Oxytocin Receptor Activation Rescues Opioid-Induced Respiratory Depression by Systemic Fentanyl in the Rat.

Area of Science:

• Neuroscience
• Pharmacology
• Cardiorespiratory Physiology

Background:

• Opioid overdose causes life-threatening respiratory depression, typically reversed by naloxone.
• Systemic naloxone stimulates oxytocin release, a neuropeptide with analgesic and cardiorespiratory regulatory functions.
• The potential of oxytocin to reverse opioid-induced respiratory depression (OIRD) remains largely unexplored.

Purpose of the Study:

• To investigate the hypothesis that oxytocin can reverse OIRD.
• To assess the dose-dependent efficacy of oxytocin in reversing fentanyl-induced respiratory depression in rats.
• To explore the role of oxytocin and vasopressin 1A receptors in OIRD reversal.

Main Methods:

• Phrenic nerve activity (PNA) was recorded in anesthetized rats to index neural inspiration.
• Graded intravenous doses of oxytocin were administered to counter fentanyl-induced respiratory depression.
• Oxytocin receptor and vasopressin 1A receptor antagonism were employed, along with a nonpeptide oxytocin receptor agonist (WAY-267464).

Main Results:

• Oxytocin dose-dependently reversed fentanyl OIRD, restoring PNA frequency and amplitude at low doses, exhibiting an inverted bell-shaped dose-response curve.
• Oxytocin receptor antagonism blocked the reversal effect, while vasopressin 1A receptor antagonism restored high-dose oxytocin efficacy.
• The nonpeptide oxytocin receptor agonist WAY-267464 effectively reversed OIRD without adverse hemodynamic effects.

Conclusions:

• Activation of oxytocin receptors, by both peptide (oxytocin) and nonpeptide agonists, can reverse fentanyl-induced cardiorespiratory depression.
• Selective oxytocin receptor agonists show promise as resuscitation agents for opioid overdose.
• Targeting oxytocin receptors could provide a resuscitation strategy that enhances opioid analgesia while mitigating overdose risks.