Hippocampal Adult Neurogenesis Is Maintained by Neil3-Dependent Repair of Oxidative DNA Lesions in Neural Progenitor Cells

SummaryAccumulation of oxidative DNA damage has been proposed as a potential cause of age-related cognitive decline. The major pathway for removal of oxidative DNA base lesions is base excision repair, which is initiated by DNA glycosylases. In mice, Neil3 is the main DNA glycosylase for repair of hydantoin lesions in single-stranded DNA of neural stem/progenitor cells, promoting neurogenesis. Adult neurogenesis is crucial for maintenance of hippocampus-dependent functions involved in behavior. Herein, behavioral studies reveal learning and memory deficits and reduced anxiety-like behavior in Neil3−/− mice. Neural stem/progenitor cells from aged Neil3−/− mice show impaired proliferative capacity and reduced DNA repair activity. Furthermore, hippocampal neurons in Neil3−/− mice display synaptic irregularities. It appears that Neil3-dependent repair of oxidative DNA damage in neural stem/progenitor cells is required for maintenance of adult neurogenesis to counteract the age-associated deterioration of cognitive performance

Supplementation of a western diet with golden kiwifruits (Actinidia chinensis var.'Hort 16A':) effects on biomarkers of oxidation damage and antioxidant protection

<p>Abstract</p> <p>Background</p> <p>The health positive effects of diets high in fruits and vegetables are generally not replicated in supplementation trials with isolated antioxidants and vitamins, and as a consequence the emphasis of chronic disease prevention has shifted to whole foods and whole food products.</p> <p>Methods</p> <p>We carried out a human intervention trial with the golden kiwifruit, Actinidia chinensis, measuring markers of antioxidant status, DNA stability, plasma lipids, and platelet aggregation. Our hypothesis was that supplementation of a normal diet with kiwifruits would have an effect on biomarkers of oxidative status. Healthy volunteers supplemented a normal diet with either one or two golden kiwifruits per day in a cross-over study lasting 2 × 4 weeks. Plasma levels of vitamin C, and carotenoids, and the ferric reducing activity of plasma (FRAP) were measured. Malondialdehyde was assessed as a biomarker of lipid oxidation. Effects on DNA damage in circulating lymphocytes were estimated using the comet assay with enzyme modification to measure specific lesions; another modification allowed estimation of DNA repair.</p> <p>Results</p> <p>Plasma vitamin C increased after supplementation as did resistance towards H₂O₂-induced DNA damage. Purine oxidation in lymphocyte DNA decreased significantly after one kiwifruit per day, pyrimidine oxidation decreased after two fruits per day. Neither DNA base excision nor nucleotide excision repair was influenced by kiwifruit consumption. Malondialdehyde was not affected, but plasma triglycerides decreased. Whole blood platelet aggregation was decreased by kiwifruit supplementation.</p> <p>Conclusion</p> <p>Golden kiwifruit consumption strengthens resistance towards endogenous oxidative damage.</p

Alarmreaksjon hos karuss (Carassius Carassius L) : prosessering av luktstimuli i telencephalon

Når karuss, Carassius carassius L., eksponeres for substanser fra skadet skinn fra fisk av samme art, utløses en karakteristisk atferd kalt alarmreaksjon. Fisken svømmer mot bunnen og virvler opp mudder, som kan gi skjul for en predator. Tidligere studier har vist at reaksjonen formidles av spesifikke deler av lukteorganet. I denne oppgaven ble det undersøkt hvordan et høyere hjernesenter, telencephalon, er involvert i prosessering av alarmstimuli. Tre ulike metoder ble benyttet for å kartlegge hvordan alarmstimuli prosesseres i telencephalon: • Projeksjoner fra sekundærnevronene i bunten av tractus olfactorius som formidler alarmreaksjonen, mMOT (den mediale delen av den mediale bunten) og de andre buntene av traktus ble sporet anatomisk med nervefargen DiI. Studiet viste at bunten mMOT projiserte til et ventromedialt felt prekommissuralt, mens LOT (den laterale bunten) og lMOT (den laterale delen av den mediale bunten) projiserte mer basolateralt. Buntenes projeksjoner overlappet i det ventrolaterale feltet prekommissuralt og i det sentrale feltet postkommissuralt. • Tertiære og høyere ordens nevroner som ble aktivert ved stimulering med skinnekstrakt ble kartlagt immunohistokjemisk ved å farge for transkripsjonsfaktoren c-Fos, som kan brukes som en markør for nervøs aktivitet. Immunoreaktive celler ble markert i fire områder i telencephalon: det mediale området prekommissuralt, det ventrolaterale området prekommissuralt, det dorsolaterale området postkommissuralt, og det sentrale området postkommissuralt. • Nervøs aktivitet fra nevroner i telencephalon ble registrert ekstracellulært mens lukteepitelet ble stimulert med alarm- og andre luktstimuli: gallesalt, kjønnsferomon og en aminosyreblanding. Nevroner i telencephalon svarte på kjemisk stimuli 0-15 s etter at stimuli nådde lukteepitelet, med en frekvensøkning på ca. 100 % som varte i minimum 5 s. De fleste cellene var spesifikke, og svarte kun på en type stimulus. Noen celler svarte på to eller tre stimuli, men ingen svarte på alle fire stimuli. Eksperimentene viser at flere områder i telencephalon kan være involvert i alarmprosessering: det mediale og ventrolaterale området prekommissuralt og det dorsolaterale og sentrale området postkommissuralt. Funn fra alle tre metoder viser overensstemmelse for tre av områdene: Det ventromediale området prekommissuralt, det ventrolaterale området prekommissuralt og det sentrale området postkommissuralt. I tillegg ble aktiverte celler påvist immunohistokjemisk og elektrofysiologisk i to områder: det dorsomediale området prekommissuralt og det dorsolaterale området postkommissuralt. Disse to områdene er sannsynligvis involvert i høyere ordens prosessering av alarmstimuli. Både feltene som ble kartlagt anatomisk med DiI, og områdene som ble kartlagt immunohistokjemisk var bilaterale

Anatomi, fysiologi og biokjemi: Sykepleier­studenters opplevde læringsutbytte ved omvendt undervisning.

Bakgrunn: Emnet «Anatomi, fysiologi og biokjemi» (AFB) er et fag som oppleves som krevende av sykepleierstudenter. Omvendt undervisning med studentaktive samlinger som erstatning for tradisjonelle forelesninger har tidligere vist et godt læringsutbytte i dette emnet på radiografutdanningen ved Oslomet. Tilsvarende undervisningsmodell basert på omvendt undervisning ble derfor testet ut ved sykepleierutdanningen ved Oslomet, studiested Pilestredet, høsten 2018. Hensikt: Hensikten med denne studien var å undersøke sykepleierstudentenes egenopplevde læringsutbytte av ulike læringsressurser og -aktiviteter, med hovedvekt på dem som inngikk i en læringsmodell for omvendt undervisning, kalt PISA. I tillegg ønsket vi å undersøke om oppmøte til samlinger og ulike bakgrunnsfaktorer påvirket det samlede opplevde læringsutbyttet med læringsmodellen for omvendt undervisning. Metode: Vi undersøkte studentenes (n = 232) egenopplevde læringsutbytte med ulike læringsressurser og aktiviteter i emnet ved hjelp av et kvantitativt spørreskjema, som også inneholdt noen bakgrunnspørsmål. Vi undersøkte hvilke variabler som påvirket det samlede opplevde læringsutbyttet av læringsmodellen ved hjelp av en multippel regresjon. Resultat: Læringsaktiviteter og -ressurser, som inkluderte lærerkontakt eller sosial samhandling studentene imellom, var blant de aktivitetene som studentene mente ga høyest læringsutbytte. Av aktiviteter og ressurser som inngikk i modellen for omvendt undervisning, oppga studentene lavest opplevd læringsutbytte av Oslomets interne digitale ressurser. Antall stedlige samlinger som studentene hadde deltatt på, samt det at studentene vektla det sosiale ved å lære sammen med andre, viste en signikant sammenheng med samlet læringsutbytte av læringsmodellen for omvendt undervisning. Konklusjon: Oppmøte til stedlige samlinger ser ut til å være en suksessfaktor for opplevd læringsutbytte av en læringsmodell med omvendt undervisning. Videre ga lærerstyrte instruksjoner og forelesninger høyt opplevd læringsutbytte. Det samme gjaldt studentaktiviserende aktiviteter

Upregulation of the lactate transporter monocarboxylate transporter 1 at the blood-brain barrier in a rat model of attention-deficit/hyperactivity disorder suggests hyperactivity could be a form of self-treatment

The energy deficit hypothesis of attention-deficit/hyperactivity disorder (ADHD) suggests that low lactate production by brain astrocytes causes the symptoms of the disorder. Astrocytes are the main producers of lactate in the brain; however, skeletal muscles can produce the most lactate in the body. The lactate production by skeletal muscles increases with physical activity, as does the expression of the lactate transporter monocarboxylate transporter 1 (MCT1) at the blood-brain barrier (BBB). We hypothesise that children with ADHD, by being hyperactive, increase lactate production by skeletal muscles and transport it into the brain to compensate for low supply by astrocytes. The aim of this study was to explore whether the level of MCT1 is altered in the brain in an animal model of ADHD. The MCT1 expression was quantified on hippocampal brain sections from the best available rat model of ADHD, i.e., the spontaneously hypertensive rat (SHR) (n=12), and the relevant control, the Wistar Kyoto rat (WKY) (n=12), by the use of quantitative immunofluorescence laser scanning microscopy and postembedding immunogold electron microscopy. The results revealed significantly higher levels of hippocampal MCT1 immunoreactivity in SHR compared to WKY, particularly at the BBB. These results indicate that lactate flux through MCT1 between the body and the brain could be upregulated in children with ADHD. This study adds to previous research suggesting hyperactivity may be beneficial in ADHD; Children with ADHD possibly display a hyperactive behaviour in order to raise skeletal muscle lactate production, MCT1 expression and flux over the BBB to supply the brain with lactate

Upregulation of the lactate transporter monocarboxylate transporter 1 at the blood-brain barrier in a rat model of attention-deficit/hyperactivity disorder suggests hyperactivity could be a form of self-treatment

The energy deficit hypothesis of attention-deficit/hyperactivity disorder (ADHD) suggests that low lactate production by brain astrocytes causes the symptoms of the disorder. Astrocytes are the main producers of lactate in the brain; however, skeletal muscles can produce the most lactate in the body. The lactate production by skeletal muscles increases with physical activity, as does the expression of the lactate transporter monocarboxylate transporter 1 (MCT1) at the blood-brain barrier (BBB). We hypothesise that children with ADHD, by being hyperactive, increase lactate production by skeletal muscles and transport it into the brain to compensate for low supply by astrocytes. The aim of this study was to explore whether the level of MCT1 is altered in the brain in an animal model of ADHD. The MCT1 expression was quantified on hippocampal brain sections from the best available rat model of ADHD, i.e., the spontaneously hypertensive rat (SHR) (n=12), and the relevant control, the Wistar Kyoto rat (WKY) (n=12), by the use of quantitative immunofluorescence laser scanning microscopy and postembedding immunogold electron microscopy. The results revealed significantly higher levels of hippocampal MCT1 immunoreactivity in SHR compared to WKY, particularly at the BBB. These results indicate that lactate flux through MCT1 between the body and the brain could be upregulated in children with ADHD. This study adds to previous research suggesting hyperactivity may be beneficial in ADHD; Children with ADHD possibly display a hyperactive behaviour in order to raise skeletal muscle lactate production, MCT1 expression and flux over the BBB to supply the brain with lactate

Altered α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor function and expression in hippocampus in a rat model of attention-deficit/hyperactivity disorder (ADHD)

Glutamatergic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) carry the bulk of excitatory synaptic transmission. Their modulation plays key roles in synaptic plasticity, which underlies hippocampal learning and memory. A dysfunctional glutamatergic system may negatively affect learning abilities and underlie symptoms of attention-deficit/hyperactivity disorder (ADHD). The aim of this study was to investigate whether the expression and function of AMPARs were altered in ADHD. We recorded AMPAR mediated synaptic transmission at hippocampal excitatory synapses and quantified immunogold labelling density of AMPAR subunits GluA1 and GluA2/3 in a rat model for ADHD; the spontaneously hypertensive rat (SHR). Electrophysiological recordings showed significantly reduced AMPAR mediated synaptic transmission at the CA3-to-CA1 pyramidal cell synapses in stratum radiatum and stratum oriens in SHRs compared to control rats. Electronmicroscopic immunogold quantifications did not show any statistically significant changes in labelling densities of the GluA1 subunit of the AMPAR on dendritic spines in stratum radiatum or in stratum oriens. However, there was a significant increase of the GluA2/3 subunit intracellularly in stratum oriens in SHR compared to control, interpreted as a compensatory effect. The proportion of synapses lacking AMPAR subunit labelling was the same in the two genotypes. In addition, electronmicroscopic examination of tissue morphology showed the density of this type of synapse (i.e., asymmetric synapses on spines), and the average size of the synaptic membranes, to be the same. AMPAR dysfunction, possibly involving molecular changes, in hippocampus may in part reflect altered learning in individuals with ADHD

Altered α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor function and expression in hippocampus in a rat model of attention-deficit/hyperactivity disorder (ADHD)

Glutamatergic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) carry the bulk of excitatory synaptic transmission. Their modulation plays key roles in synaptic plasticity, which underlies hippocampal learning and memory. A dysfunctional glutamatergic system may negatively affect learning abilities and underlie symptoms of attention-deficit/hyperactivity disorder (ADHD). The aim of this study was to investigate whether the expression and function of AMPARs were altered in ADHD. We recorded AMPAR mediated synaptic transmission at hippocampal excitatory synapses and quantified immunogold labelling density of AMPAR subunits GluA1 and GluA2/3 in a rat model for ADHD; the spontaneously hypertensive rat (SHR). Electrophysiological recordings showed significantly reduced AMPAR mediated synaptic transmission at the CA3-to-CA1 pyramidal cell synapses in stratum radiatum and stratum oriens in SHRs compared to control rats. Electronmicroscopic immunogold quantifications did not show any statistically significant changes in labelling densities of the GluA1 subunit of the AMPAR on dendritic spines in stratum radiatum or in stratum oriens. However, there was a significant increase of the GluA2/3 subunit intracellularly in stratum oriens in SHR compared to control, interpreted as a compensatory effect. The proportion of synapses lacking AMPAR subunit labelling was the same in the two genotypes. In addition, electronmicroscopic examination of tissue morphology showed the density of this type of synapse (i.e., asymmetric synapses on spines), and the average size of the synaptic membranes, to be the same. AMPAR dysfunction, possibly involving molecular changes, in hippocampus may in part reflect altered learning in individuals with ADHD

An ameloblastin C-terminus variant is present in human adipose tissue

Objective: Transcriptional regulatory elements in the ameloblastin (AMBN) promoter indicate that adipogenesis may influence its expression. The objective here was to investigate if AMBN is expressed in adipose tissue, and have a role during differentiation of adipocytes. Design: AMBN expression was examined in adipose tissue and adipocytes by real-time PCR and ELISA. Distribution of ameloblastin was investigated by immunofluorescence in sections of human subcutaneous adipose tissue. The effect of recombinant proteins resembling AMBN and its processed products on proliferation of primary human pre-adipocytes and murine 3T3-L1 cell lines was measured by [3H]-thymidine incorporation. The effect on adipocyte differentiation was evaluated by the expression profile of the adipogenic markers PPARγ and leptin, and the content of lipids droplets (Oil-Red-O staining). Results: AMBN was found to be expressed in human adipose tissue, human primary adipocytes, and in 3T3-L1 cells. The C-terminus of the AMBN protein and a 45 bp shorter splice variant was identified in human subcutaneous adipose tissue. The expression of AMBN was found to increase four-fold during differentiation of 3T3-L1 cells. Administration of recombinant AMBN reduced the proliferation, and enhanced the expression of PPARγ and leptin in 3T3-L1 and human pre-adipocytes, respectively. Conclusions: The AMBN C-terminus variant was identified in adipocytes. This variant may be encoded from a short splice variant. Increased expression of AMBN during adipogenesis and its effect on adipogenic factors suggests that AMBN also has a role in adipocyte development