JOURNAL zyxwvutsrqp OF APPLIED TOXICOLOGY, VOL. zyxwvu 11(5), 317-321 zyxwv (1991) Ultrastructural Localization of Silver in Rat Testis and Organ Distribution of Radioactive Silver in the Rat ~~~~~ Erik Ernstt Department of Neurobiology, Institute of Anatomy. University of Aarhus, DK-8000 Aarhus C, Denmark J~rgen Rungby Erik Baatrup University Dept. of Endocrinology and Internal Medicine, Aarhus County Hospital, DK-8000 Aarhus C. Denmark Institute of Zoology and Zoophysiology, University of Aarhus, DK-8000 Aarhus zyxwvu C, Denmark Key words: silver; ultrastructural localization; rat; testis. The deposition of silver after a single intravenous injection (2 pg Ag g-' body weight) was studied in the testes of Wistar rats 24 h and I and 2 weeks after dosing with radiolabelled "'AgNo3 (2 pg Ag and 1.2 zyx kBq g-' body weight). Also, the temporal accumulation of silver during the experimental period was monitored in the blood, testes, epididymides, kidney, liver and brain. The subcellular distribution of silver within the testes was demonstrated by using the histochemical technique of autometallography. Silver was cleared rapidly from the blood. After an initial rise, concentrations in organs remained almost stable throughout the experimental period. Silver was especially abundant in interstitial macrophages and in the basement membrane. Deposits of silver were found in all cell types of spermatogenesis and in the lysosomes of the Sertoli cells. INTRODUCTION ~~~~ ~ ~~ ~ ~~ ~ ~ Industrial or medical exposure to silver results in increased body burdens,',2 but toxic effects in humans are presumed to be rare and primary target organs have not been defined yet. Peroxidation of membrane lipids3q4 and decreased viability of macrophages have been r e p ~ r t e d . ~ , ~ In experimental animals, silver has been proved to be neurotoxic' and hepatotoxic,3-4.8 and a number of other organ systems may be a f f e ~ t e d . ~ The effects of systemic silver treatment on repro- duction have not been investigated. Holland and White1(' demonstrated the inhibition of motility and glucose utilization in human sperm exposed to metallic silver zyxwvutsr in vitro. Intratesticular injection of silver nitrate was shown by Kamboj and Karl1 to cause localized testicular necrosis. A number of heavy metals may affect male repro- duction." Lead has been found to reduce sperm counts in battery workers without causing endocrine dysfunction. l3 Exposure to ethylmercury can affect sperm production and reduce libido.I4 In this paper, we examine the temporal quantitative accumulation and cytological deposition of silver in rat testes after a single i.v. dose of silver nitrate. MATERIALS AND METHODS Sixteen male Wistar rats, each weighing ca. 300 g, were obtained from M~llegaardsAvlslaboratorium, Ejby, Denmark. The animals were housed in plastic t Author to whom correspondence should be addressed. cages at 20 * 2°C and a 12-h light/l2-h dark schedule for 4 weeks prior to experimentation. Before and during the experimental period, food (Altromin 1324, Altromin Specialfutterwerke, Lange, FRG) and tap water were available zyxw ad zyxw libitum. Radioactive injection solution High-specific-activity ""AgN03 (146 GBq g-l Ag) was purchased from Research Establishment Ris~, Denmark. The injection solution was prepared immedi- ately before administration by adding radioactive ""AgNO, to a solution of stable AgN03 (of analytical grade, purchased from Merck, Darmstadt, Germany) dissolved in distilled water to yield a final silver concentration of 4 mg ml-' or 1.8 MBq ml-I. Scintil- lation vials and a phantom sized and shaped to imitate rats weighing 300 g (to be used as gamma scintillation standards) containing known quantities of stable and radioactive silver nitrate were made from the injection solution and frozen. Administration of silver Under light ether anaesthesia, each of twelve rats were injected in the left jugular vein with 200 pe of radioactive silver nitrate solution (2 pg Ag and 1.2 kBq g-' body weight). The remaining four rats were injected with distilled water alone, serving as histologi- cal controls. After weighing and injection, the rats were returned to their respective cages. Quantitative measurement and tissue preparation Four rats were sampled 24 h and 7 and 14 days after dosing. Each rat was anaesthetized with sodium barbital Received 28 November zy 1990 Accepted 13 March 1991 0260-437X/91/050317-05$05.00 zyxwvutsrq 0 1991 by John Wiley & Sons. Ltd