Effects of iontophoretically applied morphine on respiration related units in the medial part of the nucleus retrofacialis region in rats.
The effects of morphine on 108 spontaneously discharging units in the medial part of the nucleus retrofacialis (mNRF) were studied in 13 SD rats anesthetized with urethane and allowed to breathe spontaneously. A 5-barrelled microelectrode was inserted into the mNRF region to record discharges of respiration related units (RRUs) and nonrespiration related units (NRRUs), and then morphine was administered by iontophoresis. Among the 27 inspiration related units (InRUs) recorded, morphine exerted an inhibitory effect on 8 units and an excitatory effect on 6 units; while among the 36 expiration related units (ExRUs), the excitatory effect was much more obvious than the inhibitory effect (12 vs 2). This difference was statistically significant. The results revealed a difference between the effects of morphine on InRUs and ExRUs in the mNRF region. The excitatory effect of morphine on ExRUs in the mNRF region might play a role in the mechanism by which morphine depresses respiration.
Tian
G
G
Department of Physiology, Shanghai Medical University.
Qian
Z
Z
Xu
H
H
Zhang
J
J
D000818:Animals; D004594:Electrophysiology; D005260:Female; D007478:Iontophoresis; D008297:Male; D008839:Microelectrodes; D009020:Morphine / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012119:Respiration / Q000187:drug effects*; D012125:Respiratory Center / Q000187:drug effects* / Q000502:physiology
D009020:Morphine