Arginine helps in mercury toxicity.
[Mercury toxicity: trace element interactions and detoxification activity by L-arginine]
[Article in Italian]
Santarelli L, Piacenza F, Bonacucina V, Malavolta M, Mocchegiani E, Bracci M.
Medicina del Lavoro- Dipartimento di Patologia Molecolare e Terapie Innovative, Facoltà di Medicina e Chirurgia, Università Politecnica delle Marche, Via Tronto 10/A, Torrette Ancona. l.santarelli@univpm.it
Mercury (Hg) exposure makes happen disease to humans and animals spreading in all body compartments, especially in liver and kidney. In these ones, copper, zinc, manganese and iron were investigated to assess perturbation of essential metals' homeostasis due to Hg chronic intoxication. Because L-arginine, is able to induce beneficial influence on immunologic functions on mice intoxicated with Hg, we also studied the efficiency of detoxification process before and after treatment with this aminoacid. Adding L-arginine to diet of the intoxicated mice we achieved a good restoration to normal homeostatic conditions.
L-arginine reduces mercury accumulation in thymus of mercury-exposed mice: role of nitric oxide synthase activity and metallothioneins.
Bracci M, Tomasetti M, Malavolta M, Bonacucina V, Mocchegiani E, Santarelli L.
Department of Molecular Pathology and Innovative Therapies, Occupational Medicine, Polytechnic University of Marche, Ancona, Italy.
Mercury, an occupational and environmental contaminant, is a well-recognized health hazard. The thymus is a target for inorganic mercury (Hg2+); thymic function is impaired in Hg2+ intoxication and is partially restored by simultaneous L-arginine supplementation. The nitric oxide (NO)-nitric oxide synthase (NOS) pathway and metallothioneins (MTs) were studied to investigate the role of L-arginine in thymic function restoration after mercury exposure. Mice received a higher and a lower dose of inorganic mercury, with and without L-arginine supplementation. Saline-treated mice were used as controls. Thymus weight and thymulin were measured as indices of thymic function. Mice treated with Hg2+ alone displayed an accumulation of metal in the thymus, reduced NOS activity, a lower plasma nitrite plus nitrate concentration and an increased MTs expression compared with control mice. L-arginine supplementation was associated with lower Hg2+ concentrations in the organ and partial preservation of other measures. Reduced accumulation of Hg2+ in mice dosed with L-arginine was probably related to greater NO production and NO-MTs interactions.
The role of L-arginine in toxic liver failure: interrelation of arginase, polyamine catabolic enzymes and nitric oxide synthase.
Nikolic J, Stojanovic I, Pavlovic R, Sokolovic D, Bjelakovic G, Beninati S.
Department of Biochemistry, School of Medicine, University of Nis, Nis, Serbia and Montenegro. nikdan@bankerinter.net
The existing interrelation in metabolic pathways of L-arginine to polyamines, nitric oxide (NO) and urea synthesis could be affected in sepsis, inflammation, intoxication and other conditions. The role of polyamines and NO in the toxic effect of mercury chloride on rat liver function was studied. Administration of mercury chloride for 24 h led to significantly elevated plasma activities of Alanine transaminase (ALT) and Aspartate transaminase (AST). Malondyaldehyde (MDA) levels were unaffected (p > 0.05) and arginase activity was significantly decreased (p < 0.05) while nitrate/nitrite production was significantly elevated (p < 0.001) in liver tissue. Polyamine oxidase (PAO) and diamine oxidase (DAO) activities, enzymes involved in catabolism of polyamines, were decreased. L-arginine supplementation to intoxicated rats potentiated the effect of mercury chloride on NO production and it was ineffective on arginase activity. Results obtained in this study show that mercury chloride-induced toxicity leads to abnormally high levels of ALT and AST that may indicate liver damage with the involvement of polyamine catabolic enzymes and NO.
l-Arginine normalizes NOS activity and zinc-MT homeostasis in the kidney of mice chronically exposed to inorganic mercury.
Piacenza F, Malavolta M, Cipriano C, Costarelli L, Giacconi R, Muti E, Tesei S, Pierpaoli S, Basso A, Bracci M, Bonacucina V, Santarelli L, Mocchegiani E.
Department of Molecular Pathology and Innovative Therapies, Occupational Medicine, Polytechnic University of Marche, Torrette, Ancona, Italy.
Inorganic mercury (HgCl2) exposure provokes damage in many organs, especially kidney. Inducible nitric oxide synthase (iNOS) expression, total NOS activity and the profiles of zinc (Zn), copper (Cu) and Hg as well as their distribution when bound to specific intracellular proteins, including metallothioneins (MT), were studied during HgCl2 exposure and after l-arginine treatment in C57BL/6 mouse kidney. HgCl2 exposure modulates differently iNOS expression and NOS activity, increasing iNOS expression but, conversely, decreasing total NOS activity in the mouse kidney. Moreover, during Hg exposure an increased MT production occurs. The kidney damage leads to a loss of urinary proteins, increased plasma creatinine and high Zn mobilization with consequent increased urinary Zn excretion. l-arginine treatment recovers NOS activity and induces a normalization of MT induction, plasma creatinine values and urinary proteins excretion, suggesting that l-arginine may limit kidney damages by Hg exposure.