REPEATED EXPOSURE OF GOLDFISH (CARASSIUS AURATUS) TO TRICAINE METHANESULFONATE (MS-222)

Abstract

Goldfish that have been repeatedly exposed to tricaine methanesulfonate (MS-222) require greater concentration of the drug to attain equivalent planes of anesthesia, but the mechanism for this increased anesthetic need is unknown. Minimum anesthetic concentration (MAC) is a commonly used method with which to compare anesthetics. It was hypothesized that fish exposed to MS-222 daily would have an increased MAC. It was also hypothesized that fish exposed daily to MS-222 would develop histomorphologic changes to their gills to explain the increasing demand. Forty-nine Serasa comet goldfish were enrolled and were divided into three populations (n = 15, n = 15, and n = 19). In trial 1, using an up-down method, MAC was determined daily after 4 min of exposure to MS-222 for which the starting concentration was 160 mg/L. In trial 2, MAC was determined following 2 min of exposure to MS-222 for which the starting concentration was 260 mg/L. In trial 3, four naive fish were euthanatized and gills collected for histology and electron microscopy (EM). The remaining fish were exposed to MS-222 daily for 4 wk. Four fish were euthanatized and their gills submitted for similar examination at 2 wk and 4 wk. MAC for fish exposed to MS-222 for 4 min increased from 120 to 160 mg/L. The regression line had a slope of 1.51 +/- 0.26 (R2 = 0.65; P < 0.0001). MAC for fish exposed to MS-222 for 2 min increased from 210 pmm to 220 mg/L; the regression line had a slope of 0.52 +/- 0.38 (R2 = 0.12; P = 0.2). Histologic and EM examination of gills did not show morphologic changes indicative of a reaction to MS-222. Goldfish in this study had an increased requirement for MS-222 following daily exposure for 4 min but not following daily exposure for 2 min at a higher concentration. The cause of this increased anesthetic need is not related to morphologic changes to the gills.

Effects of repeated anaesthesia on gill and general health of Atlantic salmon, Salmo salar

“…No significant increase in induction time was seen for any of the anaesthetics used in this study, showing that repeat anaesthesia of post‐smolt S. salar does not result in increased tolerance or habituation to the administered doses (Figure ). This result is in contrast with an increase in concentration needed to repeatedly anaesthetize goldfish Carassius auratus (L. 1758) (Posner et al ., ) or angelfish Pterophyllum scalare (Schultze 1823) (Mitjana et al . ) and to the reported decrease for hybrid tilapia [ Oreochromis niloticus (L. 1758) × Oreochromis aureus (Steindachner 1864)] with MS‐222 (Smith et al ., ), which suggests that any habituation may be species or dose dependent.…”

“…A lack of histomorphological change in gills of C. auratus after repeat exposure to 160 mg l −1 MS‐222 has been reported previously by Posner et al . (), but haematological and histological changes were seen in the Siberian sturgeon Acipenser baerii Brandt 1869¸ 24 h post a single anaesthetization with 125 mg l −1 MS‐222. Swelling in the primary and secondary lamellae due to hypertrophy of the epithelial cells was seen, alongside a depletion in leukocyte numbers, namely lymphocytes, neutrophils and eosinophils (Gomulka et al ., ).…”

“…While there are well-established guidelines in place to manage repeat anaesthesia of animals in the mammalian research sphere (Flecknell, 2016), currently, only a limited number of references reporting on teleost fish repeated anaesthetization are available and only few conducting analysis on any general effects. Available articles on the subject focus on ornamental or freshwater species, juvenile life stages, have lengthy intervals between anaesthesia or include no immunological observations in their analysis (Basrur et al, 2010;Braley & Anderson, 1992;de Lima Silva et al, 2012;Hoskonen & Pirhonen, 2004Kildea et al, 2004;Mitjana et al, 2014;Mylonas et al, 2005;Palmer & Mensinger, 2004;Posner et al, 2013;Smith et al, 1999;Soto, 1995).…”

Effective Method to Deliver Test Substance in Adult Zebrafish (Danio Rerio).

“…However, the drawback of this procedure is that in order to gavage fish, it is mandatory to anaesthetize the fish using buffered MS-222. Though the concentration of anaesthesia used was 150 mg/l which is within the acceptable limits, unfortunately it may not prove beneficial in studies involving repeated dose administration of test substance as the minimum anesthetic concentration (MAC) value may increase on repeated anaesthetizing the fish (Posner et al, 2013). The present study, however, does not require the use of anesthesia as it uses a damp tissue to hold the zebrafish in order to keep its body moist.…”

A Targeted Metabolomics Assay to Measure Eight Purines in the Diet of Common Bottlenose Dolphins, Tursiops truncates

“…Free-ranging fish samples were caught during the months of May to September 2013 from the waters off the FL west coast by local fisherman using a rod and reel, crab trap, or cast net, or with a purse-seine net during fish surveys conducted by the SDRP team in Sarasota Bay. To mimic the rapid death of fish consumed by dolphins in the wild as closely as possible, fish were euthanized humanely by immersion in 500 ppm tricaine methanesulfonate (MS-222, Western Chemical, Ferndale, WA 98248) in sea water [29,30]. Death was confirmed by cessation of opercula movement for 10 minutes, and then fish were weighed, length was measured, and samples of fish were individually bagged, placed into a cooler of dry ice and transported to the UF nutrition laboratory where fish were stored at −80°C until further processing.…”