TABLE 2.

Class B1 GPCRs relevant to cochlea.

GPCR family	Subtypes	Roles in cochlea	Localization	Genetic modulation	References
Class B1 GPCRs
VIP and PACAP receptors	VPAC1R	Possibly acting as neurotransmitters	SGN	-	Feng and Liu, 2015
	PAC1R	Protection of NIHL	HC, SC, SGN, ANF, ENF, SV	PAC1R–/– mice	Ruel et al., 2021
				TgHPAC1R mice
Corticotropin-releasing factor receptors	CRFR1	Maintaining normal auditory function	ISC, HSC, DC, BC	CRFR1–/– mice	Graham and Vetter, 2011
		Involved IHC and HC innervation development		CRFR1-GFP mice
	CRFR2	Constitutively modulates hearing sensitivity	ISC, HSC, DC, IBC, SGNs, CC, BoC	CRFR2–/– mice	Graham et al., 2010
		Protection of NIHL
Calcitonin receptors	CGRPR	Associated with increased cochlear nerve activity	-	-	Dickerson et al., 2016

SGN, Spiral Ganglion Neuron; HC, hair cell; SC, supporting cell; ANF, afferent nerve fiber; ENF, efferent nerve fiber; SV, Stria Vascularis; ISC, inner sulcus cell; HSC, Hensen cell; DC, Deiters’ cell; BC, border cell; IBC, inner border cell; CC, Claudius cell; BoC, Boettcher cell.