Effects of progestogens on the neuroendocrine system of an invertebrate model species (Lymnaea stagnalis)
01/30/2020
István Fodor1, Zita Zrínyi1, Réka Svigruha1, Éva Molnár1, Péter Urbán1, Pei-San Tsai1, Joris M. Koene1, and Zsolt Pirger1
1 Adaptive Neuroethology Research Group, Department of Experimental Zoology, Balaton Limnological Institute, MTA Centre for Ecological Research, 8237Tihany, Hungary
2 Bioinformatics Research Group, Szentágothai Research Centre, University of Pécs, 7624Pécs, Hungary
3 Department of Integrative Physiology and Center for Neuroscience, University of Colorado, Boulder, United States
4 Department of Ecological Science, Faculty of Science, Vrije Universiteit, Amsterdam, the Netherlands
In the era of globalization, the production and consumption of pharmacologically active compounds have been constantly increasing. One of the most prevalent group of these pharmacons is the oral contraceptives (progestogens and estrogens). Their presence in freshwaters can be originated from their widely usage and low bioutilization, and the lack of the adequate wastewater treatment technologies (which are still not suitable to eliminate all kinds of pollutants). Although their concentrations are generally low (ng/L) in surface waters, their continuous and simultaneous presence can exert different invertebrate and vertebrate aquatic species. Since these contaminants mainly impair the reproductive processes of the animals, the use of molluscan species including the freshwater pond snail (Lymnaea stagnalis) seems to be a logical choice for studying their effects. Central and peripheral nervous and neuroendocrine systems of this invertebrate model species are well-characterized from key molecules to behavioural processes. Our general aim was to reveal the progestogens-induced effects on the neuroendocrine system of L. stagnalis. We examined the alterations at molecular (reproduction-mediating key molecule(s)) and individual (male sexual role) levels. To this, specimens of L. stagnalis were exposed to chronic treatment of progestogen mixtures (progesterone, drospirenone, gestodene, levonorgestrel) applying environmental relevant concentration (~ 10 ng/L). Using quantitative real-time PCR, we determined that corazonin expression decreased in the central nervous system after progestogen treatment. The main change in the male sexual function was the decreased sperm number just like in case of human population where this phenomenon has just emerged to a global problem. Despite all that, the potential offspring increased (manifested in increased number of fertilized ova in egg masses), while the quality of egg masses decreased (e.g. increased number of dead embryos, polyembryony). For summary, progestogens in surface waters exert the neuroendocrine system of L. stagnalis even at ~ 10 ng/L environmental relevant concentration. The sperm number decreasing effect of progestogens cannot be interpreted as an independent ecological risk at population level, however their overall effects definitely pose a risk. This work was supported by National Brain Project (No. 2017-1.2.1-NKP-2017-00002)