Complex molecular changes induced by chronic progestogens exposure in roach, Rutilus rutilus

Abstract

In our previous study, we measured 0.23–13.67ng/L progestogens (progesterone, drospirenone, levonorgestrel) in natural waters in the catchment area of the largest shallow lake of Central Europe, Lake Balaton. Progestogen contaminations act as potent steroids with mixed progestagenic, androgenic and mild estrogenic effects that is why our aim was to investigate the morphological and molecular effects of mixture of progesterone, drospirenone, and levonorgestrel in environmentally relevant (10ng/L) and higher (50 and 500ng/L) exposure concentrations in common roach, Rutilus rutilus. Steroids (e.g. progestogens) and the protein deglycase DJ-1 chaperon molecule aim the same target molecules in cells, therefore, we hypothesized that a relationship may exist between progestogens and DJ-1. Furthermore, our other aim was to follow the changes of signal molecules of different biological function due to progestogen treatment in serum and brain.Adult roaches were exposed to 10, 50 and 500ng/L of mixture of progestogen for 42 days and their somatic indices (brain-somatic, liver-somatic, gonadosomatic and kidney-somatic) were measured. Vitellogenin (VTG) expression (estrogen effect) or inhibition (androgen effect) in fish is a widely used biomarker so we measured its changes in liver by ELISA. To determine the quantity and to map the spatial distribution of DJ-1 chaperon protein the brain and liver tissues were analyzed by ELISA and immunohistochemistry. Furthermore, we also studied molecular alterations: a) in the serum by measuring cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglyceride concentrations and b) in brain homogenate using a cell stress array kit (26 protein).The somatic index of liver and kidney significantly in all the treated groups, whereas the gonadosomatic index of 500ng/L treated group showed significant decrease compared to control animals. VTG level increased significantly in 500ng/L progestogen treated group. Since the concentration of DJ-1 significantly increased in brain and liver in all progestogen treatment groups, the DJ-1 protein could be able to a more sensitive marker than VTG. Serum LDL and cholesterol levels of exposed fish were significantly decreased. DJ-1 was mediated through the stimulation of the expression of LDL-receptor which facilitates reuptake subsequently.In summary, our observations unfolded new data about molecular alterations induced by the combined action of environmental progestogens. In addition, the DJ-1 chaperon protein as a possible biomarker helped to trace the abiotic chemical environmental contaminations, like progestogens in the freshwater ecosystems.