title: Functional and morphological effects of β-estradiol in eyes with N-methyl-D-Aspartate-induced retinal neurotoxicity in rats.
abstract: Glutamate-mediated excitotoxicity, mainly induced by N-methyl-d-aspartate (NMDA) receptors, is known to cause retinal ganglion cell death in retinal ischemia, glaucoma, and several other retinal diseases. We evaluated the effects of β-estradiol (E2) against a single intravitreal injection of NMDA using a functional and morphological approach. Male rats were randomly divided into 3 treatment groups: (1) Control; (2) NMDA (intravitreal injection of 5 mM NMDA); and (3) NMDA + E2 (intravitreal injection of 5 mM NMDA and pretreatment with subcutaneous E2 implantation). Seven days after NMDA injection, full-field electroretinograms (ERGs) and quantitative morphological analyses using transverse sections of the retina were conducted. In the NMDA group, full-field ERGs showed reductions in the amplitudes of the negative-scotopic threshold response, rod response b-wave, oscillatory potentials, flicker response second b-wave and cone response b-wave. Morphological evaluations of transverse sections of the retina demonstrated a reduction in the thickness of the inner plexiform layer, increases in the thickness of the outer plexiform and outer nuclear layers, and a loss of cells in the ganglion cell layer. In the NMDA + E2 group, pretreatment with E2 prevented the aggravations in the amplitudes of the ERGs except for oscillatory potential 2 (OP2); however, no morphological differences between the NMDA and NMDA + E2 groups were seen. These findings indicate that E2 can protect retinal function against NMDA-induced neurotoxicity. In addition, these indications suggested that the effect of E2 may have therapeutic benefits in NMDA related diseases, such as retinal ischemia and glaucoma.
authors: Drug Safety Laboratory, Drug Safety and Pharmacokinetics Laboratories, Taisho Pharmaceutical Co., Ltd., 1-403, Yoshino-cho, Kita-ku, Saitama-shi 331-9530, Japan. h.yamashita@po.rd.taisho.co.jp
authors: Haruhiro
authors: H
authors: Yamashita
authors: Chiaki
authors: C
authors: Yamada-Nakayama
authors: Kazunari
authors: K
authors: Sugihara
authors: Satoshi
authors: S
authors: Tsuji
authors: Takanobu
authors: T
authors: Sakurai
authors: Yoshiki
authors: Y
authors: Ban
authors: Shunsuke
authors: S
authors: Tsutsumi
authors: Yasushi
authors: Y
authors: Sato