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17beta-Estradiol affects osmoregulation in Fundulus heteroclitus
Juan Miguel Mancera1, Marcel Smolenaars, Raúl Laiz-Carrión
1Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Puerto Real, Cádiz 11510, Spain. juanmiguel.mancera@uca.es
Summary
17beta-estradiol (E(2)) impairs the ability of killifish to regulate salt balance when moving to saltier water. This hormone negatively affects osmoregulatory capacity, impacting fish health in changing environments.
Area of Science:
- Environmental Endocrinology
- Fish Physiology
- Osmoregulation
Background:
- Euryhaline teleosts, like Fundulus heteroclitus, can adapt to a wide range of salinities.
- Estrogens, such as 17beta-estradiol (E(2)), play roles in reproduction and may influence other physiological processes.
- Understanding how environmental contaminants or endogenous hormones affect osmoregulation is crucial for aquatic ecosystems.
Purpose of the Study:
- To investigate the effects of 17beta-estradiol (E(2)) on the osmoregulatory performance of the euryhaline killifish, Fundulus heteroclitus.
- To determine if E(2) exposure interferes with the fish's ability to adapt to different salinity levels.
- To examine the dose-dependent and duration-dependent effects of E(2) on key osmoregulatory parameters.
Main Methods:
- Killifish were injected with varying doses of E(2) (single or multiple administrations).
- Fish were subsequently transferred between low salinity (1 ppt) and full strength seawater (40 ppt).
- Plasma osmolality, ion concentrations (Na+, Cl-), and gill Na+-K+-ATPase activity (K+-pNPPase) were measured post-transfer.
Main Results:
- Transfer from low to high salinity increased plasma osmolality but did not affect gill enzyme activity.
- E(2) administration prior to transfer to high salinity dose-dependently increased plasma osmolality and decreased gill enzyme activity.
- Prolonged E(2) exposure impaired hypoosmoregulation, while effects on hyperosmoregulation were less pronounced and dependent on dose and duration.
Conclusions:
- 17beta-estradiol (E(2)) significantly inhibits the hypoosmoregulatory capacity in Fundulus heteroclitus.
- E(2) interferes with the physiological mechanisms responsible for adapting to increased environmental salinity.
- These findings highlight a potential endocrine disruption impacting fish survival in fluctuating salinity environments.