Naslov
Induction of Cytochrome P450 Enzymes of Fish by Oxytetracycline and Combination Ormetoprim-Sulfadimethoxine

Autori
Topić Popović, Natalija

Vrsta, podvrsta i kategorija rada
Ocjenski radovi, doktorska disertacija

Fakultet
Veterinarski fakultet

Mjesto
Zagreb

Datum
21.02

Godina
2003

Stranica
108

Mentor
Bowser, Paul

Neposredni voditelj
Srebočan, Emil

Ključne riječi
cytochrome P450; fish; induction; antibiotics

Sažetak
The impact of two aquaculture antibiotics, Terramycin for Fish (oxytetracycline) and Romet-30 (combination of ormetoprim and sulfadimethoxine), on hepatic microsomes of hybrid striped bass, summer flounder, tilapia and channel catfish was assayed. Fish were treated via medicated feed and samplings were performed on day 1, 6, 10/11, and 21 after termination of treatment. Western blotting analyses were performed with mammalian primary antibodies, goat anti-rat CYP1A1 and rabbit anti-human CYP3A4, to demonstrate the possibility of their application in piscine immunochemical assays. Kinetic assays with substrates developed for humans were used: 3-cyano-7-ethoxycoumarin (CEC), /-benzyloxy-4-triflouromethylcoumarin (BFC) and resorufin benzyl ether (BzRes), CES being a CYP1A2 substrate, while BFC and BzRes being CYP3A4 substrates. The results demontrate presence and putative induction of CYP1A and CYP3A enzymes in all sampling periods. Both goat anti rat CYP1A1 and rabbit anti-human CYP3A4 showe good cross-reactivity with the four fish species tested in the study, with a number of non-specific binding. In majority of blots, two immunoreactive bands were displayed. Both antibiotics induced CYP expression in all tested fish, although with different intensities in band signals. Clear responses were found in the hepatic xenobiotic metabolizing enzyme system of four different fish species in a directly comparative manner with differences both in control activities and in the timing and extent of induction responses. BzRes showed to be a better substrate than BFC for monitoring CYP3A activities in fish. Age influenced the pattern of activity in tilapia microsomes after treatment wth Romet-30. While young of the year fish had increased activities of CEC and BzRes in day 1, immature tilapia had all three measured activities decreased below control levels. Summer flounder males displayed slightly stronger signal in Western blots and higher BFC activity, while females had higher activity of CEC and BzRes. In channel catfish treated with Romet-30, there was an apparent increase of CYP3A-related protein acitivity manifested through both BFC and BzRes activities, which suggests that channel catfish may be a good model for investigating the regulation of those proteins. It can be concluded that the use of antibiotics and substrated to CYP enzymes across phyla can be of value of caution is excercised and that standardized protocols for antibiotic impact on fish P450 are necessary for the future application on teleosts.

Izvorni jezik
Engleski

Znanstvena područja
Biologija, Veterinarska medicina, Poljoprivreda (agronomija)

POVEZANOST RADA