Radiation induced inflammatory changes in the mouse bladder: the role of cyclooxygenase-2.
OBJECTIVE
We assessed the effect of irradiation on COX-2 expression in blood vessels of the mouse bladder wall during the early and late radiation response phases. Vasodilatation was quantified as an additional marker of inflammation related to COX-2 activity.


METHODS
Female C3H/Neu mice were irradiated with a single dose of 20 Gy. The intensity of the COX-2 immunohistochemical staining signal was assessed using an arbitrary semiquantitative score of 0 to 3. To evaluate vasodilatation the percent of the bladder wall covered by the lumen of the blood vessels, depicted as vascular area, was determined.


RESULTS
Constitutive COX-2 expression was found in the tunica intima and media of bladder blood vessels. During the early response significant biphasic changes were detected in the COX-2 staining signal as well as in the vascular area with peak values on days 4 and 16 after irradiation. A significant association was found between vascular area and COX-2 expression in blood vessels during the early radiation response (p <0.0001). No changes in COX-2 expression were observed during the late phase, that is between days 90 and 360 after irradiation. Minor vasodilatation seen during the late phase did not correlate with COX-2 activity.


CONCLUSIONS
Irradiation resulted in pronounced COX-2 dependent inflammatory changes in the bladder wall during the early but not during the late radiation reaction. Therefore, a potential effect of COX-2 inhibition on early radiation side effects in the bladder can be proposed.
Jaal
Jana
J
Clinic of Radiotherapy and Radiation Oncology, University of Technology of Dresden, Dresden, Germany. Jana.Jaal@klinikum.ee
Dörr
Wolfgang
W
D000818:Animals; D001808:Blood Vessels / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000096:biosynthesis* / Q000502:physiology / Q000528:radiation effects; D003556:Cystitis / Q000201:enzymology* / Q000209:etiology*; D005260:Female; D051379:Mice; D008809:Mice, Inbred C3H; D011832:Radiation Injuries / Q000150:complications*; D001743:Urinary Bladder / Q000098:blood supply
D051546:Cyclooxygenase 2