Toshihiko Ariyoshi

Studies on the metabolism of d-Limonene (p-Mentha-1,8-diene). III. Effects of d-Limonene on the lipids and drug-metabolizing enzymes in rat livers.

1. After a single oral dose of d-limonene (200-1200 mg/kg) no effects were observed on liver triglyceride, microsomal protein, cytochrome b5, and the drug-metabolizing enzymes. Glycogen content was slightly decreased at doses higher than 800 mg/kg, and cytochrome P-450 and delta-aminolaevulinic acid synthetase activity was slightly increased at 1200 mg/kg. 2. After repeated treatment (400 mg/kg/day) for 30 days, the relative liver weight and hepatic phospholipid content were only slightly increased, and liver and serum cholesterol were decreased 49 and 8%, respectively. Of the phospholipid fatty acids, palmitic, linoleic and arachidonic acids were increased, and stearic acid was decreased. Aminopyrine demethylase and aniline hydroxylase were increased 26 and 22%, respectively, and cytochrome P-450 and b5 were likewise increased 31 and 30%.

Profile of metal-binding proteins and heme oxygenase in red carp treated with heavy metals, pesticides and surfactants

A family of hemoproteins known as cytochrome P-450, which is known to perform a major role in the metabolism of various agents, has been investigated in fish as a criterion for monitoring water pollution. This enzyme is well known to be induced by various chemicals in fish as well as mammals. However, very little information is available concerning the effects of environmental pollutants on the activity of heme oxygenase, the first and rate-limiting enzyme for heme degradation. To investigate the nature of heme oxygenase is of particular interest in that if heme oxygenase activity is altered by contaminants, that may contribute to the effect on physiological changes of heme and hemoprotein P-450. In this study the authors investigated the effects of heavy metals, pesticides and surfactants on the MBP and the heme oxygenase in the hepatopancreas and kidney of a fresh water red carp (Cyprinus carpio Linne).

Isolation and sequence of cDNA encoding a 3-methylcholanthrene-inducible cytochrome P450 from wild red sea bream,Pagrus major

We have isolated a cDNA clone of mRNA for the cytochrome P450 from a 3-methylcholanthrene (MC)-treated red sea bream,Pagrus major, using a cDNA fragment for rat P4501A2 as a probe. The cloned cDNA is ca. 1.8 kb long and contains an open reading frame of 1545 nucleotides for polypeptides of 515 amino acids. The deduced N-terminal amino acid sequence of the cDNA is very similar to that for purified cytochrome P450 protein from the marine fish scup, which was reported previously (Klotz et al. 1983). A conserved amino acid sequence containing a putative heme-binding cysteine is present in the equivalent position proximate to the C-terminus of the molecules. The deduced amino acid sequence shows more than 50% positional identity with known members of the mammalian aromatic hydrocarbon-inducible P450 family. RNA blot analysis indicates that P450 mRNA (s) is expressed in the liver, kidney, gill and gut of the MC-treatedP. major.

Effects of the Environmental Pollutants on Heme Oxygenase Activity and Cytochrome P-450 Content in Fish

We have investigated the activities of heme oxygenase as well as other drug metabolizing enzymes and the content of P-450 in the hepatopancreas of fish as the biochemical indicator, and thereby have made an attempt to clarify the range of pollution in the aquatic environment

Purification of metallothionein-like protein in rat placenta.

A report is given of a metal-binding protein which was isolated and purified from rat placenta. Pregnant Wistar rats were injected subcutaneously with cadmium chloride at a dose of 1 mg/kg once daily for three days on day 15 to 17 of gestation. Sacrifice was on day 18 of gestation. Isolation and purification yielded two fractions of cadmium-binding protein. The molecular weights agreed with that of metallothionein from other tissues but the amino acid composition was markedly different. Cadmium analysis was performed by atomic absorption spectrophotometry. (JMT)

Biliary excretion of exogenous cadmium, and endogenous copper and zinc in the Eisai hyperbilirubinuric (EHB) rat with a near absence of biliary glutathione

Mutant Eisai hyperbilirubinuric (EHB) rats derived from an inbred strain of Sprague-Dawley (SD) rats are characterized by a near absence of biliary excretion of glutathione (GSH) due to inherently impaired ATP-driven organic anion transport. Cd (0.1 mg/kg bw from CdCl2) was injected intravenously into EHB rats and control SD rats. Output of biliary excretion of Cd was followed over 15-min intervals up to 60 min. Cd was excreted rapidly and reached the maximum level (73.2 ng/15 min) in the period from 15 to 30 min in SD rats. Its excretion in EHB rats, however was one-fortieth (only 1.8 ng/15 min) of that in SD rats. Biliary concentrations of two endogenous metals, Cu and Zn were also measured. The output of Cu in EHB rat bile (50 ng/15 min before Cd injection) was about one-fifth of that in SD rat bile (270 ng/15 min). The output was not influenced by the Cd injection in the two groups. There was a slight difference of Zn output between the two groups. The biliary excretion of GSH was 500 to 700 micrograms/15 min and only 1 to 2 micrograms/15 min in SD and EHB rats, respectively. Sixty min after Cd injection, the Cd concentrations in the serum, liver and kidney were slightly higher in EHB rats than in SD rats. There was no difference in the hepatic metallothionein (MT-I and-II) concentration between SD (34 micrograms/g liver) and EHB (33 micrograms/g liver) rats. The renal Cu concentration was about four times in the higher in the EHB rat than in the SD rat. These results suggest that reduced biliary excretion of Cd is mainly, but that of Cu is only partly, based in reduced canalicular transport of GSH due to lack of an ATP-driven organic anion transport system, not MT induction in EHB rats. It seems likely that biliary excretion of Cd is regulated mainly by the canalicular anion transport in rats.

Profile of hemoproteins and heme-metabolizing enzymes in rats treated with surfactants

We have undertaken to clarify the detailed effects of synthetic surfactants having different chemical structures and properties on the contents of hepatic heme, hemo-proteins and metallothionein and on the activities of heme- and drug-metabolizing enzymes in rats

Heme oxygenase activity and cytochrome P‐450 content associated with induced metallothionein in the liver of rats treated with various metals

Abstract The relationship between heme oxygenase (HO) activity and metallothionein (MT) concentration in rat liver was investigated. The responses to treatments with metals of the ?‐series metals that can bind to MT in vivo (e.g., cadmium, zinc and copper) and the B‐series metals that cannot bind to MT in vivo (e.g., cobalt, nickel and manganese) were compared. A single treatment with any metal in the A‐ or B‐series increases both hepatic HO activity and MT concentration. However, repeated treatments with ?‐series metals decreases HO activities more than a single injection despite appreciable increases in MT concentrations. Repeated treatments with B‐series metals increase both HO activities and MT concentrations. On the other hand, cytochrome P‐450 concentrations are depressed by single or repeated treatments with all metals tested. These results suggest that the binding abilities of metals to MT in vivo, or the replaceable zinc concentration in MT, affect the magnitude of HO activity.

Increased biliary excretion of cadmium and glutathione by ethanol intake in female rats

Abstract Biliary cadmium (Cd) excretion associated with reduced glutathione (GSH) following treatments of cadmium chloride (CdCl2) to female rats fed a 20% ethanol solution for six days was investigated and compared with Cd excretion in male rats. Cadmium chloride injection alone in female rats caused a 3.9‐fold increase in cumulative GSH in bile up to 12 h after treatment compared to control female rats. Cadmium chloride injection of ethanol‐fed rats caused a 5.0‐fold increase in biliary GSH compared to controls. A similar pattern was observed in the biliary concentration of Cd. At 12 h after CdCl2 treatment, the cumulative content of Cd in bile for the CdCl2 and ethanol group was 7.9% of the administered dose. This was almost twice that seen in the CdCl2 alone group (4.2%). The majority of biliary excretion of both GSH and Cd were excreted into bile within 6 h after CdCl2 injection. The enhancement of Cd excretion into bile presented by combination treatment with CdCl2 and ethanol in female rats was hig...

Purification and characterization of lead-induced zinc thionein in the liver of rats.

Metallothioneins are involved in homeostasis of essential metals, but its exact biological function remains obscure. Recently it was observed that the administration of lead increased zinc content in the low molecular-weight protein fraction in the rat hepatic 105000x g soluble fraction by using Sephadex G-75 gel filtration, and that this fraction contained only zinc, not lead, as metal. Therefore, the authors have investigated the effects of some drugs on this zinc contained low molecular-weight protein (zinc binding protein, Zn-BP), and further isolated and purified the ZN-BP from liver of rats treated with lead.