Strain, stress, neurodegeneration and longevity

Sex-related differences in behavioural markers in adult mice for the prediction of lifespan

Finding biomarkers to assess the rate of ageing and consequently, to forecast individual lifespan is a challenge in ageing research. We recently published a mathematical model for lifespan prediction in adult female mice using behavioural parameters such as internal locomotion and time spent in open arms in the hole board (HB) and elevated plus maze (EPM) tests, respectively. Nevertheless, it is still not known if these behavioural variables could be useful in forecasting lifespan in male mice. Therefore, two groups of ICR-CD1 mice, male and female were subjected to the EPM, HB and T-maze tests at the adult age. Mice were monitored until they died and individual lifespans were registered. In general, adult male mice showed more anxiety-like behaviours than females. The mathematical model previously developed in females was validated with the female cohort, but found to be suboptimal for lifespan prediction in males. Thus, a new model for male lifespan prediction was constructed including the behavioural variables that were predictive of lifespan in males: time in the central platform of the EPM, inner locomotion, number of groomings and number and duration of head-dippings in the HB. These results confirm that the higher the anxiety-like behaviour at the adult age, the shorter the lifespan.

Premature aging in behavior and immune functions in tyrosine hydroxylase haploinsufficient female mice. A longitudinal study

Aging is accompanied by impairment in the nervous, immune, and endocrine systems as well as in neuroimmunoendocrine communication. In this context, there is an age-related alteration of the physiological response to acute stress, which is modulated by catecholamine (CA), final products of the sympathetic-adreno-medullary axis. The involvement of CA in essential functions of the nervous system is consistent with the neuropsychological deficits found in mice with haploinsufficiency (hemizygous; HZ) of tyrosine hydroxylase (TH) enzyme (TH-HZ). However, other possible alterations in regulatory systems have not been studied in these animals. The aim of the present work was to analyze whether adult TH-HZ female mice presented the impairment of behavioral traits and immunological responses that occurs with aging and whether they had affected their mean lifespan. ICR-CD1 female TH-HZ and wild type (WT) mice were used in a longitudinal study. Behavioral tests were performed on adult and old mice in order to evaluate their sensorimotor abilities and exploratory capacity, as well as anxiety-like behaviors. At the ages of 2 ± 1, 4 ± 1, 9 ± 1, 13 ± 1 and 20 ± 1 months, peritoneal leukocytes were extracted and several immune functions were assessed (phagocytic capacity, Natural Killer (NK) cytotoxicity, and lymphoproliferative response to lipopolysaccharide (LPS) and concanavalin A (ConA)). In addition, several oxidative stress parameters (catalase, glutathione reductase and glutathione peroxidase activities, and reduced glutathione (GSH) concentrations as antioxidant compounds as well as xanthine oxidase activity, oxidized glutathione (GSSG) concentrations, and GSSG/GSH ratio as oxidants) were analyzed. As inflammatory stress parameters TNF-alpha and IL-10 concentrations, and TNF-alpha/IL-10 ratios as inflammatory/anti-inflammatory markers, were measured. Animals were maintained in standard conditions until their natural death. The results indicate that adult TH-HZ mice presented worse sensorimotor abilities and exploratory capacity than their WT littermates as well as greater anxiety-like behaviors. With regards to the immune system, adult TH-HZ animals exhibited lower values of phagocytic capacity, NK cytotoxicity, and lymphoproliferative response to LPS and ConA than WT mice. Moreover, immune cells of TH-HZ mice showed higher oxidative and inflammatory stress than those of WT animals. Although these differences between TH-HZ and WT, in general, decreased with aging, this premature immunosenescence and impairment of behavior of TH-HZ mice was accompanied by a shorter mean lifespan in comparison to WT counterparts. In conclusion, haploinsufficiency of th gene in female mice appears to provoke premature aging of the regulatory systems affecting mean lifespan.

Advantages of Structure-Based Drug Design Approaches in Neurological Disorders

OBJECTIVE

The purpose of the review is to portray the theoretical concept on neurological disorders from research data.

BACKGROUND

The freak changes in chemical response of nerve impulse causes neurological disorders. The research evidence of the effort done in the older history suggests that the biological drug targets and their effective feature with responsive drugs could be valuable in promoting the future development of health statistics structure for improved treatment for curing the nervous disorders.

METHODS

In this review, we summarized the most iterative theoretical concept of structure based drug design approaches in various neurological disorders to unfathomable understanding of reported information for future drug design and development.

RESULTS

On the premise of reported information we analyzed the model of theoretical drug designing process for understanding the mechanism and pathology of the neurological diseases which covers the development of potentially effective inhibitors against the biological drug targets. Finally, it also suggests the management and implementation of the current treatment in improving the human health system behaviors.

CONCLUSION

With the survey of reported information we concluded the development strategies of diagnosis and treatment against neurological diseases which leads to supportive progress in the drug discovery.

Early Life Stress Activates Glial Cells in the Hippocampus but Attenuates Cytokine Secretion in Response to an Immune Challenge in Rat Pups

OBJECTIVE

Early life stress (ELS) increases the vulnerability to developing psychopathological disorders in adulthood that are accompanied by brain inflammatory processes. However, it is not known how a combined double hit (stress and immune) at an early age affects the response of the neuroimmune system. Here we investigated the effect of periodic maternal separation (MS) followed by administration of lipopolysaccharide (LPS) on glial cells in the CA3 region and hilus of the hippocampus and on cytokine release on postnatal day (PN) 15.

METHODS

Male rat pups were subjected to MS (3 h/day, PN1-14). MS and control pups received a single LPS injection (1 mg/kg of body weight) on PN14. They were subjected to an open field test 1 h later. The pups were sacrificed 90 min after LPS injection (PN14) or on PN15 for cytokine or immunohistological analyses, respectively.

RESULTS

LPS reduced the locomotion and induced high corticosterone levels in treated pups. MS or LPS reduced microglial density and activated microglial cells in the hippocampal CA3 and hilus regions. Microglial activation was highest in MS-LPS pups. The astrocyte density was mildly reduced by MS or LPS in the CA3 region and hilus, but the reduction was maximal in MS-LPS pups. LPS increased the secretion of plasmatic interleukin (IL)-1β, tumor necrosis factor-α, and IL-6, and of hippocampal IL-1β protein, but these were attenuated in MS-LPS pups.

CONCLUSION

Although MS and LPS activate neuroimmune cells, stress attenuates the hippocampal and peripheral cytokine response to LPS through an as-yet unidentified adaptive mechanism. These results provide information regarding the neurobiology of stress and inflammation.

Impaired responses to gliadin and gut microbes of immune cells from mice with altered stress-related behavior and premature immune senescence

Stress is associated with impaired communication between the nervous and immune systems leading to immunosenescence and increased disease risk. We investigated whether leukocytes from mice with altered stress-related behavior and premature immunosenescence, as well as from chronologically aged mice differently responded ex vivo to celiac disease (CD) triggers (gliadin) and intestinal bacteria by ELISA and flow cytometry and differed in microbiota composition. We found that altered stress-related behavior and premature immunosenescence led to alterations in T lymphocytes and cytokine release of immune cells basally and in response to peptic fragments of gliadin and commensal and pathogenic bacteria, possibly increasing susceptibility to CD in adulthood.

Age-associated epigenetic upregulation of the FKBP5 gene selectively impairs stress resiliency

Single nucleotide polymorphisms (SNPs) in the FK506 binding protein 5 (FKBP5) gene combine with traumatic events to increase risk for post-traumatic stress and major depressive disorders (PTSD and MDD). These SNPs increase FKBP51 protein expression through a mechanism involving demethylation of the gene and altered glucocorticoid signaling. Aged animals also display elevated FKBP51 levels, which contribute to impaired resiliency to depressive-like behaviors through impaired glucocorticoid signaling, a phenotype that is abrogated in FKBP5^−/− mice. But the age of onset and progressive stability of these phenotypes remain unknown. Moreover, it is unclear how FKBP5 deletion affects other glucocorticoid-dependent processes or if age-associated increases in FKBP51 expression are mediated through a similar epigenetic process caused by SNPs in the FKBP5 gene. Here, we show that FKBP51-mediated impairment in stress resiliency and glucocorticoid signaling occurs by 10 months of age and this increased over their lifespan. Surprisingly, despite these progressive changes in glucocorticoid responsiveness, FKBP5^−/− mice displayed normal longevity, glucose tolerance, blood composition and cytokine profiles across lifespan, phenotypes normally associated with glucocorticoid signaling. We also found that methylation of Fkbp5 decreased with age in mice, a process that likely explains the age-associated increases in FKBP51 levels. Thus, epigenetic upregulation of FKBP51 with age can selectively impair psychological stress-resiliency, but does not affect other glucocorticoid-mediated physiological processes. This makes FKBP51 a unique and attractive therapeutic target to treat PTSD and MDD. In addition, aged wild-type mice may be a useful model for investigating the mechanisms of FKBP5 SNPs associated with these disorders.

Can stress trigger Parkinson's disease?

In this manuscript we summarize the role of chronic stress as a potential trigger factor for Parkinson's disease. Underlying mechanisms and stress-induced changes to the neuronal networks have been highlighted. Examples of stress induced reversible symptoms that resemble parkinsonism in humans and in animal models raise the question whether emotional stress can cause striatal degeneration in susceptible patients. A Pubmed literature review searching for the terms 'Stress', 'Distress and Parkinson's disease', 'Emotional Distress and Parkinson's disease', 'Stress and Parkinson's disease', 'Prodromal Parkinson's disease', 'Non motor symptoms and Parkinson's disease', 'Paradoxical kinesia', 'Psychogenic parkinsonism', 'Functional somatic syndromes', 'Chronic fatigue syndrome', 'Irritable bowel syndrome', 'Fibromyalgia', 'Dopamine and fibromyalgia', 'Dopamine and chronic fatigue syndrome' and 'Dopamine and irritable bowel syndrome' was carried out until April 2013. Articles were also identified through searches of the authors' own files. Only papers published in English were reviewed. The final reference list was generated on the basis of originality and relevance to the broad scope of this viewpoint.

Interleukin-1β-immunoreactive neurons in the hippocampus and paraventricular nucleus of the hypothalamus after stress stimulation in aged versus adult rats

It is believed that the impact of stress on interleukin-1β (IL-1β) depends on the ontogenetic age. This study examines the influence of acute or chronic exposure to forced-swim (FS) stress or high-light open-field (HL-OF) stimulation on the expression of IL-1β. Double immunofluorescence staining was used to reveal the density of IL-1β/NeuN (NeuN is a neuronal nuclear marker)-immunoreactive (-ir) cells in the hippocampal subfields CA1 and CA3, dentate gyrus (DG), and paraventricular nucleus (PVN) of the hypothalamus. Adult postnatal day 90 (P90) and aged (P720) rats were used in this experiment. The data showed a significant increase in the density of IL-1β/NeuN-ir cells in the CA1, CA3, DG, and PVN in P720 nonstressed rats in relation to P90 control animals. Neither FS nor HL-OF acute stimulation caused alteration in the density of IL-1β-ir neurons in any of the investigated structures in P90 and P720 rats in comparison with control groups. However, chronic FS caused a significant increase in CA3 and DG of P720 rats, and chronic HL-OF led to a significant increase in the density of IL-1β-ir neurons in the PVN of P90 rats and in all hippocampal subfields of P720 animals. These results indicate that chronic HL-OF stimulation is a factor that induces changes in the number of IL-1β-ir neurons in the PVN of adult rats, whereas both chronic FS and HL-OF are aggravating factors for the hippocampus of aged (P720) animals.

Being a grump only makes things worse: a transactional account of acute stress on mind wandering

The current work investigates the influence of acute stress on mind wandering. Participants completed the Positive and Negative Affect Schedule as a measure of baseline negative mood, and were randomly assigned to either the high-stress or low-stress version of the Trier Social Stress Test. Participants then completed the Sustained Attention to Response Task as a measure of mind-wandering behavior. In Experiment 1, participants reporting a high degree of negative mood that were exposed to the high-stress condition were more likely to engage in a variable response time, make more errors, and were more likely to report thinking about the stressor relative to participants that report a low level of negative mood. These effects diminished throughout task performance, suggesting that acute stress induces a temporary mind-wandering state in participants with a negative mood. The temporary affect-dependent deficits observed in Experiment 1 were replicated in Experiment 2, with the high negative mood participants demonstrating limited resource availability (indicated by pupil diameter) immediately following stress induction. These experiments provide novel evidence to suggest that acute psychosocial stress briefly suppresses the availability of cognitive resources and promotes an internally oriented focus of attention in participants with a negative mood.

Omega-3 fatty acids and brain resistance to ageing and stress: body of evidence and possible mechanisms

The increasing life expectancy in the populations of rich countries raises the pressing question of how the elderly can maintain their cognitive function. Cognitive decline is characterised by the loss of short-term memory due to a progressive impairment of the underlying brain cell processes. Age-related brain damage has many causes, some of which may be influenced by diet. An optimal diet may therefore be a practical way of delaying the onset of age-related cognitive decline. Nutritional investigations indicate that the ω-3 poyunsaturated fatty acid (PUFA) content of western diets is too low to provide the brain with an optimal supply of docosahexaenoic acid (DHA), the main ω-3 PUFA in cell membranes. Insufficient brain DHA has been associated with memory impairment, emotional disturbances and altered brain processes in rodents. Human studies suggest that an adequate dietary intake of ω-3 PUFA can slow the age-related cognitive decline and may also protect against the risk of senile dementia. However, despite the many studies in this domain, the beneficial impact of ω-3 PUFA on brain function has only recently been linked to specific mechanisms. This review examines the hypothesis that an optimal brain DHA status, conferred by an adequate ω-3 PUFA intake, limits age-related brain damage by optimizing endogenous brain repair mechanisms. Our analysis of the abundant literature indicates that an adequate amount of DHA in the brain may limit the impact of stress, an important age-aggravating factor, and influences the neuronal and astroglial functions that govern and protect synaptic transmission. This transmission, particularly glutamatergic neurotransmission in the hippocampus, underlies memory formation. The brain DHA status also influences neurogenesis, nested in the hippocampus, which helps maintain cognitive function throughout life. Although there are still gaps in our knowledge of the way ω-3 PUFA act, the mechanistic studies reviewed here indicate that ω-3 PUFA may be a promising tool for preventing age-related brain deterioration.

The stressful life events and Parkinson's disease: a case-control study

A case-control study was conducted in order to investigate the possible link between stressful life events and Parkinson's disease (PD). A group of 110 consecutive newly diagnosed PD cases treated at the Institute of Neurology, Faculty of Medicine, Belgrade University, was compared with a control group comprising 220 subjects with degenerative joint disease and some diseases of the digestive tract. The case and control subjects were matched by sex, age (±2 years) and place of residence (urban/rural). According to conditional multivariate logistic regression analysis, PD was found to be significantly related to retirement (odds ratio--OR 18.73, 95% confidence interval--95%CI 1.9-175.4), birth of own child (OR 66.22, 95%CI 8.3-526.3) and air raids (OR 5.66, 95%CI 2.4-13.5). The risk of PD significantly increased with the number of stressful events. The results of the present study support the hypothesis that stress may play a role in the development of PD.

Long-term maternal separation differentially alters serum corticosterone levels and blood neutrophil activity in A/J and C57BL/6 mouse offspring

OBJECTIVES

In this work, we searched for maternal separation effects on serum corticosterone levels and blood neutrophil activity in adult male A/J and C57BL/6 mouse offspring.

METHODS

40 male A/J mice and 40 male C57BL/6 mice were divided within each strain into two groups. Mice in the maternal separation group were separated from their mothers (1 h/day) on postnatal days 0-13. Mice in the control group were left undisturbed. On postnatal day 45, blood was drawn from all mice and used to assess neutrophil activity by flow cytometry and serum corticosterone levels by radioimmunoassay.

RESULTS

The results showed that each mouse strain responded differently to maternal separation, but in both cases, serum corticosterone levels were affected. In both strains, adult mice that experienced maternal separation showed lower serum corticosterone levels than control mice. In relation to control mice kept together with their mothers, the levels of serum corticosterone were 72.7 and 36.36% lower in A/J and C57BL/6 mice submitted to maternal separation, respectively. The current findings showed that maternal separation increased neutrophil activity in mice after reaching adulthood. The observed effects, although in the same direction, differed between A/J and C57BL/6 mice. Maternal separation increased both the percentage and intensity of phagocytosis in C57BL/6 mice, but had no effects on A/J mice. Furthermore, maternal separation increased basal and propidium iodide-labeled Staphylococcus aureus-induced oxidative burst in A/J mice but did not affect oxidative burst in C57BL/6 mice. Finally, phorbol myristate acetate-induced oxidative burst increased in both strains.

CONCLUSION

These results indicate that early maternal separation increases innate immunity, most likely by modifying hypothalamus-pituitary-adrenal axis activity. This suggests that maternal separation is a good model for stress which produces long-term neuroimmune changes whatever the animal species and strain used.

Brain mitochondrial dysfunction in aging, neurodegeneration, and Parkinson's disease

Brain senescence and neurodegeneration occur with a mitochondrial dysfunction characterized by impaired electron transfer and by oxidative damage. Brain mitochondria of old animals show decreased rates of electron transfer in complexes I and IV, decreased membrane potential, increased content of the oxidation products of phospholipids and proteins and increased size and fragility. This impairment, with complex I inactivation and oxidative damage, is named “complex I syndrome” and is recognized as characteristic of mammalian brain aging and of neurodegenerative diseases. Mitochondrial dysfunction is more marked in brain areas as rat hippocampus and frontal cortex, in human cortex in Parkinson's disease and dementia with Lewy bodies, and in substantia nigra in Parkinson's disease. The molecular mechanisms involved in complex I inactivation include the synergistic inactivations produced by ONOO− mediated reactions, by reactions with free radical intermediates of lipid peroxidation and by amine–aldehyde adduction reactions. The accumulation of oxidation products prompts the idea of antioxidant therapies. High doses of vitamin E produce a significant protection of complex I activity and mitochondrial function in rats and mice, and with improvement of neurological functions and increased median life span in mice. Mitochondria-targeted antioxidants, as the Skulachev cations covalently attached to vitamin E, ubiquinone and PBN and the SS tetrapeptides, are negatively charged and accumulate in mitochondria where they exert their antioxidant effects. Activation of the cellular mechanisms that regulate mitochondrial biogenesis is another potential therapeutic strategy, since the process generates organelles devoid of oxidation products and with full enzymatic activity and capacity for ATP production.

Stable behavioral inhibition and glucocorticoid production as predictors of longevity

Several personality/temperament traits have been linked to health outcomes in humans and animals but underlying physiological mechanisms for these differential outcomes are minimally understood. In this paper, we compared the strength of a behavioral trait (behavioral inhibition) and an associated physiological trait (glucocorticoid production) in predicting life span. In addition, we examined the relative stability of both the behavioral and physiological traits within individuals over a significant portion of adulthood, and tested the hypothesis that a stable behavioral trait is linked with a stable physiological bias. In a sample of 60 Sprague-Dawley male rats, we found that stable inhibition/neophobia was a stronger predictor of life span than stably elevated glucocorticoid production. In addition, these predictors appeared to have an additive influence on life span in that males with both risk factors (stable inhibition and consistently high glucocorticoid production) had the shortest life spans of all, suggesting both traits are important predictors of life span. Across a 4-month period in young adulthood, inhibition and glucocorticoid reactivity were relatively stable traits, however these two traits were not highly correlated with one another. Interestingly, baseline glucocorticoid production was a better predictor of life span than reactivity levels. The results indicate that glucocorticoid production in young adulthood is an important predictor of life span, although not as strong a predictor as inhibition, and that other physiological processes may further explain the shortened life span in behaviorally-inhibited individuals.

Hippocampal mitochondrial dysfunction in rat aging

Hippocampus mitochondrial dysfunction with impaired electron transfer and increased oxidative damage was observed upon rat aging. Hippocampal mitochondria of aged (12 mo) and senescent (20 mo) rats showed, compared with young (4 mo) rats, marked decreases in the rate of state 3 respiration with NAD-dependent substrates (32-51%) and in the activities of mitochondrial complexes I (57-73%) and IV (33-54%). The activity of mitochondrial nitric oxide synthase was also decreased, 53-66%, with age. These losses in enzymatic activity were more marked in the hippocampus than in brain cortex or in whole brain. The histochemical assay of mitochondrial complex IV in the hippocampus showed decreased staining upon aging. Oxidative damage, determined as the mitochondrial content of thiobarbituric-acid reactive substances (TBARS) and protein carbonyls, increased in aged and senescent hippocampus (66-74% in TBARS and 48-96% in carbonyls). A significant statistical correlation was observed between mitochondrial oxidative damage and enzymatic activity. Mitochondrial dysfunction with shortage of energy supply is considered a likely cause of dysfunction in aged hippocampus.

Effects of prenatal stress on motor performance and anxiety behavior in Swiss mice

Stressor presence during the last weeks of gestation has been associated with behavioral disorders in later life. In this study we support further research on the long term effects of prenatal stress on Swiss mice descendant's behavior. Prenatal stress procedure consisted on restraining the dams under bright light for 45 min, three times per day from the 15th day of pregnancy, until birth. After weaning, offspring's motor performance and spontaneous exploratory behavior were measured by the tight-rope and T-maze tests, respectively. We also evaluated anxiety behavior using elevated plus maze test. We found that maternal stress improves the performance of the animals in the tight rope test and that this effect was sex and age dependent: prenatal stressed males obtained the best scores during the first month of life, while in females the same was achieved at the second month. Spontaneous exploratory behavior analysis revealed that it was elevated in prenatal stressed males and that this effect persisted on time. However, we did not find significant differences on this behavioral response among both females groups. Finally, differences on anxiety behavior were found only in females: prenatally stressed animals showed a higher proportion of entries into the open arms of a plus maze (reduced anxiety) compared to the control group. Our results show that prenatal stress modifies the normal behavior of the progeny: prenatal stressed animals have a better performance in the carried out test. These notably results suggest the existence of an adaptive response to prenatal stress.

Stress and ageing interactions: A paradox in the context of shared etiological and physiopathological processes

Gerontology has made considerable progress in the understanding of the mechanisms underlying the ageing process and age-related neurodegenerative disorders. However, ways to improve quality of life in the elderly remain to be elucidated. It is now clear that stress and the ageing process share a number of underlying mechanisms bound in a very close, if not indissociable, relationship. The ageing process is regulated by the factors underlying the ability to adjust to stress, whilst stress has an influence on the life span and the quality of ageing. In addition, the ability to cope with stress in adulthood predicts life expectancy and quality of life at senescence. The ageing process and stress also share several common mechanisms, particularly in relation to the energy factor. Stress consumes energy and ageing may be considered as a cost of the energy expended to deal with the stressors to which the body is exposed throughout its lifetime. This suggests that the ageing process is associated with and/or a consequence of a long-lasting activation of the major stress responsive systems. However, despite common features, the interaction between stress and the ageing process gives rise to some paradoxes. Stress can either diminish or exacerbate the ageing process just as the ageing process can worsen or counter the effects of stress. There has been little attempt to understand how ageing and stress might interact to promote "successful" or pathological ageing. A key factor in this respect is the individual's ability to adapt to stress. Viewed from this angle, the quality of life of aged subjects may be improved through therapy designed to improve the tolerance to stress.

A model of premature aging in mice based on altered stress-related behavioral response and immunosenescence

The intensity of behavioral and neuroendocrine responses to stressful stimuli in rodent strains seems to be inversely related to their life span. We have previously shown that interindividual differences in members of outbred Swiss and inbred BALB/c mouse populations, both male and female, may be related to their behavior in a simple T-maze test. The animals that explore the maze slowly show impaired neuromuscular vigor and coordination, decreased locomotor activity, increased level of emotionality/anxiety, decreased levels of brain biogenic amines as well as immunosenescence and decreased life span, when compared to their control counterparts, which quickly explore the maze. These traits are similar to some of the alterations previously observed in aging animals and therefore we proposed that those 'slow mice' are biologically older than the fast animals and may be a model of prematurely aging mice (PAM). Although most of our work on this model has been performed on chronologically adult-mature animals, we have also shown that certain characteristics of PAM, such as increased anxiety and deficient immune response, are already present in chronologically young animals. Thus, it is tempting to hypothesize that chronic hyperreactivity to stress (trait anxiety) leading to immune dysfunction may have a causal relationship with impaired health and premature aging. In view of the link between oxidative stress and the aging process, the redox state of peritoneal leukocytes from PAM has been studied, showing an oxidative stress situation. In the present work we have determined the levels of a key antioxidant, reduced glutathione (GSH), and the oxidant malondialdehyde (MDA), a marker of lipid peroxidation, both in the spleen and brain of male and female PAM and non-PAM (NPAM). We found that GSH and MDA are decreased and increased, respectively, in PAM with respect to NPAM. Moreover, diet supplementation with antioxidants showed to be an effective strategy for protection against early immune and behavioral decline, altered redox state of leukocytes and premature mortality in PAM, which supports the validity of this model of premature aging as well as its link with oxidative stress.

The mitochondrial energy transduction system and the aging process

Aged mammalian tissues show a decreased capacity to produce ATP by oxidative phosphorylation due to dysfunctional mitochondria. The mitochondrial content of rat brain and liver is not reduced in aging and the impairment of mitochondrial function is due to decreased rates of electron transfer by the selectively diminished activities of complexes I and IV. Inner membrane H(+) impermeability and F(1)-ATP synthase activity are only slightly affected by aging. Dysfunctional mitochondria in aged rodents are characterized, besides decreased electron transfer and O(2) uptake, by an increased content of oxidation products of phospholipids, proteins and DNA, a decreased membrane potential, and increased size and fragility. Free radical-mediated oxidations are determining factors of mitochondrial dysfunction and turnover, cell apoptosis, tissue function, and lifespan. Inner membrane enzyme activities, such as those of complexes I and IV and mitochondrial nitric oxide synthase, decrease upon aging and afford aging markers. The activities of these three enzymes in mice brain are linearly correlated with neurological performance, as determined by the tightrope and the T-maze tests. The same enzymatic activities correlated positively with mice survival and negatively with the mitochondrial content of lipid and protein oxidation products. Conditions that increase survival, as vitamin E dietary supplementation, caloric restriction, high spontaneous neurological activity, and moderate physical exercise, ameliorate mitochondrial dysfunction in aged brain and liver. The pleiotropic signaling of mitochondrial H(2)O(2) and nitric oxide diffusion to the cytosol seems modified in aged animals and to contribute to the decreased mitochondrial biogenesis in old animals.

Establishment and characterization of new osteoclast progenitor cell lines derived from osteopetrotic and wild type mice

Malignant infantile osteopetrosis is a rare and lethal disease characterized by the absence of bone resorption due to inactive osteoclasts (OCLs). Among the murine models of osteopetrosis, the Tcirg1oc/oc mouse is the most resembling to the human pathology. In the majority of patients as in Tcirg1oc/oc mouse, the gene involved is the Tcirg1 gene, encoding the a3 subunit of the vacuolar proton pump. However, to date, no osteoclastic cell lines from osteopetrotic mice are available to facilitate the study of either OCL differentiation in osteopetrosis or the factors involved in the control of Tcirg1 gene expression. Heterozygotes Tcirg1+/oc mice were crossed with p53+/- mice to obtain homozygotes p53-/-Tcirg1oc/oc and p53-/-Tcirg1+/+ animals. The p53-/-Tcirg1oc/oc mice display the same bone and hematological phenotype as the original Tcirg1oc/oc mice. From the bone marrow of these mice, we have derived cell lines named POC-MGoc/oc and POC-MG+/+. These cell lines express standard osteoclastogenic markers and differentiate into OCLs in the presence of RANK-L and M-CSF. Furthermore, both cell lines can be transduced by a lentiviral vector with a high efficiency and without alteration of their OCL differentiation potential. Therefore, these cell lines provide valuable new tools to study the differentiation and function of osteoclasts in normal and resorption defective conditions.

Vitamin E at high doses improves survival, neurological performance, and brain mitochondrial function in aging male mice

Male mice receiving vitamin E (5.0 g α-tocopherol acetate/kg of food) from 28 wk of age showed a 40% increased median life span, from 61 ± 4 wk to 85 ± 4 wk, and 17% increased maximal life span, whereas female mice equally supplemented exhibited only 14% increased median life span. The α-tocopherol content of brain and liver was 2.5-times and 7-times increased in male mice, respectively. Vitamin E-supplemented male mice showed a better performance in the tightrope (neuromuscular function) and the T-maze (exploratory activity) tests with improvements of 9–24% at 52 wk and of 28–45% at 78 wk. The rates of electron transfer in brain mitochondria, determined as state 3 oxygen uptake and as NADH-cytochrome c reductase and cytochrome oxidase activities, were 16–25% and 35–38% diminished at 52–78 wk. These losses of mitochondrial function were ameliorated by vitamin E supplementation by 37–56% and by 60–66% at the two time points considered. The activities of mitochondrial nitric oxide synthase and Mn-SOD decreased 28–67% upon aging and these effects were partially (41–68%) prevented by vitamin E treatment. Liver mitochondrial activities showed similar effects of aging and of vitamin E supplementation, although less marked. Brain mitochondrial enzymatic activities correlated negatively with the mitochondrial content of protein and lipid oxidation products ( r2= 0.58–0.99, P < 0.01), and the rates of respiration and of complex I and IV activities correlated positively ( r2= 0.74–0.80, P < 0.01) with success in the behavioral tests and with maximal life span.

Behavioral, endocrine and immunological characteristics of a murine model of premature aging

We have previously shown that differences in life span among members of Swiss mouse populations appear to be related to their exploration of a T-maze, with a slow exploration ('slow mice') being linked to alteration of spontaneous behavior and monoaminergic systems, impaired immune function and shorter life span. In general these traits resemble some of the characteristics of chronologically old animals. Thus, we proposed the 'slow mice' as a model of prematurely aging mice (PAM). Now, we have compared female PAM with non-prematurely aging mice (NPAM) as regards a number of behavioral, endocrine and immunological parameters which were studied under both basal and stress conditions. In the present study the animals were chronologically younger than those used in our previous work. When compared to NPAM, the PAM showed increased anxiogenic-like responses in the plus-maze, increased basal corticosterone levels and decreased corticosterone responses to stress. The PAM also showed a decreased natural killer activity as well as decreased lymphoproliferative responses to mitogens. Moreover, the mitogen-induced lymphoproliferative responses of the PAM appeared to be more susceptible to stress. The data indicate that certain characteristics of the PAM are already present in animals of very young chronological age and provide new information for a more complete characterization of the PAM from a neuroimmunoendocrine viewpoint.

Long-term treatment with the antioxidant drug EGb 761 at senescence restored some neurobehavioral effects of chronic ultramild stress exposure seen in young mice

In this study, we compared the effects of chronic ultramild stress (CUMS) exposure on decision-making behavior in a validated test, and on the stress responsive serotoninergic and dopaminergic systems in four age groups of B6D2F1 female mice (5-6, 11-12, 17-18 and 23-24 months old). The levels of serotonin (5-HT) and its metabolite 5-hydroxyindolacetic acid (5-HIAA) were measured in the brain stem, the cortex, the striatum and the hippocampus; the levels of dopamine (DA) and its metabolite dihydroxyphenylacetic acid (DOPAC) were measured in the brain stem and the striatum. The influence of a long-term treatment with the extract of Ginkgo biloba leaves EGb 761 (Tanakan) on age- and stress-related changes was also investigated in the two oldest age groups. In the absence of drug treatment, middle-age mice were the least efficient in making a decision, and senescent mice exhibited reduced levels of both 5-HT and DA and their metabolites in all the brain areas examined. CUMS facilitated evaluation and choice behavior in all age groups, but induced age-dependent reduction of hesitation, acceleration of information processing and reduction in serotoninergic neurotransmission. In senescent mice, EGb 761 reduced the impact of stress on evaluation and hesitation, and restored some stress-related neurobehavioral changes that were only seen in young mice, i.e. acceleration of information processing and reduction in brain 5-HIAA levels. Restoration of some plasticity of the serotoninergic systems might contribute to the stress alleviating influence of EGb 761 in old age.

Overview of the brain polyamine-stress-response: regulation, development, and modulation by lithium and role in cell survival

An early transient increase in brain polyamine (PA) metabolism, termed the PA-stress-response (PSR), is a common reaction to stressful stimuli, including physical, emotional, and hormonal stressors, with a magnitude related to the stress intensity. In the extreme, traumatic injury can result in an incomplete PSR, with persistent accumulation of putrescine and eventual reduction in the concentrations of the higher polyamines (PAs), spermidine and spermine. Chronic intermittent application of stressors causes a recurrence of the brain PSR, but, in contrast, it leads to habituation of the response in the periphery (liver). Severe continuous stress, however, may lead to accumulation of brain PAs. Long-term inhibition of PA synthesis depletes brain PAs and can result in altered emotional reactivity to stressors. Furthermore, the brain PSR, in contrast to the periphery, can be blocked by a long-term, but not by short-term, treatment with lithium, the most efficacious treatment of manic-depressive illness. The brain PSR is developmentally regulated, and the switch to the mature pattern coincides with the cessation of the "stress hyporesponsive period" in the hypothalamic-pituitary-adrenocortical (HPA) system. In contrast to the brain and liver, the PSR in the adrenal and thymus is down-regulated by acute stressors. Transient up-regulation of the PSR, as in the brain and liver, is implicated in cell survival while its down-regulation is implicated in cell death. Taken together, the findings indicate that the PSR is a dynamic process that varies with the type, intensity, and duration of stressors, and implicate this response as an adaptive mechanism in the reaction to stressful events. Under persistent stressful conditions, however, the PSR may be maladaptive as may be reflected by PA accumulation. This raises the hypothesis that proper regulation of brain PSR may be critical for neuronal function and for an appropriate behavioral response to stressors.

Beneficial effects of moderate exercise on mice aging: survival, behavior, oxidative stress, and mitochondrial electron transfer

Moderate exercise in a treadmill (10, 15, and 20 cm/s, for 5 min each, weekly) from 28 to 78 wk of age extended male and female mice life span by 19 and 9% accompanied by 36 and 13% and 13 and 9% increased performance in behavioral assays (tightrope and T-maze tests) at 52 wk of age. Moderate exercise significantly decreased the aging-associated development of oxidative stress by preventing 1) the increase in protein carbonyls and thiobarbituric acid-reactive substances contents of submitochondrial membranes; 2) the decrease in antioxidant enzyme activities (Mn- and Cu,Zn-superoxide dismutase and catalase); and 3) the decrease in mitochondrial NADH-cytochrome- c reductase and cytochrome oxidase activities observed at 52 wk of mice age in brain, heart, liver, and kidney. These effects were no longer significant at 78 wk of age in mice. Moderate exercise, started at young age in mice, increased life span, decreased oxidative stress, and prevented the decline of cytochrome oxidase activity and behavioral performance at middle age but not at old age.

Fear of novelty in infant rats predicts adult corticosterone dynamics and an early death

Individuals who are fearful of novelty have a larger hypothalamic-pituitary-adrenal axis response than do nonfearful individuals. We hypothesized that a fearful behavioral style emerging early in life would be associated with life-long altered adrenal activity. Because there is ample physiological evidence both costs and benefits of adrenal activation, we determined whether such a stable emotional-neuroendocrine trait was associated with differential morbidity and mortality. To conduct such lifespan work, we studied a relatively short-lived mammal: the Norway rat. We first established that an animal's hesitation or willingness to explore a novel environment ("neophobia" and "neophilia," respectively) is an identifiable and stable behavioral trait in young-adult males and that neophobia, compared with neophilia, was associated with a greater glucocorticoid response to novelty. Second, we were able to detect behavioral differences among infant rats within a family, and this behavioral disposition at infancy predicted the magnitude of the glucocorticoid response in late middle age. Males identified as neophobic during infancy died sooner than their less fearful brothers. Although both types of males died with similar pathologies (tumors), neophobic males were 60% more likely to die at any point in time. This lifespan study identifies an emotional trait in infancy that predicts an early death and an associated neuroendocrine trait in adulthood that is a potential mechanism underlying the relationship between behavioral style and longevity.

Characterization of monoaminergic systems in brain regions of prematurely ageing mice

We have previously shown that differences in life span among members of Swiss mouse populations appear to be related to their exploration of a T-maze, with a slow exploration ("slow mice") being linked to increased levels of emotionality/anxiety, an impaired immune function and a shorter life span. Thus, we proposed the slow mice as prematurely ageing mice (PAM). We have now compared the monoaminergic systems of the PAM and of the non-prematurely ageing mice (NPAM), in discrete brain regions. PAM had decreased noradrenaline (NA) levels in all the brain regions analysed, whereas the 3-methoxy-4-hydroxyphenyl glycol (MHPG)/NA ratios were not significantly modified. PAM also showed decreased serotonine (5-HT) levels in hypothalamus, striatum and midbrain, as well as increased 5-hydroxyindol-3-acetic acid (5-HIAA)/5-HT ratios in hypothalamus and hippocampus. The dopamine (DA) content was lower in PAM in most regions, whereas the 3,4-dihydroxyphenylacetic acid (DOPAC)/DA and homovanillic acid (HVA)/DA ratios were either increased or unchanged depending on the region analysed. In most cases, the differences between PAM and NPAM involved both sexes. One exception was the hypothalamus where the differences only affected the male mice. The neurochemical alterations found in PAM resemble some changes reported for aged animals and are related with their behavioural features.

An impairment of phagocytic function is linked to a shorter life span in two strains of prematurely aging mice

In previous cross-sectional studies on Swiss mouse populations we have shown that at the same chronological age, animals that take longer to explore a simple T-maze (slow mice) are hyper-emotional and show an impairment of the immune system than those which quickly explore the maze (fast mice). Therefore, we have proposed that the slow mice are a model of prematurely aging mice (PAM). In the present work we have carried out a longitudinal study of age-dependent changes in key functions of phagocytic cells (peritoneal macrophages) such as phagocytosis and superoxide anion production in both male and female Swiss (outbred strain) and BALB/c (inbred strain) PAM and non-prematurely aging mice (NPAM). Gender differences were found showing the females better phagocytic and digestion capacities with concomitant longer life span. The PAM showed an impaired phagocytosis capacity and intracellular superoxide anion production as well as an increase of its extracellular production as compared to NPAM, which could be related to the shortened life span of those animals in both sexes and strains.

Effects of N-acetylcysteine on macrophage and lymphocyte functions in a mouse model of premature ageing

In previous studies, we have observed that mice of the same strain and age show striking interindividual differences in behavior when exposed to a T-maze test. The animals that take longer to explore a T-shaped maze ("slow" animals) show high levels of emotionality/anxiety in other standard behavioral tests, prematurely aged immune functions, and a shorter life span, in comparison to "fast" mice. In these slow mice, which are a model of premature immunosenescence, the immune functions were improved after the ingestion of the thiolic antioxidant thioproline in the diet. In the present work, we studied the effects in vivo (0.1% w/w, for 4 weeks) and in vitro (0.001, 0.01, 0.1, 1, and 2.5 mM) of the thiolic antioxidant N-acetylcysteine (NAC) on different functions of peritoneal macrophages and lymphocytes from slow and fast adult Swiss mice. The results showed an improvement of all the functions studied, namely adherence to substrate, directed migration or chemotaxis, phagocytosis, and reactive oxygen species (ROS) production, after in vivo and in vitro treatment with NAC. The effect of this antioxidant was stronger in the cells from the slow than in those from the fast mice.

Relation of behaviour and macrophage function to life span in a murine model of premature immunosenescence

According to our previous work, mice of the same strain and age show striking inter-individual differences in behaviour when exposed to a T-maze test. Further, the animals exploring the maze slowly (slow mice) or staying at the starting point (freezing behaviour), which show high levels of emotionality/anxiety in other standard behavioural tests, have a less competent immune system (earlier immunosenescence) than those which explore it quickly (fast mice). The present longitudinal study on OF-1 Swiss female mice confirms and extends the above findings. Thus, the animals showing a lower performance in the T-test (slow mice) which is accompanied by a poor neuromuscular coordination in a tightrope test, have a shorter life span than the good performers (fast mice). Moreover, the slow mice have a less competent immune system as regards the following functions of peritoneal macrophages: adherence to substrate, chemotaxis, ingestion of particles and superoxide anion production. This suggests that, at the same chronological age and as regards their immune competence, the slow mice are biologically older than the fast mice. This agrees with current ideas on the close functional relationship between the nervous and the immune system in the physiological adaptation to stress, and supports the concept that an optimum level of performance of these two systems is needed to attain a long life span.

Aging is a deprivation syndrome driven by a germ-soma conflict

Evolution through natural selection can be described as driven by a perpetual conflict of individuals competing for limited resources. Recently, I postulated that the shortage of resources godfathered the evolutionary achievements of the differentiation-apoptosis programming [Rev. Neurosci. 12 (2001) 217]. Unicellular deprivation-induced differentiation into germ cell-like spores can be regarded as the archaic reproduction events which were fueled by the remains of the fratricided cells of the apoptotic fruiting body. Evidence has been accumulated suggesting that conserved through the ages as the evolutionary legacy of the germ-soma conflict, the somatic loss of immortality during the ontogenetic segregation of primordial germ cells recapitulates the archaic fate of the fruiting body. In this heritage, somatic death is a germ cell-triggered event and has been established as evolutionary-fixed default state following asymmetric reproduction in a world of finite resources. Aging, on the other hand, is the stress resistance-dependent phenotype of the somatic resilience that counteracts the germ cell-inflicted death pathway. Thus, aging is a survival response and, in contrast to current beliefs, is antagonistically linked to death that is not imposed by group selection but enforced upon the soma by the selfish genes of the "enemy within". Environmental conditions shape the trade-off solutions as compromise between the conflicting germ-soma interests. Mechanistically, the neuroendocrine system, particularly those components that control energy balance, reproduction and stress responses, orchestrate these events. The reproductive phase is a self-limited process that moulds onset and progress of senescence with germ cell-dependent factors, e.g. gonadal hormones. These degenerate the regulatory pacemakers of the pineal-hypothalamic-pituitary network and its peripheral, e.g. thymic, gonadal and adrenal targets thereby eroding the trophic milieu. The ensuing cellular metabolic stress engenders adaptive adjustments of the glucose-fatty acid cycle, responses that are adequate and thus fitness-boosting under fuel shortage (e.g. during caloric restriction) but become detrimental under fuel abundance. In a Janus-faced capacity, the cellular stress response apparatus expresses both tolerogenic and mutagenic features of the social and asocial deprivation responses [Rev. Neurosci. 12 (2001) 217]. Mediated by the derangement of the energy-Ca(2+)-redox homeostatic triangle, a mosaic of dedifferentiation/apoptosis and mutagenic responses actuates the gradual exhaustion of functional reserves and eventually results in a multitude of aging-related diseases. This scenario reconciles programmed and stochastic features of aging and resolves the major inconsistencies of current theories by linking ultimate and proximate causes of aging. Reproduction, differentiation, apoptosis, stress response and metabolism are merged into a coherent regulatory network that stages aging as a naturally selected, germ cell-triggered and reproductive phase-modulated deprivation response.

Behavioral dysfunction, brain oxidative stress, and impaired mitochondrial electron transfer in aging mice

Behavioral tests, tightrope success, and exploratory activity in a T maze were conducted with male and female mice for 65 wk. Four groups were defined: the lower performance slow males and slow females and the higher performance fast males and fast females. Fast females showed the longest life span and the highest performance, and slow males showed the lowest performance and the shortest life span. Oxidative stress and mitochondrial electron transfer activities were determined in brain of young (28 wk), adult (52 wk), and old (72 wk) mice in a cross-sectional study. Brain thiobarbituric acid reactive substances (TBARS) were increased by 50% in old mice and were approximately 15% higher in males than in females and in slow than in fast mice. Brain Cu,Zn-superoxide dismutase (SOD) activity was increased by 52% and Mn-SOD by 108% in old mice. The activities of mitochondrial enzymes NADH-cytochrome c reductase, cytochrome oxidase, and citrate synthase were decreased by 14-58% in old animals. The cumulative toxic effects of oxyradicals are considered the molecular mechanism of the behavioral deficits observed on aging.

Leukocyte function and life span in a murine model of premature immunosenescence

Aging associates with a decline of physiological functions, including the function of the nervous and the immune system. These aged-related changes occur in various degrees in different members of a mouse outbred population. Accordingly, we have proposed a model of premature immunosenescence in mice, based on the demonstration of premature decline in the behavioral response in a simple T-maze and in several immune functions in Swiss outbred mice. Those mice with a worst (slow) performance in this test (linked to a higher emotional response to stress) show a shorter life span and a decreased immune function when compared to fast mice. In order to provide biomarkers of "biological aging" related to health and survival, the present longitudinal study includes the analysis of several immunological parameters such as, proliferative response to mitogen Con A, NK activity and cytokine (TNFalpha, IL-1beta and IL-2) release by peritoneal leukocytes from female Swiss mice. Slow mice showed a lower proliferative response to Con A, IL-2 and IL-1beta release, an impaired NK activity and an increased TNFalpha production as compared to fast mice. Moreover, the age-associated decline of these functions is more strikingly slow than in fast mice. In summary, we propose the above immunological parameters, that change with aging at a different rate in members of a same population, as useful biomarkers to asses the rate of biological aging in mice.

Behavioral characterization of a mouse model of premature immunosenescence

In previous studies we have shown that differences in life span among members of Swiss mouse populations appear to be related to their performance in a T-maze, with a slow performance ("slow" mice) being linked to an impaired immune function and a shorter life span when compared to "fast" mice, which led us to propose the slow mice as a model of immunosenescence. In the present study we demonstrate that in a tightrope test of neuromuscular vigor and coordination the slow mice show a worse performance, needing more time to complete the task. Moreover, these animals show a decreased locomotor activity and an increased level of emotionality/anxiety in three standard behavioral tests (the holeboard, the open field and the plus-maze) when compared to fast mice. All these behavioral features were most marked in the slow females. The results also indicate that slow animals show a decreased chemotaxis of macrophages and lymphocytes, as well as a reduced lymphoproliferative response to mitogens. The data supports our claim that slow or hyperemotional mice, in which immune and neurobehavioural functions appear to be impaired, may be a useful model of premature aging.

Age-dependent effects of a chronic ultramild stress procedure on open-field behaviour in B6D2F1 female mice

Few studies have been devoted to the interaction between age and stress. However, in view of the age-related changes in various components of the stress responses, the effects of stress may not be constant with age. In this study, we used a dimensional approach to compare open-field behaviour of B6D2F1 female mice, aged 5-6, 11-12, 17-18 and 23-24 months, exposed to a chronic ultramild stress (CUMS) procedure, solely based on nonnociceptive socioenvironmental stressors. Three behavioural dimensions emerged from the principal-component analysis; these were labelled as motor reactivity, exploratory activity, and emotional reactivity. Despite a major effect of age on the three dimensions, we could not conclude that CUMS had any influence as a function the age of the subjects. At all ages, CUMS increased motor activity and had no clear-cut effect on emotional reactivity and exploratory activity. The results are discussed in terms of the influence of the nature of the stressors on behavioural responses to novelty.

A unifying hypothesis of Alzheimer's disease. III. Risk factors

Normal ageing and Alzheimer's disease (AD) have many features in common and, in many respects, both conditions only differ by quantitative criteria. A variety of genetic, medical and environmental factors modulate the ageing-related processes leading the brain into the devastation of AD. In accordance with the concept that AD is a metabolic disease, these risk factors deteriorate the homeostasis of the Ca(2+)-energy-redox triangle and disrupt the cerebral reserve capacity under metabolic stress. The major genetic risk factors (APP and presenilin mutations, Down's syndrome, apolipoprotein E4) are associated with a compromise of the homeostatic triangle. The pathophysiological processes leading to this vulnerability remain elusive at present, while mitochondrial mutations can be plausibly integrated into the metabolic scenario. The metabolic leitmotif is particularly evident with medical risk factors which are associated with an impaired cerebral perfusion, such as cerebrovascular diseases including stroke, cardiovascular diseases, hypo- and hypertension. Traumatic brain injury represents another example due to the persistent metabolic stress following the acute event. Thyroid diseases have detrimental sequela for cerebral metabolism as well. Furthermore, major depression and presumably chronic stress endanger susceptible brain areas mediated by a host of hormonal imbalances, particularly the HPA-axis dysregulation. Sociocultural and lifestyle factors like education, physical activity, diet and smoking may also modulate the individual risk affecting both reserve capacity and vulnerability. The pathophysiological relevance of trace metals, including aluminum and iron, is highly controversial; at any rate, they may adversely affect cellular defences, antioxidant competence in particular. The relative contribution of these factors, however, is as individual as the pattern of the factors. In familial AD, the genetic factors clearly drive the sequence of events. A strong interaction of fat metabolism and apoE polymorphism is suggested by intercultural epidemiological findings. In cultures, less plagued by the 'blessings' of the 'cafeteria diet-sedentary' Western lifestyle, apoE4 appears to be not a risk factor for AD. This intriguing evidence suggests that, analogous to cardiovascular diseases, apoE4 requires a hyperlipidaemic lifestyle to manifest as AD risk factor. Overall, the etiology of AD is a key paradigm for a gene-environment interaction. Copyright 2000 John Wiley & Sons, Ltd.

Effects of age, sex and physical exercise on the phagocytic process of murine peritoneal macrophages

Different stages of the phagocytic process, i.e. chemotaxis, ingestion of latex beads and superoxide anion production, were measured in peritoneal macrophages from young (12 +/- 2 weeks old) and old (60 +/- 2 weeks old) male and female BALB/C mice, which were subjected to an acute bout of exercise (swimming until exhaustion) or to a period of training exercise (90 min of swimming each day during 20 days). Sedentary male and female mice as well as young and old animals were used as sex and age controls. The results show that both acute and training exercise stimulate the phagocytic process of murine peritoneal macrophages. The macrophage functions from sedentary controls were lower in the old than in the young animals. The chemotaxis and ingestion capacities of macrophages were higher in the female young and old sedentary mice than in their male counterparts. After exercise, the stimulation of the phagocytic process was higher in old and female mice than in young and male animals. In addition, serum corticosterone levels were measured in order to investigate the relations between stress and macrophage activity. Old and female mice as well as animals subjected to exercise showed, in general, higher corticosterone levels than young, male and sedentary animals.

Hypertensive rats exhibit heightened expression of corticotropin-releasing factor in activated central neurons in response to restraint stress

To test the hypothesis that chronically elevated sympathetic drive is associated with hyperreactiveness of autonomic centers in the brain to stress, adult spontaneously hypertensive rats (SHRs) and two strains of normotensive rats (Wistar Kyoto [WKY] and Sprague Dawley [SD] rats) were acutely exposed to restraint stress; controls from each strain were not stressed. Brain sections were prepared for Fos immunohistochemistry to identify activated neurons in the paraventricular nucleus of the hypothalamus, Barrington's nucleus of the pons, nucleus of the tractus solitarius, and ventrolateral medulla, or for combined Fos immunohistochemistry and corticotropin-releasing factor (CRF) in situ hybridization in the paraventricular nucleus and Barrington's nucleus. Restraint led to increased activation of neurons in all nuclei. Strain differences were found only in the caudal and rostral paraventricular nucleus where restraint resulted in greater numbers of activated neurons in SHRs compared to either normotensive strain. Levels of CRF mRNA in Barrington's nucleus of unrestrained rats were similar among strains. After restraint, mRNA levels and double labeled neurons were increased in Barrington's nucleus of SHRs. In unstressed rats, CRF mRNA levels were elevated in some regions of the paraventricular nucleus in SHRs. After restraint, mRNA levels increased throughout the paraventricular nucleus of SHRs. Significantly greater numbers of double labeled neurons were found in the dorsolateral medial and ventral medial parvocellular paraventricular nucleus of stressed SHRs compared to WKY or SD rats. These data show that chronic elevation in sympathetic activity, present in SHRs, is associated with hyperreactiveness of the paraventricular and Barrington's nucleus including recruitment of neurons to express CRF, and may have important implications for the response of the hypothalamo-pituitary-adrenal axis during stress.

Effect of a diet supplemented with thioproline on murine macrophage function in a model of premature ageing

A previous study has shown that diet supplementation with thioproline (thiazolidine-4-carboxylic acid, TCA), an intracellular sulfhydril antioxidant and free radical scavenger, stimulates lymphocyte functions in old mice. In the present work, the effect of thioproline ingestion on the phagocytic functions of peritoneal macrophages, namely adherence, chemotaxis, phagocytosis and superoxide anion production was studied in adult female OF1-Swiss mice, that were fed thioproline (0.1% w/w) for five weeks, starting this ingestion at the age of 22 +/- 2 weeks. Mice were divided into a fast and a slow group based on their exploratory activity, which was assessed by their performance in a T-shaped maze. Slow mice showed a worse phagocytic activity with respect to fast animals. After thioproline treatment, a stimulation of all the functions studied as well as a neutralization of the superoxide radical were observed. The effect of this antioxidant was stronger in the slow than in the fast group. Thus, a diet supplemented with thioproline may enhance the immune functions, especially when they are depressed.

Changes in several functions of murine peritoneal macrophages by N-acetylcysteine and thioproline ingestion. Comparative effect between two strains of mice

The administration of the thiol compounds, N-acetylcysteine (NAC) and in particular thioproline (thiazolidine-4-carboxylic acid) at 0.1% w/w concentration in the diet, improves lymphocyte functions in old female Swiss mice, as has been shown in our previous studies. In the present work, adult mice from two different strains, namely BALB/c (an inbred strain) and OF1-Swiss (noninbred strain), were fed a diet supplemented with the above dose of each thiol compound jointly for five weeks. At 28 weeks of age, peritoneal cell suspensions were obtained and different steps of the phagocytic process, the most representative activity of macrophages, as well as interleukin-1beta (IL-1beta) production, were studied. Thus, adherence to substrate, mobility directed to a chemoattractant gradient (chemotaxis), ingestion of inert particles and superoxide anion production were analysed. The results show that diet supplementation with NAC plus thioproline increased all macrophage functions studied with the exception of superoxide anion production, which was decreased. These effects were more evident in macrophages from Swiss mice, whereas in BALB/c mice the stimulation of phagocytosis and IL-1beta production was lower and no differences were seen after treatment in adherence and superoxide anion production. These data suggest that immune function can be improved in adult mice by administration of the above thiol compounds, especially in the noninbred strain of OF1-Swiss mice.

Relation between exploratory activity and immune function in aged mice: a preliminary study

Previous studies show that fast exploration of a T-shaped maze by mature mice may predict an above average longevity. Since the nervous and the immune systems work in a coordinated fashion, and it seems that these two homeostatic systems both influence organismic aging and suffer a senescent decline, we have performed a comparative study of the above behavioral parameter and different functions of three representative immune cells: lymphocytes, macrophages and natural killer (NK) cells obtained from old (76 +/- 1 weeks of age) female OF1-Swiss mice. At 70 weeks of age the mice were divided into a 'fast' and a 'slow' group, containing 100 and 0%, respectively, of animals able to explore the 50 cm-long first arm of the maze in 20 s or less. At 76 +/- 1 weeks of age the animals were sacrificed, the peritoneal cell suspensions were obtained and the immune organs (axillary nodes, spleen and thymus) were isolated. The following leukocyte functions were studied in peritoneal macrophages: adherence to substrate, mobility (spontaneous and chemotaxis), ingestion of particles and superoxide anion production whereas mobility, lymphoproliferative response to the mitogen Con A and NK activity were studied in the immune-organ leukocyte suspensions. The results show that the aged fast mice have better immune functions than the aged slow mice.

Effect of restraint stress on immune system and experimental B16 melanoma metastasis in aged mice

An overnight restraint stress was given to young and old mice and its effect was examined in terms of the number and function of T cells and natural killer (NK) cells in spleen and patterns of lung metastasis of B16 melanoma cells. A great decrease was observed in the number and proliferative activity of splenic T cells in old mice after the stress. The decrease in young mice was rather temporary with a quick recovery. The number of NK cells in spleen was not different between young and old mice before giving the stress, but a significant decrease was observed in the old after the stress. NK activity was always much lower in old than in young throughout the experiment. The pattern of metastasis of B16 melanoma cells was different between young and old mice. Metastatic colonies in lungs were larger in number and bigger in size in young mice than in old mice. After the stress, the number increased and the size unchanged in old mice, while the size increased and the number remained unchanged in young mice. It was shown that the same restraint stress resulted in a more serious influence on the immune cells in old than in young mice and gave rise to a differential effect on the pattern of tumor metastasis between young and old mice.

CRH-R1 mRNA expression in two strains of inbred mice and its regulation after repeated restraint stress

Using in-situ hybridization histochemistry we investigated the distribution of CRH receptor 1 (CRH-R1) mRNA in the cortex of C57BL/6 (C57) and DBA/2 (DBA) strains and its regulation after repeated restraint stress. We show that DBA mice have a higher concentration of CRH-R1 mRNA than C57 mice. Repeated restraint stress produced an increase in CRH-R1 mRNA expression of C57 mice, whereas it was uneffective in DBA mice.

Interleukin-6-associated inflammatory processes in Alzheimer's disease: new therapeutic options

The cytokine interleukin-6 is consistently detected in the brains of Alzheimer's disease patients but not in the brains of nondemented elderly persons. Until recently it was unclear whether an interleukin-6-associated inflammatory mechanism is an early or late event in the pathological cascade of Alzheimer's disease. We investigated whether interleukin-6 could be detected in plaques of Alzheimer's disease patients prior to the onset of neuritic degeneration. We found interleukin-6 mostly in plaques where neuritic pathology has not yet developed. This indicates that the appearance of interleukin-6 may precede neuritic changes and is not just a consequence of neuritic degeneration. Therefore, one may hypothesize that activation of inflammatory mechanisms may cause neuritic degeneration in plaques. A suppression of interleukin-6 synthesis could, therefore, be of therapeutic value. Upon screening a number of substances, we found that a small number of nonsteroidal antiinflammatory drugs, including tenidap, were able to inhibit interleukin-6 synthesis in cultured human astrocytoma cells. These substances may be therapeutically useful in Alzheimer's disease and should be evaluated in clinical studies.