Injury to the blood-testis barrier after low-dose-rate chronic radiation exposure in mice

Exposure to ionising radiation induces male infertility, accompanied by increasing permeability of the blood-testis barrier. However, the effect on male fertility by low-dose-rate chronic radiation has not been investigated. In this study, the effects of low-dose-rate chronic radiation on male mice were investigated by measuring the levels of tight-junction-associated proteins (ZO-1 and occludin-1), Niemann-Pick disease type 2 protein (NPC-2) and antisperm antibody (AsAb) in serum. BALB/c mice were exposed to low-dose-rate radiation (3.49 mGy h(-1)) for total exposures of 0.02 (6 h), 0.17 (2 d) and 1.7 Gy (21 d). Based on histological examination, the diameter and epithelial depth of seminiferous tubules were significantly decreased in 1.7-Gy-irradiated mice. Compared with those of the non-irradiated group, 1.7-Gy-irradiated mice showed significantly decreased ZO-1, occludin-1 and NPC-2 protein levels, accompanied with increased serum AsAb levels. These results suggest potential blood-testis barrier injury and immune infertility in male mice exposed to low-dose-rate chronic radiation.

[Microwave radiation decreases the expressions of occludin and JAM-1 in rats]

OBJECTIVE

To explore the changes in the expressions of the tight junction related protein occludin and junctional adhesion molecule-1 (JAM-1) of the blood-testis barrier and their significance in rats after microwave radiation.

METHODS

Eighty male Wistar rats were exposed to microwave radiation with average power density of 0, 10, 30 and 100 mW/cm2 for five minutes, and dynamic changes in the expressions of testicular occludin and JAM-1 were observed by Western blot and image analysis at 6 h, 1 d, 3 d, 7 d and 14 d after the radiation.

RESULTS

There was a significant down-regulation in the expression of the occludin protein at 3 - 7 d, 6 h - 7 d and 6 h - 14 d (P < 0. 05), as well as in that of JAM-1 at 3 - 7 d, 1 - 7 d and 1-14 d (P < 0.05) after exposure to 10, 30 and 100 mW/cm2 microwave radiation.

CONCLUSION

The decreased protein expressions of occludin and JAM-1 may play an important role in the microwave radiation induced-damage to the blood-testis barrier.

[High power microwave radiation damages blood-testis barrier in rats]

OBJECTIVE

To determine the effect of high power microwave (HPM) radiation on the structure and function of blood-testis barrier (BTB) in rats.

METHODS

One hundred and sixty-six male Wistar rats were treated by heart perfusion of lanthanum-glutaraldehyde solution and tail vein injection of evans blue (EB) at 6 h, 1, 3, 7 and 14 d after exposed to 0, 10, 30 and 100 mW/cm2 HPM radiation for 5 minutes, the structural change of BTB and distribution of lanthanum or EB observed through the light microscope, electron microscope and laser scanning confocal microscopy (LSCM).

RESULTS

Testicular interstitial edema, vascular congestion or hyperemia with accumulation of plasma proteins and red blood cells in the inner compartment of seminiferous tubules were observed after exposure to HPM. The above-mentioned pathological changes were aggravated at 1-7 d and relieved at 14 d after radiation, obviously more severe in the 30 and 100 mW/cm2 exposure groups than in the 10 mW/cm2. Both lanthanum precipitation and EB were deposited in the inner compartment.

CONCLUSION

HPM radiation may damage the structure and increase the permeability of BTB.

Effect of electromagnetic pulse exposure on permeability of blood-testicle barrier in mice

OBJECTIVE

To study the effect of electromagnetic pulse (EMP) exposure on the permeability of blood-testicle barrier (BTB) in mice.

METHODS

Adult male BALB/c mice were exposed to EMP at 200 kV/m for 200 pulses with 2 seconds interval. The mice were injected with 2% Evans Blue solution through caudal vein at different time points after exposure, and the permeability of BTB was monitored using a fluorescence microscope. The testis sample for the transmission electron microscopy was prepared at 2 h after EMP exposure. The permeability of BTB in mice was observed by using Evans Blue tracer and lanthanum nitrate tracer.

RESULTS

After exposure, cloudy Evans Blue was found in the testicle convoluted seminiferous tubule of mice. Lanthanum nitrate was observed not only between testicle spermatogonia near seminiferous tubule wall and sertoli cells, but also between sertoli cells and primary spermatocyte or secondary spermatocyte. In contrast, lanthanum nitrate in control group was only found in the testicle sertoli cells between seminiferous tubule and near seminiferous tubule wall.

CONCLUSION

EMP exposure could increase the permeability of BTB in the mice.

Transferrin-mediated uptake of radionuclides by the testis

In an attempt to explain the deleterious effects of gonadal radionuclide localization, we examined the role of transferrin in testicular radionuclide uptake.

METHODS

In vivo testicular uptake and retention of the transferrin binding radionuclides 114mIn-citrate and 59Fe-citrate were compared with that of the nontransferrin binding isotopes 137Cs-citrate and Na125I for 63 days postinjection. Isotope uptake mechanisms were investigated in vitro using isolated seminiferous tubules and Sertoli cell monolayers grown in bicameral culture chambers.

RESULTS

Indium-114m, 59Fe and 137Cs were localized in the testis by 24 hr postinjection, but accumulation of 125I was minimal. Although testicular 114mIn remained constant, 59Fe declined slowly over the following 63 days and 137Cs fell very rapidly. When 114mIn- or 59Fe-loaded testes were fractionated, and markedly more 114mIn was associated with the seminiferous tubules than 59Fe, suggesting that 114mIn may be retained. In vitro uptake of 59Fe, 67Ga and 114mIn by isolated seminiferous tubules was inhibited by transferrin, but uptake of 137Cs and 125I was unaffected. Iron-59, 67Ga and 114mIn were retained by isolated tubules in contrast to 137Cs and 125I. Whereas 137Cs, 59Fe and 114mIn all crossed Sertoli cell monolayers, the rate of transcellular transport of 137Cs was faster than that of 59Fe or 114mIn, suggesting differences in the intracellular processing of transferrin binding and nontransferrin binding radionuclides.

CONCLUSION

These data suggest that some radionuclides may access the seminiferous epithelium through receptor-mediated endocytosis of transferrin. Such radionuclide localization could lead to continuous irradiation of the testes, resulting in mutagenic damage to spermatogenic cells.