Aminooxyacetic acid improves learning and memory in a rat model of chronic alcoholism

Chronic alcoholism seriously damages the central nervous system and leads to impaired learning and memory.Cell damage in chronic alcoholism is strongly associated with elevated levels of hydrogen sulfide（H2S） and calcium ion overload.Aminooxyacetic acid is a cystathionine-β-synthase activity inhibitor that can reduce H2S formation in the brain.This study sought to observe the effect of aminooxyacetic acid on learning and memory in a chronic alcoholism rat model.Rats were randomly divided into three groups.Rats in the control group were given pure water for 28 days.Rats in the model group were given 6% alcohol for 28 days to establish an alcoholism rat model.Rats in the aminooxyacetic acid remedy group were also given 6% alcohol for 28 days and were also intraperitoneally injected daily with aminooxyacetic acid（5 mg/kg） from day 15 to day 28.Learning and memory was tested using the Morris water maze test.The ultrastructure of mitochondria in the hippocampus was observed by electron microscopy.H2S levels in the hippocampus were measured indirectly by spectrophotometry,and ATPase activity was measured using a commercial kit.The expression of myelin basic protein was determined by immunohistochemistry and western blotting.Compared with the control group,latency and swimming distance were prolonged in the navigation test on days 2,3,and 4 in the model group.In the spatial probe test on day 5,the number of platform crosses was reduced in the model group.Cristae cracks,swelling or deformation of mitochondria appeared in the hippocampus,the hippocampal H2S level was increased,the mitochondrial ATPase activity was decreased,and the expression of myelin basic protein in the hippocampus was down-regulated in the model group compared with the control group.All the above indexes were ameliorated in the aminooxyacetic acid remedy group compared with the model group.These findings indicate that aminooxyacetic acid can improve learning and memory in a chronic alcoholism rat model,which may be associated with reduction of hippocampal H2S level and mitochondrial ATPase activity,and up-regulation of myelin basic protein levels in the hippocampus.

Neuroprotective mechanism of L-cysteine after subarachnoid hemorrhage

Hydrogen sulfide,which can be generated in the central nervous system from the sulfhydryl-containing amino acid,L-cysteine,by cystathionine-β-synthase,may exert protective effects in experimental subarachnoid hemorrhage;however,the mechanism underlying this effect is unknown.This study explored the mechanism using a subarachnoid hemorrhage rat model induced by an endovascular perforation technique.Rats were treated with an intraperitoneal injection of 100 mM L-cysteine(30μL)30 minutes after subarachnoid hemorrhage.At 48 hours after subarachnoid hemorrhage,hematoxylin-eosin staining was used to detect changes in prefrontal cortex cells.L-cysteine significantly reduced cell edema.Neurological function was assessed using a modified Garcia score.Brain water content was measured by the wet-dry method.L-cysteine significantly reduced neurological deficits and cerebral edema after subarachnoid hemorrhage.Immunofluorescence was used to detect the number of activated microglia.Reverse transcription-polymerase chain reaction(RT-PCR)was used to detect the levels of interleukin 1β and CD86 mRNA in the prefrontal cortex.L-cysteine inhibited microglial activation in the prefrontal cortex and reduced the mRNA levels of interleukin 1βand CD86.RT-PCR and western blot analysis of the complement system showed that L-cysteine reduced expression of the complement factors,C1q,C3αand its receptor C3aR1,and the deposition of C1q in the prefrontal cortex.Dihydroethidium staining was applied to detect changes in reactive oxygen species,and immunohistochemistry was used to detect the number of NRF2-and HO-1-positive cells.L-cysteine reduced the level of reactive oxygen species in the prefrontal cortex and the number of NRF2-and HO-1-positive cells.Western blot assays and immunohistochemistry were used to detect the protein levels of CHOP and GRP78 in the prefrontal cortex and the number of CHOP-and GRP78-positive cells.L-cysteine reduced CHOP and GRP78 levels and the number of CHOP-and GRP78-positive cells.The cystathionine-β-synthase inhibitor,aminooxyacetic acid,significantly reversed the above neuroprotective effects of L-cysteine.Taken together,L-cysteine can play a neuroprotective role by regulating neuroinflammation,complement deposition,oxidative stress and endoplasmic reticulum stress.The study was approved by the Animals Ethics Committee of Shandong University,China on February 22,2016(approval No.LL-201602022).