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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Animals, Body Temperature, Consciousness, Disease Models, Animal, Hyperventilation, Hypoxia, Male, Microinjections, Narcotic Antagonists, Peptide Fragments, Pulmonary Ventilation, Raphe Nuclei, Rats, Rats, Wistar, Receptors, Opioid, mu, Respiratory Mechanics, Somatostatin, Time Factors.
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Do opioid μ-receptors in the rostral medullary raphe modulate hypoxia-induced hyperpnea in unanesthetized rats? Context: It has been suggested that the medullary raphe (MR) plays a key role in the physiological responses to hypoxia. As opioid μ-receptors have been found in the MR, we studied the putative role of opioid μ-receptors in the rostral MR (rMR) region on ventilation in normal and 7% hypoxic conditions. We measured pulmonary ventilation (VE) and the body temperatures (Tb) of male Wistar rats before and after the selective opioid μ-receptor antagonist CTAP (D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2, cyclic, 0.1 μg per 0.1 μL) was microinjected into the rMR during normoxia or after 60 min of hypoxia. The animals treated with intra-rMR CTAP exhibited an attenuation of the ventilatory response to hypoxia (430 ± 86 mL kg(-1) min(-1)) compared with the control group (790 ± 82 mL kg(-1) min(-1) ) (P < 0.05). No differences in the Tb were observed between groups during hypoxia.
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These data suggest that opioids acting on μ-receptors in the rMR exert an excitatory modulation of hyperventilation induced by hypoxia. Final Decision: yes