Natural products improve healthspan in aged mice and rats: a systematic review and meta-analysis

Over the last decades a decrease in mortality has paved the way for late onset pathologies such as cardiovascular, metabolic or neurodegenerative diseases. This evidence has led many researchers to shift their focus from researching ways to extend lifespan to finding ways to increase the number of years spent in good health; “healthspan” is indeed the emerging concept of such quest for ageing without chronic or disabling diseases and dysfunctions. Regular consumption of natural products might improve healthspan, although the mechanisms of action are still poorly understood. Since preclinical studies aimed to assess the efficacy and safety of these compounds are growing, we performed a systematic review and meta-analysis on the effects of natural products on healthspan in mouse and rat models of physiological ageing. Results indicate that natural compounds show robust effects improving stress resistance and cognitive abilities. These promising data call for further studies investigating the underlying mechanisms in more depth

Trehalose administration in C57BL/6N old mice affects healthspan improving motor learning and brain anti-oxidant defences in a sex-dependent fashion: a pilot study

Aim of this study was to characterize the effects of oral trehalose administration (2%w/v) on healthspan in old mice. Trehalose was administered in drinking water for 1 month to male and female C57BL/6N mice aged 25-months. After behavioral phenotyping (grip strength, beam walking and rotarod tests), autophagy (LC3-II/actin) and oxidative stress were tested in the cerebral cortex and gastrocnemius muscle. The latter parameter was indirectly assessed by evaluating carbonyl groups added to proteins as a result of oxidative reactions, in addition to central levels of NRF2 protein, a transcription factor that regulates the expression of antioxidant enzymes. In comparison with sex-matched controls, trehalose-treated males performed better in motor planning and coordination tasks. This behavioral phenotype was associated with an activation of the ubiquitin-proteasome system, autophagy and antioxidant defences in cerebral cortex. Independently from trehalose administration, females were characterized by better motor performance and showed higher levels of ubiquitinated proteins and NRF2 in cerebral cortex, suggesting an up-regulation of basal antioxidant defences. In conclusion, trehalose was effective in counteracting some aspects of age-related decay, with specific effects in male and female subjects

Ion-pairing chromatography and amine derivatization provide complementary approaches for the targeted LC-MS analysis of the polar metabolome.

Liquid chromatography coupled to mass spectrometry is a key metabolomics/metabonomics technology. Reversed-phase liquid chromatography (RPLC) is very widely used as a separation step, but typically has poor retention of highly polar metabolites. Here, we evaluated the combination of two alternative methods for improving retention of polar metabolites based on 6-aminoquinoloyl-N-hydroxysuccinidimyl carbamate derivatization for amine groups, and ion-pairing chromatography (IPC) using tributylamine as an ion-pairing agent to retain acids. We compared both of these methods to RPLC and also to each other, for targeted analysis using a triple-quadrupole mass spectrometer, applied to a library of ca. 500 polar metabolites. IPC and derivatization were complementary in terms of their coverage: combined, they improved the proportion of metabolites with good retention to 91%, compared to just 39% for RPLC alone. The combined method was assessed by analyzing a set of liver extracts from aged male and female mice that had been treated with the polyphenol compound ampelopsin. Not only were a number of significantly changed metabolites detected, but also it could be shown that there was a clear interaction between ampelopsin treatment and sex, in that the direction of metabolite change was opposite for males and females

Prenatal psychological or metabolic stress increases the risk for psychiatric disorders: the “funnel effect” model

Adverse stressful experiences in utero can redirect fetal brain development, ultimately leading to increased risk for psychiatric disorders. Obesity during pregnancy can have similar effects as maternal stress, affecting mental health in the offspring. In order to explain how similar outcomes may originate from different prenatal conditions, we propose a “funnel effect” model whereby maternal psychological or metabolic stress triggers the same evolutionarily conserved response pathways, increasing vulnerability for psychopathology. In this context, the placenta, which is the main mother-fetus interface, appears to facilitate such convergence, re-directing “stress” signals to the fetus. Characterizing converging pathways activated by different adverse environmental conditions is fundamental to assess the emergence of risk signatures of major psychiatric disorders, which might enable preventive measures in risk populations, and open up new diagnostics, and potentially therapeutic approaches for disease prevention and health promotion already during pregnancy

Maternal obesity as a risk factor for brain development and mental health in the offspring

Maternal obesity plays a key role in the health trajectory of the offspring. Although research on this topic has largely focused on the potential of this condition to increase the risk for child obesity, it is becoming more and more evident that it can also significantly impact cognitive function and mental health. The mechanisms underlying these effects are starting to be elucidated and point to the placenta as a critical organ that may mediate changes in the response to stress, immune function and oxidative stress. Long-term effects of maternal obesity may rely upon epigenetic changes in selected genes that are involved in metabolic and trophic regulations of the brain. More recent evidence also indicates the gut microbiota as a potential mediator of these effects. Overall, understanding cause-effect relationships can allow the development of preventive measures that could rely upon dietary changes in the mother and the offspring. Addressing diets appears more feasible than developing new pharmacological targets and has the potential to affect the multiple interconnected physiological pathways engaged by these complex regulations, allowing prevention of both metabolic and mental disorders

High-fat diet during adulthood interacts with prenatal stress, affecting both brain inflammatory and neuroendocrine markers in male rats

Prenatal stress (PNS) affects foetal programming and, through an interaction with subsequent challenges, can increase vulnerability to mood and metabolic disorders. We have previously shown that, following PNS, adult male rats are characterized by increased vulnerability to a metabolic stressor experienced at adulthood (8-week-high-fat diet—HFD). In this study, we specifically assessed whether PNS might interact with an adult metabolic challenge to induce an inflammatory phenotype. Changes in the expression levels of inflammatory (Il-1β, Tnf-α, Il-6) and of stress response mediators (Nr3c1, Fkbp5) as well as of mood and metabolic regulators (Bdnf, Ghs-R) were investigated in the hippocampus, prefrontal cortex and hypothalamus, brain regions involved in the pathogenesis of depression and prone to inflammation in response to stress. Overall, PNS reduced the expression of Bdnf and Tnf-α, while HFD administered at adulthood counteracted this effect suggesting that PNS impinges upon the same pathways regulating responses to a metabolic challenge at adulthood. Furthermore, HFD and PNS affected the expression of both Nr3c1 and Fkbp5, two neuroendocrine mediators involved in the response to stress, metabolic challenges and in the modulation of the emotional profile (as shown by the correlation between Fkbp5 and the time spent in the open arms of the elevated plus-maze). Overall, these results indicate that the same metabolic and neuroendocrine effectors engaged by PNS are affected by metabolic challenges at adulthood, providing some mechanistic insight into the well-known comorbidity between mood and metabolic disorders

Prenatal N-acetyl-cysteine administration alleviates the long-term effects of maternal obesity of adolescent male and female mouse offspring

Introduction. High-fat diet (HFD) consumption during pregnancy may act as a prenatal stressor affecting foetal brain developmental and representing an important risk factor for mental health. Indeed, offspring of obese mothers are prenatally over-exposed to increased levels of oxidative stress, hormones and pro-inflammatory cytokines, that all together can dramatically alter the development of neuronal circuits involved in the regulation of behaviour and mood. N-acetyl-cysteine (NAC) is a promising antioxidant compound that has revealed beneficial effects in the treatment of psychopathology. Aim. The aim of this study was to evaluate the general neurodevelopment, the social behaviour and the emotional phenotype of male and female offspring of dams exposed to a HFD (a mouse model of maternal obesity) before and during pregnancy. Furthermore, we tested the efficacy of prenatal NAC administration in preventing the negative effects of maternal HFD. We focused on adolescence, an age of main vulnerability for the onset of psychopathologies. Methods. Female C57BL/6N mice were fed either HFD (energy 5.56 kcal/g, fat 58%, carbohydrate 25.5% and protein 16.4%) or control diet (CD, energy 4.07 kcal/g, fat 10.5%, carbohydrate 73.1% and protein 16.4%) for 13 weeks and, after 5 weeks, were also exposed to NAC (1 g/kg body weight) via drinking water, until delivery. The general neurodevelopment of offspring was assessed through the Homing test at post-natal day (PND) 10; emotionality and social behaviour were assessed during adolescence (PND 35-45) by means of the elevated-plus-maze (EPM) and social interaction tests (SIT). A forced swimming test was used both to evaluate depressive-like behaviour as well as a stressful challenge to measure hypothalamic-pituitary-adrenal (HPA) axis reactivity. Transcriptomic analysis on hippocampus were performed in order to identify mechanisms of action of both HFD and NAC. Data were analysed using parametric analysis of variance (ANOVA) with Prenatal diet (HFD vs. CD), Prenatal treatment (NAC vs. WATER), Sex (females vs. males) as between subjects factors and time blocks as within-subjects repeated measures (i.e. body weight). Post hoc comparisons were performed using the Tukey’s test. Results. NAC was effective in moderating body weight gain in HFD-fed dams (Diet x Treatment x time p=0.0078, post hoc HFD-WATER vs. HFD-NAC p<0.05). Neither HFD or NAC affected neurodevelopment of offspring at PND 10. Prenatal HFD reduced exploratory behaviours in the EPM (main effect of Prenatal diet in frequency of crossings p=0.0001; frequency of head dipping p=0.0292; frequency of wall-rearing p=0.0255) and decreased sociability (Prenatal diet x Prenatal treatment in the duration of sniff the cospecific subject p=0.0002, post hoc CD-WATER vs. HFD-WATER p<0.05) in the SIT in periadolescent offspring. Prenatal NAC administration was effective in preventing social anxiety in offspring of HFD-fed dams (post hoc HFD-WATER vs. HFD NAC p<0.05). HPA axis functionality and brain transcriptomics are currently ongoing for mechanistic insight. Conclusions. Data from this study indicate that the long-term effects of maternal obesity may be mediated by changes in oxidative stress and point to NAC as a potential preventive strategy. ERANET-NEURON-JTC 2018 (Mental Disorders) Project ‘‘EMBED”

Prenatal N-acetyl-cysteine administration moderates the long-term negative effects of maternal obesity in adolescent male and female mouse offspring

Obesity during pregnancy may affect offspring developmental trajectories representing a risk factor for mental health. Amongst the mechanisms called into question inflammation, oxidative stress and the hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis appear as the most suitable. We investigated the emotional phenotype of male and female offspring of dams exposed to a high-fat diet (HFD, a mouse model of maternal obesity) before and during pregnancy. We also tested the efficacy of N-acetyl-cysteine (NAC – an antioxidant) in preventing the negative effects of HFD. We focused on adolescence, an age of main vulnerability for the onset of psychopathologies. Female C57BL/6N mice were fed HFD for 13 weeks and, after 5 weeks, were also exposed to NAC (1 g/kg b.w.) via drinking water, until delivery. Emotionality was assessed in 35-45-day-old adolescent mice by means of the elevated-plus-maze (EPM) and social interaction tests (SIT). A forced swimming test was used both to evaluate depressive-like behaviour as well as a stressful challenge to measure HPA axis reactivity. NAC was effective in moderating body weight gain in HFD-treated dams. Prenatal HFD reduced exploratory behaviours in the EPM in periadolescent offspring; NAC administration resulting in increased social interactions in the offspring of HFD dams. Analyses of depression-like behaviours, HPA axis functionality and brain transcriptomics are currently ongoing for mechanistic insight. Data from these studies indicate that the long-term effects of maternal obesity may be mediated by changes in oxidative stress and point to NAC as a potential preventive strategy. ERANET-NEURON-JTC 2018 (Mental Disorders) Project ‘‘EMBED”

N-acetyl-cysteine administration during foetal life improves social behaviour and restores hippocampal BDNF levels in adolescent mice prenatally exposed to a high-fat diet

Maternal obesity may affect foetal programming representing a risk for adult mental health. Oxidative stress and inflammation associated with maternal obesity can alter the maturation of neuronal circuits affecting behaviour and mood. We investigated the emotional phenotype of male and female mouse offspring born from a high-fat diet (HFD) fed dams. We also tested the efficacy of N-acetyl-cysteine (NAC – an antioxidant) in preventing the negative effects of HFD. We focused on adolescence, an age of main vulnerability for the onset of psychopathology. Female C57BL/6N mice were fed HFD for 13 weeks and, after 5 weeks, were also exposed to NAC (1 g/kg b.w.) via drinking water, until delivery. The neurodevelopment of offspring was assessed through the homing test. Emotionality was assessed in 35-45-day-old adolescent mice through elevated-plus-maze (EPM) and social interaction tests (SIT). Transcriptomic analysis of hippocampal tissue were performed to identify mechanisms of action of both HFD and NAC. NAC was effective in moderating body weight gain in HFD-fed dams. Neither HFD or NAC affected offspring development. Regardless of sex, prenatal HFD reduced exploration and decreased sociability, in EPM and SIT respectively. Prenatal HFD decreased hippocampal levels of BDNF in female offspring. Prenatal NAC administration prevented social anxiety and restored BDNF levels in the HFD group. Data indicate long-term effects of maternal obesity on dams’ weight, offspring’s behaviour and hippocampal BDNF levels. These effects may be mediated by changes in oxidative stress as NAC was effective as a preventive agent. ERANET-NEURON-JTC 2018 (Mental Disorders) Project “EMBED”

Prenatal N-acetyl-cysteine prevents social anxiety and modulates hippocampal inflammatory-and plasticity-related genes in adolescent mice prenatally exposed to a high-fat diet

High-fat diet (HFD) consumption during pregnancy is associated with increased oxidative stress (OS) and low-grade chronic inflammation, and may affect fetal brain development, setting the stage for increased vulnerability to mood disorders later in life [1,2]. However, the biological mechanisms underlying the negative long-term effects of maternal HFD are poorly understood. N-acetyl-cysteine (NAC) is a promising antioxidant compound [3] that has revealed beneficial effects in the treatment of psychopathology. The aim of this study was to investigate inflammation, OS and hypothalamic-pituitary-adrenal (HPA) axis reactivity in a mouse model of maternal HFD as potential mechanisms affecting brain development and emotional behavior in the offspring. The prenatal NAC treatment was tested to prevent the negative effects of maternal HFD on adolescent offspring, an age of main vulnerability for the onset of psychopathologies. Female C57BL/6N mice were fed either HFD (energy 5.56 kcal/g, fat 58%, carbohydrate 25.5% and protein 16.4%) or control diet (CD, energy 4.07 kcal/g, fat 10.5%, carbohydrate 73.1% and protein 16.4%) before and during pregnancy (13 weeks); after 5 weeks on diets, half of them received NAC (1g/kg) for 8 weeks, until delivery. Emotionality and social behavior of male and female adolescent offspring (35-45 days) were assessed through the elevated plus maze (EPM) and the social interaction test (SIT); HPA axis functionality was assessed measuring plasma corticosterone levels by ELISA under basal conditions and following an acute stress. Gene expression levels of CD68, Bdnf and Nrf2 were measured in hippocampus as markers of microglial activation, brain plasticity and antioxidant capacity respectively by RealTime PCR. Data were analyzed using parametric analysis of variance (ANOVA) with diet (HFD vs. CD), treatment (NAC vs. WATER), sex (females vs. males) as between subjects factors. Post hoc comparisons were performed using the Tukey’s test. Prenatal exposure to HFD affected sociability reducing social behaviors (p<0.01, post hoc HFD-WATER vs. CD-WATER p<0.05) in the SIT and reduced exploration in the EPM (frequency of crossings p<0.01; head dipping p=0.0292; wall-rearing p=0.0255). As for the HPA axis functionality, reduced levels of basal corticosterone were found in HFD males (p<0.01, post hoc HFD-WATER vs. CD-WATER p<0.05). Moreover, prenatal HFD decreased hippocampal Bdnf levels in females (p<0.01, post hoc HFD-WATER vs. CD-WATER p<0.05), while males showed increased CD68 expression (p<0.01). Prenatal NAC administration prevented social anxiety, restored HPA axis basal activity in males and Bdnf levels in females (p<0.01, post hoc HFD-WATER vs. HFD-NAC p<0.05). In addition, hippocampal levels of Nrf2 resulted increased in both males and females (p<0.01), suggesting that NAC may act, at least in part, through an upregulation of this important regulator of brain antioxidant defenses. Overall, these data showed that maternal HFD induces long-term negative effects on the adolescent offspring, affecting brain, neuroendocrine system and emotional/social behavior. These effects are partially prevented by prenatal administration of NAC suggesting that immune and OS pathways may play an important role in fetal programming of mental disorders. Funding: ERANET-NEURON-JTC-2018 Project EMBE