甲状腺素腹腔注射对负透镜诱导近视豚鼠生长发育和屈光状态的影响

Effects of intraperitoneal injection of thyroxine on growth and refractive status of myopic guinea pigs induced by negative lens

目的观察甲状腺素腹腔注射对负透镜诱导近视豚鼠生长发育和屈光状态的影响。方法2周龄三色短毛健康雄性豚鼠36只,随机分为对照组、模型组和实验组,各12只。实验组给予左旋甲状腺素钠水溶液0.05 mg/kg腹腔注射,对照组和模型组注射等量生理盐水,每日1次,注射4周。从注射第4天起,模型组、实验组右眼佩戴-6.00 D透镜,左眼不戴镜作为自身对照;对照组双眼不戴镜。造模期间观察各组豚鼠一般情况并测量体质量和肛温。造模4周后检测血清游离三碘甲状腺原氨酸(FT_(3))、游离甲状腺素(FT_(4))、雌二醇(E_(2))、睾酮(T)、环磷酸腺苷(cAMP)、环磷酸鸟苷(cGMP),检测各组豚鼠双眼散瞳后屈光度和眼轴长度,观察眼球后极部巩膜厚度。结果造模后实验组豚鼠体质量下降明显,肛温升高,活动频率增高,毛发枯槁无光泽、易脱落,多食消瘦,大便干结色黑,易怒躁动,兴奋好斗,不易被抓取;对照组和模型组豚鼠体征正常。造模4周后,模型组体质量高于实验组(P<0.05)。从造模第2周开始,实验组肛温高于模型组(P均<0.05)。实验组造模后血清FT_(3)、FT_(4)、E_(2)、cAMP、cAMP/cGMP水平高于对照组和模型组,T水平低于对照组和模型组(P均<0.05)。模型组屈光度和两眼屈光度差值低于对照组,眼轴和两眼眼轴差值长于对照组(P均<0.05);实验组造模眼屈光度和两眼屈光度差值低于模型组,左右眼眼轴短于模型组,左右眼眼轴差值高于模型组(P均<0.05)。实验组豚鼠眼球后极部巩膜厚度较模型组变薄,胶原纤维最细、最稀疏,间隙最大,且部分纤维出现断裂。结论甲状腺素作用后,负透镜诱导的近视豚鼠生长发育受到影响,激素水平发生变化,并可导致豚鼠近视程度加深。

Objective To observe the effects of intraperitoneal injection of thyroxine on the growth and refractive status of myopia guinea pigs induced by negative lens.Methods Thirty-six two-week-old pigmented short-haired male guinea pigs were randomly divided into the normal control group(NC group),lens-induced myopia group(LIM group),and thyroxine+lens-induced myopia group(TH+LIM group),with 12 in each group.The guinea pigs in the TH+LIM group were intraperitoneally injected with levothyroxine sodium aqueous solution at a dose of 0.05 mg/kg daily;guinea pigs in the NC group and LIM group were injected with the same amount of normal saline once a day for 4 weeks.Since the 4th day,the guinea pigs in the LIM group and TH+LIM group all wore-6.00D lens in the right eyes,while guinea pigs of NC group did not wear glasses.During modeling,the general conditions of guinea pigs in each group were observed and their bodyweight and anal temperature were measured.Four weeks after modeling,free triiodothyronine(FT_(3)),free thyroxine(FT_(4)),estradiol(E2),testosterone(T),cyclic adenosine monophosphate(cAMP)and cyclic guanosine monophosphate(cGMP)were detected in serum.After mydriasis,the refraction and axial length of guinea pigs in each group were measured,and the sclera thickness of the posterior pole of eyes were observed.Results After modeling,the bodyweight of guinea pigs in the TH+LIM group decreased obviously and the anal temperature increased.They showed symptoms such as frequent activity,eating too much but losing weight,black and dry stools,irritability,aggression and difficulty grasping,and the hair was dull and easy to fall off.The guinea pigs in the LIM group and the NC group behaved normally.At 4 weeks after modeling,the bodyweight of guinea pigs in the LIM group were heavier than that of the TH+LIM group(P<0.05).From the second week of modeling,the anal temperature of the TH+LIM group was higher than that of the LIM group(P<0.05).After modeling,the levels of serum FT_(3),FT_(4),E2,cAMP and cAMP/cGMP in the TH+LIM group were higher than those in the NC group and the LIM group,while the levels of T were lower than those in the NC group and the LIM group(all P<0.05).The refraction and the difference of refraction between two eyes in the LIM group were lower than that of the NC group,and the axial length and the difference of axial length between two eyes were longer than that of the NC group(P<0.05).In the TH+LIM group,the refraction and the difference of refraction between two eyes were lower than that of the LIM group,and the axial length of two eyes were shorter than that of the LIM group,while the difference of axial length between two eyes were longer than that of the LIM group(P<0.05).Compared with the LIM group,the sclera thickness at the posterior pole of the guinea pigs in the TH+LIM group was thinner,and the collagen fibers were the thinnest and sparsest with the largest gap,and some fibers were broken.Conclusion After the treatment of thyroxine,the growth and development of negative lens-induced myopic guinea pigs are affected,the hormone levels change,and the degree of myopia deepens.