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(W/EH041) Distribution and TCDD-induction of cytochrome P4501A (CYP1A) in seabream Sparus aurata brain. Ortiz Delgado, Juan Bosco1, Behrens, Anja2, González de Canales, María Luisa1, Segner, Helmut2, Sarasquete, Carmen3, 1 2 3 ABSTRACT- Cytochrome P450 (CYP1A) participates in the activation and detoxification of endogenous components and environmental pollutants such as PCBs, PAHs, dioxins, etc. The presence of CYP1A in the brain might thus be of physiological and toxicological importance. In order to study distribution and inducibility of CYP1A in the brain of seabream, Sparus aurata, we performed immunohistochemical and RT-PCR analysis on CYP1A in the brain of control and TCDD-exposed fish. CYP1A-immunoreactive fibres were found in control and in TCDD-exposed sebream, in the ventral telencephalon (Vv nuclei), in the glomerular layer of the olfactory bulbs, and, generally, in the endothelia of the cerebral vascular system. In the pituitary, the GTH cells stained positive for CYP1A, however, only in TCDD-exposed fish. For a quantitative estimate of CYP1A expression, an enzyme linked immunosorbent assay, ELISA, was performed on tissue homogenates from different regions of the brain. The ELISA findings were confirmed by Western blots. The results indicate substantial levels of CYP1A in the telencephalon (olfactory bulbs) of both control and TCDD-treated fish. TCDD led to an induction of CYP1A in all brain regions of Sparus aurata brain, with the highest absolute ELISA values being measured in the telencephalon. Thus, the olfactory bulbs of the telencephalon may be particularly susceptible for possible neurotoxic effects of CYP1A-inducing xenobiotics. Further exploration of the distribution of CYP1A in different regions and cell types of fish brain will be relevant for the understanding of the toxicological implications of cerebral CYP1A expression and induction in fish. Key words: CYP1A, immunohistochemistry, brain, Sparus aurata |
