Micro-opioid receptor agonist injections into the presumed pre-Botzinger complex and the surrounding region of awake goats do not alter eupneic breathing. J Appl Physiol (1985) 2009 Nov;107(5):1591-9
Date
09/12/2009Pubmed ID
19745186Pubmed Central ID
PMC2777792DOI
10.1152/japplphysiol.90548.2008Scopus ID
2-s2.0-72749094683 (requires institutional sign-in at Scopus site) 23 CitationsAbstract
Opioids are clinically important in the alleviation of pain. An undesirable side effect of opioids is depression of breathing. Data from isolated preparations suggest this effect is due to attenuation of discharge activity of neurons in the pre-Bötzinger complex (preBötzC), a medullary area with respiratory rhythmogenic properties. The purpose of this study was to examine how [d-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin (DAMGO), a mu-opioid receptor agonist, affected breathing after injection into the presumed preBötzC of the adult awake goat. We hypothesized that DAMGO would cause breathing to decrease and become irregular when injected into the presumed preBötzC and the surrounding region of the conscious animal. We further hypothesized that ventilatory sensitivity to CO(2) and hypoxia would be blunted after the injection of DAMGO. Microtubules were bilaterally implanted into the presumed preBötzC of 10 adult female goats. After recovery from the surgery, DAMGO (0.5-10 mul, 1 nM-10 muM) was injected into the presumed preBötzC during the awake state. DAMGO had no effect on pulmonary ventilation [inspiratory minute ventilation (Vi)], respiratory rhythm and pattern, the activation pattern of inspiratory and expiratory muscles, or arterial blood gases during eupneic breathing conditions (P > 0.10). However, DAMGO attenuated (P < 0.05) the evoked increase in breathing frequency when inspired CO(2) was increased, and DAMGO attenuated the Vi response to reduction of inspired O(2) to 10.8% (P < 0.05). We conclude that our data do not provide support for the concept that in awake mammals opioid depression of breathing is due to a directed action of opioids on preBötzC neurons.
Author List
Krause KL, Neumueller SE, Marshall BD, Kiner T, Bonis JM, Pan LG, Qian B, Forster HVAuthor
Hubert V. Forster PhD Professor in the Physiology department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
AnimalsEnkephalin, Ala(2)-MePhe(4)-Gly(5)-
Female
Goats
Injections
Medulla Oblongata
Receptors, Opioid, mu
Respiratory Center
Respiratory Mechanics
Wakefulness
