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-β-estradiol), when administered to ovariectomized rats commencing 1 week before γ 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.

Expression and function of miRNA in postoperative radiotherapy sensitive and resistant patients of non-small cell lung cancer

“…Not only the spectrum of miRNA expressed in malignant cells is significantly different from that of normal counterpart cells but also miRNA expression profiles better classify poorly differentiated tumors as compared with the mRNA (EST)-based classifier [21]. Given this point, we hypothesize that the miRNA fingerprints in patients who are sensitive to radiotherapy are different from those who are resistant to radiotherapy.…”

Radiation cataract

“…More recently, in a series of papers, the contribution of gender and sex hormones to the development of radiation cataract, and the possibility of both negative and positive radioprotective effects of oestrogen in Co-60 gamma-irradiated rat eyes has been described (Dynlacht et al, 2006(Dynlacht et al, , 2008Henderson et al, 2009).…”

The Protective Effect of Curcumin on Ionizing Radiation-induced Cataractogenesis in Rats

“…L-carnitine, melatonin, Ginkgo biloba, vitamin E, estrogen, metalloporphyrin and verapamil protected irradiation-induced cataract development by virtue of their antioxidant properties (2,11,12,16,17,19,22,23,40,41). The investigators measured MDA and the antioxidant enzyme levels such as SOD, catalase, total antioxidant in the lens tissues and graded the lens opacification.…”