Monitoring of environmental psychoactive drug contaminations and investigation of the induced neuronal changes
Gabor Maasz1, Istvan Fodor1, Eva Molnar1, Zita Zrínyi1, Reka Svigruha1, Richard Udvardi1, Zita Laszlo1, Tibor Kiss1, Zsolt Pirger1
The anthropogenic contaminants including the psychoactive agents pose serious threats to the aquatic systems around the world. Their presence in the freshwaters are originated from the consumption habits of drug-users such as intensive use and chronic administration complemented by incomplete biodegradation, as well as, the wastewater treatment technology used today is still not able to eliminate all kinds of pollutants. The average concentration in the different type of waters are lower than the effective therapeutically blood concentration, but the continuous presence as a chronic exposure could lead to remarkable changes in physiological and neuronal processes. Since psychoactive drugs exert their effects mainly through the central nervous system (CNS), use of the molluscan species including the great pond snail (Lymnaea stagnalis) seem to be logical choice for studying their effects, because central and peripheral nervous system of Lymnaea are well-characterized from key molecules to behavioural processes and vice versa. Here, our general aim was to understand the biochemical and molecular background of neuronal processes given to external chemical impact, such as chemical contamination of anthropogenic origin (e.g. psychoactive drugs). Firstly, the contamination conditions of psychoactive drugs were determined in catchment area of Lake Balaton and River Zala. Furthermore, specimens of Lymnaea stagnalis were exposed to chronic psychoactive drug treatments (carbamazepine-CBZ, citalopram-CIT, alprazolam-ALP) to reveal what kind of alterations are induced in the Lymnaea CNS at system levels. The environmental survey revealed 69 out of the traced 134 chemical compounds, including psychoactive agents, where their average contamination levels were generally low (ng/L to µg/L). Using these data, effects to locomotion activity were tested examining the synergistic effects of the active substances. The antiepileptic CBZ using environmentally relevant concentration already decreased the locomotion activity of snails after first treatment week but this was also eliminated during cleaning period. Furthermore, study of a complex adaptive behavioral process such as associative learning and memory was conducted. To this investigations, food-reward classical conditioning with amyl acetate and gamma nonalactone (as unconditioning stimuli) as well as sucrose (as conditional stimulus) were applied. The long-time memory formation (LTM) was significantly attenuated by 1 µg/L CBZ and ALP due to 21 days chronic treatment and not improved even after 21 days cleaning period. The CIT had no effect to the LTM formation. Based on our results we conclude that the environmentally psychoactive contaminations could affect the behavioural activity of non-targeted organisms. In further research, the mass spectrometry based single cell analysis will be applied to understand how the molecular content of neurons and various neural processes is influenced by the psychoactive drugs. This work was supported by PD-OTKA grants No. 124161 (MG), National Brain Project No. 2017-1.2.1-NKP-2017-00002 (PZ).