Related Experiment Video
Updated: Sep 22, 2025
09:54
A Model to Simulate Clinically Relevant Hypoxia in Humans
Published on: December 22, 2016
9.0K
Is serotonin uptake by peripheral tissues sensitive to hypoxia exposure?
Molly H B Amador1, M Danielle McDonald2
1Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL, 33149, USA.
Fish Physiology and Biochemistry
|May 18, 2022
Summary
Hypoxia exposure in Gulf toadfish did not alter serotonin transporter (SERT) activity in key tissues. However, cardiac uptake of serotonin (5-HT) increased, suggesting a role in regulating blood flow during low oxygen conditions.
Area of Science:
- Comparative Physiology
- Environmental Stress Response
- Neuroendocrinology
Background:
- The serotonin (5-HT) transporter (SERT) is highly expressed in the Gulf toadfish heart and gill.
- Serotonin (5-HT) acts as a vasoconstrictor in fish, potentially impairing gas exchange.
- Hypoxia may trigger compensatory mechanisms involving 5-HT uptake and excretion.
Purpose of the Study:
- To investigate the hypothesis that hypoxia increases 5-HT uptake and excretion in toadfish tissues.
- To determine the impact of hypoxia on cardiac and branchial 5-HT handling to prevent vasoconstriction.
- To explore the role of SERT-mediated 5-HT uptake in fish adapting to hypoxic environments.
Main Methods:
- Spot sampling of blood, bile, and urine to measure 5-HT concentrations under normoxic and hypoxic conditions.
- Exposure of Gulf toadfish to chronic (24-26h) and acute (25min) hypoxia.
- Radiotracer experiments using [3H]5-HT to quantify tissue uptake, particularly in the heart and gills.
Main Results:
- Chronic hypoxia led to a 41% reduction in plasma 5-HT in the ventral aorta compared to the hepatic vein, indicating enhanced cardiac 5-HT uptake.
- Bile 5-HT concentrations were higher than urine 5-HT, but hypoxia did not affect 5-HT levels in these fluids.
- Contrary to expectations, neither acute nor chronic hypoxia altered [3H]5-HT uptake in the heart, gill, or other examined tissues.
Conclusions:
- While cardiac 5-HT uptake appears to increase during hypoxia in Gulf toadfish, overall SERT-mediated uptake in major tissues does not change significantly.
- The observed reduction in plasma 5-HT post-cardiac output suggests a cardiac mechanism for 5-HT clearance during hypoxia.
- Further research is needed to explore the effects of milder hypoxia and the role of 5-HT degradation in this physiological response.
