The Impact of Perinatal Cobalt Chloride Exposure on Extramedullary Erythropoiesis, Tissue Iron Levels, and Transferrin Receptor Expression in Mice

Developmental exposure to cobalt chloride affected mouse testis via altered iron metabolism in adulthood

INRODUCTION

Cobalt (Co) is known to interfere with iron (Fe) metabolism that is essential for differentiating male germ cells. Our aim was to study the effect of developmental chronic cobalt exposure on mouse testis through changes in iron homeostasis in adulthood.

METHODS

Pregnant ICR mice were exposed to 75 mg (low dose) or 125 mg (high dose)/kg b.w. cobalt chloride (CoCl2) with drinking water for 3 days before delivery and treatment continued until postnatal day 90 of the pups. Age-matched control animals obtained regular tap water. Testes of control and Co-treated mice were processed for immunohistochemistry and inductively coupled plasma mass spectrometry. Sperm count was performed.

RESULTS

Chronic CoCl2 administration resulted in significant dose-dependent Co accumulation in sera and testes of the exposed mice. Fe content also showed a significant increase in sera and testes compared to the untreated controls. Surprisingly, testes of low dose-treated mice had ∼ 2.7-fold higher Fe content compared to those exposed to the high dose. A significant dose-dependent reduction in relative testis weight by 18.8% and by 37.7% was found after treatment with low and high dose CoCl2, respectively was found. Our study demonstrated that developmental chronic exposure to CoCl2 affected cellular composition of the testis manifested by germ cell loss and low sperm count, accompanied by altered androgen response in Sertoli cells (loss of stage-specific expression of androgen receptor). A possible mechanism involved is iron accumulation in the testis that was associated with altered ferroportin-hepcidin localization in seminiferous tubules depleted in germ cells. As a protective mechanism for germ cells in condition of iron excess, ferroportin was distributed in Sertoli cells around elongating spermatids. Similar changes in expression of transferrin receptor 1 (TfR1) and divalent metal transporter 1 (DMT1) implied that both factors of testicular Fe homeostasis are closely related. Outside the seminiferous tubules, Leydig cells localized ferroportin, hepcidin, DMT1 and TfR1 thus they could be considered as a main site for iron metabolism.

CONCLUSION

Our data suggest that Co exerts its effects on the testis by indirect mechanism possibly through alteration in Fe homeostasis.

The Role of Trace Elements and Minerals in Osteoporosis: A Review of Epidemiological and Laboratory Findings

The objective of the present study was to review recent epidemiological and clinical data on the association between selected minerals and trace elements and osteoporosis, as well as to discuss the molecular mechanisms underlying these associations. We have performed a search in the PubMed-Medline and Google Scholar databases using the MeSH terms "osteoporosis", "osteogenesis", "osteoblast", "osteoclast", and "osteocyte" in association with the names of particular trace elements and minerals through 21 March 2023. The data demonstrate that physiological and nutritional levels of trace elements and minerals promote osteogenic differentiation through the up-regulation of BMP-2 and Wnt/β-catenin signaling, as well as other pathways. miRNA and epigenetic effects were also involved in the regulation of the osteogenic effects of trace minerals. The antiresorptive effect of trace elements and minerals was associated with the inhibition of osteoclastogenesis. At the same time, the effect of trace elements and minerals on bone health appeared to be dose-dependent with low doses promoting an osteogenic effect, whereas high doses exerted opposite effects which promoted bone resorption and impaired bone formation. Concomitant with the results of the laboratory studies, several clinical trials and epidemiological studies demonstrated that supplementation with Zn, Mg, F, and Sr may improve bone quality, thus inducing antiosteoporotic effects.

Perinatal and early-life cobalt exposure impairs essential metal metabolism in immature ICR mice

The objective of the present study was to assess the impact of cobalt (Co) exposure on tissue distribution of iron (Fe), copper (Cu), manganese (Mn), and zinc (Zn), as well as serum hepcidin levels in immature mice (18, 25, 30 days). Pregnant mice were exposed to 75 mg/kg b.w. cobalt chloride (CoCl₂ × 6H2O) with drinking water starting from 3 days before delivery and during lactation. At weaning (day 25) the offspring were separated and housed in individual cages with subsequent exposure to 75 mg/kg b.w. CoCl₂ until 30 days postnatally. Evaluation of tissue metal levels was performed by an inductively coupled plasma-mass spectrometry (ICP-MS). Serum hepcidin level was assayed by enzyme linked immunosorbent assay (ELISA). Cobalt exposure resulted in a time- and tissue-dependent increase in Co levels in kidney, spleen, liver, muscle, erythrocytes, and serum on days 18, 25, and 30. In parallel with increasing Co levels, CoCl₂ exposure resulted in a significant accumulation of Cu, Fe, Mn, and Zn in the studied tissues, with the effect being most pronounced in 25-day-old mice. Cobalt exposure significantly increased serum hepcidin levels only in day18 mice. The obtained data demonstrate that Co exposure may alter essential metal metabolism in vivo.