ABSTRACT: Aim: To identify the genes and non-coding RNAs (ncRNAs) involved in the neuroprotective actions of a dietary anti-oxidant (saffron) and of photobiomodulation. Methods: We used a previously published assay of photoreceptor damage, in which albino Sprague Dawley rats raised in dim cyclic illumination (12h 5 lux, 12h darkness) are challenged by 24h exposure to bright (1,000 lux) light. Experimental groups were protected against light damage by pretreatment with dietary saffron (1mg/kg/day for 21d) or photobiomodulation (10 J/cm2 at the eye, daily for 5d). RNA from 1 eye of each of 4 animals in each of the 6 experimental groups (control, light damage (LD), saffron, photobiomodulation (PBM), saffronLD, and PBMLD) was hybridized to Affymetrix rat genome ST arrays. Quantitative real-time PCR analysis of 14 selected genes was used to validate microarray results. Results: LD caused the regulation of 175 entities (genes and ncRNAs) beyond criterion levels (P < 0.05 in comparisons with controls, fold-change >2). PBM pretreatment reduced the expression of 126 of these 175 LD-regulated entities below criterion; saffron pretreatment reduced the expression of 53 entities (50 in common with PBM). In addition, PBM pretreatment regulated the expression of 67 entities not regulated by LD, while saffron pretreatment regulated 122 entities not regulated by LD (48 in common with PBM). PBM and saffron, given without LD, regulated genes and ncRNAs beyond criterion levels, but in lesser numbers than during their protective action. A high proportion of the entities regulated by LD (>90%) were known genes; by contrast, ncRNAs where prominent among the entities regulated by PBM and saffron in their neuroprotective roles (73% and 62% respectively). Conclusions: Given alone, saffron and (more prominently) PBM both regulated significant numbers of genes and ncRNAs. Given prior to retinal exposure to damaging light, thus while exerting their neuroprotective action, they regulated much larger numbers of entities, among which ncRNAs were prominent. Further, the downregulation of known genes and of ncRNAs was prominent in the protective actions of both neuroprotectants. These comparisons provide an overview of gene expression induced by two neuroprotectants and provide a basis for more focused study of their mechanisms. The were 3 biological repliactes of each of the following groups: Control, Saffron pretreated, Photobiomodulation pretreated, Light Damage, Saffron Light Damage and Photobiomodulation Light Damage. 18 chips in total were performed.
