS PLAY A ROLE IN PUDENDAL DISCHARGE DURING VOMITING, Journal of the autonomic nervous system, 54(3), 1995, pp. 253-260
Pudendal motoneurons are activated in phasic bursts during the retchin
g and expulsion phases of vomiting. The resulting contraction of the a
nal and urethral sphincters serves to maintain continence during the l
arge increase in abdominal pressure that occurs during vomiting. We ev
aluated the contribution of bulbospinal expiratory neurons located in
the portion of the ventral respiratory group (VRG) caudal to the obex
(nucleus retroambigualis) to the control of pudendal motoneurons durin
g fictive vomiting in decerebrate, paralyzed cats. Pudendal nerve disc
harge is abolished by cutting the axons of caudal VRG expiratory neuro
ns as they cross the midline between the obex and C1 before descending
in the spinal cord. All caudal VRG expiratory neurons that were antid
romically activated from the sacral spinal cord, where the pudendal mo
tor pool (nucleus of Onuf) is located, discharged strongly during the
end of the expulsion phase of vomiting. However, only a small proporti
on of these neurons was active in phase with pudendal discharge during
the retching phase. The apparent involvement of caudal VRG expiratory
neurons in the control of pudendal motoneurons during vomiting is ano
ther example of the multifunctional role that can be played by respira
tory-related neurons in the mammalian nervous system.