[Morphological observation of amifostine's protective effect on radiation induced early middle ear injury].

OBJECTIVE

To assess the radio-protective effect of amifostine on the middle ear in animal models by observing the morphological changes of middle ear mucosa.

METHOD

Adult guinea pigs (n=38) were divided into the radiation group, the radiation-amifostine group and the control group. The first two groups were exposed to total 45 Gy of Gamma radiation which was administered to the right ear of each guinea pig with 3.0 Gy/fraction, 5 times per week, using a cobalt-60 machine. And the radiation+amifostine group was pretreated with the radio protector amifostine 100 mg/kg intra-peritoneally 30 min before each fraction of radiation. Sterile saline was administered intra-peritoneally in radiation group before ear irradiation. Two normal guinea pigs given no treatment were chosen as the control. The tympanic bullas were removed and the mucosae was processed for light microscope and scanning electron microscope examination on the 2nd and 30th days post irradiation to observe mucosa thickness, leukocyte and cilia.

RESULT

Light microscope and scanning transmission electron microscope examination showed in radiation groups that the middle ear effusion occurred; the cilia and micro cilia fell off, fused or collapsed; their directions changed; the mucosa became thicker; and leukocytes were also found infiltrating into the mucosa. On the 30th day,the damage was more serious. As comparison, there was no manifest damage of the middle ear mucosa in radiation+amifostine group. The mucosa thickness and the leukocyte quantity of radiation group were obviously higher than that of radiation+amifostine group (P < 0.01).

CONCLUSION

The middle ear mucosa was found to change over time after irradiation. Amifostine has a protective effect on radiation induced early middle ear injury.