Hepatoprotective and immunological functions of Nigella sativa seed oil against hypervitaminosis A in adult male rats.

PURPOSE: The toxic effects of excess vitamin A (VA) intake deserve increased attention. Nigella sativa (NS) seed possesses physiological and pharmacological actions and protects against toxic agents. This work investigated the availability of NS seed oil as a protective agent against the effects of hypervitaminosis A (HVA) on liver function and immunity. METHODS: Fifty adult albino rats were used and divided into five groups: (G1) control; (G2) experimental HVA rats administered extreme doses (10,000 IU/kg body weight) of VA oil orally, daily for 6 weeks; (G3) rats treated with NS seed oil (800 mg/kg) orally, daily for 6 weeks; (G4) HVA rats simultaneously treated with NS seed oil at the same doses and periods; and (G5) HVA recovery group. Liver function, immunoglobulin (IgG and IgM) levels, and lysosome activity were measured in serum. RESULTS: HVA rats revealed marked elevations in alanine aminotransferase and aspartate aminotransferase activities. This is the first study to demonstrate that NS seed oil possesses significant hepatoprotective activity against HVA. NS seed oil was a potent inducer of IgG and IgM in rat serum either alone or with high doses of VA. CONCLUSIONS: These findings may be considered the initial steps of the physiological and humoral immune responses for NS seed oil against HVA, but further studies examining longer periods are needed prior to recommending the use of NS seed oil as an alternative medicine for hepatic and immune diseases.

Alteraciones clínicas y bioquímicas en ratas tratadas con dosis altas de vitamina A / Clinical and biochemical alterations in rats treated with high doses of vitamin A

En el presente trabajo se estudió el efecto de la administración intramuscular de 30.000, 50.000 y 100.000 UI de palmitato de vitamina A/día, durante 7 días, respectivamente, sobre la actividad enzimática hepática en 45 ratas Wistar machos, de 12 semanas de edad, con pesos entre 180 y 200 gramos. El grupo control estuvo integrado por 15 ratas Wistar sanas, con género, edad y peso similares a los animales tratados. El consumo de alimentos y de agua, y el peso de las ratas se determinó al finalizar el período experimental. Las ratas se examinaron en busca de manifestaciones clínicas de toxicidad. Al final el estudio, las ratas se sacrificaron bajo anestesia con éter y se tomaron muestras de tejido hepático para la determinación de la actividad enzimática. La administración de vitamina A en exceso incrementó de manera significativa (p menor que 0,05) el contenido hepático del retinol, determinó diversos y variados signos clínicos (tales como: anorexia, pérdida de peso, alopecia, conjuntivitis, hemorragias internas y externas, alteraciones cutáneas y muerte de los animales) e incrementó (p menor que 0,05) la actividad de las siguientes enzimas: alanina aminotransferasa, aspartato aminotransferasa, maltasa ácida (alfa-1,4-glucosidasa ácida), proteasas ácidas, lactato dehidrogenasa y fosfatasa alcalina mientras que las actividades de la glucosa-6-fosfatasa, glucógeno fosforilasa, alfa-amilasa, colinesterasa y arginasa disminuyeron (p menor que 0,05) al comparar con los controles no tratados. Estos cambios son proporcionales a las dosis inyectadas de vitamina A. En conclusión, nuestros resultados proporcionan evidencias que la administración de dosis altas de vitamina A a corto plazo determina diversos y variados signos clínicos y produce una marcada alteración de la actividad enzimática hepática.

In the present work the effect of intramuscular administration of 30.000, 50.000 and 100.000 IU of vitamin A palmitate daily for seven days, respectively, on the liver enzyme activity in 45 white male Wistar rats, aged 12 weeks and weighing 180-200 g, have been studied. The group control was integrated by 15 healthy rats with similar characteristics (strain, gender, age and weight) to treated animals. Food and water consumption and body weights were recorded at the end of the experimental period. Rats were observed for clinical signs of toxicity. At the end of the study, rats were sacrificed under ether anesthesia. Liver samples were taken for the determination of enzyme activity. Administration of excess of vitamin A produced a significant (p menor 0.05) increase in the content of liver vitamin A, determined diverse and variable clinical signs (such as, anorexia, loss of body weight, alopecia, conjunctivitis, external and internal hemorrhages, skin abnormalities and death) and increased (p menor que 0.05) the activity of the following enzymes: alanine aminotransferase, aspartate aminotransferase, acid maltase (acid alfa-1,4-glucosidase), acid proteases, lactate dehydrogenase and alkaline phosphatase while glucose-6-phosphatase, glycogen phosphorylase, alfa-amylase, cholinesterase and arginase decreased (p menor que 0.05) as compared with untreated controls. These changes depend on the doses given of vitamin A. In conclusion, our results provide evidence that short-term administration of high doses of vitamin A determined diverse and variable clinical signs and produces a marked alteration of activity of liver enzymes.

[Clinical and biochemical alterations in rats treated with high doses of vitamin A]. / Alteraciones clínicas y bioquímicas en ratas tratadas con dosis altas de vitamina A.

In the present work the effect of intramuscular administration of 30.000, 50.000 and 100.000 IU of vitamin A palmitate daily for seven days, respectively, on the liver enzyme activity in 45 white male Wistar rats, aged 12 weeks and weighing 180-200 g, have been studied. The group control was integrated by 15 healthy rats with similar characteristics (strain, gender, age and weight) to treated animals. Food and water consumption and body weights were recorded at the end of the experimental period. Rats were observed for clinical signs of toxicity. At the end of the study, rats were sacrificed under ether anesthesia. Liver samples were taken for the determination of enzyme activity. Administration of excess of vitamin A produced a significant (p < 0.05) increase in the content of liver vitamin A, determined diverse and variable clinical signs (such as, anorexia, loss of body weight, alopecia, conjunctivitis, external and internal hemorrhages, skin abnormalities and death) and increased (p < 0.05) the activity of the following enzymes: alanine aminotransferase, aspartate aminotransferase, acid maltase (acid alpha-1,4-glucosidase), acid proteases, lactate dehydrogenase and alkaline phosphatase while glucose-6-phosphatase, glycogen phosphorylase, alpha-amylase, cholinesterase and arginase decreased (p < 0.05) as compared with untreated controls. These changes depend on the doses given of vitamin A. In conclusion, our results provide evidence that short-term administration of high doses of vitamin A determined diverse and variable clinical signs and produces a marked alteration of activity of liver enzymes.

Excess vitamin A decreases the specific activity of galactosyltransferase in Golgi apparatus of rat liver.

This study investigated the effects of vitamin A excess on hepatic galactosyltransferase (EC 2.4.1.13) activity in livers of rats achieved either by feeding of high levels of retinyl palmitate for 16 wk or gavaging with retinol in olive oil for 3 d. Both hypervitaminotic conditions were characterized by hepatic lipid accumulation. Golgi apparatus fractions were isolated and purity of the fractions was monitored by marker-enzyme analyses and electron microscopy. The quality of the fractions isolated from livers of rats receiving vitamin A excess was not different from that of fractions from control rats. An increase in fat-storing cells in liver, observed in vitamin A excess, coincided with the presence of a floating lipid layer present during isolation of the Golgi apparatus. Galactosyltransferase specific activity (with ovomucoid as acceptor) of Golgi apparatus of rats fed excess vitamin A was 27% of control with chronic feeding and 59% of control with administration by gavage. Activity of another luminally oriented protein, uridine 5'-diphosphate phosphatase, was increased under both in vivo regimens. Vitamin A content of Golgi apparatus, as determined by high performance liquid chromatography, correlated negatively with galactosyltransferase activity after both chronic and acute administration of excess vitamin A.