Opioids depress breathing through two small brainstem sites

Area of Science:

• Neuroscience
• Respiratory Physiology
• Pharmacology

Background:

• Opioid overdose deaths have quadrupled in the US since 1999, with 130 daily fatalities.
• Opioid-induced respiratory depression is a major cause of overdose fatalities.
• Innovative solutions require identifying the neural circuits underlying respiratory depression.

Purpose of the Study:

• To pinpoint the brain areas and cell types responsible for opioid-induced respiratory depression.
• To understand the mechanisms by which opioids affect breathing control.
• To identify potential targets for novel therapeutic interventions.

Main Methods:

• Administered opioids to murine models to observe changes in breathing.
• Locally eliminated the µ-Opioid receptor in the brainstem.
• Utilized genetic tools to identify specific neurons in the preBötzinger Complex.

Main Results:

• Identified two primary changes in murine breathing patterns after opioid administration.
• Confirmed the involvement of the brainstem's respiratory circuitry.
• Localized the critical brain site to the preBötzinger Complex.
• Revealed that 70-140 neurons in the preBötzinger Complex mediate opioid sensitivity.

Conclusions:

• The preBötzinger Complex is a critical site for opioid-induced respiratory depression.
• A small population of neurons within this complex is responsible for opioid sensitivity.
• Further characterization of these neurons could lead to therapies preventing respiratory depression while preserving pain relief.