DESCRIPTION

Climate change and pharmaceuticals contamination constitute two of the most relevant stressors on the aquatic ecosystems, however, there is a huge lack of information.

For that, a mesocosm experiment was implemented where adult zebrafish were exposed to climate change and the progestin levonorgestrel (LNG) for 21 days.

The main objective of this work was to assess the effects of both stressors on the female zebrafish hepatocytes morphology and functioning, through immunohistochemical techniques.

Our results revealed an increase of coefficient of variation of the number distribution of hepatocytes volume (CV_N(υ)) for individuals exposed to LNG, which denotes an increase of the hepatocytes size variability and is suggestive of functional impacts.

This was corroborated by the signs of increased glycogen content with the exposure to increased LNG concentrations and temperature, indicating modified hepatocyte glycogen metabolism.

Such disturbances can be considered indicators that the fish had to deal with impacts caused by the stress factors.

Regarding the immunoreactivity, from the four proteins selected, just in two of them were observed some responses to both stressors.

For catalase there was a hormetic response, in which exposure to lower LNG concentrations caused a significant higher positive immunostaining than under higher LNG concentrations.

While, for Vtg, significant effects of temperature and LNG existed, in which a decline in Vtg immunostaining was observed with exposure to higher temperature.

These results should be seen as a warning sign about fine impacts of multiple stressors, such as temperature and progestogens, on the structure and functioning of zebrafish liver and potentially in other aquatic organisms, and on their health implications.

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