ABSTRACT
The wolf Canis lupus is a major terrestrial predator in eastern Europe and, as a top carnivore, may be exposed to high concentrations of contaminants that are readily transferred through the food chain. Despite this, there are few published data on pollutant and pesticide levels in wolves. This study utilised tissues from animals legally killed by hunters for other reasons (animals were not killed for the purposes of this study) to carry out the only detailed investigation of contaminants in wolves in Europe and the first in animals from Eastern Europe. The livers of 58 wolves from the Tver and Smoliensk regions of northwest Russia (54 degrees N 31 degrees E to 57 degrees N 35 degrees E) were analysed for seven organochlorine pesticides, 24 PCB congeners, Aroclor 1254-matched summed PCBs (sigmaPCBs), total mercury, cadmium and lead. Cadmium, most of the organochlorine pesticides and many PCB congeners were not detectable in any of the wolves. Hexachlorobenzene, alpha-HCH, pp'DDE, PCB congeners 118, 138, 149 and 156 and lead were detected in up to 6% of livers. Dieldrin, PCB congeners 153, 170 and 180, sigmaPCBs and mercury were detected more frequently. Contaminant levels were generally low; maximum wet weight concentrations of any of the organochlorine pesticides, sigmaPCBs and mercury were less than 0.1, 1 and 0.25 microg g(-1), respectively. PCB congeners 153, 170 and 180 accounted for 41% of the sigmaPCBs. Dieldrin, sigmaPCBs and mercury concentrations did not vary significantly between males and females nor between adult and juvenile (< 12 months old) wolves apart from the sigmaPCB concentration, which was on average five times higher in adults than juveniles. Liver residues were generally below the level normally associated with adverse effects except for lead levels which exceeded the critical 5 microg g(-1) dry wt. concentration in three of the 58 animals examined.
Subject(s)
Environmental Pollutants/pharmacokinetics , Insecticides/pharmacokinetics , Metals, Heavy/pharmacokinetics , Polychlorinated Biphenyls/pharmacokinetics , Wolves , Age Factors , Animals , Environmental Monitoring , Environmental Pollutants/analysis , Female , Food Chain , Insecticides/analysis , Liver/chemistry , Male , Metals, Heavy/analysis , Polychlorinated Biphenyls/analysis , Russia , Sex Factors , Tissue DistributionABSTRACT
A reduction in tumour yield was apparent when progesterone administration was begun 25 days before feeding 7,12-dimethylbenz(a)anthracene (DMBA). This effect was most obvious when the duration of hormone administration was brief. Continuation of progesterone for some time after feeding DMBA caused a progressive diminution of the inhibitory effect, and 135 days of continuous hormone treatment entirely abolished the effects of 25 days pretreatment with the hormone.In contrast, when progesterone injections were begun 2 days after feeding DMBA, there was a trend towards enhancement of tumour yield. Continuous hormone administration appeared more effective than shorter treatment regimens.
Subject(s)
Mammary Neoplasms, Experimental , Progesterone/pharmacology , Animals , Benz(a)Anthracenes/antagonists & inhibitors , Depression, Chemical , Drug Synergism , Female , Mammary Neoplasms, Experimental/chemically induced , Rats , Time FactorsABSTRACT
Experiments were undertaken to investigate the early effects of DMBA or progesterone, or the two in combination, on DNA synthesis in rat mammary epithelial cells, and also to determine whether there was any correlation between the level of DNA synthesis observed in the first 96 hours after administration of DMBA, either alone or combined with progesterone, and subsequent tumour development.It was found that DMBA alone caused an insignificant reduction in DNA synthesis in the first 96 hours, whereas progesterone significantly enhanced DNA synthesis. When the carcinogen and hormone were administered together, a greater rise was seen in the level of DNA synthesis than that occurring in rats treated only with DMBA, but the increase was not significantly greater than that in untreated animals. A two-way analysis of variance revealed no interaction between DMBA and progesterone in relation to mammary epithelial cell DNA synthesis.Mammary neoplasms occurred only in the groups of rats which had received DMBA, either alone or in combination with progesterone. No correlation could be demonstrated between the extent of DNA synthesis observed in mammary glands biopsied between 6 and 96 hours after carcinogen administration and the occurrence of tumours in the host rats 135 days later.
