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Liver oxidative stress, Kupffer cell functioning, and cell injury were studied in control rats and in animals subjected to L-3,3',5-tri-iodothyronine (T3) and/or acute iron overload. Thyroid calorigenesis with increased rates of hepatic O2 uptake was not altered by iron treatment, whereas iron enhanced serum and liver iron levels independently of T3. Liver thiobarbituric acid reactants formation increased by 5.8-, 5.7-, or 11.0-fold by T3, iron, or their combined treatment, respectively. Iron enhanced the content of protein carbonyls independently of T3 administration, whereas glutathione levels decreased in T3- and iron-treated rats (54%) and in T3Fe-treated animals (71%). Colloidal carbon infusion into perfused livers elicited a 109% and 68% increase in O2 uptake in T3 and iron-treated rats over controls. This parameter was decreased (78%) by the joint T3Fe administration and abolished by gadolinium chloride (GdCl3) pretreatment in all experimental groups. Hyperthyroidism and iron overload did not modify the sinusoidal efflux of lactate dehydrogenase, whereas T3Fe-treated rats exhibited a 35-fold increase over control values, with a 54% reduction by GdCl3 pretreatment. Histological studies showed a slight increase in the number or size of Kupffer cells in hyperthyroid rats or in iron overloaded animals, respectively. Kupffer cell hypertrophy and hyperplasia with presence of inflammatory cells and increased hepatic myeloperoxidase activity were found in T3Fe-treated rats. It is concluded that hyperthyroidism increases the susceptibility of the liver to the toxic effects of iron, which seems to be related to the development of a severe oxidative stress status in the tissue, thus contributing to the concomitant liver injury and impairment of Kupffer cell phagocytosis and particle-induced respiratory burst activity.

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Brachypelma vagans is an endangered tarantula included in Appendix II of CITES because of its popularity as a pet. However, little is known about its ecology, in particular microhabitat choices. In this work we analyse the structure of the vegetation surrounding burrows of this tarantula, as well as soil preference for the burrow at different sites in relation to the density of the species. We also offer the first description of the burrow of this spider. Brachypelma vagans mostly uses open sites with low vegetation for establishing its burrow, rather than primary or secondary forest. The burrows are essentially built in sites with deep clay soils, whereas sandy soils or soils with a high density of roots and stones are avoided. The soil characteristics may be the key factor determining the presence of B. vagans. The burrow of B. vagans is deep and complex, exhibiting various chambers, even if only one seems to be used by the occupant. The structure of the burrow and soil characteristics are obviously related. These results could help determine the real distribution of B. vagans within its geographic range, and might be useful for a better management focused on protection and reintroduction.

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