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Giuseppina Giusi,¹ Rosa Maria Facciolo,¹ Raffaella Alò,¹ Antonio Carelli,¹ Maria Madeo,¹ Pietro Brandmayr,² and Marcello Canonaco¹

¹Comparative Neuroanatomy Laboratory, and ²Zoocenoses Laboratory, Ecology Department, University of Calabria, Cosenza, Italy

Abstract
Common environmental contaminants such as heavy metals and pesticides pose serious risks to behavioral and neuroendocrine functions of many aquatic organisms. In the present study, we show that the heavy metal cadmium and the pesticide endosulfan produce such effects through an interaction of specific cerebral histamine receptor subtypes in the teleost ornate wrasse (Thalassoma pavo) . Treatment of this teleost with toxic cadmium levels for 1 week was sufficient to induce abnormal swimming movements, whereas reduced feeding behaviors were provoked predominantly by elevated endosulfan concentrations. In the brain, these environmental contaminants caused neuronal degeneration in cerebral targets such as the mesencephalon and hypothalamus, damage that appeared to correlate with altered binding levels of the three major histamine receptors (subtypes 1, 2, and 3) . Although cadmium accounted for reduced binding activity of all three subtypes in most brain regions, it was subtype 2 that seemed to be its main target, as shown by a very great (p < 0.001) down-regulation in mesencephalic areas such as the stratum griseum central layer. Conversely, endosulfan provided very great and great (p < 0.01) up-regulating effects of subtype 3 and 1 levels, respectively, in preoptic-hypothalamic areas such as the medial part of the lateral tuberal nucleus, and in the suprachiasmatic nucleus. These results suggest that the neurotoxicant-dependent abnormal motor and feeding behaviors may well be tightly linked to binding activities of distinct histamine subtypes in localized brain regions of the Thalassoma pavo. Key words: cadmium, diencephalon, endosulfan, histamine receptor subtype, mesencephalon, teleost fish. Environ Health Perspect 113:1522-1529 (2005) . doi:10.1289/ehp.7983 available via http://dx.doi.org/ [Online 14 July 2005]

Address correspondence to M. Canonaco, Comparative Neuroanatomy Laboratory, Ecology Department, University of Calabria, 87030 Rende (CS) , Italy. Telephone: 0039-984-492974. Fax: 0039-984-492986. E-mail: canonaco@unical.it

This study was supported partially by the contract sponsor MEMO-BIOMAR research program and COFIN (Cofinancial Projects) of MIUR (Italian University Research Ministry) .

The authors declare they have no competing financial interests.

Received 1 February 2005 ; accepted 14 July 2005.

Errata were published in Environ Health Perspect 113:A807 (2005) .

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