TY - JOUR

T1 - Neuroprotection Against NMDA-Induced Retinal Damage by Philanthotoxin-343 Involves Reduced Nitrosative Stress

AU - Mohamad, Mohamad Haiqal Nizar

AU - Abu, Izuddin Fahmy

AU - Fazel, Muhammad Fattah

AU - Agarwal, Renu

AU - Iezhitsa, Igor

AU - Juliana, Norsham

AU - Mellor, Ian R.

AU - Franzyk, Henrik

N1 - Funding Information: This work was supported by funding from the Ministry of Higher Education, Malaysia under the Fundamental Research Grant Scheme (FRGS/1/2017/SKK10/UNIKL/02/1). Funding Information: The authors thank the Ministry of Higher Education (MOHE) Malaysia for the financial support provided via the Fundamental Research Grant Scheme (ref no. FRGS/1/2017/SKK10/UNIKL/ 02/1). The authors acknowledge the technical assistance provided by Mohd Aizuddin Mohd Lazaldin, Lidawani Lambuk, Azliana Ahmad Jafri and Natasha Najwa Nor Arfuzir from Centre for Neuroscience Research (NeuRon), Universiti Teknologi MARA in running the experimental procedures. Publisher Copyright: Copyright © 2021 Mohamad, Abu, Fazel, Agarwal, Iezhitsa, Juliana, Mellor and Franzyk.

PY - 2021

Y1 - 2021

N2 - N-methyl-D-aspartate receptor (NMDAR) overstimulation is known to mediate neurodegeneration, and hence represents a relevant therapeutic target for neurodegenerative disorders including glaucoma. This study examined the neuroprotective effects of philanthotoxin (PhTX)-343 against NMDA-induced retinal injury in rats. Male Sprague Dawley rats were divided into three groups; group 1 received phosphate buffer saline as the negative control, group 2 was injected with NMDA (160 nM) to induce retinal excitotoxic injury, and group 3 was pre-treated with PhTX-343 (160 nM) 24 h before NMDA exposure. All treatments were given intravitreally and bilaterally. Seven days post-treatment, rats were subjected to visual behaviour assessments using open field and colour recognition tests. Rats were then euthanized, and the retinas were harvested and subjected to haematoxylin and eosin (H&E) staining for morphometric analysis and 3-nitrotyrosine (3-NT) ELISA protocol as the nitrosative stress biomarker. PhTX-343 treatment prior to NMDA exposure improved the ability of rats to recognize visual cues and preserved visual functions (i.e., recognition of objects with different colours). Morphological examination of retinal tissues showed that the fractional ganglion cell layer thickness within the inner retina (IR) in the PhTX-343 treated group was greater by 1.28-fold as compared to NMDA-treated rats (p < 0.05) and was comparable to control rats (p > 0.05). Additionally, the number of retinal cell nuclei/100 μm2 in IR for the PhTX-343-treated group was greater by 1.82-fold compared to NMDA-treated rats (p < 0.05) and was comparable to control group (p > 0.05). PhTX-343 also reduced the retinal 3-NT levels by 1.74-fold compared to NMDA-treated rats (p < 0.05). In conclusion, PhTX-343 pretreatment protects against NMDA-induced retinal morphological changes and visual impairment by suppressing nitrosative stress as reflected by the reduced retinal 3-NT level.

AB - N-methyl-D-aspartate receptor (NMDAR) overstimulation is known to mediate neurodegeneration, and hence represents a relevant therapeutic target for neurodegenerative disorders including glaucoma. This study examined the neuroprotective effects of philanthotoxin (PhTX)-343 against NMDA-induced retinal injury in rats. Male Sprague Dawley rats were divided into three groups; group 1 received phosphate buffer saline as the negative control, group 2 was injected with NMDA (160 nM) to induce retinal excitotoxic injury, and group 3 was pre-treated with PhTX-343 (160 nM) 24 h before NMDA exposure. All treatments were given intravitreally and bilaterally. Seven days post-treatment, rats were subjected to visual behaviour assessments using open field and colour recognition tests. Rats were then euthanized, and the retinas were harvested and subjected to haematoxylin and eosin (H&E) staining for morphometric analysis and 3-nitrotyrosine (3-NT) ELISA protocol as the nitrosative stress biomarker. PhTX-343 treatment prior to NMDA exposure improved the ability of rats to recognize visual cues and preserved visual functions (i.e., recognition of objects with different colours). Morphological examination of retinal tissues showed that the fractional ganglion cell layer thickness within the inner retina (IR) in the PhTX-343 treated group was greater by 1.28-fold as compared to NMDA-treated rats (p < 0.05) and was comparable to control rats (p > 0.05). Additionally, the number of retinal cell nuclei/100 μm2 in IR for the PhTX-343-treated group was greater by 1.82-fold compared to NMDA-treated rats (p < 0.05) and was comparable to control group (p > 0.05). PhTX-343 also reduced the retinal 3-NT levels by 1.74-fold compared to NMDA-treated rats (p < 0.05). In conclusion, PhTX-343 pretreatment protects against NMDA-induced retinal morphological changes and visual impairment by suppressing nitrosative stress as reflected by the reduced retinal 3-NT level.

KW - excitotoxicity

KW - glaucoma

KW - N-methyl-D-aspartate receptor

KW - N-methyl-D-aspartate receptor overstimulation

KW - neurodegeneration

KW - philanthotoxin-343

KW - retinal ganglion cell

KW - visual behavioural analysis

U2 - 10.3389/fphar.2021.798794

DO - 10.3389/fphar.2021.798794

M3 - Journal article

C2 - 34970151

AN - SCOPUS:85121981742

VL - 12

JO - Frontiers in Pharmacology

JF - Frontiers in Pharmacology

SN - 1663-9812

M1 - 798794

ER -