Induction and recovery of morphofunctional changes in the intestine of juvenile carnivorous fish (Epinephelus coioides) upon exposure to foodborne benzo[a]pyrene.
The sublethal toxicity of dietary benzo[a]pyrene, B[a]P, on fish growth and intestinal morphofunctional changes [as measured by epithelial turnover, cell proliferation, hyperplasia, de novo crypt formation and protein absorption efficiency (i.e. expression of proton/peptide co-transporter, PepT-1, on the mucosal brush border)] were studied for the carnivorous orange-spotted grouper (Epinephelus coioides). Juvenile fish were force-fed daily with pellets containing environmentally realistic concentrations of B[a]P (dissolved in corn oil) at 0.25 microg/g body weight (low-dose) and 12.5 microg/g body weight (high-dose) for 4 weeks, followed by a control diet for a further 4 weeks to assess recovery. Although growth inhibition was observed in fish treated with high-dose B[a]P during the exposure period, no mortality was observed throughout the 8-week experiment. Significant hyperplasia of basal enterocytes of mucosal folds was detected shortly after 3-day exposure to the high-dose B[a]P. Moreover, a faster epithelial turnover was measured in the high-dose B[a]P exposed fish at exposure week 1, which was followed by an increase of basal cell proliferation and a reduction of PepT-1 expression at exposure week 2. The formation of de novo crypts, resemblance to the cancer predisposition syndrome "juvenile polyposis", was significantly higher in the intestine of high-dose treated fish as compared to the control at exposure week 2 and onwards. Abnormal cytoplasmic extrusions were frequently observed in mucosal folds of high-dose fish at exposure week 4. In the low-dose treatment group, only the expression of PepT-1 was significantly reduced at exposure week 2 and an early adaptive response was observed at exposure week 4. Despite all these intestinal disturbances were reversible in fish upon the abatement to dietary B[a]P (within 1-4 weeks), environmental realistic levels of foodborne B[a]P could induce sublethal toxicity to E. coioides, and probably impose potential risk to the marine environment. As an increase in de novo crypts was observed towards the end of the 4-week depuration period, the long-term impacts of dietary B[a]P on fish intestinal neoplasm formation worth further investigation.
Yuen
Bonny B H
BB
Centre for Coastal Pollution and Conservation, Department of Biology and Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, China.
Wong
Chris K C
CK
Woo
N Y S
NY
Au
Doris W T
DW
D000821:Animal Feed; D000818:Animals; D001492:Bass / Q000502:physiology*; D001564:Benzo(a)pyrene / Q000633:toxicity*; D001835:Body Weight / Q000187:drug effects; D001973:Bromodeoxyuridine / Q000032:analysis / Q000378:metabolism; D016923:Cell Death; D049109:Cell Proliferation / Q000187:drug effects; D004781:Environmental Exposure; D015870:Gene Expression / Q000187:drug effects; D006965:Hyperplasia / Q000139:chemically induced; D007413:Intestinal Mucosa / Q000187:drug effects; D009092:Mucous Membrane / Q000187:drug effects; D000074011:Peptide Transporter 1; D027981:Symporters / Q000032:analysis / Q000096:biosynthesis; D014873:Water Pollutants / Q000633:toxicity*
D000074011:Peptide Transporter 1; D027981:Symporters; D014873:Water Pollutants; D001564:Benzo(a)pyrene; D001973:Bromodeoxyuridine