Dietaryl‐carnitine prevents histopathological changes in tilapia (Oreochromis Niloticus) exposed to cylindrospermopsin

Abstract

Cylindrospermopsin (CYN) is a cytotoxin highly water-soluble, which is easily taken up by several aquatic organisms. CYN acts as a potent protein and glutathione synthesis inhibitor, as well as inducing genotoxicity, oxidative stress, and histopathological alterations. This is the first study reporting the protective effect of a l-carnitine (LC) pretreatment (400 or 880 mg LC/kg bw fish/day, for 21 days) on the histopathological alterations induced by pure CYN or Aphanizomenon ovalisporum lyophilized cells (400 µg CYN/kg bw fish) in liver, kidney, heart, intestines, and gills of tilapia (Oreochromis niloticus) acutely exposed to the toxin by oral route. The main histopathological changes induced by CYN were disorganized parenchyma with presence of glycogen and lipids in the cytoplasm (liver), glomerulonephritis, glomerular atrophy, and dilatation of Bowman's capsule (kidney), myofibrolysis, loss of myofibrils, with edema and hemorrhage (heart), intestinal villi with necrotic enterocytes and partial loss of microvilli (gastrointestinal tract), and hyperemia and hemorrhage (gills). LC pretreatment was able to totally prevent those CYN-induced alterations from 400 mg LC/kg bw fish/day in almost all organs, except in the heart, where 880 mg LC/kg bw fish/day were needed. In addition, the morphometric study indicated that LC managed to recover totally the affectation in the cross sections of the proximal and distal convoluted tubules in CYN-exposed fish. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 241-254, 2017.

Potential Use of Chemoprotectants against the Toxic Effects of Cyanotoxins: A Review

“…More recently, these antioxidant properties of LC also protected from the histopathological lesions caused by CYN under the same conditions as in the oxidative stress assay [143]. The lower dose of 20 mg LC/fish/day, managed to prevent completely the histological damage produced by CYN in liver, kidney, intestines, and gills, as well as morphometric damage in the proximal and distal convoluted tubules (PCT and DCT) in the kidney.…”

“…Moreover, work regarding protective effects against CYN has been conducted mainly on fish ( O. niloticus ) [138,139,140,141,142,143]. The other studies were carried out on aquatic invertebrates ( Artemia salina , Daphnia magna , and Daphnia galeata ), showing cyanobacterial LPS protection against subsequent exposure to CYN [50], on primary rat hepatocytes, where resveratrol appears to possess a cytoprotective effect against CYN insult [144], and on rats, in which resveratrol and L-arginine prevented CYN-induced cardiovascular, liver, and renal changes [145].…”

“…The protective effects of these compounds on CYN intoxication are summarized in Table 3 [138,139,140,141,142,143], and the most important aspects are described below.…”

“…Guzmán-Guillén et al [140,143] demonstrated the usefulness of LC dietary pretreatment for the first time with 400 or 880 mg LC/kg bw (corresponding to 20 or 44 mg LC/fish/day), for 21 days, as prophylaxis for the oxidative stress and histopathological harm caused in tilapia fish ( O. niloticus ) by acute exposure to an extract of CYN from lyophilized A. ovalisporum cells or pure CYN (400 µg CYN/kg bw) (Table 3). LC supplementation per se did not result in any toxic effect in fish not exposed to CYN, only ameliorating or preventing the effects of the toxin.…”

“…The lowest dose tested for LC (20 mg LC/fish/day) was normally enough for prevention of the histopathological injuries produced by CYN in most organs, with the exception of the heart [143]. In addition, LC managed to prevent the toxic effects of double the CYN dose (400 µg CYN/kg bw) tested in the work of Gutiérrez-Praena et al [139] (200 µg CYN/kg bw).…”