Functional and morphological alterations in a glaucoma model of acute ocular hypertension

7,8-Dihydroxiflavone Maintains Retinal Functionality and Protects Various Types of RGCs in Adult Rats with Optic Nerve Transection

“…The scotopic threshold responses are thought to reflect RGC activity [ 75 , 76 , 77 ]. Our longitudinal analysis showed in vehicle-treated retinas a significant progressive and permanent reduction of the pSTR that likely reflects the massive loss of RGCs, and is in agreement with previous studies following optic nerve axotomy [ 67 , 68 , 74 ] and other types of retinal injury such as acute [ 70 , 78 ] or chronic [ 79 , 80 , 81 ] elevation of the intraocular pressure. In contrast, the DHF-treated retinas showed a much smaller reduction of the pSTR, which was first significantly smaller by day five, but did not progress further until d 21, suggesting that the larger population of rescued RGCs contributes to the greater amplitude of the pSTR, thus indicating that DHF not only protected RGCs against IONT-induced cell loss, but preserved their function.…”

“…This response provides a wave with two components, one positive (pSTR) and one negative (nSTR). In this work we have focused on the positive component of the wave that is directly related to the depolarization of the RGCs [ 67 , 70 ], and is measured from baseline to the highest point of the wave that was generated under normal conditions at approximately 130 ms after stimulus presentation ( Figure 1 ). In our experimental vehicle- and DHF-treated groups the pSTR was reduced by 5 d to 40% when compared to control ( p = 0.001, One-way Anova).…”

“…Although ERG changes related to optic nerve injury have been previously documented [ 67 , 68 , 70 , 74 ], it was unknown if DHF-afforded rescue of axotomized RGCS also involved protection of retinal function. The scotopic threshold responses are thought to reflect RGC activity [ 75 , 76 , 77 ].…”

“…Longitudinal ERG recordings were registered simultaneously from both eyes of the same rats as follows: (i) at five and seven days (DHF n = 24; Veh n = 18) (ii) at 10, 12 and 14 days (DHF n = 16; Veh n = 12), and; (iii) at 21 days (DHF n = 8; Veh n = 6). For the electroretinographic study we used previously described methods in our laboratory [ 67 , 68 , 70 , 111 ]. In brief, after dark adaptation for 12 h, animals were anaesthetized, both eyes were dilated with topical mydriatic (Tropicamida 1% ® , Alcon-Cusí, S.A., El Masnou, Barcelona, Spain) and electroretinogram (ERG) recordings were performed under red light, while animals were kept on a heating pad at 37 °C.…”

“…Image reconstructions of flattened immunolabelled retinas were obtained as described [ 70 ]. In brief, using an epifluorescence microscope (Leica DM6-B; Leica Microsytems, Wetzlar, Germany), the retinas were photographed (×10) in a raster-scan pattern without overlap or gap between images.…”