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Caspases are a family of cysteinyl aspartate-specific proteases that are highly conserved in multicellular organisms and function as central regulators of apoptosis. A member of this family, caspase-3, has been identified as a key mediator of apoptosis in neuronal cells. Recent studies in snail, fly and rat suggest that caspase-3 also functions as a regulatory molecule in neurogenesis and synaptic activity. In this study, in addition to providing an overview of the mechanism of caspase-3 activation, we review genetic and pharmacological studies of apoptotic and nonapoptotic functions of caspase-3 and discuss the regulatory mechanism of caspase-3 for executing nonapoptotic functions in the central nervous system. Knowledge of biochemical pathway(s) for nonapoptotic activation and modulation of caspase-3 has potential implications for the understanding of synaptic failure in the pathophysiology of neurological disorders. Fine-tuning of caspase-3 lays down a new challenge in identifying pharmacological avenues for treatment of many neurological disorders. [ABSTRACT FROM AUTHOR]

The deficiency of vitamins, a condition known as "hidden hunger", causes comprehensive pathological states. Research over the years has identified a relationship between liver diseases and hypovitaminosis or defects in vitamin metabolism. The exact mechanisms remain elusive; however, the crucial involvement of specific vitamins in metabolic functions, alongside the reclassification of liver disease as metabolic dysfunction-associated steatotic liver disease (MASLD), has prompted researchers to investigate the potential cause-effect dynamics between vitamin deficiency and liver disease. Moreover, scientists are increasingly investigating how the deficiency of vitamins might disrupt specific organ crosstalk, potentially contributing to liver disease. Although the concept of a dysmetabolic circuit linking adipose tissue and the liver, leading to liver disease, has been discussed, the possible involvement of vitamin deficiency in this axis is a relatively recent area of study, with numerous critical aspects yet to be fully understood. In this review, we examine research from 2019 to July 2024 focusing on the possible link between liver-adipose tissue crosstalk and vitamin deficiency involved in the onset and progression of non-alcoholic fatty liver disease (NAFLD). Studies report that vitamin deficiency can affect the liver-adipose tissue axis, mainly affecting the regulation of systemic energy balance and inflammation.

Vitamin B12 (VitB12) is a micronutrient and acts as a cofactor for fundamental biochemical reactions: the synthesis of succinyl-CoA from methylmalonyl-CoA and biotin, and the synthesis of methionine from folic acid and homocysteine. VitB12 deficiency can determine a wide range of diseases, including nervous system impairments. Although clinical evidence shows a direct role of VitB12 in neuronal homeostasis, the molecular mechanisms are yet to be characterized in depth. Earlier investigations focused on exploring the biochemical shifts resulting from a deficiency in the function of VitB12 as a coenzyme, while more recent studies propose a broader mechanism, encompassing changes at the molecular/cellular levels. Here, we explore existing study models employed to investigate the role of VitB12 in the nervous system, including the challenges inherent in replicating deficiency/supplementation in experimental settings. Moreover, we discuss the potential biochemical alterations and ensuing mechanisms that might be modified at the molecular/cellular level (such as epigenetic modifications or changes in lysosomal activity). We also address the role of VitB12 deficiency in initiating processes that contribute to nervous system deterioration, including ROS accumulation, inflammation, and demyelination. Consequently, a complex biological landscape emerges, requiring further investigative efforts to grasp the intricacies involved and identify potential therapeutic targets.

Recent studies have confirmed the direct role of vitamin B12 (VitB12) in the central nervous system (CNS) homeostasis; nevertheless, the detailed mechanisms are poorly understood. By analyzing RNA-Seq and microarray datasets obtained from databanks, this study aims to identify possible basic mechanisms, related to the brain, involved in altering the gene expression under VitB12 deficiency mimicking conditions. The database inquiry returned datasets generated from distinctly heterogeneous experimental sets and considering the quality and relevance requirements, two datasets from mouse and one from rat models were selected. The analyses of individual datasets highlighted a change in ribosomal gene expression in VitB12 deficiency mimicking conditions within each system. Specifically, a divergent regulation was observed depending on the animal model: mice showed a down regulation of the ribosomal gene expression, while rats an upregulation. Interestingly, E2f1 was significantly upregulated under VitB12 deficiency mimicking conditions in the animal models, with a greater upregulation in rats. The rat model also revealed putative E2F1 Transcription Factor Binding Sites (TFBSs) in the promoter of the differently regulated genes involved in ribosomal gene expression. This suggested the possibility that E2F1, being greater expressed in rats, could activate the ribosomal genes having E2F1 TFBSs, thus giving a plausible explication to the divergent regulation observed in animal models. Despite the great diversity of the experimental sets used to generate the datasets considered, a common alteration of the ribosomes exists, thereby indicating a possible basic and conserved response to VitB12 deficiency. Moreover, these findings could provide new insights on E2F1 and its association with CNS homeostasis and VitB12 deficiency., (© 2023. The Author(s).)

Intestinal bacterial communities participate in gut homeostasis and are recognized as crucial in bowel inflammation and colorectal cancer (CRC). Fusobacterium nucleatum ( Fn ), a pathobiont of the oral microflora, has recently emerged as a CRC-associated microbe linked to disease progression, metastasis, and a poor clinical outcome; however, the primary cellular and/or microenvironmental targets of this agent remain elusive. We report here that Fn directly targets putative colorectal cancer stem cells (CR-CSCs), a tumor cell subset endowed with cancer re-initiating capacity after surgery and chemotherapy. A patient-derived CSC line, highly enriched (70%) for the stem marker CD133, was expanded as tumor spheroids, dissociated, and exposed in vitro to varying amounts (range 100-500 MOI) of Fn . We found that Fn stably adheres to CSCs, likely by multiple interactions involving the tumor-associated Gal-GalNac disaccharide and the Fn -docking protein CEA-family cell adhesion molecule 1 (CEACAM-1), robustly expressed on CSCs. Importantly, Fn elicited innate immune responses in CSCs and triggered a growth factor-like, protein tyrosine phosphorylation cascade largely dependent on CEACAM-1 and culminating in the activation of p42/44 MAP kinase. Thus, the direct stimulation of CSCs by Fn may contribute to microbiota-driven colorectal carcinogenesis and represent a target for innovative therapies.

Adult neurogenesis (i.e., the life-long generation of new neurons from undifferentiated neuronal precursors in the adult brain) may contribute to brain repair after damage, and participates in plasticity-related processes including memory, cognition, mood and sensory functions. Among the many intrinsic (oxidative stress, inflammation, and ageing), and extrinsic (environmental pollution, lifestyle, and diet) factors deemed to impact neurogenesis, significant attention has been recently attracted by the myriad of saprophytic microorganismal communities inhabiting the intestinal ecosystem and collectively referred to as the gut microbiota. A growing body of evidence, mainly from animal studies, reveal the influence of microbiota and its disease-associated imbalances on neural stem cell proliferative and differentiative activities in brain neurogenic niches. On the other hand, the long-claimed pro-neurogenic activity of natural dietary compounds endowed with antioxidants and anti-inflammatory properties (such as polyphenols, polyunsaturated fatty acids, or pro/prebiotics) may be mediated, at least in part, by their action on the intestinal microflora. The purpose of this review is to summarise the available information regarding the influence of the gut microbiota on neurogenesis, analyse the possible underlying mechanisms, and discuss the potential implications of this emerging knowledge for the fight against neurodegeneration and brain ageing.

β-Hydroxy-β-Methyl Butyrate (HMB) is a natural catabolite of leucine deemed to play a role in amino acid signaling and the maintenance of lean muscle mass. Accordingly, HMB is used as a dietary supplement by sportsmen and has shown some clinical effectiveness in preventing muscle wasting in cancer and chronic lung disease, as well as in age-dependent sarcopenia. However, the molecular cascades underlying these beneficial effects are largely unknown. HMB bears a significant structural similarity with Butyrate and β-Hydroxybutyrate (βHB), two compounds recognized for important epigenetic and histone-marking activities in multiple cell types including muscle cells. We asked whether similar chromatin-modifying actions could be assigned to HMB as well. Exposure of murine C2C12 myoblasts to millimolar concentrations of HMB led to an increase in global histone acetylation, as monitored by anti-acetylated lysine immunoblotting, while preventing myotube differentiation. In these effects, HMB resembled, although with less potency, the histone deacetylase (HDAC) inhibitor Sodium Butyrate. However, initial studies did not confirm a direct inhibitory effect of HMB on HDACs in vitro. β-Hydroxybutyrate, a ketone body produced by the liver during starvation or intense exercise, has a modest effect on histone acetylation of C2C12 cells or in vitro HDAC inhibitor activities, and, unlike Butyrate and HMB, did not interfere with myotube formation in a myoblast differentiation assay. Instead, βHB dramatically increased lysine β-hydroxybutyrylation (Kbhb) of histone tails, an epigenetic mark associated with fasting responses and muscle catabolic states. However, when C2C12 cells were exposed to βHB in the presence of equimolar HMB this chromatin modification was drastically reduced, pointing to a role for HMB in attenuating ketosis-associated muscle wasting. In conclusion, while their mechanistic underpinnings remain to be clarified, these preliminary observations highlight novel and potentially important activities of HMB as an epigenetic regulator and βHB antagonist in muscle precursor cells, to be further explored in their biomedical implications.

Adult neurogenesis, the generation of mature functional neurons from neural stem cells in specific regions of the adult mammalian brain, is implicated in brain physiology, neurodegeneration and mood disorders. Among the many intrinsic and extrinsic factors that modulate neurogenic activity, the role of nutrients, energy metabolism, and gut microbiota has recently emerged. It is increasingly evident that excessive calorie intake accelerates the age-dependent decline of neurogenesis, while calorie restriction and physical exercise have the opposite effect. Mechanistically, nutrient availability could affect neurogenesis by modulating autophagy, a cell-rejuvenating process, in neural stem cells. In parallel, diet can alter the composition of gut microbiota thus impacting the intestine-neurogenic niche communication. These exciting breakthroughs are here concisely reviewed., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Appreciation of the physiological relevance of mammalian adult neurogenesis has in recent years rapidly expanded from a phenomenon of homeostatic cell replacement and brain repair to the current view of a complex process involved in high order cognitive functions. In parallel, an array of endogenous or exogenous triggers of neurogenesis has also been identified, among which metabolic and nutritional cues have drawn significant attention. Converging evidence from animal and in vitro studies points to nutrient sensing and energy metabolism as major physiological determinants of neural stem cell fate, and modulators of the whole neurogenic process. While the cellular and molecular circuitries underlying metabolic regulation of neurogenesis are still incompletely understood, the key role of mitochondrial activity and dynamics, and the importance of autophagy have begun to be fully appreciated; moreover, nutrient-sensitive pathways and transducers such as the insulin-IGF cascade, the AMPK/mTOR axis and the transcription regulators CREB and Sirt-1 have been included, beside more established "developmental" signals like Notch and Wnt, in the molecular networks that dictate neural-stem-cell self-renewal, migration and differentiation in response to local and systemic inputs. Many of these nutrient-related cascades are deregulated in the contest of metabolic diseases and in ageing, and may contribute to impaired neurogenesis and thus to cognition defects observed in these conditions. Importantly, accumulating knowledge on the metabolic control of neurogenesis provides a theoretical framework for the trial of new or repurposed drugs capable of interfering with nutrient sensing as enhancers of neurogenesis in the context of neurodegeneration and brain senescence., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Spinal cord injuries (SCIs) are devastating conditions of the central nervous system (CNS) for which there are no restorative therapies. Neuronal death at the primary lesion site and in remote regions that are functionally connected to it is one of the major contributors to neurological deficits following SCI.Disruption of autophagic flux induces neuronal death in many CNS injuries, but its mechanism and relationship with remote cell death after SCI are unknown. We examined the function and effects of the modulation of autophagy on the fate of axotomized rubrospinal neurons in a rat model of spinal cord dorsal hemisection (SCH) at the cervical level. Following SCH, we observed an accumulation of LC3-positive autophagosomes (APs) in the axotomized neurons 1 and 5 days after injury. Furthermore, this accumulation was not attributed to greater initiation of autophagy but was caused by a decrease in AP clearance, as demonstrated by the build-up of p62, a widely used marker of the induction of autophagy. In axotomized rubrospinal neurons, the disruption of autophagic flux correlated strongly with remote neuronal death and worse functional recovery. Inhibition of AP biogenesis by 3-methyladenine (3-MA) significantly attenuated remote degeneration and improved spontaneous functional recovery, consistent with the detrimental effects of autophagy in remote damage after SCH. Collectively, our results demonstrate that autophagic flux is blocked in axotomized neurons on SCI and that the inhibition of AP formation improves their survival. Thus, autophagy is a promising target for the development of therapeutic interventions in the treatment of SCIs.

Alterations of the dopaminergic (DAergic) system are frequently reported in Alzheimer's disease (AD) patients and are commonly linked to cognitive and non-cognitive symptoms. However, the cause of DAergic system dysfunction in AD remains to be elucidated. We investigated alterations of the midbrain DAergic system in the Tg2576 mouse model of AD, overexpressing a mutated human amyloid precursor protein (APPswe). Here, we found an age-dependent DAergic neuron loss in the ventral tegmental area (VTA) at pre-plaque stages, although substantia nigra pars compacta (SNpc) DAergic neurons were intact. The selective VTA DAergic neuron degeneration results in lower DA outflow in the hippocampus and nucleus accumbens (NAc) shell. The progression of DAergic cell death correlates with impairments in CA1 synaptic plasticity, memory performance and food reward processing. We conclude that in this mouse model of AD, degeneration of VTA DAergic neurons at pre-plaque stages contributes to memory deficits and dysfunction of reward processing.

Experimental and clinical observations indicate that amyloid-β 1-42 (Aβ 1-42 ) peptide not only represents a major actor in neurodegenerative mechanisms but also induce hyperexcitation in individual neurons and neural circuits. In this abnormal excitability, possibly leading to seizures, the D1 dopamine (DA) receptors may play a role. Cerebrospinal fluid levels of Aβ 1-42 were measured in patients with late-onset epilepsy of unknown etiology. Moreover, the effect of amyloid peptide on the hippocampal epileptic threshold and synaptic plasticity and its link to D1 receptor function were tested in experimental mouse model of cerebral amyloidosis and in acute model of Aβ 1-42 -induced neurotoxicity. Among 272 evaluated epileptic patients, aged >55 years, 35 suffered from late-onset epilepsy of unknown etiology. In these subjects, cerebrospinal fluid Aβ 1-42 levels were measured. The effects of Aβ 1-42 , amyloid oligomers, and D1 receptor modulation on epileptic threshold were analyzed by electrophysiological recordings in the dentate gyrus of mice hippocampal slices. We found that Aβ 1-42 levels were significantly decreased in cerebrospinal fluid of patients with late-onset epilepsy of unknown etiology with respect to controls suggesting the cerebral deposition of this peptide in these patients. Aβ 1-42 enhanced epileptic activity in mice through a mechanism involving increased surface expression of D1 receptor, and this effect was mimicked by D1 receptor stimulation and blocked by SCH 23390, a D1 receptor antagonist. Aβ 1-42 may contribute to the pathophysiology of late-onset epilepsy of unknown origin. Our preclinical findings indicate that the D1 receptor is involved in mediating the epileptic effects of Aβ 1-42 . This novel link between Aβ 1-42 and D1 receptor signaling might represent a potential therapeutic target., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Adult neurogenesis initiated by neural stem cells (NSCs) contributes to brain homeostasis, damage repair, and cognition. Energy metabolism plays a pivotal role in neurogenic cell fate decisions regarding self-renewal, expansion and multilineage differentiation. NSCs need to fine-tune quiescence and proliferation/commitment to guarantee lifelong neurogenesis and avoid premature exhaustion. Accumulating evidence supports a model whereby calorie restriction or increased energy expenditure reinforce NSC quiescence and promote self-renewal. Conversely, growth/proliferation inputs and anabolic signals, although necessary for neurogenesis, deplete the NSCs pool in the long run. This framework incorporates the emerging neurogenic roles of nutrient-sensing signaling pathways, providing a rationale for the alarming connection between nutritional imbalances, metabolic disorders and accelerated brain aging., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The compensation that follows cerebellar lesions is based on synaptic modifications in many cortical and subcortical regions, although its cellular mechanisms are still unclear. Changes in glutamatergic receptor expression may represent the synaptic basis of the compensated state. We analyzed in rats the involvement of glutamatergic system of the cerebello-frontal network in the compensation following a right hemicerebellectomy. We evaluated motor performances, spatial competencies and molecular correlates in compensated hemicerebellectomized rats which in the frontal cortex contralateral to the hemicerebellectomy side received injections of anti-NMDA antibodies from patients affected by anti-NMDA encephalitis. In the compensated hemicerebellectomized rats, the frontal injections of anti-NMDA antibodies elicited a marked decompensation state characterized by slight worsening of the motor symptoms as well as severe impairment of spatial mnesic and procedural performances. Conversely, in the sham-operated group the frontal injections of anti-NMDA antibodies elicited slight motor and spatial impairment. The molecular analyses indicated that cerebellar compensatory processes were related to a relevant rearrangement of glutamatergic synapses (NMDA and AMPA receptors and other glutamatergic components) along the entire cortico-cerebellar network. The long-term maintenance of the rearranged glutamatergic activity plays a crucial role in the maintenance of recovered function.

Functional and ultrastructural investigations support the concept that altered brain connectivity, exhausted neural plasticity, and synaptic loss are the strongest correlates of cognitive decline in age-related neurodegenerative dementia of Alzheimer's type. We have previously demonstrated that in transgenic mice, expressing amyloid-β precursor protein-Swedish mutation active caspase-3 accumulates in hippocampal postsynaptic compartments leading to altered postsynaptic density (PSD) composition, increased long-term depression (LTD), and dendritic spine loss. Furthermore, we found strong evidence that dendritic spine alteration is mediated by calcineurin activation, a calcium-dependent phosphatase involved in synapse signaling. In the present work, we analyzed the molecular mechanism linking alteration of synaptic plasticity to the increase of calcineurin activity. We found that acute treatment of young and plaque-free transgenic mice with the calcineurin inhibitor FK506 leads to a complete rescue of LTD and PSD composition. Our findings are in agreement with other results reporting that calcineurin inhibition improves memory function and restores dendritic spine density, confirming that calcineurin inhibition may be explored as a neuroprotective treatment to stop or slowdown synaptic alterations in Alzheimer's disease.

Spermine oxidase is a FAD-containing enzyme involved in polyamines catabolism, selectively oxidizing spermine to produce H2O2, spermidine, and 3-aminopropanal. Spermine oxidase is highly expressed in the mouse brain and plays a key role in regulating the levels of spermine, which is involved in protein synthesis, cell division and cell growth. Spermine is normally released by neurons at synaptic sites where it exerts a neuromodulatory function, by specifically interacting with different types of ion channels, and with ionotropic glutamate receptors. In order to get an insight into the neurobiological roles of spermine oxidase and spermine, we have deregulated spermine oxidase gene expression producing and characterizing the transgenic mouse model JoSMOrec, conditionally overexpressing the enzyme in the neocortex. We have investigated the effects of spermine oxidase overexpression in the mouse neocortex by transcript accumulation, immunohistochemical analysis, enzymatic assays and polyamine content in young and aged animals. Transgenic JoSMOrec mice showed in the neocortex a higher H2O2 production in respect to Wild-Type controls, indicating an increase of oxidative stress due to SMO overexpression. Moreover, the response of transgenic mice to excitotoxic brain injury, induced by kainic acid injection, was evaluated by analysing the behavioural phenotype, the immunodistribution of neural cell populations, and the ultrastructural features of neocortical neurons. Spermine oxidase overexpression and the consequently altered polyamine levels in the neocortex affects the cytoarchitecture in the adult and aging brain, as well as after neurotoxic insult. It resulted that the transgenic JoSMOrec mouse line is more sensitive to KA than Wild-Type mice, indicating an important role of spermine oxidase during excitotoxicity. These results provide novel evidences of the complex and critical functions carried out by spermine oxidase and spermine in the mammalian brain.

The transcription factor cAMP response element binding protein (CREB) is a key protein implicated in memory, synaptic plasticity and structural plasticity in mammals. Whether CREB regulates the synaptic incorporation of hippocampal glutamatergic receptors under basal and learning-induced conditions remains, however, mostly unknown. Using double-transgenic mice conditionally expressing a dominant negative form of CREB (CREBS133A, mCREB), we analyzed how chronic loss of CREB function in adult hippocampal glutamatergic neurons impacts the levels of the AMPA and NMDA receptors subunits within the post-synaptic densities (PSD). In basal (naïve) conditions, we report that inhibition of CREB function was associated with a specific reduction of the AMPAR subunit GluA1 and a proportional increase in its Ser845 phosphorylated form within the PSD. These molecular alterations correlated with a reduction in AMPA receptors mEPSC frequency, with a decrease in long-term potentiation (LTP), and with an increase in long-term depression (LTD). The basal levels other major synaptic proteins (GluA2/3, GluN1, GluN2A, and PSD95) within the PSD were not affected by CREB inhibition. Blocking CREB function also impaired contextual fear conditioning (CFC) and selectively blocked the CFC-driven enhancement of GluA1 and its Ser845 phosphorylated form within the PSD, molecular changes normally observed in wild-type mice. CFC-driven enhancement of other synaptic proteins (GluA2/3, GluN1, GluN2A, and PSD95) within the PSD was not significantly perturbed by the loss of CREB function. These findings provide the first evidence that, in vivo, CREB is necessary for the specific maintenance of the GluA1 subunit within the PSD of hippocampal neurons in basal conditions and for its trafficking within the PSD during the occurrence of learning., (Copyright © 2013 Wiley Periodicals, Inc.)

Mitochondria play a pivotal role in a number of biochemical processes in the neuron including energy metabolism and ATP production, intracellular Ca2+ homeostasis and cell signalling which are all implicated in the regulation of neuronal excitability. For this reason, it is not surprising that alterations in mitochondrial function have emerged as a hallmark of aging and various age-related neurodegenerative diseases in which a progressive functional decline of mitochondria has been described. The evidence that mitochondria are concentrated in synapses, together with the observation that synaptic dysfunction identifies an early forerunner of a later neurodegeneration, strongly suggests that significant alterations to synaptic mitochondrial localization, number, morphology, or function can be detrimental to synaptic transmission and might characterize the early stages of many neurological diseases. Thus, the characterization of both molecular players and pathway involved in mitochondria dysfunction will provide new chances to identify pharmacological target for new mitochondria-based drugs aimed at interrupting or slowing down pathological processes and/or ameliorating symptoms of neurological disorders. In this review we provide a current view on the role of mitochondria for neuronal function and how mitochondrial functions impinge on neurological diseases.

Neuronal transmission and functional synapses require mitochondria, which are mainly involved in the generation of energy (ATP and NAD(+)), regulation of cell signaling and calcium homeostasis. Particularly intriguing is emerging data suggesting the relationship between mitochondria and neurotrophic factors that can act at the synaptic level promoting neuronal transmission and plasticity. On the other hand, disturbances in mitochondrial functions might contribute to impaired synaptic transmission and neuronal degeneration in Alzheimer's Disease and other chronic and acute neurodegenerative disorders. Here, we review the molecular mediators controling mitochondrial function and their impact on synaptic dysfunction associated with the pathogenesis of Alzheimer's Disease.

The insulin receptor (IR) is a protein tyrosine kinase playing a pivotal role in the regulation of peripheral glucose metabolism and energy homoeostasis. IRs are also abundantly distributed in the cerebral cortex and hippocampus, where they regulate synaptic activity required for learning and memory. As the major anabolic hormone in mammals, insulin stimulates protein synthesis partially through the activation of the PI3K/Akt/mTOR pathway, playing fundamental roles in neuronal development, synaptic plasticity and memory. Here, by means of a multidisciplinary approach, we report that long-term synaptic plasticity and recognition memory are impaired in IR β-subunit heterozygous mice. Since IR expression is diminished in type-2 diabetes as well as in Alzheimer's disease (AD) patients, these data may provide a mechanistic link between insulin resistance, impaired synaptic transmission and cognitive decline in humans with metabolic disorders.

Alzheimer's Disease (AD), the most common age-related neurodegenerative disorder, is characterized by progressive cognitive decline, synaptic loss, the formation of extracellular β-amyloid plaques and intracellular neurofibrillary tangles, and neuronal cell death. Despite the massive neuronal loss in the 'late stage' of disease, dendritic spine loss represents the best pathological correlate to the cognitive impairment in AD patients. The 'amyloid hypothesis' of AD recognizes the Aβ peptide as the principal player in the pathological process. Many lines of evidence point out to the neurotoxicity of Aβ, highlighting the correlation between soluble Aβ oligomer accumulation, rather than insoluble Aβ fibrils and disease progression. Pathological increase of Aβ in AD brains, resulting from an imbalance between its production, aggregation and clearance, might target mitochondrial function promoting a progressive synaptic impairment. The knowledge of the exact mechanisms by which Aβ peptide impairs neuronal function will help us to design new pharmacological tools for preventing AD neurodegeneration.

Autophagy is the evolutionarily conserved degradation and recycling of cellular constituents. In mammals, autophagy is implicated in the pathogenesis of many neurodegenerative diseases. However, its involvement in acute brain damage is unknown. This study addresses the function of autophagy in neurodegeneration that has been induced by acute focal cerebellar lesions. We provide morphological, ultrastructural, and biochemical evidence that lesions in a cerebellar hemisphere activate autophagy in axotomized precerebellar neurons. Through time course analyses of the apoptotic cascade, we determined mitochondrial dysfunction to be the early trigger of degeneration. Further, the stimulation of autophagy by rapamycin and the employment of mice with impaired autophagic responses allowed us to demonstrate that autophagy protects from damage promoting functional recovery. These findings have therapeutic significance, demonstrating the potential of pro-autophagy treatments for acute brain pathologies, such as stroke and brain trauma.

Neurodegenerative diseases that include amyotrophic lateral sclerosis, Huntington's disease, Alzheimer's disease, Parkinson's disease, stroke, brain trauma and spinal cord injury, are associated with the inappropriate activation of a neuronal cell-suicide program called apoptosis. Given that central nervous system tissue has very limited regenerative capacity it is of extreme importance to limit the damage caused by neuronal death. During the past decade, considerable progress has been made in understanding the process of apoptosis and, significantly, a number of studies have shown that a variety of small molecules can activate or inhibit cell death by acting on crucial checkpoints of apoptosis. Here, we review evidence linking apoptosis to brain diseases and discuss how knowledge of the mechanisms of cell death has led to novel therapeutic strategies.

Synaptic loss is the best pathological correlate of the cognitive decline in Alzheimer's disease; however, the molecular mechanisms underlying synaptic failure are unknown. We found a non-apoptotic baseline caspase-3 activity in hippocampal dendritic spines and an enhancement of this activity at the onset of memory decline in the Tg2576-APPswe mouse model of Alzheimer's disease. In spines, caspase-3 activated calcineurin, which in turn triggered dephosphorylation and removal of the GluR1 subunit of AMPA-type receptor from postsynaptic sites. These molecular modifications led to alterations of glutamatergic synaptic transmission and plasticity and correlated with spine degeneration and a deficit in hippocampal-dependent memory. Notably, pharmacological inhibition of caspase-3 activity in Tg2576 mice rescued the observed Alzheimer-like phenotypes. Our results identify a previously unknown caspase-3-dependent mechanism that drives synaptic failure and contributes to cognitive dysfunction in Alzheimer's disease. These findings indicate that caspase-3 is a potential target for pharmacological therapy during early disease stages.

Apoptosis, often defined as programmed cell death, plays a very important role in many physiologic and pathologic conditions. Therefore, detecting apoptotic cells or monitoring the cells progressing to apoptosis is an essential step in basic and/or applied research. Apoptosis is characterized by many biologic and morphologic changes of cells, for example, cytochrome c release from mitochondria, activation of caspases, DNA fragmentation, membrane blebbing, and formation of apoptotic bodies. On the basis of these changes, various assays have been designed to detect or quantify apoptotic cells. The goal of this chapter is to provide readers with a scientific guide to proven methods that highlight the current strategies for detecting apoptosis in the nervous system.