Long-term visual deprivation inhibit the visual lobe neocortex cytoarchitecture increment in 42 days male rats (Rattus norvegicus): a stereological study

Abstract

Background: The inhibition of nerve impulse transmission between the onset of the nervus opticus pathway and the terminal of radiatio opticus can reduce cortical reflex so that visual deprivation appears. Visual deprivation at the level of the neocortex can change the structure itself if it occurs over a critical period of neuron development in the neocortex layer in infants. Strategies to measure the quality and quantity of neocortex cytoarchitecture of visual lobe require unbiased stereological methods.Aim: This study aimed at proving long-term visual deprivation can reduce the visual lobe neocortex cytoarchitecture.Methods: This research was an experimental study with post test only control group design from 2018 till 2019. The sample was 30 male 42-day-old rats (Rattus norvegicus) about 60-80 g in weight regarding the inclusion criteria. This study involved six random groups divided into control groups, monocular deprivation, and binocular deprivation where each group was further divided into groups that experienced treatment for 7 and 14 days.Results: There was a difference in mean volume of visual lobe neocortex between groups P1 and P2 compared to P0 (7) or P0 (14) (p <0.05). The P1 group (14) had a lower average than the P1 group (7) (p <0.05); (2) There was a difference in the mean of pyramidal visual lobe neocortex cell density between groups P1 and P2 against group P0 (7) or P0 (14) (p <0.05). There was no significant difference in the 14-days deprivation group against 7-days, both monocular and binocular; (3) there was a difference in the total number of visual lobe neocortex pyramidal cells between groups P1 and P2 compared to groups P0 (7) or P0 (14) (p <0.05). Group P1 (14) has a lower average cell number than group P1 (7); (4) The group P0 (14) has the highest neocortex volume, density, and pyramidal cells total number compared to groups P0 (7), P1, and P2. The CE value is 0.2, which is the optimal estimated strength used.Conclusion: Visual deprivation for more than seven days has been shown to reduce mean difference neocortex volume, cell density, and the pyramidal cells number of visual lobe neocortex against either 7 days or 14 days group.