Tat Wei Tay

Di(n-butyl) phthalate induces vimentin filaments disruption in rat sertoli cells: a possible relation with spermatogenic cell apoptosis.

With 3 figures

Disappearance of Vimentin in Sertoli Cells: A Mono(2-ethylhexyl) Phthalate Effect

The effects of mono(2-ethylhexyl) phthalate (MEHP) on 21-day-old C57Bl/6N mice and their Sertoli cell cultures were studied. Mice were given a single dose of 800 mg/kg MEHP by oral gavage and sacrificed 24 h later. At the same time, testes were harvested from another batch of mice for Sertoli cell cultures. Cultures were subsequently exposed to 0, 1, and 100 nmol/ml MEHP for 0, 3, 6, 12, and 24 h. An antivimentin antibody was used to detect intermediate filament changes in Sertoli cells. Meanwhile, detection of preapoptotic signals and presence of apoptotic cells were done using annexin V–FITC (fluorescein isothiocyanate) and TUNEL (deoxynucleotidyltransferase-mediated dUTP nick end labeling) analyses, respectively. In vivo results showed a correlation between the increase in TUNEL-positive cells and the vimentin disruption in treated mice. Toluidine blue staining of the Sertoli cell cultures showed the increased number and size of vacuoles in Sertoli cell cytoplasm. Vimentin immunohistochemistry showed gradual disappearance of vimentin in Sertoli cell cultures as time and dose increased. Some Sertoli cells were found to be annexin V–FITC positive, but no TUNEL-positive cells were found. Taken together, these results show that the appearance of vacuoles and the vimentin disappearance caused by MEHP in the Sertoli cells are related with each other and can be observed in relation to time. This can be used as an indicator of the loss of mechanical support for spermatogenic cells, which in the end causes apoptosis of spermatogenic cells.

Testicular Dynamics in Syrian Hamsters Exposed to Both Short Photoperiod and Low Ambient Temperature

The object of this study was to determine the details of morphological dynamics of spermatogenesis in Syrian hamsters exposed to both short photoperiod and low ambient temperature. Eight‐week‐old male hamsters, kept in a long photoperiod (14 h L, 10 h D), were transferred to a short photoperiod (6 h L, 18 h D) and kept there for 13 weeks to induce testicular regression. Some hamsters were then transferred from the room at 23°C to that at 5°C (5°C group). Remaining hamsters were continuously kept at 23°C (23°C group). Thereafter, the morphology was examined. As a result, it took only 8 weeks until spermatogenesis recovered in the 23°C group. However, it was not until 20 weeks that spermatogenesis was recognized in the 5°C group. As the regulation of seasonal testicular activity is characterized by coordinated shifts in the relationships among mitosis, meiosis, and apoptosis, the changes in the proliferative and apoptotic activities were examined. Although no significant difference in proliferative activity of spermatogonia between the 5°C and the 23°C groups was confirmed, a notable increase in the rate of apoptosis was observed in the 5°C group. Furthermore, this increase was more salient during the hibernation period. These findings suggest that both cold ambient temperature and hibernation caused the delay of testicular recrudescence and this delay arose from the increase of apoptotic activity but not the change in proliferative activity in spermatogonia in the 5°C group.

Single administration of di(n-butyl) phthalate delays spermatogenesis in prepubertal rats

Morphological alterations in seminiferous tubules caused by single administration of di(n-butyl) phthalate (DBP) in 3-week-old rats were investigated throughout the first wave of spermatogenesis. Single administration of DBP (500 mg/kg) showed progressive detachment and displacement of spermatogenic cells and disappearance of tubular lumen at 3h after treatment, and then showed thin seminiferous epithelia and wide tubular lumen at day 1 (D1). At D1, quite significant numbers of apoptotic spermatogenic cells were detected, and then they gradually decreased in accordance with the passage of time. In contrast, the testes revealed lower weight gain, even after completion of first wave of spermatogenesis in the DBP-treated group, compared to the control. In order to clarify whether spermatogenic cells differentiate into mature spermatids in the DBP-treated rats, immunohistochemical staining for Hsc 70t, a specific marker for elongate spermatids, was carried out. As a result, the decrease in mature spermatids in the DBP-treated testes, compared to the control, was demonstrated. For example, at D20 (41-day-old) after treatment, the most advanced spermatids in the tubules from rats in the DBP-treated groups were steps 2-4, while those of the control were steps 12-13. Moreover, in some tubules, pachytene spermatocytes were the most advanced spermatogenic cell. At D30 (51-day-old) after treatment, maturation of spermatogenic cells in the DBP-treated rats proceeded further, and the most advanced spermatids in tubules were steps 8-9, while those of the control were steps 15-19. These results lead us to the postulation that a single administration of DBP to prepubertal rats delays maturation of spermatogenic cells, even after completion of first wave of spermatogenesis.

Bisphenol A‐induced morphological alterations in Sertoli and spermatogenic cells of immature Shiba goats in vitro: An ultrastructural study

Background and aimsThere is no information currently available regarding the effects of bisphenol A (BPA) on testes in ruminants. Therefore, to establish and clarify the effects of BPA in ruminants, testicular tissue cultures were obtained from immature Shiba goats.MethodsThe testes of 2-month-old Shiba goats were cut into smaller pieces and seeded in medium. At 1, 3, 6 and 9 h after administration of various concentrations of BPA, the specimens underwent light and transmission electron microscopic observationsResultsAt 1 h after BPA treatment, vacuolization and nuclear membrane rupture appeared within the nudeoplasm and cytoplasm of Sertoli cells. Such alterations tended to gradually increase in number in time- and dose-dependent manners. Thus, because of BPA treatment, apoptotic spermatogenic cells, necrotic spermatogenic cells, apoptotic Sertoli cells and necrotic Sertoli cells could be identified. Particularly in the Sertoli cell, ruptured vesicles could be found within the multivesicular nuclear body.ConclusionThe treatment with BPA at a low concentration tends to lead spermatogenic and Sertoli cells to apoptosis, whereas a higher concentration tends to lead spermatogenic and Sertoli cells to necrosis. Therefore, this study showed that testicular tissue culture is an advantageous avenue for screening the testicular toxicity of chemicals in ruminants.

Verifying of endocrine disruptor chemical affect to the mouse testes: can raman spectroscopy support histology study?

One of suspect environmental endocrine disruptors that affect mouse male reproduction by altering the morphology of Sertoli cells and spermatogenic cells is phthalate. The effects of mono(2-ethylhexyl)phthalate (MEHP), one of metabolites of di(2-ethylhexyl)phthalate , on immature mouse testes in vivo were examined. We have recently shown that MEHP induced Sertoli cells necrosis and spermatogenic cells apoptosis in mice by TUNEL method, F-actin staining, and ultrastructural study, but there is no data for biochemical changing of testes due to those methods could not explore. To verify in detail of it, we conducted Raman spectroscopy study with 785 nm wavelength laser line, 50mW of laser power and 3 minutes of exposure time to analysis the MEHP-treated testicular tissue, which has been fixatived by 4% paraformaldehyde (PFA). Five weeks old (5 w.o) male mice were used in this experiment. As the results, the alterations were observed by Raman spectroscopy that there are significantly differences of DNA, actin filament, type IV collagen and amide I between control group (0 μM MEHP) and treatment group (100 μM MEHP). These results significantly support histology staining observation (such as the apoptotic spermatogenic cells which is associated with DNA fragmentation and F-actin disruption) and ultrastructural observation (such as mitochondria rupture and disintegration of nucleus membrane). Raman spectroscopy can be used for 4% PFA-fixatived tissue observation. However, we recommend that Raman spectroscopy may be able to be expanded as an armamentarium not just for the clarification of histology staining and ultrastructural study, but furthermore, it may be as a non-invasion assessment for screening animal tissue toxicity of chemical in future.