Uptake of 203Hg2+ in the olfactory system in pike.

Inorganic mercury (203Hg2+) was applied to the olfactory chambers or was given i.v. to pike (Esox lucius) and the uptake of the metal in the olfactory system and the brain was examined by autoradiography and gamma spectrometry. Application of 203Hg2+ in the olfactory chambers resulted in an accumulation of the metal in the olfactory nerves and the anterior parts of the olfactory bulbs of the brain. The levels of 203Hg2+ in other brain areas, such as the telencephalon, the optic tecti and the cerebellum, remained low. Application of 203Hg2+ in only one olfactory chamber resulted in an uptake of the metal only in the ipsilateral olfactory nerve and olfactory bulb. Intravenous injection of the 203Hg2+ resulted in a labelling of the olfactory system and the brain, which was much lower than of the blood. These results indicate that the 203Hg2+ is taken up in the olfactory neurones from the olfactory receptor cells in the olfactory rosettes and is transported to the terminal parts of the olfactory neurones in the olfactory bulbs. The uptake of mercury as well as some other metals in the olfactory system may result in noxious effects and this may be an important component in the toxicology of metals in fish.