title: Estrogen protects against radiation-induced cataractogenesis.
abstract: Cataractogenesis is a complication of radiotherapy when the eye is included in the treatment field. Low doses of densely ionizing space radiation may also result in an increased risk of cataracts in astronauts. We previously reported that estrogen (17-beta-estradiol), when administered to ovariectomized rats commencing 1 week before gamma irradiation of the eye and continuously thereafter, results in a significant increase in the rate and incidence of cataract formation and a decreased latent period compared to an ovariectomized control group. We therefore concluded that estrogen accelerates progression of radiation-induced opacification. We now show that estrogen, if administered continuously, but commencing after irradiation, protects against radiation cataractogenesis. Both the rate of progression and incidence of cataracts were greatly reduced in ovariectomized rats that received estrogen treatment after irradiation compared to ovariectomized rats. As in our previous study, estradiol administered 1 week prior to irradiation at the time of ovariectomy and throughout the period of observation produced an enhanced rate of cataract progression. Estrogen administered for only 1 week prior to irradiation had no effect on the rate of progression but resulted in a slight reduction in the incidence. We conclude that estrogen may enhance or protect against radiation cataractogenesis, depending on when it is administered relative to the time of irradiation, and may differentially modulate the initiation and progression phases of cataractogenesis. These data have important implications for astronauts and radiotherapy patients.
authors.affiliation: Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA. jdynlach@iupui.edu
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Dynlacht
authors.forename: Shailaja
authors.initials: S
authors.lastname: Valluri
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lopez
authors.forename: Falon
authors.initials: F
authors.lastname: Greer
authors.forename: Colleen
authors.initials: C
authors.lastname: Desrosiers
authors.forename: Andrea
authors.initials: A
authors.lastname: Caperell-Grant
authors.forename: Marc S
authors.initials: MS
authors.lastname: Mendonca
authors.forename: Robert M
authors.initials: RM
authors.lastname: Bigsby
mesh_terms: D000818:Animals; D002386:Cataract / Q000209:etiology* / Q000473:pathology / Q000517:prevention & control*; D004967:Estrogens / Q000008:administration & dosage / Q000494:pharmacology*; D005123:Eye / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects; D005260:Female; D011829:Radiation Dosage; D011833:Radiation Injuries, Experimental / Q000473:pathology / Q000517:prevention & control*; D018787:Radiation Oncology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D004967:Estrogens