Presence of type I and type II/IB receptors for adrenocorticosteroid hormones in the inner ear.
Aldosterone-Type I and dexamethasone-Type II/IB receptor complexes were identified in cytosol prepared from both cochlear and vestibular tissue samples. The specific binding capacity of Type I receptors in the cochlear tissues was approximately equal to that in the vestibular tissues. Likewise, the binding capacity of Type II/IB receptors in the cochlea was approximately equal to that in the vestibular endorgans. Based on the total specific binding measured with dexamethasone, the Type II/IB receptors appeared to outnumber the Type I receptors in cochlear and vestibular tissues by a factor of approximately 2.6; however, when adjustments were made for the probable cross-binding of dexamethasone to Type I receptors, these ratios were decreased to approximately 1.6. The existence of protein receptors for adrenocorticosteroid hormones demonstrated in the present study clearly suggests a mechanism whereby such hormones may directly regulate fluid and ionic gradients in the inner ear.
Rarey
K E
KE
Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville 32610-0235.
Luttge
W G
WG
D000450:Aldosterone / Q000378:metabolism; D000818:Animals; D003051:Cochlea / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D003907:Dexamethasone / Q000378:metabolism; D007758:Ear, Inner / Q000378:metabolism*; D006706:Homeostasis; D008297:Male; D051381:Rats; D011965:Receptors, Glucocorticoid / Q000145:classification / Q000378:metabolism*; D018161:Receptors, Mineralocorticoid; D014722:Vestibule, Labyrinth / Q000378:metabolism
D011965:Receptors, Glucocorticoid; D018161:Receptors, Mineralocorticoid; C028697:dexamethasone receptor; D000450:Aldosterone; D003907:Dexamethasone