beta2-adrenergic but not vasopressin V2 receptor mRNAs are expressed in the stria vascularis of the rat inner ear.
Activation of beta2-adrenergic receptors (beta2-AR) and of V2-vasopressin receptors (V2-VR) has been shown to stimulate cAMP production in the stria vascularis. Expression of these receptors in this epithelial structure has never been investigated at the mRNA level. A quantitative assay based on the reverse transcriptase-polymerase chain reaction (RT-PCR) method was developed to study the expression of beta2-AR, vasopressin (V1a,V1b, V2) and oxytocin receptors in rat microdissected stria vascularis fragments. Steady-state mRNA levels were measured using mutant cRNAs as internal standards. We consistently found evidence of the expression of beta2-AR transcripts in the stria vascularis; however, no such evidence of V2-VR mRNA expression was found in studies of the same samples. As our method is sensitive enough to detect 200 mRNA molecules, V2-VR mRNA is thought to be present, if at all, at a concentration that is 40 times lower than that of the beta2-AR transcripts. V1a-VR mRNA was found to be present in trace amounts and is the only subtype of the vasopressin-oxytocin receptor family expressed in this epithelium. These data demonstrate, at the mRNA level, the expression of beta2-AR in the stria vascularis, and indicate that V2-VR transcripts are not present in this structure.
de Minteguiaga
C
C
UPRESA 7060-CNRS Laboratoire d'Otologie Expérimentale, Faculté de Médecine Lariboisière, 10 Avenue de Verdun, F-75010, Paris, France. cdemint@club-internet.fr
Clerget
M S
MS
Tran Ba Huy
P
P
Elalouf
J M
JM
D000818:Animals; D015870:Gene Expression; D008297:Male; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism*; D051381:Rats; D020318:Rats, Long-Evans; D011943:Receptors, Adrenergic, beta / Q000235:genetics*; D017483:Receptors, Vasopressin / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013316:Stria Vascularis / Q000737:chemistry / Q000378:metabolism*
D012333:RNA, Messenger; D011943:Receptors, Adrenergic, beta; D017483:Receptors, Vasopressin