Key resources table.

Reagent type (species) or resource	Designation	Source or reference	Identifiers	Additional information
Strain, strain background (Mus musculus, male and female)	Arrb2-/-	The Jackson Laboratory	011130
Strain, strain background (Mus musculus, male and female)	C57Bl/6 J	The Jackson Laboratory	000664
Peptide, recombinant protein	DAMGO	Abcam	Ab12067
Chemical compound, drug	Morphine sulfate	Henry Schein	057202
Chemical compound, drug	Naloxone	Sigma Aldrich	N7758
Software, algorithm	Matlab	Mathworks		https://github.com/YackleLab/Opioids-depress-breathing-through-two-small-brainstem-sites