[The responses of phrenic discharges to microinjection of morphine and naloxone into central nucleus amygdala in rabbits].
Experiments were done on 24 urethan anesthetized (20%, 1 g/kg), vagotomized and spontaneously breathing rabbits (2-3 kg). The effects on phrenic activity by microinjection of morphine and naloxone into central nucleus amygdala (ACE) were observed. The main results were as follows: (1) Injection of morphine resulted in two respiratory effects, firstly a marked increase in inspiratory time (Ti) and amplitude of phrenic activity (AMP) with little changes of respiratory frequency (RF), and secondly a significant decrease in AMP with little changes in Ti. (2) Injection of naloxone resulted in increases in RF, AMP and decreases in Ti with no marked changes in blood pressure. (3) Prolongation of inspiratory time by morphine can be blocked by previous injection of naloxone. The results suggested that endogenous morphine in ACE have different effects on respiration mediated by different receptor.
Department of Physiology, Shangdong Medical University, Jinan.
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D000679:Amygdala / Q000502:physiology*; D000818:Animals; D004594:Electrophysiology; D005260:Female; D008297:Male; D008845:Microinjections; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology*; D010791:Phrenic Nerve / Q000187:drug effects* / Q000502:physiology; D011817:Rabbits; D012119:Respiration / Q000187:drug effects*
D009270:Naloxone; D009020:Morphine