Browsing by Subject "MS-222"

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    Daily rhythms of toxicity and effectiveness of anaesthetics (MS222 and Eugenol) in zebrafish (Danio rerio)
    (2011) Sánchez Vázquez, Francisco J.; Terry, Marta I.; Felizardo, Viviane O.; Vera, L. M.; Fisiología
    Although the chronotoxicity of xenobiotics is relatively well known in mammals, the existence of daily rhythms of drug toxicity and effectiveness in fish have been neglected to date. The aim of this research was to investigate the influence of the time (middle of the light phase, ML vs middle of the dark phase, MD) of exposure to two anesthetics (MS-222 or clove oil) commonly used in fish on the median lethal concentration (LC50) and swimming activity of zebrafish (Danio rerio). To this end, adult zebrafish were kept under a 12:12h LD cycle and exposed to different concentrations of anesthetic for 15 minutes at ML or MD. The LC 50 calculations were performed using the Spearman Karber program, while swimming activity was video recorded and analyzed with specialized software. In the trials zebrafish exhibited a mostly diurnal activity pattern (77.9% of activity occurring during daytime). The acute toxicity and mortality caused by MS-222 and eugenol varied with the time of exposure. In the case of MS-222, the LC50 was 170. 6 ± 7.4 mg/L in fish exposed at ML, and 215.6 ± 3.9 mg/L at MD while the LC50 of eugenol was 70.3 ± 3.1 mg/L at ML, and 104.9 ± 5.4 mg/L at MD. Exposure to sublethal concentrations of MS-222 and eugenol also altered the swimming patterns of zebrafish in a different manner depending on the time of exposure. Thus, the time required for decreasing swimming activity during exposure to anaesthetics was shorter at ML than at MD whereas the recovery period was longer during the day. In conclusion, these results revealed that the toxicity and effectiveness of both anesthetics is highest during daytime, coinciding with the active phase of fish and suggesting a link between the daily rhythms of behaviour and toxicity.
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    Open Access
    MS-222 toxicity in juvenile seabream correlates with diurnal activity, as measured by a novel video-tracking method
    (2010) Vera, L.M; Ros Sánchez, G.; García Mateos, Ginés; Sánchez Vázquez, F.J.; Fisiología
    Fish are frequently exposed to anaesthetics since their use is necessary in several aquaculture procedures. The aim of this study was to investigate the existence of day night differences in toxicity and effectiveness of a common fish anaesthetic (MS-222) in juvenile gilthead seabream (Sparus aurata), determining the induction time of anaesthesia and subsequent recovery by a novel video-recording system. Our results showed that MS-222 toxicity was significantly higher at ML (mid-light) (LC50=85.5 mg/L) than at MD (mid-darkness) (LC50=107.6 mg/L) (trimmed Spearman-Karber method). In addition, when fish were exposed to a sublethal but effective MS-222 concentration (65 mg/L), 7 min passed before 50% a reduction in swimming activity was observed at ML compared to the 9 min required at MD. As regards recovery, fish showed activity levels similar to basal levels 10 min after MS-222 removal at ML, but only 6 min at MD. These results indicated that both toxicity and effectiveness were higher during the day than at night, coinciding with the diurnal activity pattern displayed by seabream, which should be taken into account when designing and applying daily protocols for anaesthesia in aquaculture