Objective To investigate the toxic effects of combined yttrium and lead exposure on liver and kidney functions in male Sprague-Dawley (SD) rats. Methods Adult male specific pathogen-free SD rats were randomly divided into four groups. Rats in the low-, medium-, and high-dose groups were co-administered with yttrium acetate (10.0, 50.0, and 100.0 mg/kg body weight, respectively) and lead acetate (4.0, 20.0, and 40.0 mg/kg body weight, respectively) by intragastric gavage, once per day for 28 consecutive days. Rats in the control group received an equal volume of deionized water. Yttrium and lead levels in whole blood, liver, and kidney tissues of the rats were measured using inductively coupled plasma mass spectrometry. Serum index of liver and kidney function were measured by a double reagent method, and histopathological changes in the liver and kidney were observed. Results The body weights of rats in all the three exposure groups were lower than those in the control group from day 14 of exposure until the end of exposure (all P<0.05). Body weight gain of rats was observed only in the low-dose group at day 28, whereas no body weight gain was observed throughout the exposure period in the medium- and high-dose groups. Histopathological examination showed dose-dependent liver and kidney injuries in rats of the three exposure groups compared with the control group. Specifically, the liver exhibited widening of intercellular spaces and increased inflammatory cell infiltration, while the kidney showed increased tissue hemorrhage and increased damage to glomeruli and renal tubules. Lead levels in whole blood, liver, and kidney tissues of the rats were higher than yttrium levels in all the three exposure groups (all P<0.05). Blood yttrium levels in rats of the high-dose group were higher than those in the other three groups (all P<0.05), and yttrium levels in the liver and kidney tissues of the three exposure groups were higher than those in the control group (all P<0.05). Lead levels in whole blood, liver, and kidney tissues of the rats increased with increasing exposure dose (all P<0.05). At the end of exposure, the kidney organ coefficient of rats in the high-dose group was higher than those in the other three groups (all P<0.05). The serum alanine aminotransferase (ALT)/aspartate aminotransferase (AST) ratio of rats in the high‑dose group was lower than that in the control group (P<0.05). The serum urea and uric acid levels in the medium‑ and high‑dose groups were lower than those in the control group (both P<0.05). The serum cystatin C level in the high‑dose group was higher than that in the control group (P<0.05). Blood yttrium and blood lead levels were each negatively correlated with serum ALT/AST ratio, serum urea nitrogen, and uric acid levels (both P<0.05). Both yttrium and lead levels in liver tissue were each negatively correlated with serum ALT/AST ratio (all P<0.05). Both yttrium and lead levels in kidney tissue were each negatively correlated with both serum urea nitrogen and uric acid levels (all P<0.05), and each positively correlated with serum cystatin C levels (both P<0.05). Conclusion Co-exposure to yttrium and lead induces dose‑dependent hepatotoxicity and nephrotoxicity in male SD rats. Lead exhibits a more pronounced accumulation effect and contributes more substantially to the observed toxicity.

ObjectiveTo observe the effects of Cuscutae Semen on the learning and memory ability， N6-methyladenosine （m⁶A）-related modification enzymes and total m⁶A level in hippocampus of the offspring of fear-damaged pregnant rats. MethodForty-five pregnant rats were randomly divided into blank group， model group and Cuscutae Semen group. From the 1^st day to the 19^th day of pregnancy， rats in the model group and the Cuscutae Semen group were induced by observing electric shock of other rats. The Cuscutae Semen group was treated with 5 g·kg^-1·d^-1 Cuscutae Semen decoction （ig）， while the other two groups were treated with the same amount of purified water. The offspring were assigned following the grouping method of their maternal generation. The behavioral changes of the offspring were tested by Morris water maze on 21^st day after birth， and the development of hippocampal neurons was observed by transmission electron microscopy. The mRNA and protein expression levels of methyltransferase-like 3 （METTL3）， METTL14， Wilms tumor 1 associated protein （WTAP）， fat mass and obesity-associated protein （FTO） and Alk B homologue 5 （ALKBH5） were detected by Real-time polymerase chain reaction （Real-time PCR）， Western blot and immunohistochemistry （IHC）. The total content of m⁶A in hippocampus was determined by high performance liquid chromatography tandem mass spectrometry （LC-MS/MS）. ResultCompared with the conditions in the blank group， the average latency duration in the model group was prolonged， and the number of entries in the target quadrant， the target quadrant duration and the number of crossing the platform were decreased （P<0.01）. Additionally， the model group had seriously damaged structure of hippocampal CA1 and CA3 neurons， swollen mitochondria， expanded endoplasmic reticulum， and small number of synapses with some having blurred structure， and the expression levels of METTL3， METTL14， FTO， ALKBH5 as well as the total m⁶A level were lower than those in the blank group （P<0.05，P<0.01）. Compared with the model group， the Cuscutae Semen group had shortened average latency duration， increased number of entries in the target quadrant， target quadrant duration and number of crossing the platform （P<0.01）， alleviated damage of hippocampal CA1 and CA3 neurons， fine structure of mitochondrial and endoplasmic reticulum， and clear， intact and dense synapses. And the expression levels of METTL3， METTL14， FTO as well as the total level of m⁶A were up regulated， while the expression level of ALKBH5 was down regulated in the Cuscutae Semen group （P<0.05，P<0.01）. ConclusionCuscutae Semen improved the learning and memory ability of the offspring of the rats affected by fear damaging kidney during pregnancy， protected hippocampal neurons， and up-regulated the expression levels of METTL3， METTL14， FTO and the total m⁶A level in hippocampus.

The spread of COVID-19 has greatly threatened human health and economic growth. Angiotensin-converting enzyme 2 (ACE2) is a receptor for severe acute respiratory syndrome coronavirus 2 (SARS-COV-2). By attaching to ACE2, SARS-COV-2 reduces its expression and induces lung injury. Vitamin D can inhibit the progression of COVID-19 by inhibiting the activity of ROCK pathway, up-regulating ACE2 expression and bio-availability, and slowing down the adverse reactions caused by Ang II accumulation. This study explored a novel mechanism, i.e., vitamin D protects against COVID-19-induced injury by upregulating ACE2 expression. It provides theoretical guidance for the role of Vitamin D in the prevention and treatment of COVID-19.