Age-related alterations in cytochrome c-mediated caspase activation in rhesus macaque monkey (Macaca mulatta) brains

Adult neurogenesis augmentation attenuates anhedonia and HPA axis dysregulation in a mouse model of chronic stress and depression

Major depressive disorder is a common debilitating mental health problem that represents one of the leading causes of disability. Up to date, the therapeutic targets and approaches are still limited. Adult hippocampal neurogenesis (AHN) has been proposed as a critical contributor to the pathophysiology and treatment of depression, altering the hippocampal control over stress response at network, neuroendocrine and behavioral levels. These findings together have suggested that manipulating AHN may be a promising therapeutic strategy for depression. To investigate this question, we assessed whether increasing adult neurogenesis would be sufficient to produce antidepressant-like effects at behavioral and neuroendocrine levels in a mouse model of depression; the unpredictable chronic mild stress (UCMS). For this purpose, we used a bi-transgenic mouse line (iBax) in which AHN increase was induced by deletion of the pro-apoptotic gene Bax from the neural progenitors following the tamoxifen-dependent action of CreERT2 recombinases. UCMS induced a syndrome that is reminiscent of depression-like states, including anhedonia (cookie test), physical changes (coat deterioration, reduced weight gain), anxiety-like behaviors (higher latency in the novelty-supressed feeding -NSF- test), passive stress-coping behaviors (immobility in the forced swim test -FST-) and a blunted hypothalamo-pituitary-adrenal (HPA) axis reactivity to acute stress in addition to AHN decrease. Tamoxifen injection reversed the AHN decrease as well as partly counteracted UCMS effects on the cookie test and HPA axis but not for the coat state, weight gain, NSF test and FST. Taken together, our results suggest that a strategy directing at increasing AHN may be able to alleviate some depression-related behavioral and neuroendocrine dimensions of UCMS, such as anhedonia and HPA axis reactivity deficits, but may be hardly sufficient to produce a complete recovery.

Role of Plant-Derived Flavonoids and Their Mechanism in Attenuation of Alzheimer's and Parkinson's Diseases: An Update of Recent Data

Neurodegeneration is a progressive loss of neuronal cells in certain regions of the brain. Most of the neurodegenerative disorders (NDDs) share the communal characteristic such as damage or reduction of various cell types typically including astrocytes and microglial activity. Several compounds are being trialed to treat NDDs but they possess solitary symptomatic advantages along with copious side effects. The finding of more enthralling and captivating compounds to suspend and standstill the pathology of NDDs will be considered as a hallmark of present times. Phytochemicals possess the potential to alternate the synthetic line of therapy against NDDs. The present review explores the potential efficacy of plant-derived flavonoids against most common NDDs including Alzheimer's disease (AD) and Parkinson's disease (PD). Flavonoids are biologically active phytochemicals which possess potential pharmacological effects, including antiviral, anti-allergic, antiplatelet, anti-inflammatory, anti-tumor, anti-apoptotic and anti-oxidant effects and are able to attenuate the pathology of various NDDs through down-regulating the nitric oxide (NO) production, by reducing the tumor necrosis factor-α (TNF-α), by reducing the excitotoxicity of superoxide as well as acting as tyrosine kinase (TK) and monoamine oxidase (MAO) inhibiting enzyme.

TUNEL and growth factor expression in the prefrontal cortex of Alzheimer patients over 80 years old

To elucidate factors underlying the increased risk of developing Alzheimers disease (AD) in older individuals, the prefrontal cortices of younger (58-79 years) and of older (over 80 years) AD patients were examined by silver impregnation, TUNEL assay and immunohistochemistry for hyperphosphorylated tau, LDH and two growth factors (BDNF, NGF). Quantitative data were compared with those of age-matched controls. TUNEL-positive cells were mainly located in superficial cortical layers of younger and in deeper layers of older AD patients. Their density was more than 5 times higher in older AD than in younger AD (p < or = 0.05), but apoptotic cell morphology was rarely seen. Significantly more neuronal somas were contacted by degenerating fibers both in younger and older AD cortices. Density of tau-immunoreactive cells, which were virtually absent in controls, was twice as high in older AD patients as in younger AD individuals (p < or = 0.05). In younger AD, TUNEL positive cells generally lacked tau immunoreaction, whereas in older AD, most cells were double-labeled for hyperphosphorylated tau and TUNEL (p < or = 0.05). Numerical density of BDNF-immunoreactive cells was significantly reduced by 20 percent in older AD patients, compared to both control individuals and younger AD patients, whereas density of NGF-positive cells was the same in all patient groups examined. The distinct differences between younger and older AD patients suggest a faster progression of AD in older patients.

Treadmill exercise prevents aging-induced failure of memory through an increase in neurogenesis and suppression of apoptosis in rat hippocampus

Aging leads to functional changes in the hippocampus, and consequently induces cognitive deficits, such as failure of memory. Neurogenesis in the hippocampal dentate gyrus continues throughout life, but steadily declines from early adulthood. Apoptosis occurs under various pathologic and physiologic conditions, and excessive apoptotic cell death can cause a number of functional disorders in humans. Apoptosis in the hippocampus also disturbs cognitive functions. In this study, we examined the effect of treadmill exercise on memory in relation to neurogensis and apoptosis in the hippocampal dentate gyrus of old-aged rats. The present results showed that loss of memory by aging was associated with a decrease in neurogenesis and an increase in apoptosis in the hippocampal dentate gyrus. Treadmill exercise improved short-term and spatial memories by enhancing neurogenesis and suppressing apoptosis in the hippocampal dentate gyrus of old-aged rats. In the present study, we showed that treadmill exercise is a very useful strategy for preventing failure of memory in the elderly.

Chronic application of nonylphenol-induced apoptosis via suppression of bcl-2 transcription and up-regulation of active caspase-3 in mouse brain

Nonylphenol (NP) is an endocrine disruptor, which has been reported to have adverse effects on reproductive and immune systems. However, the influence of NP on the central nervous system (CNS) has not been extensively explored. The present study was performed to investigate the effects of chronic administration of NP on the apoptosis-related protein expression in mouse brain by in situ hybridization, RT-PCR and immunoblotting assays. The expression of bcl-2 mRNA was down-regulated by NP at the doses of 100 and 200mg/(kg day) (p<0.05), whereas the expression of bax mRNA was not affected in NP treated mice (p>0.05). Furthermore, as the main executor of apoptosis, the expression of active caspase-3 was up-regulated by 100 and 200mg/(kg day) NP (p<0.01), which is in accord with the results of terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling (TUNEL) (p<0.05). These results suggest that chronic application of NP could sensitize the mice brain to apoptosis.

Differential response of apoptosis-regulatory Bcl-2 and Bax proteins to an inflammatory challenge in the cerebral cortex and hippocampus of aging mice

Apoptosis plays a key role in normal aging and neurodegeneration. It is now known that normal aging implies low-grade inflammation and increases susceptibility to neurodegenerative diseases, which, in turn, include a neuroinflammatory component. We here investigated, using mice of 2-3 months, 10-11 months, or 18-21 months of age, the expression of apoptosis-regulatory proteins in cortical brain regions in response to intracerebroventricular administration of pro-inflammatory cytokines. A mixture of interferon-gamma and tumor necrosis factor-alpha was injected, using vehicle (phosphate-buffered saline) as control. At 4 days, levels of the anti-apoptotic Bcl-2 and pro-apoptotic Bax proteins in the cerebral cortex and hippocampus, examined with Western blotting, were markedly upregulated by cytokine exposure in mice of all age groups with respect to controls. Interestingly, cytokine-elicited Bcl-2 upregulation was aging-dependent, with significant enhancement paralleling the animals' age. Cytokine-elicited Bax expression did not exhibit instead significant aging-related variation. Using the same paradigm and 1 or 2 day survival, Bcl-2 immunoreactivity was observed mainly in neurons of cortex and hippocampus of both control and cytokine-treated mice of all age groups. Furthermore, immunohistochemistry confirmed the enhancement of cytokine-elicited Bcl-2 expression in the cerebral cortex and hippocampus of old mice, and showed that this finding was already evident in the second day after cytokine exposure. The data point out the novel finding that Bcl-2 and Bax expression in cortical brain regions is differentially regulated during senescence in response to an acute inflammatory challenge. Aging-related Bcl-2 increases in neurons after cytokine exposure could contribute to amplify neuroprotective mechanisms in the old brain.

The anti-apoptosis effects of daidzein in the brain of D-galactose treated mice

The purpose of this study was to explore the neuroprotective effects of daidzein on the apoptotic pathway in the hippocampus and cortex of D-galactose treated mice. For this purpose we have examined the expression of bcl-2 mRNA, bax mRNA and caspase-3 in the hippocampus and cortex of D-galactose-treated mice after fed with 10 or 5 mg/kg of daidzein. The results of in situ hybridization experiments indicate that daidzein could help increase the transcriptions of bcl-2 and decrease the transcriptions of bax in those brain regions of D-galactose-treated mice. Furthermore, immunohistochemical studies showed that daidzein could reduce the expression of caspase-3 in both brain regions. These results suggest that daidzein in soybean can inhibit the D-gal induced apoptosis via Bcl-2/Bax apoptotic pathway and be a potential medical candidate for neurodegeneration therapy.

The eyes of anencephalic babies: a morphological and immunohistochemical evaluation

This study studied the eyes of three anencephalic stillborns to evaluate whether brain degeneration affected eye development and/or survival. The study encompassed histology, scanning electronmicroscopy, and immunocytochemistry. The corneae were otherwise normal except for the presence of blood vessels in the stroma and the posterior surface of the cornea demonstrated wrinkles. Synaechia was present and the lens had occasional vacuolated cells. The retinae had normal layers in most regions except the center where fibroblasts infiltration was observed. The optic nerve was atypical and composed of aggregates of disoriented fibroblasts and disoriented nerve fibers. Anti-cleaved caspase 3 immunocytochemistry revealed only few positive dying cells in the visual cell layer. Antineurofilament 200 reactions demonstrated positive ganglion cells even in the anencephalic eyes. The choroids in anencephaly had more VEGF positive sites, indicating vascularization in both control and anencephalic eyes. If the brains degenerate before retinal maturation, then such degenerations may not have an effect on subsequent retinal development except for the degeneration of the nerve fiber layer. If the brains degenerate after retinal maturation, then the survival of the retinae does not appear to rely on its linkage with the brain at birth, again apart from the degeneration of nerve fibers.

Changes of brain activity in the aged SAMP mouse

This study investigates characteristics of aging in the central nervous system of the senescence accelerated prone mice (SAMP8). We examined 3 and 10-months old senescence-accelerated-prone mice (SAMP8) for functional and molecular changes in their brains, specifically in the hippocampus and somatosensory cortex. There was no statistically significant increase in the apoptosis indicators as revealed by Western Blotting for BAD and TUNEL experiments. However, the functional magnetic resonance imaging showed an increase in the area of BOLD images from the 3-month old to the 10-months old SAMP mice upon the application of tail stimulus. These results demonstrated a lack of neuronal deaths but an increase in the activated brain area with age.

Caspase-3 immunoreactivity in different cortical areas of young and aging macaque (Macaca mulatta) monkeys

It has been shown that cytochrome-c-dependent caspase-3 activation is significantly elevated in the aging macaque brain. To assess the underlying age-related changes in the cellular distribution of caspase-3, we have examined the motor cortex, cerebellum and hippocampus of young (4-year-old, n = 4) and old (20-year-old, n = 4)rhesus monkeys by immunohistochemistry. Western blot analyses of brain homogenate showed that the antibody reacted only with inactive 32-kDa procaspase and its active 20- and 17-kDa subunits, formed after granzyme B exposure. In the motor cortex, pyramidal cells of layers III and V were moderately labeled; the underlying white matter contained weakly stained astrocytes. In the hippocampus, hilar neurons and pyramidal cells in CA3 showed the strongest immunoreaction, pyramidal cells in CA1 and granule cells of the dentate gyrus were also strongly labeled. In contrast, CA2 pyramidal cells were only weakly stained, and neurons of the molecular layer were unlabeled. Weak caspase-3 immunoreaction of CA2 neurons parallels known decreased susceptibility to apoptosis. In the cerebellar cortex, clusters of strongly labeled Purkinje cells were observed next to groups of weakly and unstained cells; granule cells were generally unstained. The brains of aging monkeys displayed a similar pattern of caspase-3 immunoreactivity. In neocortical layer V, however, scattered very strongly labeled pyramidal cells were regularly detected, which were not observed in younger animals. This clustering of caspase-3 indicates increased vulnerability of a subset of pyramidal cells in the aging brain.

Molecular evidence of the neuroprotective effect of Ginkgo biloba (EGb761) using bax/bcl-2 ratio after brain ischemia in senescence-accelerated mice, strain prone-8

In the present studies, we investigated the molecular mechanism of one of the active ingredients of Ginkgo biloba, EGb761, to affect the levels of several apoptotic markers in six brain regions following global ischemia in senescence-accelerated mice. A 4-day treatment with EGb761 significantly decreased bax/bcl-2 ratios in all brain regions in both young and aged mice. Our findings indicate that the bax/bcl-2 ratio provides a suitable index of apoptosis and modulation of these markers may explain the neuroprotective action of EGb761.

Changes of apoptosis-related proteins in hippocampus of SAM mouse in development and aging

Expression of Caspase and Bcl-2 proteins was examined in the hippocampus of senescence-accelerated mice (SAM, P8 and R1 strain) from E19 to 16 months of age. Immunoblotting analysis showed no upregulation of pro-apoptotic proteins (caspase-2L, -3, -6, -8, -9, and Bax) with age while all the anti-apoptotic proteins (caspase-2S, Bcl-2, and Bcl-XL) remained unchanged during aging. Terminal dUTP nick end labeling (TUNEL) and electron microscopy on the hippocampus of 3- and 16-month-old SAM revealed very few TUNEL positive cells in both groups. Morphometric study further showed neuronal loss in the hippocampus was not age-related. Our results suggest apoptosis and cell loss are minor events in the hippocampus of SAM mice and are unlikely to be the cause of functional decline during aging in SAM.