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We studied the effects of a 10-day oral 10 micromol/kg oleoyl-estrone (OE) treatment on streptozotocin-diabetic Wistar, Goto-Kakizaki and control Wistar rats. Streptozotocin rats lost more than half the energy ingested as urine glucose. Oleoyl-estrone induced the loss of body weight (mainly body fat) in all groups. Energy expenditure was similar in the three groups of rats studied. Water turnover was deranged in streptozotocin rats, which spent 14% of energy available heating the water drunk. Body lipids were highest in Goto-Kakizaki; lipid levels in streptozotocin rats were very low. Oleoyl-estrone decreased body lipid content in Wistar and Goto-Kakizaki; oleoyl-estrone decreased triacylglycerols (44% in Wistar and Goto-Kakizaki and 22% in streptozotocin rats) and phospholipids but did not affect body cholesterol. Oleoyl-estrone decreased insulin and leptin, did not affect blood glucose but decreased plasma glucose in all groups. There were no changes in plasma triacylglycerols or fatty acids, but HDL, LDL and cholesterol decreased in all groups. The same effects of OE on insulin, plasma (but not blood) glucose and leptin were observed in both models, but the presence of insulin seems to be needed for OE to normalise glycaemia and to facilitate the uptake and utilisation of glucose by tissues. This different handling of glucose and triacylglycerol energy accounts for the disparate effects of OE on energy balance. The main conclusion of this study is that OE function as a lipid-mobilising hormone is dependent on the mass of reserves available, which in turn is closely related to insulin status. Lack of insulin thus results in limited OE effects, and insulin resistance does not prevent or limit the effects of OE on energy homeostasis or the mobilisation of fat.

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Ethanol and a variety of other compounds previously have been shown to acutely inhibit the metabolism of ethyl carbamate (EC) when given concurrently in mice. On the other hand, ethanol pretreatment (10% in drinking water for the period 48 to 12 hr prior to EC treatment) is known to have the opposite effect and enhance the clearance of EC from blood of mice. In the present work, acetone has been shown to act similarly. Concurrent acetone treatment inhibits the metabolism of EC (11.1 mg/kg po) in male A/JAX mice in a dose-response manner. Blood clearance (Cl) of this po dose of EC from mice following concurrent acetone treatment (50 mg/kg, 0.86 mmol/kg ip) averaged 185 +/- 5.4 (SE) ml hr-1 kg-1 vs. controls of 804 +/- 24.6 ml hr-1 kg-1. Comparing doses that produce equal effects on the blood clearance values of EC, acetone is approximately 50-fold more potent as an inhibitor than ethanol. Pretreatment of mice with acetone (2 g/kg ip) 48 hr and 24 hr before EC administration po increased the clearance of EC approximately 3-fold (CI = 2623 +/- 123 ml hr-1 kg-1). 2-Propanol was found to be at least as potent as inhibitor as acetone, but with a longer duration of inhibition; this longer duration was explained by the longer persistence of acetone in blood from conversion of 2-propanol to acetone.(ABSTRACT TRUNCATED AT 250 WORDS)

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The excretion of radioisotope following the administration of three specifically 14C-labelled forms of streptozotocin was investigated in the rat using ureter and bile duct cannulation techniques. The urine collected during the first hour following the administration of the drug contained the highest proportion of injected radioactivity (approximately 34% with (3'-methyl-14C)-streptozotocin and approximately 40% each with (1-14C)-and (2'-14C)-streptozotocin. Over the entire experimental period (6 hours), approximately 70% of the injected radioactivity of (1-14C)- and (2'-14C)-streptozotocin appeared in the urine. With (3'-methyl-14C)-streptozotocin, only 53% of the injected radioactivity appeared in the urine over the same period. In contrast to the high urinary excretion, less than 3% of the injected radioactivity from all three radiolabelled streptozotocin samples appeared in the bile. The in vivo and in vitro metabolism of streptozotocin was also investigated. In addition to substantial amounts of unchanged drug, three radiolabelled metabolites (two major and one minor) were detected in the urine during the 6 hour collection period following the administration of (1-14C)- and (2'-14C)-streptozotocin. In contrast, only unchanged (3'-methyl-14C)-streptozotocin was detected in the urine collected over the same period following the administration of the methyl labelled drug. The two major metabolites were also produced when (1-14C)-and (2'-14C)-streptozotocin were incubated with a rat liver supernatant fraction (100,000 X g). The liver was further demonstrated to be the major site of metabolism in isolated liver perfusion studies in which both (1-14C)- and (2'-14C)-streptozotocin were quantitatively converted to the two major metabolites. The two major metabolites of (1-14C)-streptozotocin, whether produced in vivo or in vitro, were chromatographically homogenous with the two major metabolites formed from (2'-14C)-streptozotocin. Nicotinamide pretreatment had no apparent effect on the urinary excretion of streptozotocin and its metabolites.

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We have investigated the distribution, biotranformation, and excretion of streptozotocin and its 14C- and 3H-labeled metabolities in 15 patients with advanced cancer. Streptozotocin was detected in the plasma during the first 3 hours after administration while radioactive products were present for longer than 24 hours. No unchanged streptozotocin was detected in the cerebrospinal fluid (CSF); however, 14C-labeled metabolites were detected in the 2-hour CSF sample in a concentration equivalent to the 2-hour plasma level. H activity is the CSF was not detected at this time period. Radioactivity measured in biopsied tissues indicated that streptozotocin labeled with 14C and 3H or its metabolites penetrated tumor tissue. 14C tissue levels were found to approximate plasma levels; however, 3H levels were found to be greater than the corresponding plasma levels. Fifteen percent of the total dose of streptozotocin administered was recovered in the urine. 3H-labeled metabolites were recovered in excess of 60% in the urine, and approximately 30% of the 14C-labeled metabolites were recovered in the urine during a similar interval. Less than 1% of the administered 14C and 3H was recovered in the feces. 14C-labeled CO2 was also recovered, although quantitative recovery was not attained. At least three major metabolites of streptozotocin were detected in the urine by radiochromatography. Two metabolites contained only 3H and one metabolite contained both 14C and 3H in the same ratio as administered.

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[(14)C]Streptozotocin was synthesized specifically labelled at three positions in the molecule. The biological activity of synthetic streptozotocin was characterised by studies in vivo of its diabetogenic activity and its dose-response curves. After this characterization the excretion pattern of all three labelled forms of streptozotocin was studied. With [1-(14)C]streptozotocin and [2'-(14)C]streptozotocin the injected radioactivity was excreted (approx. 70% and 80% respectively) mainly in the urine, the greater part of the excretion occurring in the first 6h period; small amounts (approx. 9% and 8% respectively) were found in the faeces. In contrast, with [3'-methyl-(14)C]streptozotocin a much smaller proportion (approx. 42%) of the injected radioactivity was excreted in the urine, the major proportion appearing in the first 6h, whereas approx. 53% of the injected radioactivity was retained in the carcasses. In whole-body radioautographic studies very rapid renal clearance and hepatic accumulation of the injected radioactivity was observed with all three labelled forms of the drug. There was some evidence for biliary and intestinal excretion. Major differences were apparent in the tissue-distribution studies, with each of the three labelled forms, particularly with [3'-methyl-(14)C]streptozotocin. There was no accumulation of [1-(14)C]streptozotocin in the pancreas for the 6h period after administration. However, with [3'-methyl-(14)C]streptozotocin (and also [2'-(14)C]streptozotocin) there was evidence of some pancreatic accumulation after 2h. The results indicate that streptozotocin is subjected to considerable metabolic transformation and to rapid renal clearance. The implication of these suggestions is evaluated with particular reference to the diabetogenic action of streptozotocin.

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