Beatriz Vidal-Villegas1, Johnny Di Pierdomenico2, Alejandro Gallego-Ortega2, Caridad Galindo-Romero2, Jose M Martínez-de-la-Casa3, Julian García-Feijoo3, María P Villegas-Pérez1, Manuel Vidal-Sanz4. 1. Servicio de Oftalmología, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), 28040 Madrid, Spain; Departamento de Oftalmología, Universidad de Murcia e Instituto Murciano de Investigación Biosanitaria (IMIB) Virgen de la Arrixaca. Campus de CC de la Salud, 30120, El Palmar, Murcia, Spain. 2. Departamento de Oftalmología, Universidad de Murcia e Instituto Murciano de Investigación Biosanitaria (IMIB) Virgen de la Arrixaca. Campus de CC de la Salud, 30120, El Palmar, Murcia, Spain. 3. Servicio de Oftalmología, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), 28040 Madrid, Spain. 4. Departamento de Oftalmología, Universidad de Murcia e Instituto Murciano de Investigación Biosanitaria (IMIB) Virgen de la Arrixaca. Campus de CC de la Salud, 30120, El Palmar, Murcia, Spain. Electronic address: manuel.vidal@um.es.
Abstract
PURPOSE: To analyze responses of different RGC populations to left intraorbital optic nerve transection (IONT) and intraperitoneal (i.p.) treatment with 7,8-Dihydroxyflavone (DHF), a potent selective TrkB agonist. METHODS: Adult albino Sprague-Dawley rats received, following IONT, daily i.p. injections of vehicle (1%DMSO in 0.9%NaCl) or DHF. Group-1 (n = 58) assessed at 7days (d) the optimal DHF amount (1-25 mg/kg). Group-2, using freshly dissected naïve or treated retinas (n = 28), investigated if DHF treatment was associated with TrkB activation using Western-blotting at 1, 3 or 7d. Group-3 (n = 98) explored persistence of protection and was analyzed at survival intervals from 7 to 60d after IONT. Groups 2-3 received daily i.p. vehicle or DHF (5 mg/kg). Retinal wholemounts were immunolabelled for Brn3a and melanopsin to identify Brn3a+RGCs and m+RGCs, respectively. RESULTS: Optimal neuroprotection was achieved with 5 mg/kg DHF and resulted in TrkB phosphorylation. The percentage of surviving Brn3a+RGCs in vehicle treated rats was 60, 28, 18, 13, 12 or 8% of the original value at 7, 10, 14, 21, 30 or 60d, respectively, while in DHF treated retinas was 94, 70, 64, 17, 10 or 9% at the same time intervals. The percentages of m+RGCs diminished by 7d-13%, and recovered by 14d-38% in vehicle-treated and to 48% in DHF-treated retinas, without further variations. CONCLUSIONS: DHF neuroprotects Brn3a + RGCs and m + RGCs; its protective effects for Brn3a+RGCs are maximal at 7 days but still significant at 21d, whereas for m+RGCs neuroprotection was significant at 14d and permanent.
PURPOSE: To analyze responses of different RGC populations to left intraorbital optic nerve transection (IONT) and intraperitoneal (i.p.) treatment with 7,8-Dihydroxyflavone (DHF), a potent selective TrkB agonist. METHODS: Adult albino Sprague-Dawley rats received, following IONT, daily i.p. injections of vehicle (1%DMSO in 0.9%NaCl) or DHF. Group-1 (n = 58) assessed at 7days (d) the optimal DHF amount (1-25 mg/kg). Group-2, using freshly dissected naïve or treated retinas (n = 28), investigated if DHF treatment was associated with TrkB activation using Western-blotting at 1, 3 or 7d. Group-3 (n = 98) explored persistence of protection and was analyzed at survival intervals from 7 to 60d after IONT. Groups 2-3 received daily i.p. vehicle or DHF (5 mg/kg). Retinal wholemounts were immunolabelled for Brn3a and melanopsin to identify Brn3a+RGCs and m+RGCs, respectively. RESULTS: Optimal neuroprotection was achieved with 5 mg/kg DHF and resulted in TrkB phosphorylation. The percentage of surviving Brn3a+RGCs in vehicle treated rats was 60, 28, 18, 13, 12 or 8% of the original value at 7, 10, 14, 21, 30 or 60d, respectively, while in DHF treated retinas was 94, 70, 64, 17, 10 or 9% at the same time intervals. The percentages of m+RGCs diminished by 7d-13%, and recovered by 14d-38% in vehicle-treated and to 48% in DHF-treated retinas, without further variations. CONCLUSIONS:DHF neuroprotects Brn3a + RGCs and m + RGCs; its protective effects for Brn3a+RGCs are maximal at 7 days but still significant at 21d, whereas for m+RGCs neuroprotection was significant at 14d and permanent.
Authors: Vivek Gupta; Nitin Chitranshi; Veer Gupta; Yuyi You; Rashi Rajput; Joao A Paulo; Mehdi Mirzaei; Maarten van den Buuse; Stuart L Graham Journal: Neuroscience Date: 2022-02-23 Impact factor: 3.708