Background:
@EN The action of ultraviolet rays on DNA causes the main photobiologic response of cells to ultraviolet rays. To study this effect, tritiated thymidine autoradiography was used. Recently 5-bromo-2deoxyuridine(BrdU), an analogue of thymidine,
immunohistochemistry has been developed and is used in the detection of synthetic phase cells. Compared to autoradiography, there are several advantages of BrdU immunohistochemistry; a shorter processing time, no requirement of specific
facilites.
PUVA,
the combination method of UVA and Psoralen has lots of photobiologic effects.
@ES Objective:
@EN Using Brdu immunohistochemistry, the effect of PUVA on the DNA synthesis of tape stripped mouse epdermis was studied.
@ES Method:
@EN Mice stripped by adhesive tape for enhancing DNA synthesis were injected intraperitoneally with 50mg/kg of BrdU immediately after stripping and at 6, 12, 14, 16, 18, 20, 22, 24 and 48 hours after tape stripping for decision of the time for
PUVA. The
skin diopsies were taken and the specimens were stained by BrdU immunohistochemistry. Single systemic PUVA exposure was performed on the stripped epidermis in peak synthetic time after tape stripping. The irradiation dose of UVA was 5J/cm².
8-MOP
was
administered at 90 minutes before UVA irradiation via a feeding tube with the dose of 16mg/kg. Mice were injected intraperitoneally with 50mg/kg of BrdU immediately after PUVA and at 12, 24, 48, 72 hours, and 7 days after PUVA. The skin biopsies
were
taken and the specimens were stained by BrdU immunohistochemistry. Positively labeled cells were counted per 5mm epidermis.
@ES Result:
@EN The results can be summerized as follows :
1. The mean numbers of BrdU labeled cells of each groups according to time after tape stripping were 11.0±4.4 at immediate, 24.0±9.7 at 6 hours 31.4±18.1 at 12 hours, 55.0±16.1 at 14 hors, 25.8±9.7 at 16 hors, 44.2±15.7 at 18 hors,
47.6±15.6 at
20 hors, 33.4±12.3 at 22 hors, 38.0±16.3 at 24 hors, and 22.0±8.2 at 48 hors group. The mean number of BrdU labeled cells was observed at 14 hors after tape stripping (p<0.05). So by tape stripping DNA synthesis was enhanced maximally at 14
hours
after tape stripping.
2. The man numbers of BrdU labeled cells of each groups according to time after PUVA were 11.0±7.5 at immediate, 32.2±13.2 at immediate, 32.2±13.2 at 6hors, 26.4±13.4 at 24 hours, 18.0±3.4 at 48 hours, 40.3±8.3 at 72 hours, and 27.8±11.0
at
7
days group. The lowest number of BrdU labeled cells was observed immediately after PUVA(p<0.05). The decreasein the number of BrdU labeled cells significantly persisted 48 hours after PUVA(p<0.05).
@ES Conclusion:
@EN The inhibitory effect on DNA synthesis of PUVA might be sustained 48 hours after PUVA. DNA synthesis was recovered at 72 hours after PUVA and sustained for 7 days.(Kor J Dermatol 1993;31(5):738~745)
|