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Vasopressin and oxytocin receptor mRNAs are expressed in the rat inner ear
1Department of Otolaryngogly, Shiga University of Medical Science, Otsu, Japan.
Abstract:
The cause of endolymphatic hydrops, a characteristic finding in Menière's disease, is not known. To study the possible involvement of the neurohormones vasopressin and oxytocin in this condition, we investigated whether transcripts of the genes encoding the arginine vasopressin (AVP) and oxytocin receptors are expressed in the rat inner ear. Utilizing the reverse transcription-polymerase chain reaction (RT-PCR) method, primers specific for each receptor showed a single message band of the expected size in the rat inner ear. When the PCR products were cloned, the sequences were identical to those of the real-type (V2) AVP receptor and oxytocin receptor transcripts. The finding of vasopressin and oxytocin receptor mRNAs in the inner ear suggests that these neurohypophyseal hormones may have roles in the regulation of inner ear fluid. In particular, the presence of vasopressin receptor mRNA in the inner ear supports the hypothesis of a relationship between high plasma vasopressin levels and endolymphatic hydrops.
Insights
Researchers found evidence that vasopressin and oxytocin receptors are present in the rat inner ear. This suggests these neurohormones may influence inner ear fluid balance, potentially linking vasopressin to endolymphatic hydrops.
Area of Science:
- Neuroendocrinology
- Otolaryngology
- Molecular Biology
Background:
- Endolymphatic hydrops, a key feature of Menière's disease, lacks a known cause.
- Neurohormones like vasopressin and oxytocin are potential regulators of fluid balance.
- Investigating their role in the inner ear could elucidate Menière's disease mechanisms.
Purpose of the Study:
- To determine if arginine vasopressin (AVP) and oxytocin receptor gene transcripts are expressed in the rat inner ear.
- To explore the potential involvement of these neurohormones in inner ear fluid regulation.
Main Methods:
- Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect gene expression.
- Specific primers were designed for arginine vasopressin (AVP) and oxytocin receptors.
- PCR products were cloned and sequenced for verification.
Main Results:
- RT-PCR analysis revealed single message bands of the expected size for both AVP and oxytocin receptors in the rat inner ear.
- Sequencing confirmed the identity of the amplified transcripts as V2 AVP receptor and oxytocin receptor.
- This indicates the presence of mRNA for these receptors in the inner ear.
Conclusions:
- The detection of vasopressin and oxytocin receptor mRNAs in the inner ear suggests a role for these neurohypophyseal hormones in regulating inner ear fluid.
- The presence of vasopressin receptor mRNA supports a potential link between elevated plasma vasopressin levels and endolymphatic hydrops.
- Further research is warranted to fully understand the implications for Menière's disease.