Temporal profile of arginine vasopressin release from the neurohypophysis in response to hypertonic saline and hypotension measured using a fluorescent fusion protein.

Abstract

Methods currently employed to study the release of hormones such as arginine vasopressin (AVP), while sensitive, suffer from a low temporal resolution such that the monitoring of AVP release on a moment-to-moment basis is not possible. Here, we describe a new approach to indirectly monitor the temporal profile of AVP release from the neurohypophysis of transgenic rats expressing an AVP-eGFP fusion gene. Using fibre-optic probes (termed 'optrodes') we were able to indirectly monitor AVP release via a reporter moiety in real-time. This method is a major advance over current methods used to monitor AVP release. Intravenous administration of hypertonic saline (3M NaCl) induced a rapid (latency of 2-3s) increase in fluorescence detected in the neurohypophysis that lasted on average for 60s - a response that was highly reproducible. Infusion of sodium nitroprusside induced a rapid fall in blood pressure accompanied by a rapid, stimulus-locked increase in fluorescent signal that returned to baseline with the recovery of blood pressure to pre-stimulus levels - again this response was highly reproducible. Withdrawal of blood (to simulate haemorrhage) also resulted in a stimulus-locked increase in fluorescence that return to baseline after the withdrawn blood was returned to the animal. In conclusion, we developed a highly sensitive approach that allows the indirect measurement of AVP release via the monitoring of a reporter gene in real-time. This technology can be adapted to permit the study of a whole array of neurohormones/chemicals in transgenic animals expressing a fluorescent reporter construct.

• Authors: Song T Yao, Vagner R Antunes, Peter M J Bradley, Sergey Kasparov, Yoichi Ueta, Julian F R Paton, David Murphy
• Journal: Journal of neuroscience methods (J Neurosci Methods) Vol. 201 Issue 1 Pg. 191-5 (Sep 30 2011) ISSN: 1872-678X [Electronic] Netherlands
• PMID: 21855574 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

Chemical References

• Recombinant Fusion Proteins
• Saline Solution, Hypertonic
• Arginine Vasopressin
• Green Fluorescent Proteins

Topics

• Animals
• Arginine Vasopressin (analysis, metabolism)
• Female
• Green Fluorescent Proteins (analysis, metabolism)
• Hypotension (diagnosis, metabolism)
• Male
• Pituitary Gland, Posterior (chemistry, drug effects, metabolism)
• Rats
• Rats, Transgenic
• Recombinant Fusion Proteins (analysis, metabolism)
• Saline Solution, Hypertonic (pharmacology)
• Time Factors