title: Restoration of endogenous substance P is associated with inhibition of apoptosis of retinal cells in diabetic rats.
abstract: This study was designed to investigate the alterations of substance P (SP) and its correlation with apoptosis of the retinal neurons in diabetic rats. The study was carried out with diabetic rats induced by streptozotocin. Changes of SP and its mRNA were examined using enzyme-linked immunosorbent assay and reverse transcription polymerase chain reaction. The effect of restoration of SP level by capsaicin (20mg/kg, s.c.) on the apoptosis of the retinal cells was studied. The apoptosis was evaluated by change of ratio of the apoptotic cells and caspase-3 activity in the retina. It was found that increase in apoptosis of retinal cells, by 3.5 fold of control, was accompanied by reduction of SP, by 28% in protein and 32% in the mRNA in the retina at 10 weeks of induction of diabetes, compared to the controls. Capsaicin significantly elevated endogenous SP, by 29% in the mRNA and 17% in protein in the retina, with marked inhibition of the apoptosis and the activity of caspase-3 in the diabetic rats. Induction of diabetes leads to the increase of cell apoptosis and the decrease of SP in the retina. The reduction of the endogenous SP and the increase of the cell apoptosis in the retina of the diabetic rats were reversed by pretreatment with capsaicin. Restoration of SP in the retina may be a novel option for prevention of the retinal injury during development of diabetes.
authors.affiliation: Department of Comprehensive Examination for Eye Diseases, Shanxi Eye Hospital, PR China. Electronic address: 13603566922@163.com.
authors.forename: Ji-Hong
authors.initials: JH
authors.lastname: Yang
authors.forename: Zheng
authors.initials: Z
authors.lastname: Guo
authors.forename: Ting
authors.initials: T
authors.lastname: Zhang
authors.forename: Xian Xian
authors.initials: XX
authors.lastname: Meng
authors.forename: Li-Sha
authors.initials: LS
authors.lastname: Xie
mesh_terms: D000818:Animals; D017209:Apoptosis; D002211:Capsaicin / Q000494:pharmacology; D003921:Diabetes Mellitus, Experimental / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D003930:Diabetic Retinopathy / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000473:pathology*; D012165:Retinal Ganglion Cells / Q000378:metabolism; D013373:Substance P / Q000235:genetics / Q000378:metabolism*
chemical_list: D013373:Substance P; D002211:Capsaicin
keywords: Apoptosis; Capsaicin; Diabetic retinopathy; ELISA; ELM; GCL; INL; Retina; SP; STZ; Substance P (SP); TUNEL; enzyme linked immunosorbent assay; external limiting membrane; ganglion cell layer; inner nuclear layer; s.c; streptozotocin; subcutaneous injection; substance P; terminal deoxynucleotidyl transferase dUTP nick end labeling