| Objective: To research the mechanism of different wavelength of flashing light inducing guinea pig to form myopia, and to determine the relationship with Muscarinic acetylcholine 1 receptor.Methods: In this experiment, 24 fifteen-day-old to twenty-day-old guinea pigs with the same refraction in both eyes were selected. They were divided stochasticly into 6 groups, each group has 4 guinea pig: the first group was in a closed tightly paper box and irradiated by red flashing light, the second group was in a closed tightly paper box and irradiated by yellow flashing light, the third group was in a closed tightly paper box and irradiated by green flashing light, the fourth group was in a closed tightly paper box and irradiated by white flashing light, the fifth group was in a space-limited paper box and irradiated by natural light, the sixth group was in a sight-widen cage and irradiated by natural light. Before experiment and after & weeks, refaction was measured by using retinoscopy and the ocular axial was determined by A-scan ultransonography. At the end of experiment, guinea pigs were given over dose of pentobarbital and dead. The eyes were enucleated and residual orbital tissue carefully removed. Ocular weight was recorded by electric scale. Then anterior ocular tissues and vitreous body were removed. Posterior retina, choroids and sclera were carefully dissected. The totaltissue iiA was extracted from the posterior retina, choroids and sclera respecti?*ly. The expression of mRNA of Ml receptor in posterior retina, choroid^TSnd sclera was detected by quantitative analysis of products of reverse—transcription polyserase chain reaction.Results: Before experiment, the refaction of the first group is+ 3>09±Q. 7SD, the ocular axial length is 1. 58+0. 31 m; the refaction of the second group is +2?93d;1.02D, the ocular axial length is 7. 54± 0.43?- the refaction of the third group is +2. 86±0.22D, the ocular axial length is 7. 51±0.22 ??; the refaction of the fourth group is + 3.17±0,i8By the ocular;axial length is 7.61±0.55m; the refaction of the fifth group is +3.05+J. 54D, the ocular axial length is 7.66±0.16 flW; the refaction of the sixth group is +2.89 + 0.96 0, the ocular axial length i# 7.53±0. 34 MB; fey statistic analysis, there is no remarkable difference in refaction and axial length among 6 groups (P>0.05). After 8 weeks, the refaction of the first group is ~8. 75±1.13D, the ocular axial length is 8.96±0.18?; the refaction of the second group is ~6- 56 ±0.98$> the ocular axial length is 8.61+0. 27 ?; the refaction of the third group is -3.88+0.87D, the ocular axial length is 8. 32±0*78?; the refaction of the fourth group is -4.84±0.76D, the ocular axial length is 8.42+0. 49 am; the refaction of the fifth group is +0.75± 0. 59D, the ocular axial length is 8.10±0. 35 ram; the refaction of the sixth group is +1.69±0. 70B, the ocular axial length is 8. 00+0.53 HB; by statistic analysis, there is remarkable difference in refaction, axial length and eye weight: among I Vgroups, remarkable difference among II $ groups, remarkable difference among III V groups, remarkable difference among IV Vgroups, remarkable difference among I IIIH groups, remarkable difference among V $1 groups. Reverse-transcription polymerase chain reaction shows that there is expression of mRNA of Ml receptor in sclera and retina, but not in choroids in guinea pigs among6 group. Ijnage analysis shows that the product of inRMA of Ml receptor in posterior selera is 30.12±2.16 in first group, 38. 75±3. 47 in second group, 58.40+2.73 in third group, 57.19+3.32 in fourth group, 70.59 + 1.89 in fifth group, and 72.60+2.81 in sixth group. The expression of twRNA of 111 receptor in posterior sclera in light-stimulated group is remarkably lower than in the normal group. The product of mRNA of Ml receptor iia posterior retina is 31.82±3.39 in first group, 35. 54±2.97 in second group, 56.38±3.34 in third group, 55.67±2. 53 in fourth group, 70.16 ±2,45 in fifth group, and 73.34 + 2.83 in sixth group. The expression of mRNA of 111 receptor in posterior retina in light-stimulated group is rwarkably lower than in the normal group.Conclusion: After stimulated by different wavelength of flashing light for 9 weeks, myopia has come into being in guinea pigs. Different wavelength of unique flashing light has different influences in myopia, red light(TJiOnm)>yellow light(550nm)>green light(480nm). The gene transcription of Ml receptor exist in posterior retina and sclera, but not in choroid The expression of fliKNA of Muscarinic acetylcholijie 1 receptor in sclera mni in retina has reduced in guinea pigs which were stimulated by different wavelength of flashing light.
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