| Abstract No.: | 111 |
| Country: | Canada |
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| Title: | The Transient Receptor Potential Vanilloid 1 is a Major Candidate for Instrinsic Osmoreception in Organum Vasculosum Lamina Terminalis Neurons and for Thirst Responses to Systemic Hyperosmolality |
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| Authors/Affiliations: | Charles W. Bourque*
Centre for Research in Neuroscience, McGill University, Montreal, QC, Canada |
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| Content: | Osmosensitive neurons in the organum vasculosum lamina terminalis (OVLT) detect increases in plasma osmolality via reversible increases in firing rate. The information encoded by this response is then relayed synaptically to downstream neurons that are responsible for the stimulation of water intake and the release of vasopressin, the antidiuretic hormone. Steady state current voltage analysis has shown that hyperosmolality causes a decrease in cell volume linked to the activation of a non-selective cation current in acutely isolated rat and mouse OVLT neurons. This current, but not the volume change, can be blocked by ruthenium red, an inhibitor of transient receptor potential vanilloid (Trpv) channels. Analogously, OVLT neurons obtained from mice lacking expression of the trpv1 gene (Trpv1-KO mice) show normal decreases in cell volume but no increase in cation conductance under hyperosmotic conditions. OVLT neurons recorded in-situ from Trpv1-KO mice are not responsive to hypertonic conditions. Moreover these mice show an elevated serum osmolality under resting conditions, and impaired water intake when exposed to an acute hyperosmotic stimulus. These data indicate that a product of the Trpv1 gene is required for normal osmosensing by OVLT neurons, and for thirst stimulation under hyperosmotic conditions. |
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