Anesthesia of fish with benzocaine does not interfere with comet assay results

• Published in: Mutation research Vol. 534; no. 1; pp. 165 - 172
• Main Authors: de Miranda Cabral Gontijo, Álisson Marques, Barreto, Rodrigo Egydio, Speit, Günter, Valenzuela Reyes, Victor Alexis, Volpato, Gilson Luiz, Favero Salvadori, Daisy Maria
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 10.01.2003; Elsevier
• Subjects: Alkylating Agents - toxicity; Anesthetic benzocaine (ethyl p-aminobenzoate); Anesthetics, Local - pharmacology; Anesthetics, Local - toxicity; Animal welfare; Animals; benzocaine; Benzocaine - pharmacology; Benzocaine - toxicity; Biological and medical sciences; Chemical mutagenesis; Comet Assay - methods; Comet Assay - standards; DNA damage; Erythrocytes - drug effects; Fish; General aspects. Methods; Hydrogen Peroxide - toxicity; Medical sciences; Methyl Methanesulfonate - toxicity; Nile tilapia; Single cell gel (SCG)/comet assay; Tilapia - blood; Tilapia - genetics; Tilapia nilotica; Toxicology; Fish; Single cell gel (SCG)/comet assay; Anesthetic benzocaine (ethyl p-aminobenzoate); Animal welfare; Nile tilapia; DNA damage; Toxicity; Genotoxicity; Red blood cell; Hydrogenperoxides; Tilapia; Bath; Comet assay; Benzocaine; Vertebrata; Anesthetic; Pisces; DNA; Lesion
• ISSN: 1383-5718; 0027-5107; 1879-3592
• DOI: 10.1016/S1383-5718(02)00276-0

Fish blood erythrocytes are frequently used as sentinels in biomonitoring studies. Usually, fish blood is collected by painful cardiac or caudal vein punctures. Previous anesthesia could decrease animal suffering but it is not known at present whether anesthesia can cause confounding effects. Therefore, using the alkaline single cell gel (SCG)/comet assay with blood erythrocytes of the cichlid fish Nile tilapia, we tested for a possible modulation of induced DNA damage (methyl methanesulfonate; MMS) by the anesthetic benzocaine administered by bath exposure (80 mg/l for ∼10 min). Furthermore, benzocaine (80–600 mg/l) was tested for its genotoxic potential on fish erythrocytes in vitro and for potential interactions with two known genotoxins (MMS and hydrogen peroxide). Our results did neither indicate a significant increase in the amount of DNA damage (even after a 48 h follow-up), nor indicated interactions with MMS-induced DNA damage when fish were exposed to benzocaine in vivo. There was also no increase in DNA damage after in vitro exposure of fish erythrocytes to benzocaine. Clear concentration-related effects were observed for the two genotoxins in vitro, which were not significantly altered by the presence of benzocaine. These results suggest that anesthesia of fish does not confound comet assay results and the use of blood samples from anesthetized fish can be recommended with regard to animal welfare.