Melatonin alleviates heme-induced ferroptosis via activating the Nrf2/HO-1 pathway in neurons.

OBJECTIVE: Ferroptosis of neurons is a significant cause of brain injury following intracerebral hemorrhage (ICH). As an iron-containing compound in hemoglobin, heme contributes to nerve injury post-ICH. Melatonin has been shown to mitigate the effects of ICH, yet its specific functions remain largely elusive. In this study, we aimed to explore the roles and mechanisms of melatonin in heme-induced ferroptosis subsequent to ICH. MATERIALS AND METHODS: C57BL/6 mice were intracranially injected with heme and then treated with melatonin. Behavior tests [modified neurological severity score (mNSS), forelimb placing, and corner turn tests], H&E staining, Nissl staining, and Prussian blue staining were used to evaluate mouse brain tissue injury. In vitro, HT-22 cells were stimulated with heme and cell viability was determined by crystal violet staining. The iron contents were determined in heme-treated brains and cells, and the levels of 4-hydroxynonenal (4-HNE) and malonaldehyde (MDA) were assessed by ELISA. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to investigate the mRNA levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). Immunoblotting was used to analyze the protein expression of glutathione peroxidase 4 (GPX4), solute carrier family 7 member 11 (SLC7A11), Nrf2, and HO-1. Finally, small interfering RNA (siRNA) was used to knock down Nrf2 in HT-22 cells. RESULTS: Melatonin treatment alleviated heme-induced injuries to neural function, as indicated by improved behavior in the mice. Moreover, melatonin decreased cell death and iron concentrations, increased MDA and 4-HNE levels, and reversed the decreases in GPX4, SLC7A11, Nrf2, and HO-1 induced by heme in vitro and in vivo. These results indicated that melatonin could improve the ferroptosis induced by heme. In addition, we found that Nrf2 knockdown attenuated the therapeutic effect of melatonin on neuronal ferroptosis induced by heme. CONCLUSIONS: In general, melatonin alleviates heme-induced ferroptosis by activating the Nrf2/HO-1 pathway, which implies that melatonin is a promising treatment for ferroptosis in ICH.

[Investigation on population dynamics and Echinococcus infections in small rodents around human settlement in Yushu City, Qinghai Province].

OBJECTIVE: To investigate the population dynamics and Echinococcus infections in small rodents around human settlement in Yushu City, Qinghai Province. METHODS: Rodents were captured using the mouse trap method in pastures from Batang Township and Longbao Township of Yushu City, Qinghai Province on May, August and October, 2018. The body weight and snout-vent length of all captured rodents were measured, and the species was identified according to the rodent morphology. Genomic DNA was extracted from rodent liver specimens and lesion specimens, and the mitochondrial cox1 gene of Echinococcus was amplified using PCR assay for identification of parasite species. In addition, the tissue specimens positive for PCR assay were sampled for pathological examinations. The prevalence of Echinococcus infections was estimated in rodents, and a phylogenetic tree was created based on Echinococcus cox1 gene sequences. RESULTS: A total of 285 small rodents were captured, including 143 Ochotona curzoniae (50.2%), 141 Lasiopodomys fuscus (49.5%), and 1 Neodon irene (0.3%), and there was a remarkable variation in habitat selection among these three rodent species. The number of L. fuscus correlated positively with vegetation coverage (r = 0.350, P = 0.264), with the greatest number seen in August, and the number of O. curzoniae negatively with vegetation coverage (r = -0.371, P = 0.235), with the highest number seen in August and the lowest number in May. The female/male ratios of O. curzoniae and voles were 1:0.96 and 0.82:1, respectively. The body weight (r = 0.519, P < 0.01) and snout-vent length (r = 0.578, P < 0.01) of O. curzoniae showed a tendency towards a rise with month, while the body weight (r = -0.401, P < 0.01) and snout-vent length (r = -0.570, P < 0.01) of voles presented a tendency towards a reduction with month. No Echinococcus infection was detected in voles, while 2.1% prevalence of E. shiquicus infection was seen in O. curzoniae. Phylogenetic analysis revealed consistent sequences of cox1 gene from E. shiquicus in Yushu City of Qinghai Province and Shiqu County, Ganzi Tibetan Autonomous Prefecture of Sichuan Province. CONCLUSIONS: The small rodents around the human settlement in Yushu City of Qinghai Province mainly include O. curzoniae and L. fuscus, with the greatest numbers seen in May and August, respectively. Following the concerted efforts for echinococcosis control, the prevalence of Echinococcus infections is low in small rodents around the human settlement in Yushu City; however, there is still a risk of echinococcosis transmission.