Dose and time response study to develop retinal degenerative model of zebrafish with lead acetate.

Objective: Animal models are the silent scouts that help to understand the complex biological processes and gather data that aid our understanding of how organisms function. Various animal models are being sacrificed to assess the impact of toxic chemicals. Mortality calculations should be minimised and much data should be collected on the basis of clinical signs that can contribute to identifying robust humane endpoints linked to mortality. This study was designed to calculate the lowest possible dose of PbAc (lead acetate), a neurotoxicant, that can have a toxicological impact on the zebrafish retina and to minimise animal usage. Dose and time-dependent changes were observed in the zebrafish retina following PbAc exposure with zero mortality. Vision and visual behaviour response are the foremost indicators that can be recorded to mark the risk assessment of any chemical. Therefore, the present study aims at dose and time response to find the lowest dose of PbAc affecting the zebrafish retina and its visual behaviour.Materials and methods: Zebrafish were treated for 3 weeks with four concentrations of 0.04, 0.06, 0.08, and 0.1 mg/L of PbAc for a dose-response study. Then for the time response study, two doses 0.08 and 0.1 mg/L were selected and zebrafish were exposed to those concentrations for 2 and 4 weeks.Results: The results of qualitative and quantitative analyses of retinal histology showed that 15 days of treatment with 0.08 mg/L concentration can cause appropriate damage to the photoreceptor layer. At the ultrastructural level, it was further observed that PbAc induces damage to the photoreceptors, especially the rod cells. Escape response sbehaviour showed a significant decrease in visual response to changing contrasts in an increasing dose-dependent manner.Conclusion: In conclusion, it has been shown that 15 days treatment with 0.08 mg/L lead acetate induce retinal degeneration in zebrafish without causing any mortality.

Role of Spirulina in Structural Remodeling of Synapse in Telencephalon of Chronic Unpredictable Stress Model of Zebrafish.

Background: Stress can affect the morphology and synaptic organization of the telencephalon. These structural changes at the cellular level can lead to the development of various psychopathologies. Purpose: Given that the telencephalon plays a major role in stress responses, the current study aimed to investigate the role of Spirulina platensis as a neuroprotectant supplement in the early life of zebrafish in averting the alteration of synapse morphology in the telencephalon caused by chronic unpredictable stress (CUS) in the later stage. Methods: 5dpf larvae were divided into two groups: one group was fed with a commercial fish diet and a second group with a 1% Spirulina-supplemented diet for 90 days. After 90 days, the adult zebrafish were exposed to CUS with different chronic stressors for 15 days. The synaptic plasticity was evaluated by morphometric analysis of synapse in telencephalon of zebrafish by transmission electron microscopy. Results: The ultrastructural study demonstrated the protective role of Spirulina in the CUS model as no significant alterations in the length of the active zone, postsynaptic density, and synaptic cleft were observed as compared to the control group in the CUS model. Conclusion: Thus, suggesting that the Spirulina supplementation can avert the remodeling effect of stress on synapse ultrastructure.

Ultrastructural studies of photoreceptor cell degeneration with organophosphate and its regeneration in Cyprinus carpio communis L.

Organophosphates are highly neurotoxic to aquatic fauna if they enter the water bodies as runoff, thus affecting the nervous system of the fishes. The present study was undertaken to investigate the vision changes, especially on the photoreceptor layer of the retina, of Cyprinus carpio communis L. when exposed to monocrotophos, an organophosphate. Fish were exposed to three sub-lethal concentrations of LC50, i.e. 0.038 ppm (1/10 LC50), 0.062 ppm (1/6 LC50), and 0.126 ppm (1/3 LC50), to observe the changes in the photoreceptor cells at the behavioral, histopathological and ultrastructural levels. Further, acetylcholinesterase activity was also evaluated. Behavioral changes, such as long resting period, inactivity, increase in air gulps and decrease in opercular and fin movements, were observed. A semi-quantitative analysis of the histological sections showed shrinkage in retinal layers at 0.038 ppm concentration of monocrotophos. At 0.062 ppm, the disappearance of the outer nuclear layer was observed and at the highest concentration of 0.126 ppm, damage in all retinal layers involving necrosis of the outer segment of the photoreceptor cells was observed. Further, at the ultrastructural level, detachment of photoreceptor cells and damage in the inner and outer segments of the photoreceptors were observed in an increasing dose-dependent manner. A reduction in the acetylcholinesterase level was observed in the treated groups. The treated fish were then transferred to toxicant-free water for 60 days to study self-regeneration, but no regeneration was observed in photoreceptor cells of the fish retina. This study shows that exposure to of monocrotophos effectively damages and disturbs the functioning of photoreceptor cells of retina of C. carpio communis L., thus affecting its vision.

Yoga as a Preventive Intervention for Cardiovascular Diseases and Associated Comorbidities: Open-Label Single Arm Study.

Aim: Common Yoga Protocol (CYP) is a standardized yoga protocol authored by experts from all over the world under the aegis of the Ministry of AYUSH, Ayurveda, Yoga and Naturopathy, Unani, Siddha, Sowa Rigpa and Homeopathy (AYUSH). The potential of CYP can be determined as a cost-effective lifestyle modification to prevent the risk of developing cardiovascular diseases (CVD). Methods: In this prospective trial, we compared the effect of CYP at baseline and after 1 month. A total of 374 yoga-naïve participants performed CYP under the supervision of experienced trainers. Physiological [body mass index (BMI), blood pressure, percent oxygen saturation], biochemical (fasting blood glucose and lipid profile), and neurocognitive parameters were measured before and after the intervention. Results: At day 30 of yoga practice, serum levels of low-density lipoprotein (LDL), total cholesterol (TC), and high-density lipoprotein (HDL) were found significantly improved as compared to the baseline levels observed at the time of enrollment. Similarly, the lipid profile was also obtained from experienced trainers and found to be significantly different from those of yoga-naïve volunteers. When the intervention was compared between the healthy yoga-naïve participants with yoga-naïve participants suffering from medical issues, it was found that cholesterol profile improved significantly in the healthy-naive group as compared to the diseased group (hypertension, diabetes, underwent surgery, and CVD). Conclusion: These results highlight the need for further research to better understand the effects of yoga on the primary prevention of CVD.