Endosulfan exposure inhibits brain AChE activity and impairs swimming performance in adult zebrafish (Danio rerio)

Abstract

Endosulfan is a broad spectrum organochlorine pesticide that is still widely in use in many developing countries. Following application, endosulfan can get to watercourses through surface runoff from agricultural fields and disturb the non-target aquatic animals including freshwater fish species. Given that the activity of the enzyme acetylcholinesterase (AChE) is one of the most recurrently used biomarkers of exposure to pesticides and there are controversial results concerning the effects of endosulfan exposure and AChE activity in fish, the aim of the present study was to evaluate the effects of endosulfan in brain AChE activity and its gene expression pattern using adult zebrafish (Danio rerio) as an animal model. Moreover, we have analyzed the effects of endosulfan exposure in different parameters of zebrafish swimming activity and in long-term memory formation. After 96 h of exposition, fish in the 2.4 μg endosulfan/L group presented a significant decrease in AChE activity (9.44 ± 1.038 μmol SCh h(-1) mg protein(-1); p=0.0205) when compared to the control group (15.87 ± 1.768 μmol SCh h(-1) mg protein(-1); p=0.0205) which corresponds to approximately 40%. The down-regulation of brain AChE activity is not directly related with the transcriptional control as demonstrated by the RT-qPCR analysis. Our results reinforce AChE activity inhibition as a pathway of endosulfan-induced toxicity in brain of fish species. In addition, exposure to 2.4 μg endosulfan/L during 96 h impaired all exploratory parameters evaluated: decreased line crossings (≈21%, 273.7 ± 28.12 number of line crossings compared to the control group 344.6 ± 21.30, p=0.0483), traveled distance (≈20%, 23.44 ± 2.127 m compared to the control group 29.39 ± 1.585, p=0.0281), mean speed (≈25%, 0.03 ± 0.003 m/s compared to the control group 0.04 ± 0.002, p=0.0275) and body turn angle (≈21%, 69,940 ± 4871 absolute turn angle compared to the control group 88,010 ± 4560, p=0.0114). These results suggest that endosulfan exposure significantly impairs animals' exploratory performance, and potentially compromises their ecological and interspecific interaction. Our results also showed that the same endosulfan exposure did not compromise animals' performance in the inhibitory avoidance apparatus. These findings provide further evidence of the deleterious effects of endosulfan exposure in the nervous system.

Hyperglycemia alters E-NTPDases, ecto-5′-nucleotidase, and ectosolic and cytosolic adenosine deaminase activities and expression from encephala of adult zebrafish (Danio rerio)

“…Quantitative PCR was performed using SYBR ® Green I (Invitrogen) to detect double-strand cDNA synthesis. Reactions were done in a volume of 25 μL using 12.5 μL of diluted cDNA, containing SYBR ® Green I 0.2 times diluted (Invitrogen), 100 μM dNTP, 1× PCR buffer, 3 mM MgCl 2 , 0.25 U Platinum ® Taq DNA Polymerase (Invitrogen), and 200 nM of each reverse and forward primers (Table 1) [35][36][37][38]. The PCR cycling conditions were an initial polymerase activation step for 5 min at …”

O inseticida Thiodan® sobre o desenvolvimento folicular de lambaris

“…As características para a escolha das fêmeas de lambaris em maturação avançada se basearam em aspectos corporais, como ventre abaulado, poro genital dilatado e vascularizado. , com as concentrações subletais de 1,15, 2,3 e 5,6µg L -1 , as fêmeas do presente estudo apresentaram comportamento agitado e batimento opercular acelerado, assim como foi observado na espécie Danio rerio, exposta ao endosulfan por 96 horas na concentração de 2,4µg L -1 , além desta espécie ter apresentado uma diminuição do nível de acetilcolinesterase (AChE) (PEREIRA et al, 2012).…”

“…Consequentemente, o endosulfan pode se acumular nos tecidos dos organismos, como já observado por HENRY & KISHIMBA (2006) na espécie de peixe Oreochromis niloticus. A sensibilidade ao endosulfan em organismos aquáticos tem sido descrita na literatura (CAPKIN et al, 2006;BALLESTEROS et al, 2007;PEREIRA et al, 2012). O produto é tóxico para os peixes e outros organismos aquáticos, mesmo em doses muito pequenas (PEREIRA et al, 2012), assim como verifi cado por BALLESTEROS et al (2007), com peixes adultos da espécie Jenynsia multidentata.…”

Zebrafish locomotor capacity and brain acetylcholinesterase activity is altered by Aphanizomenon flos-aquae DC-1 aphantoxins

“…AChE activity has been widely used as a bioindicator of environmental exposure and there are a number of studies in the literature concerning the effects of environmental organic pollutants, heavy metals and other chemical toxicants on AChE activity in animals (Rao et al, 2005a,b;Rico et al, 2006Rico et al, , 2007Rosemberg et al, 2010;Richetti et al, 2011;Pereira et al, 2012). However, this is the first study to correlate the effects of aphantoxins on brain AChE activity and the locomotor behavioral activity of exposed animals.…”