Leydig cell death in rats exposed to bismuth subnitrate

Bismuth Uptake in Rat Testicular Macrophages: A Follow-up Observation Suggesting that Bismuth Alters Interactions Between Testicular Macrophages and Leydig Cells

Recent studies suggest that bismuth accumulates in Leydig cells. In addition, a reduced level of serum testosterone and a statistically significant reduction of Leydig cells have been observed. It was therefore hypothesized that Bi has a direct toxic effect on rat Leydig cells. We have now developed a method for double labeling of bismuth and ED-2 (a marker for testicular macrophages). The present data demonstrate that the heavily bismuth-loaded cells in rat testis, originally interpreted as being Leydig cells, are bismuth-loaded macrophages. Consequently, our data suggest a modified hypothesis regarding bismuth-induced interactions between testicular macrophages and Leydig cells.

Silver enhancement of quantum dots resulting from (1) metabolism of toxic metals in animals and humans, (2) in vivo, in vitro and immersion created zinc–sulphur/zinc–selenium nanocrystals, (3) metal ions liberated from metal implants and particles

Autometallographic (AMG) silver enhancement is a potent histochemical tool for tracing a variety of metal containing nanocrystals, e.g. pure gold and silver nanoclusters and quantum dots of silver, mercury, bismuth or zinc, with sulphur and/or selenium. These nanocrystals can be created in many different ways, e.g. (1) by manufacturing colloidal gold or silver particles, (2) by treating an organism in vivo with sulphide or selenide ions, (3) as the result of a metabolic decomposition of bismuth-, mercury- or silver-containing macromolecules in cell organelles, or (4) as the end product of histochemical processing of tissue sections. Such nano-sized AMG nanocrystals can then be silver-amplified several times of magnitude by being exposed to an AMG developer, i.e. a normal photographic developer enriched with silver ions. The present monograph attempts to provide a review of the autometallographic silver amplification techniques known today and their use in biology. After achieving a stronghold in histochemistry by Timm's introduction of the "silver-sulphide staining" in 1958, the AMG technique has evolved and expanded into several different areas of research, including immunocytochemistry, tracing of enzymes at LM and EM levels, blot staining, retrograde axonal tracing of zinc-enriched (ZEN) neurons, counterstaining of semithin sections, enhancement of histochemical reaction products, marking of phagocytotic cells, staining of myelin, tracing of gold ions released from gold implants, and visualization of capillaries. General technical comments, protocols for the current AMG methods and a summary of the most significant scientific results obtained by this wide variety of AMG histochemical approaches are included in the present article.

Oral Toxicity of Bismuth in Rat: Single and 28‐Day Repeated Administration Studies

The consumption and production of bismuth are increasing, however there is very little information about the direct toxic effect of bismuth. The present study aimed to characterize the potential toxic effects of bismuth through oral administration and observation for fourteen days following single dose of 0 and 2,000 mg/kg (acute oral toxicity study), and repeated oral administration for twenty-eight days at dose levels of 0, 40, 200, and 1,000 mg/kg daily (28-d repeated oral dose toxicity study) to male and female Crj:CD (SD) IGS rats (SPF). We found no deaths and no abnormalities in clinical signs, body weights, and necropsy findings for any of the animals in the acute oral toxicity study and no changes attributable to bismuth in either males or females in the dose group up to 1,000 mg/kg of the 28-d repeated-dose toxicity study. Therefore, we determined that the lethal dose with a 50% mortality rate (LD50) is greater than 2,000 mg/kg and the no-observed-adverse-effect level (NOAEL) of bismuth is 1,000 mg/kg in both sexes. We conclude that the adverse toxic effects of bismuth as a simple metal substance are low compared to lead toxicity under the conditions tested in our studies.

Effects of bismuth citrate on the viability and function of Leydig cells and testicular macrophages

Bismuth is present in several popular over-the-counter drugs for nausea and diarrhea and is occasionally abused by patients with chronic gastrointestinal disorders. The most common consequence of bismuth overdose is neurological dysfunction. In experimental animals, bismuth overdose results in lowered serum testosterone levels, suggesting that reproductive dysfunction may be an additional component of bismuth toxicity. Although the precise mechanisms responsible for the lowered testosterone levels are unknown, it has been shown that bismuth accumulates within testicular macrophages. This may be important because these cells, which are commonly found in direct contact with Leydig cells, are known to exert paracrine influences on the Leydig cells for local control of testosterone production. However, bismuth may also exert direct effects on Leydig cells because it passes by these cells on its way to the phagocytic macrophages. The purpose of the present studies was to isolate both testicular macrophages and Leydig cells from rat testis and study the direct effects of bismuth on these cells with regard to their viability and function. We found that when Leydig cells were treated for 24 h with bismuth (1-100 microM) no change in viability or secretion of testosterone was observed. However, when testicular macrophages were similarly treated with bismuth a significant effect on viability was observed with as little as 6.25 microM bismuth, with near-complete cell death at 50 microM after 24 h. However, bismuth had no effect on the viability on testicular macrophages at 50 microM up to 8 h, therefore, we studied the secretion of tumor necrosis factor alpha (TNF-alpha) after 4 h of exposure to 50 microM bismuth and found no influence on the production of TNF-alpha. Taken together, it seems likely that bismuth has no direct effects on Leydig cells but, rather, lowers testosterone levels by killing testicular macrophages, thereby interrupting their local paracrine influence on Leydig cells through factors other than TNF-alpha.