Assessment of the potential reproductive toxicity of long-term exposure of adult male rats to low-dose formaldehyde

Abstract With increasing air pollution, silica nanoparticles (SiNPs), as a main inorganic member of PM2.5, have gained increasing attention to its reproductive toxicity. Most existing studies focused on the acute exposure, while data regarding the chronic effect of SiNPs on reproduction is limited. Therefore, this study was designed to evaluate the chronic toxicity of SiNPs on spermatocyte cells. The cells were continuously exposed to SiNPs for 1, 10, 20 and 30 generations at dose of 5 μg/ml SiNPs for 24 h per generation after attachment. The results showed that with the increasing generations of the exposure, SiNPs decreased the viability of spermatocyte cells, induced apoptosis and increased the level of reactive oxygen species in spermatocyte cells. Moreover, SiNPs increased the protein expression of GRP-78, p-PERK, IRE1α, ATF6 and Cleaved caspase-3 in spermatocyte cells, suggesting that SiNPs improved unfolded protein response (UPR) and apoptosis. The present results indicated that the long-term and low-dose exposure to SiNPs could induce apoptosis by triggering ROS-mediated UPR in spermatocyte cells.

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Long-term (6-wk) hindlimb suspension inhibits spermatogenesis in adult male rats

Journal of Applied Physiology ◽

10.1152/japplphysiol.00931.2001 ◽

2002 ◽

Vol 92 (3) ◽

pp. 1191-1198 ◽

Cited By ~ 28

Author(s):

Joseph S. Tash ◽

Donald C. Johnson ◽

George C. Enders

Keyword(s):

Adult Male ◽

Inguinal Canal ◽

Space Station ◽

Male Rats ◽

Hindlimb Suspension ◽

Spermatogenic Cells ◽

Cage Floor ◽

Seminal Vesicle Weight ◽

The Impact

The International Space Station will allow extended habitation in space and long-term exposure to microgravity (μG). A concern is the impact of long-term μG exposure on the ability of species to reproduce. The model often used to simulate μG is rat hindlimb suspension (HLS), where the hindlimbs are elevated above the cage floor with a tail harness. Experiments described here are the first to examine the effect of long-term HLS on testicular function in adult male rats. Free-roaming (controls), animals with only the tail harnessed but hindlimbs in contact with the cage floor (TO), and HLS animals were tested for 6 wk. Cryptorchidism was prevented in TO and HLS animals by partial constriction of the inguinal canal with sutures. All parameters were compared at the end of the 6-wk experiment. Testicular weights and spermatogenesis were significantly reduced by HLS, such that no spermatogenic cells beyond round spermatids were present and epididymides were devoid of mature sperm. In many tubules, loss of all germ cells, except a few spermatogonia, resulting in histopathology similar to the Sertoli cell, was observed. Spermatogenesis appeared unaffected in control and TO animals. Sertoli and Leydig cell appearance, testosterone, luteinizing hormone, and follicle-stimulating hormone levels, and epididymal and seminal vesicle weight were unchanged by HLS. Cortisone was not elevated by HLS; thus stress may not be a factor. These results demonstrate that spermatogenesis is severely inhibited by long-term HLS, whereas testicular androgen production is not. These results have significant implications regarding serious effects of long-term exposure to μG on the reproductive capability of scrotal mammals, including humans.

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