Absorption and distribution of cadmium in metallothionein-I transgenic mice.
نویسندگان
چکیده
Metallothionein-I transgenic (MT-TG) mice have higher concentrations of MT in the stomach (10x), small intestine (4x), large intestine (6x), liver (15x), and kidney (5x) than control mice. The purpose of the present study was to use MT-TG mice to determine whether increased concentrations of MT affect cadmium (Cd) absorption and distribution. A single dose of 109Cd was given to control and MT-TG mice orally (0.3-300 mumol/kg, 200 microCi/kg) or intravenously (0.03-10 mumol/kg, 20 microCi/kg). Cd concentrations in 15 tissues were quantified 7 days later. Higher MT concentrations in tissues of MT-TG mice had no appreciable effects on the concentration of Cd in tissues compared to controls. An exception to this was the MT-TG mice given the highest dose of Cd (300 mumol Cd/kg, po), which had twice the tissue Cd concentration of controls. Approximately 60% of the Cd administered iv was retained in the tissues; retention of Cd in MT-TG mice was similar to that in controls. In both control and MT-TG mice only 0.1-0.3% of Cd administered po was retained, except for 1-3% at the higher doses (100 and 300 mumol/kg). Cd administered iv distributed mainly to the liver (70%) and kidney (10%) and was independent of dose. In contrast, when administered po, distribution of Cd to the liver increased from 40 to 75% of the dose, whereas distribution to kidney decreased from 30 to 7% as doses were increased from 0.3 to 300 mumol/kg. No difference in pattern of Cd distribution to various organs was observed between control and MT-TG mice. These data indicate that higher concentrations of MT in MT-TG mice do not appear to inhibit the gastrointestinal absorption of Cd nor alter the organ distribution of Cd.
منابع مشابه
Analysis of the effects of overexpression of metallothionein-I in transgenic mice on the reproductive toxicology of cadmium.
Exposure to low levels of cadmium reduces fertility. In male mice spermatogenesis is highly sensitive to cadmium, whereas in females the peri-implantation period of pregnancy is sensitive. To examine the potential roles of the cadmium-binding protein, metallothionein (MT), in the reproductive toxicology of cadmium, we examined a transgenic mouse strain that overexpresses metallothionein-I (MT-I...
متن کاملMetabolism of orally administered cadmium-metallothionein in mice.
The main source of cadmium in the diet is cereal or meat, especially in liver and kidney. Since the cadmium in both liver and kidney is bound to metallothionein, a heat-stable protein, the gastrointestinal absorption and metabolism of cadmium metallothionein (CdMt) was studied in detail. The selective renal cadmium deposition after oral CdMt was analogous to the studies on injected CdMt. Metall...
متن کاملInheritance and expression of the mouse metallothionein gene in tobacco: impact on cd tolerance and tissue cd distribution in seedlings.
Genetically engineered seedlings obtained from self-fertilized transgenic tobacco (Nicotiana tabacum) contained and expressed the mouse metallothionein and kanamycin resistance marker genes and were more tolerant to cadmium stress than untransformed controls. Cadmium accumulation in leaves of transgenic seedlings exposed to a low, field-like Cd concentration (0.02 micromolar) was about 20% lowe...
متن کاملBiochemical and Molecular Roles of Nutrients Metallothionein Knockout and Transgenic Mice Exhibit Altered Intestinal Processing of Zinc with Uniform Zinc-Dependent Zinc Transporter-1 Expression
A role for metallothionein in intestinal zinc absorption has been the subject of considerable debate. If metallothionein affects zinc absorption, then those factors that induce metallothionein synthesis (e.g., heavy metals, hormones) should alter zinc absorption and homeostasis. The present studies used metallothionein transgenic mice (overexpressing) and metallothionein knockout mice (no expre...
متن کاملMetallothionein knockout and transgenic mice exhibit altered intestinal processing of zinc with uniform zinc-dependent zinc transporter-1 expression.
A role for metallothionein in intestinal zinc absorption has been the subject of considerable debate. If metallothionein affects zinc absorption, then those factors that induce metallothionein synthesis (e.g., heavy metals, hormones) should alter zinc absorption and homeostasis. The present studies used metallothionein transgenic mice (overexpressing) and metallothionein knockout mice (no expre...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Fundamental and applied toxicology : official journal of the Society of Toxicology
دوره 29 2 شماره
صفحات -
تاریخ انتشار 1996