Med.Weter. D0:dx.doi.org/10.21521/mw.6473 Praca oryginalna Original paper Comparison of neuroglobin distribution and expression between the retina of the adult Bactrian camel,rabbits and sheep1) XIAOHUA DU,JAMES BLACKAR MAWOLO*,XIA LIU* College of Veterinary Medicine,*College of Life Science and Technology, Gansu Agricultural University,Lanzhou City,Gansu Province,People's Republic of China Received 01.06.2020 Accepted 10.07.2020 Du X.,Mawolo J.B.,Liu X. Comparison of neuroglobin distribution and expression between the retina of the adult Bactrian camel, rabbits and sheep Summary Neuroglobin(Ngb)is a kind of protein largely expressed in the brain and retina of mammals.Numerous studies have reported on Ngb expression and distribution in mammals but none have compared the expression in the adult Bactrian camel,rabbits,and sheep.The study examined the distribution and expression of Ngb between the retina of adult Bactrian camel,rabbits,and sheep and provides detailed insight on the morphology of these mammals'retinae.The immunohistochemical staining procedures were performed to detect Ngb distribution and its expression in the retinae of the adult Bactrian camel,rabbits,and sheep.The results showed that strong positive Ngb expression was found in all layers of the Bactrian camel except the outer nuclear layer,while in the rabbit retina,the strong positive expression was observed in the cortex of the optic nerve fiber layer,the retina cells layer,the network layer,the photoreceptor inner segment,and the pigment,while weak positive expression was shown in the retina of the kernel layer,outside the outer nuclear layer of the retina and the light receptor section.In the adult sheep retina,Ngb was solely expressed in the nerve fiber layer,inner and outer plexiform layer,optic nerve,inner and outer limiting membrane,and photoreceptor inner segment,while weak positive expression was shown in the ganglion cell layer and inner nuclear layer.There exist no Ngb positive expression in the photoreceptor outer segment,the outer nuclear layer,and retinal pigment epithelium of the adult sheep retina.The study documented that Ngb may have a significant function in the maintenance of retinal oxygen homeostasis and participation in the repair of light damage.The study also provided detailed references for Ngb physiological function and its relationship to extreme environmental conditions. Keywords:Neuroglobin,retina,immunohistochemistry,Bactrian camel,rabbit and sheep Neuroglobin (Ngb)is a neuronal hemeprotein ofoxygen consumption(8).Scientists have studied the similar to myoglobin and hemoglobin and shares their expression of Ngb in the retina of rodents and humans capability for oxygen binding.Research has shown that (10,11)and reported significant references about these Ngb expression in the retina is higher than other neural animals.The expression level of Ngb in the retina is tissues,and its concentration is about 50-100 times much higher than in the brain tissue(12,13),suggest- (26).Yu et al.reported that in species with vascularized ing that there exists a close relationship between Ngb retina,oxygen is transported to the retina in combina- and retinal functions.Studies have shown that Ngb is tion with the choroidal vascular bed.which is located involved in the elimination of reactive oxygen species at the back of the retina and is the highest consumer of (ROS)regulation which may play an important role in oxygen(5).Another study confirmed that the ocular tis- oxygen homeostasis(14).Further research conducted sues in the retina are unique and have the highest rates by Ostoji et al.reported that the expression of Ngb was The research project was funded by the National Natural Science Foundation solely found in the ganglion cell layer,inner nuclear of China(Grant No.31760305),The Youth Foundation of Gansu Agricultural layer,inner and outer plexiform layers,and retinal pig- University (Grant No.GAU-QNDS-201501),and the National Natural Foun- dation of Gansu Province(Grant No.17JR5RA142).The funders had no role in ment epithelium but not in the glial,suggesting that study design,data collection,and analysis,decision to publish,or preparation Ngb could serve a neuroprotective role as scavengers of the manuscript. of reactive oxygen species and developing therapeuticMed. Weter. 1 Praca oryginalna Original paper DOI: dx.doi.org/10.21521/mw.6473 Neuroglobin (Ngb) is a neuronal hemeprotein similar to myoglobin and hemoglobin and shares their capability for oxygen binding. Research has shown that Ngb expression in the retina is higher than other neural tissues, and its concentration is about 50-100 times (26). Yu et al. reported that in species with vascularized retina, oxygen is transported to the retina in combina￾tion with the choroidal vascular bed, which is located at the back of the retina and is the highest consumer of oxygen (5). Another study confirmed that the ocular tis￾sues in the retina are unique and have the highest rates of oxygen consumption (8). Scientists have studied the expression of Ngb in the retina of rodents and humans (10, 11) and reported significant references about these animals. The expression level of Ngb in the retina is much higher than in the brain tissue (12, 13), suggest￾ing that there exists a close relationship between Ngb and retinal functions. Studies have shown that Ngb is involved in the elimination of reactive oxygen species (ROS) regulation which may play an important role in oxygen homeostasis (14). Further research conducted by Ostoji et al. reported that the expression of Ngb was solely found in the ganglion cell layer, inner nuclear layer, inner and outer plexiform layers, and retinal pig￾ment epithelium but not in the glial, suggesting that Ngb could serve a neuroprotective role as scavengers of reactive oxygen species and developing therapeutic Comparison of neuroglobin distribution and expression between the retina of the adult Bactrian camel, rabbits and sheep1) XIAOHUA DU, JAMES BLACKAR MAWOLO*, XIA LIU* College of Veterinary Medicine, *College of Life Science and Technology, Gansu Agricultural University, Lanzhou City, Gansu Province, People’s Republic of China Received 01.06.2020 Accepted 10.07.2020 Du X., Mawolo J. B., Liu X. Comparison of neuroglobin distribution and expression between the retina of the adult Bactrian camel, rabbits and sheep Summary Neuroglobin (Ngb) is a kind of protein largely expressed in the brain and retina of mammals. Numerous studies have reported on Ngb expression and distribution in mammals but none have compared the expression in the adult Bactrian camel, rabbits, and sheep. The study examined the distribution and expression of Ngb between the retina of adult Bactrian camel, rabbits, and sheep and provides detailed insight on the morphology of these mammals’ retinae. The immunohistochemical staining procedures were performed to detect Ngb distribution and its expression in the retinae of the adult Bactrian camel, rabbits, and sheep. The results showed that strong positive Ngb expression was found in all layers of the Bactrian camel except the outer nuclear layer, while in the rabbit retina, the strong positive expression was observed in the cortex of the optic nerve fiber layer, the retina cells layer, the network layer, the photoreceptor inner segment, and the pigment, while weak positive expression was shown in the retina of the kernel layer, outside the outer nuclear layer of the retina and the light receptor section. In the adult sheep retina, Ngb was solely expressed in the nerve fiber layer, inner and outer plexiform layer, optic nerve, inner and outer limiting membrane, and photoreceptor inner segment, while weak positive expression was shown in the ganglion cell layer and inner nuclear layer. There exist no Ngb positive expression in the photoreceptor outer segment, the outer nuclear layer, and retinal pigment epithelium of the adult sheep retina. The study documented that Ngb may have a significant function in the maintenance of retinal oxygen homeostasis and participation in the repair of light damage. The study also provided detailed references for Ngb physiological function and its relationship to extreme environmental conditions. Keywords: Neuroglobin, retina, immunohistochemistry, Bactrian camel, rabbit and sheep 1) The research project was funded by the National Natural Science Foundation of China (Grant No. 31760305), The Youth Foundation of Gansu Agricultural University (Grant No. GAU-QNDS-201501), and the National Natural Foun￾dation of Gansu Province (Grant No. 17JR5RA142). The funders had no role in study design, data collection, and analysis, decision to publish, or preparation of the manuscript