[Role of the opioidergic system in regulating respiration]

Experiments on anesthetized rats were made to study the effects of naloxone, bradykinin and thyroliberin on respiration. Naloxone, bradykinin and thyroliberin were found to eliminate respiratory depression induced by morphine and an enkephalin analog. Bradykinin primarily increased the amplitude, while thyroliberin the rate of respiration. Naloxone increased both the rate and amplitude of respiration. It is assumed that the noted difference in the action of naloxone, bradykinin and thyroliberin on respiration is linked with their effects on different types of opiate receptors involved in respiration control.