[Electrophysiological study of the relationship between rostral ventrolateral medulla and locus coeruleus of rabbits]

The electrophysiological characteristics of locus coeruleus (LC) neurons and the projection from the rostral ventrolateral medulla (RVLM) to the LC were investigated on 18 rabbits, which were lightly anesthetized, decerebelated, paralyzed and artificially ventilated. 93 of the 108 recorded LC neurons are firing spontaneously at about 5.1 Hz, while the remaining are silent but could be activated by pinching. 64 (59.2%) of the LC neurons manifested excitatory response to brushing and 93 (86.1%) to pinching. Of the 108 LC neurons, 85 (78.7%) neurons could be activated orthodromically by ipsilateral RVLM stimulation with a latency of 21.6 +/- 6.9 ms, among which 67 neurons showed excitatory response. 35 of the 123 recorded RVLM neurons responded antidromically to ipsilateral LC stimulation with a latency of 19.2 +/- 8.2 ms. These results suggest that there may exist a direct excitatory pathway from RVLM to LC.