geng, j. | bioRxiv Science

bioRxiv2022

Establishment of a hypoxia ischemia reperfusion brain damagemodel in neonatal rats

ObjectiveRice-Vannucci model has been widely used as HIE (Hypoxic ischemic encephalopathy) animal model in the past forty years, but it does not mimic reperfusion injury that occurs during HIE. The aim of the present study was to establish a new neonatal rat model by simulating hypoxia ischemia reperfusion brain damage (HIRBD) through "common carotid artery (CCA) muscle bridge". MethodsSixty 7-day-old male Sprague-Dawley rats were randomly assigned to group A (HIRBD groups, n=36), group B (Rice-Vannucci group, n=12), and group C (sham-operated group, n=12). Rats in group A were assigned to 3 subgroups (A1-A3, 12 animals/subgroup). Dynamic changes in cerebral blood flow (CBF) were evaluated by the laser speckle imaging system. The status of the CCA was observed under a stereomicroscope. Changes in body weight, gross morphology as well as pathological sections of brain tissue were examined to evaluate the feasibility of the model. ResultsThe results indicated that CCA muscle bridge successfully blocked the CBF. CBF was restored after removal of the CCA muscle bridge in HIRBD groups. The CCA was in good condition after removing the muscle bridge, and blood supply was not affected. Changes in body weight, gross morphology and pathological sections of brain tissue indicated that ischemia reperfusion induced by the CCA muscle bridge method caused varying degrees of brain damage. ConclusionCCA muscle bridge method is effective for establishing a reliable, stable, and reproducible neonatal rat model for study of HIRBD.

neuroscience↗

bioRxiv2020

Controlled-release urea combined with potassium chloride improved the soil fertility and growth of Italian ryegrass

A field experiment with a split-plot design was conducted to study the effect of nitrogen fertilizer type combined with different potassium fertilizer rates on the soil fertility and growth of Italian ryegrass. The main plots were assigned to controlled-release urea (CRU) and common urea, while low, moderate and high potassium chloride (KCl) rates (150, 300 and 450 kg ha-1, respectively) were assigned to the subplots. The results showed compared with the common urea, the CRU significantly increased the SPAD value, plant height, leaf area, and photosynthetic index. Moreover, the dry and fresh yields of the CRU increased by 10.9-25.3% and 11.8-17.7%, respectively. At the same time, compared with the KCl150 and KCl450 treatments, the KCl300 treatment resulted in better plant growth. Overall, the CRUxKCl300 maximized the soil inorganic nitrogen and different soil potassium forms. The root length, volume, surface area, average diameter, tips and branches were also improved, and there was a significant NxK interaction effect on the tips. Our analysis corroborated the CRU combined with 300 kg ha-1 KCl fertilization enhances crop growth by improving leaf photosynthesis, soil fertility, and yield and should be recommended as the best fertilizer ratio for Italian ryegrass production.

plant biology↗