Paralytic shellfish poisoning toxins induce xenobiotic metabolising enzymes in Atlantic salmon (Salmo salar)

Paralytic shellfish poisoning (PSP) toxins have been implicated as the caus ative agent of a number of fish kills. Exposure experiments indicate that f ish are susceptible to PSPs by intraperitoneal (i.p.) and oral administrati on, while sampling of fish affected by toxic blooms reveals that these toxi ns can be accumulated. In spite of the potential impact to marine fisheries , little research has been conducted on the potential metabolism and detoxi fication of PSPs in marine fishes. Previous work by this group has shown th at the xenobiotic metabolising enzyme (XME) cytochrome P-450 (CYP1A) is ind uced in Atlantic salmon (Salmo salar) following i.p. exposure to saxitoxin (STX). Salmon injected i.p. with sub-lethal doses of STX show a four- to ei ght-fold induction of hepatic CYP1A las shown by ethoxyresorufin-O-deethyla se activity) over controls after 96 h. Results presented here show that the phase II XME glutathione S-transferase (GST) is also induced in salmon fol lowing PSP exposure. Post smolts were exposed to three injections of PSPs ( 2 mug STXeq/kg) over 21 days. Injection of both STX and PSPs extracted from a toxic strain of dinoflagellate (Alexandrium fundyense, CCMP 1719) result ed in induction of hepatic GST, as measured by activity for 1-chloro 2,4-di nitrobenzene. Such inductions indicate a potential role for XMEs in PSP met abolism. Possible roles for other enzymes are also discussed. (C) 2000 Else vier Science Ltd. All rights reserved.