Protective effect of Anisodamine on ionizing radiation damage of cochlea

Objective To explore protective effect of Anisodamine against injure of cochlea hair cells induced by ionizing radiation. Methods 50 healthy guinea pigs were randomly divided into 3groups: radiation group( n = 20) , anisodamine protective group( n = 20) and control group( n = 10). 20ears were observed in each group. Tempora of guinea pigs in anisodamine protective group and radiation group were exposed to fractional doses of 6 MeV electron beam produced by linear accelerators (2 Gy/d)with a total dose of 60 Gy. Animals were injected intramuscularly with anisodamine (20 mg/kg) in protection group and equal saline solution in irradiated group, respectively, 30 min pre-irradiation.Morphological and functional changes in the guinea pig cochlea were observed. Results After radiation,the average ABR threshold value of the radiation group (52. 27 ± 2.42 dB peSPL) was significantly higher than that of the anisodamine protection group (37.65 ± 1.92 dB peSPL, t = 2.01, P＜ 0.05 ), and outer fair cells of cochlea reduced greatly in quantity by observing the stretched preparations of cochlea basilar membrane ( F=135. 362, P＜ 0.05 ). Under transmission electron microscope, outer fair cells of cochlea in the radiation group had obscure boundaries and swelled to lose their original shapes. Meanwhile, cell implement and the nucleus were obviously obnormal after radiation. In the anisodamine protection group,the boundaries of cochlea outer fair cells were very clear and the cells swelled a little. Cell implement and nuclear envelope were complete. Cochlea outer fair cells in the control group were found to line up in order with no collapse and reduction in number under scanning electron microscope, but those in the radiation group collapsed obviously, reduced in number and aligned in a state of chaos, while the outer fair cells in the anisodamine protection group regularly posed on the whole and the collapse was occasionally found.Conclusions The 60 Gy radiation at fractioned dose on the tempuses of the guinea pigs could cause damage to the cochlea hair cells. Anisodamine might have a protective effect against radiation damage. Key words: Radiational Damage; Cochlea; Guinea pings; Anisodamine; Radioprotective effect