In vitro effects of selenite and mercuric chloride on liver thiobarbituric acid-reactive substances and non-protein thiols from rats: influences of dietary cholesterol and polyunsaturated and saturated fatty acids.
OBJECTIVE
We measured the in vitro effects of mercuric chloride (Hg2+) and selenite (Se4+) on hepatic 2-thiobarbituric acid-reactive substances (TBARS) and non-protein sulfhydryl (NPSH) levels of rats fed diets enriched with polyunsaturated or saturated fatty acids with and without cholesterol.


METHODS
Male Wistar rats (21 d old) were assigned to one of four groups and fed diets containing 20% soybean oil, 20% soybean oil plus 1% cholesterol, 20% coconut oil, or coconut oil plus 1% cholesterol. After the feeding period (6 wk), body weight gain was equal in all groups. TBARS levels and NPSH content were measured after in vitro exposure to mercuric chloride (100 microM) and sodium selenite (25 microM) for 1 h.


RESULTS
The lipid peroxidation, measured as TBARS levels in the control group, were statistically higher in hepatic homogenates of rats fed diets containing soybean oil than in groups fed coconut oil (P = 0.009). However, cholesterol supplementation did not change TBARS levels. Selenite alone did not modify TBARS production, whereas mercury alone significantly increased TBARS levels. Moreover, Se4+ protected against mercury-induced lipid peroxidation only in rats fed diets containing coconut oil. In the control group, dietary fat acids did not change NPSH levels. Selenite produced higher oxidative effects toward NPSH content, whereas Hg2+ decreased NPSH levels only in liver from rats fed diets containing soybean oil. NPSH levels were higher after concomitant exposure to Se4+ and Hg2+ chloride that after exposure to Se4+ alone, suggesting an interaction between Hg2+ and Se4+. Catalase activity was higher in animals fed diets containing soybean oil. Dietary cholesterol decreased glutathione peroxidase activity.


CONCLUSIONS
Together these results indicated that the protective effect of Se4+ against mercury-induced lipid peroxidation depends on dietary fat saturation.
Farina
Marcelo
M
Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600 Anexo, Bairro Santana, 90035-0003 Porto Alegre, RS, Brazil. marcelofarina@zipmail.com.br
Soares
Félix Antunes
FA
Feoli
Ana
A
Roehring
Cíntia
C
Brusque
Ana Maria
AM
Rotta
Liane
L
Perry
Marcos Luis
ML
Souza
Diogo Onofre
DO
Rocha
João Batista T
JB
D000818:Animals; D002374:Catalase / Q000378:metabolism; D002791:Cholesterol, Dietary / Q000008:administration & dosage / Q000494:pharmacology*; D000074263:Coconut Oil; D004032:Diet; D005227:Fatty Acids / Q000008:administration & dosage / Q000494:pharmacology*; D005979:Glutathione Peroxidase / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008099:Liver / Q000737:chemistry / Q000187:drug effects*; D008297:Male; D008627:Mercuric Chloride / Q000494:pharmacology*; D010938:Plant Oils / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar; D018038:Sodium Selenite / Q000008:administration & dosage / Q000494:pharmacology*; D013024:Soybean Oil / Q000008:administration & dosage; D013438:Sulfhydryl Compounds / Q000032:analysis; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis*
D002791:Cholesterol, Dietary; D005227:Fatty Acids; D010938:Plant Oils; D013438:Sulfhydryl Compounds; D017392:Thiobarbituric Acid Reactive Substances; D008627:Mercuric Chloride; D013024:Soybean Oil; D002374:Catalase; D005979:Glutathione Peroxidase; D018038:Sodium Selenite; D000074263:Coconut Oil