Seasonal adaptations of the hypothalamo-neurohypophyseal system of the dromedary camel.

The "ship" of the Arabian and North African deserts, the one-humped dromedary camel (Camelus dromedarius) has a remarkable capacity to survive in conditions of extreme heat without needing to drink water. One of the ways that this is achieved is through the actions of the antidiuretic hormone arginine vasopressin (AVP), which is made in a specialised part of the brain called the hypothalamo-neurohypophyseal system (HNS), but exerts its effects at the level of the kidney to provoke water conservation. Interestingly, our electron microscopy studies have shown that the ultrastructure of the dromedary HNS changes according to season, suggesting that in the arid conditions of summer the HNS is in an activated state, in preparation for the likely prospect of water deprivation. Based on our dromedary genome sequence, we have carried out an RNAseq analysis of the dromedary HNS in summer and winter. Amongst the 171 transcripts found to be significantly differentially regulated (>2 fold change, p value <0.05) there is a significant over-representation of neuropeptide encoding genes, including that encoding AVP, the expression of which appeared to increase in summer. Identification of neuropeptides in the HNS and analysis of neuropeptide profiles in extracts from individual camels using mass spectrometry indicates that overall AVP peptide levels decreased in the HNS during summer compared to winter, perhaps due to increased release during periods of dehydration in the dry season.

KATP Channel Expression and Genetic Polymorphisms Associated with Progression and Survival in Amyotrophic Lateral Sclerosis.

The ATP-sensitive potassium (KATP) channel directly regulates the microglia-mediated inflammatory response following CNS injury. To determine the putative role of the KATP channel in amyotrophic lateral sclerosis (ALS) pathology, we investigated whether ALS induces changes in KATP channel expression in the spinal cord and motor cortex. We also characterized new functional variants of human ABCC8, ABCC9, KCNJ8, and KCNJ11 genes encoding for the KATP channel and analyzed their association with ALS risk, rate of progression, and survival in a Spanish ALS cohort. The expression of ABCC8 and KCNJ8 genes was enhanced in the spinal cord of ALS samples, and KCNJ11 increased in motor cortex of ALS samples, as determined by real-time polymerase chain reaction. We then sequenced the exons and regulatory regions of KATP channel genes from a subset of 28 ALS patients and identified 50 new genetic variants. For the case-control association analysis, we genotyped five selected polymorphisms with predicted functional relevance in 185 Spanish ALS (134 spinal ALS and 51 bulbar ALS) patients and 493 controls. We found that bulbar ALS patients presenting the G/G genotype of the rs4148646 variant of ABCC8 and the T/T genotype of the rs5219 variant of KCNJ11 survived longer than other ALS patients presenting other genotypes. Also, the C/C genotype of the rs4148642 variant of ABCC8 and the T/C genotype of the rs148416760 variant of ABCC9 modified the progression rate in spinal ALS patients. Our results suggest that the KATP channel plays a role in the pathophysiological mechanisms of ALS.

Neuron-Microglia Interactions in Motor Neuron Degeneration. The Inflammatory Hypothesis in Amyotrophic Lateral Sclerosis Revisited.

Research onto the pathogenesis of amyotrophic lateral sclerosis (ALS) has obtained notable gene discoveries, although, to date, only progress with regard to treatment has been very modest. Currently ALS is considered a multifactorial disease that presents diverse clinical presentations, ranging from a monogenic inherited disease to an autoimmune pathology, and develops with misfolded protein aggregation and neuroinflammation. An important factor related to ALS pathogenesis is the microglial activation associated with degenerative motor neurons. This activation leads to changes in the expression of a wide range of genes related to phagocytosis and inflammation, and to profound modifications in the dynamic interactions between neurons and glial cells. Overactivation and deregulation of microglial activity causes deleterious effects and leads to neuronal death. However, the involvement of microglia in non-inflammatory functions challenges our concept of neuroinflammation and opens up new possibilities for the study of the pathophysiological mechanisms of ALS. In this review we summarize the current knowledge on the adaptive interactions between neurons and microglia in ALS. We also discuss the hypothesis that controlling the extent of microglial activation and neuroinflammation may have clinical and therapeutic benefits for the condition.

UNC13A confers risk for sporadic ALS and influences survival in a Spanish cohort.

To investigate the association of functional variants of the human UNC13A gene with the risk of ALS, survival and the disease progression rate in a Spanish ALS cohort. 136 sporadic ALS (sALS) patients and 487 healthy controls were genotyped for the UNC13A rs12608932 variant. Clinical characterization of ALS patients included gender, age at first symptom, initial topography, disease progression rate, and survival. Genetic association was analyzed under five inheritance models. The sALS patients with the rs12608932(CC) genotype had an increased risk of ALS under a recessive genetic model [OR 2.16; 95 % CI (1.23, 3.8), p = 0.009; corrected p = 0.028]. Genotypes with a C allele are also associated with increased risk [OR 1.47; 95 % CI (1.11, 1.95); p = 0.008; corrected p = 0.023] under an additive model. sALS patients with a C/C genotype had a shorter survival than patients with A/A and A/C genotypes [HR 1.44; 95 % CI (1.11, 1.873); p = 0.007] under a recessive model. In an overdominant model, heterozygous patients had a longer survival than homozygous patients [HR 0.36; 95 % CI (0.22, 0.59); p = 0.001]. The rs12608932 genotypes modify the progression of symptoms measured using the ALSFRS-R. No association with age of onset, initial topography or rate of decline in FVC was found. Our results show that rs12608932 is a risk factor for ALS in the Spanish population and replicate the findings described in other populations. The rs12608932 is a modifying factor for survival and disease progression rate in our series. Our results also corroborated that it did not influence the age of onset.

Astroglia-Microglia Cross Talk during Neurodegeneration in the Rat Hippocampus.

Brain injury triggers a progressive inflammatory response supported by a dynamic astroglia-microglia interplay. We investigated the progressive chronic features of the astroglia-microglia cross talk in the perspective of neuronal effects in a rat model of hippocampal excitotoxic injury. N-Methyl-D-aspartate (NMDA) injection triggered a process characterized within 38 days by atrophy, neuronal loss, and fast astroglia-mediated S100B increase. Microglia reaction varied with the lesion progression. It presented a peak of tumor necrosis factor-α (TNF-α) secretion at one day after the lesion, and a transient YM1 secretion within the first three days. Microglial glucocorticoid receptor expression increased up to day 5, before returning progressively to sham values. To further investigate the astroglia role in the microglia reaction, we performed concomitant transient astroglia ablation with L-α-aminoadipate and NMDA-induced lesion. We observed a striking maintenance of neuronal death associated with enhanced microglial reaction and proliferation, increased YM1 concentration, and decreased TNF-α secretion and glucocorticoid receptor expression. S100B reactivity only increased after astroglia recovery. Our results argue for an initial neuroprotective microglial reaction, with a direct astroglial control of the microglial cytotoxic response. We propose the recovery of the astroglia-microglia cross talk as a tissue priority conducted to ensure a proper cellular coordination that retails brain damage.

Amyloid-ß immunotherapy reduces amyloid plaques and astroglial reaction in aged domestic dogs.

BACKGROUND: Alzheimer's disease (AD) is characterized by the dynamic accumulation of extracellular amyloid deposits from the interplay between amyloid-ß (Aß) plaques, reactive astrocytes and activated microglia. Several immunotherapies against Aß have been shown to reduce amyloid neuropathology. However, the role of the associated glia in the recovery process requires clarification. Previously, we described the safety and effectiveness in aged domestic canine with cognitive dysfunction syndrome of a new active vaccine candidate for the treatment of AD in humans. OBJECTIVE: The aim of this article is to gain a better understanding of how immunotherapy modifies the amyloid burden and its effects on astroglial and microglial reactivity in immunized dogs. METHODS: In order to achieve this, we compared and quantified amyloid plaques and astroglial and microglial reactions in the frontal cortex of unimmunized and immunized aged domestic dogs. RESULTS: We found amyloid plaques from immunized dogs to be smaller and more compact than those from unimmunized dogs. In these new plaques, the associated astrocytes were closer and less immunoreactive to the ß subunit of S100 protein (S100B). We also found no modification in the microglial reaction associated with immunization. CONCLUSION: The anti-Aß immunotherapy developed in our laboratory modifies the equilibrium between soluble and insoluble Aß in aged dogs in close correlation with S100B-negative astrocytosis and microglial reaction.

CX3CR1 is a modifying gene of survival and progression in amyotrophic lateral sclerosis.

The objective of this study was to investigate the association of functional variants of the human CX3CR1 gene (Fractalkine receptor) with the risk of Amyotrophic Lateral Sclerosis (ALS), the survival and the progression rate of the disease symptoms in a Spanish ALS cohort. 187 ALS patients (142 sporadic [sALS] and 45 familial) and 378 controls were recruited. We investigated CX3CR1 V249I (rs3732379) and T280M (rs3732378) genotypes and their haplotypes as predictors of survival, the progression rate of the symptoms (as measured by ALSFRS-R and FVC decline) and the risk of suffering ALS disease. The results indicated that sALS patients with CX3CR1 249I/I or 249V/I genotypes presented a shorter survival time (42.27 ± 4.90) than patients with 249V/V genotype (67.65 ± 7.42; diff -25.49 months 95%CI [-42.79,-8.18]; p = 0.004; adj-p = 0.018). The survival time was shorter in sALS patients with spinal topography and CX3CR1 249I alleles (diff =  -29.78 months; 95%CI [-49.42,-10.14]; p = 0.003). The same effects were also observed in the spinal sALS patients with 249I-280M haplotype (diff =  -27.02 months; 95%CI [-49.57, -4.48]; p = 0.019). In the sALS group, the CX3CR1 249I variant was associated with a faster progression of the disease symptoms (OR = 2.58; 95IC% [1.32, 5.07]; p = 0.006; adj-p = 0.027). There was no evidence for association of these two CX3CR1 variants with ALS disease risk. The association evidenced herein is clinically relevant and indicates that CX3CR1 could be a disease-modifying gene in sALS. The progression rate of the disease's symptoms and the survival time is affected in patients with one or two copies of the CX3CR1 249I allele. The CX3CR1 is the most potent ALS survival genetic factor reported to date. These results reinforce the role of the immune system in ALS pathogenesis.

Phagocytic microglial phenotype induced by glibenclamide improves functional recovery but worsens hyperalgesia after spinal cord injury in adult rats.

Microglial cell plays a crucial role in the development and establishment of chronic neuropathic pain after spinal cord injuries. As neuropathic pain is refractory to many treatments and some drugs only present partial efficacy, it is essential to study new targets and mechanisms to ameliorate pain signs. For this reason we have used glibenclamide (GB), a blocker of KATP channels that are over expressed in microglia under activation conditions. GB has already been used to trigger the early scavenger activity of microglia, so we administer it to promote a better removal of dead cells and myelin debris and support the microglia neuroprotective phenotype. Our results indicate that a single dose of GB (1 µg) injected after spinal cord injury is sufficient to promote long-lasting functional improvements in locomotion and coordination. Nevertheless, the Randall-Selitto test measurements indicate that these improvements are accompanied by enhanced mechanical hyperalgesia. In vitro results indicate that GB may influence microglial phagocytosis and therefore this action may be at the basis of the results obtained in vivo.

Targeting microglial K(ATP) channels to treat neurodegenerative diseases: a mitochondrial issue.

Neurodegeneration is a complex process involving different cell types and neurotransmitters. A common characteristic of neurodegenerative disorders is the occurrence of a neuroinflammatory reaction in which cellular processes involving glial cells, mainly microglia and astrocytes, are activated in response to neuronal death. Microglia do not constitute a unique cell population but rather present a range of phenotypes closely related to the evolution of neurodegeneration. In a dynamic equilibrium with the lesion microenvironment, microglia phenotypes cover from a proinflammatory activation state to a neurotrophic one directly involved in cell repair and extracellular matrix remodeling. At each moment, the microglial phenotype is likely to depend on the diversity of signals from the environment and of its response capacity. As a consequence, microglia present a high energy demand, for which the mitochondria activity determines the microglia participation in the neurodegenerative process. As such, modulation of microglia activity by controlling microglia mitochondrial activity constitutes an innovative approach to interfere in the neurodegenerative process. In this review, we discuss the mitochondrial KATP channel as a new target to control microglia activity, avoid its toxic phenotype, and facilitate a positive disease outcome.

Rapid improvement of canine cognitive dysfunction with immunotherapy designed for Alzheimer's disease.

Immunotherapy against amyloid-ß(Aß) may improve rodent cognitive function by reducing amyloid neuropathology and is being validated in clinical trials with positive preliminary results. However, for a complete understanding of the direct and long-term immunization responses in the aged patient, and also to avoid significant side effects, several key aspects remain to be clarified. Thus, to investigate brain Aß clearance and Th2 responses in the elderly, and the reverse inflammatory events not found in the immunized rodent, better Alzheimer's disease (AD) models are required. In the aged familiar canine with a Cognitive Dysfunction Syndrome (CDS) we describe the rapid effectiveness and the full safety profile of a new active vaccine candidate for human AD prevention and treatment. In these aged animals, besidesa weak immune system, the antibody response activated a coordinated central and peripheral Aß clearance, that rapidly improved their cognitive function in absence of any side effects. Our results also confirm the interest to use familiar dogs to develop innovative and reliable therapies for AD.

Glibenclamide enhances neurogenesis and improves long-term functional recovery after transient focal cerebral ischemia.

Glibenclamide is neuroprotective against cerebral ischemia in rats. We studied whether glibenclamide enhances long-term brain repair and improves behavioral recovery after stroke. Adult male Wistar rats were subjected to transient middle cerebral artery occlusion (MCAO) for 90 minutes. A low dose of glibenclamide (total 0.6 µg) was administered intravenously 6, 12, and 24 hours after reperfusion. We assessed behavioral outcome during a 30-day follow-up and animals were perfused for histological evaluation. In vitro specific binding of glibenclamide to microglia increased after pro-inflammatory stimuli. In vivo glibenclamide was associated with increased migration of doublecortin-positive cells in the striatum toward the ischemic lesion 72 hours after MCAO, and reactive microglia expressed sulfonylurea receptor 1 (SUR1) and Kir6.2 in the medial striatum. One month after MCAO, glibenclamide was also associated with increased number of NeuN-positive and 5-bromo-2-deoxyuridine-positive neurons in the cortex and hippocampus, and enhanced angiogenesis in the hippocampus. Consequently, glibenclamide-treated MCAO rats showed improved performance in the limb-placing test on postoperative days 22 to 29, and in the cylinder and water-maze test on postoperative day 29. Therefore, acute blockade of SUR1 by glibenclamide enhanced long-term brain repair in MCAO rats, which was associated with improved behavioral outcome.

Adaptation of Camelus dromedarius pars nervosa of the hypophysis to winter and summer living conditions.

The aim of this work is to study the characteristics of the dromedary nervous lobe and determine how the seasons condition its organization. To this end, electron microscopy was performed and examined quantitatively on animals from winter and summer periods. The results show a higher number of cells in the nervous lobe in summer than in winter. The most abundant glial elements in winter are light pituicytes engulfing neurosecretory nerve fibers making neuroglial contact, and dark pituicytes containing numerous heterogeneous light bodies. In summer, the most distinctive glial cells may be pituicytes in a phagocytic state making contact with characteristic large light bodies that could represent a degenerative process of large neuropeptide storage. Granular pituicytes were also observed in contact with glial and neuronal components. However, lipid droplets, described in pituicytes of other mammals, were not observed in our samples. Quantitative analysis of neurovascular contacts revealed that the number of nerve terminals contacting the basal lamina did not differ between summer and winter, but the mean number of glial processes increased in winter. Our data provides evidence that the storage of neuropeptides is very marked in summer and that, associated with an autophagic and phagocytic phenomenon, this suggests an adaptation to anticipate any situation that would cause dehydration of the dromedary. Thus, in its tough environment, the animal remains permanently prepared to avoid any large water loss.

Dogs with cognitive dysfunction syndrome: a natural model of Alzheimer's disease.

In the search for appropriate models for Alzheimer's disease (AD) involving animals other than rodents, several laboratories are working with animals that naturally develop cognitive dysfunction. Among the animals tested, dogs are quite unique in helping to elucidate the cascade of events that take place in brain amyloid-beta (Aß)deposition aging, and cognitive deficit. Recent innovative research has validated human methods and tools for the analysis of canine neuropathology and has allowed the development of two different approaches to investigate dogs as natural models of AD. The first approach relates AD-like neuropathy with the decline in memory and learning ability in aged housed dogs in a highly controlled laboratory environment. The second approach involves research in family-owned animals with cognitive dysfunction syndrome. In this review, we compare the strengths and limitations of housed and family-owned canine models, and appraise their usefulness for deciphering the early mechanisms of AD and developing innovative therapies.

Oral administration of the KATP channel opener diazoxide ameliorates disease progression in a murine model of multiple sclerosis.

BACKGROUND: Multiple Sclerosis (MS) is an acquired inflammatory demyelinating disorder of the central nervous system (CNS) and is the leading cause of nontraumatic disability among young adults. Activated microglial cells are important effectors of demyelination and neurodegeneration, by secreting cytokines and others neurotoxic agents. Previous studies have demonstrated that microglia expresses ATP-sensitive potassium (KATP) channels and its pharmacological activation can provide neuroprotective and anti-inflammatory effects. In this study, we have examined the effect of oral administration of KATP channel opener diazoxide on induced experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. METHODS: Anti-inflammatory effects of diazoxide were studied on lipopolysaccharide (LPS) and interferon gamma (IFNγ)-activated microglial cells. EAE was induced in C57BL/6J mice by immunization with myelin oligodendrocyte glycoprotein peptide (MOG35₋55). Mice were orally treated daily with diazoxide or vehicle for 15 days from the day of EAE symptom onset. Treatment starting at the same time as immunization was also assayed. Clinical signs of EAE were monitored and histological studies were performed to analyze tissue damage, demyelination, glial reactivity, axonal loss, neuronal preservation and lymphocyte infiltration. RESULTS: Diazoxide inhibited in vitro nitric oxide (NO), tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) production and inducible nitric oxide synthase (iNOS) expression by activated microglia without affecting cyclooxygenase-2 (COX-2) expression and phagocytosis. Oral treatment of mice with diazoxide ameliorated EAE clinical signs but did not prevent disease. Histological analysis demonstrated that diazoxide elicited a significant reduction in myelin and axonal loss accompanied by a decrease in glial activation and neuronal damage. Diazoxide did not affect the number of infiltrating lymphocytes positive for CD3 and CD20 in the spinal cord. CONCLUSION: Taken together, these results demonstrate novel actions of diazoxide as an anti-inflammatory agent, which might contribute to its beneficial effects on EAE through neuroprotection. Treatment with this widely used and well-tolerated drug may be a useful therapeutic intervention in ameliorating MS disease.

Alzheimer's disease modifies progenitor cell expression of monoamine oxidase B in the subventricular zone.

In the adult brain, progenitor cells remaining in the subventricular zone (SVZ) are frequently identified as glial fibrillary acidic protein (GFAP)-positive cells that retain attributes reminiscent of radial glia. Because the very high expression of monoamine oxidase B (MAO-B) in the subventricular area has been related to epithelial and astroglial expression, we sought to ascertain whether it was also expressed by progenitor cells of human control and Alzheimer's disease (AD) patients. In the SVZ, epithelial cells and astrocyte-like cells presented rich MAO-B activity and immunolabeling. Nestin-positive cells were found in the same area, showing a radial glia-like morphology. When coimmunostaining and confocal microscopy were performed, most nestin-positive cells showed MAO-B activity and labeling. The increased progenitor activity in SVZ proposed for AD patients was confirmed by the positive correlation between the SVZ nestin/MAO-B ratio and the progression of the disease. Nestin/GFAP-positive cells, devoid of MAO-B, can represent a distinct subpopulation of an earlier phase of maturation. This would indicate that MAO-B expression takes place in a further step of nestin/GFAP-positive cell differentiation. In the early AD stages, the discrete MAO-B reduction, different from the severe GFAP decrease, would reflect the capacity of this population of MAO-B-positive progenitor cells to adapt to the neurodegenerative process.

Magnetic resonance imaging of cerebral involutional changes in dogs as markers of aging: an innovative tool adapted from a human visual rating scale.

The dog is increasingly considered as a natural animal model for the study of normal and pathological human brain aging, because it exhibits anatomical, biochemical and cognitive changes that parallel those seen in humans. This study presents a novel visual semi-quantitative rating scale of canine cerebral magnetic resonance imaging (MRI). Ninety-eight dogs of both sexes from 27 pure breeds, aged 2-15 years, were used. The results suggest that (like in humans) both hippocampal and progressive global atrophy are characteristic features that correlate with aging. When classified according to head shape, cerebral atrophy was highest in mesaticephalic and brachycephalic dogs. This is the first MRI study to characterise a simple, rapid tool for studying age-related canine brain changes that can even be applied by non-experienced observers. The results confirm the possibility of transferring innovative tools developed for human diagnosis to the veterinary field.

Pattern of injury with a graded excitotoxic insult and ensuing chronic medial septal damage in the rat brain.

Brain damage caused by an acute injury depends on the initial severity of the injury and the time elapsed after the injury. To determine whether these two variables activate common mechanisms, we compared the response of the rat medial septum to insult with a graded series of concentrations of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) with the time-course effects of a low dose of AMPA. For this purpose we conducted a dose-response study at concentrations of AMPA between 0.27 and 10.8 nmol to measure atrophy of the septal area, losses of cholinergic and GABAergic neurons, astroglial and microglial reactions, and calcification. Cholinergic neurons, whose loss paralleled the degree of septal atrophy produced by AMPA, are more sensitive than GABAergic neurons to the injury produced by AMPA. At doses of AMPA above 2.7 nmol, calcification and the degree of microglial reaction increased only in the GABAergic region of the septal area, whereas atrophy and neuronal loss reached a plateau. We chose the 2.7-nmol dose of AMPA to determine how these parameters were modified between 4 days and 6 months after injection. We found that atrophy and neuronal loss increased progressively through the 6-month study period, whereas astrogliosis ceased to be observed after 1 month, and calcium precipitates were never detected. We conclude that septal damage does not increase with the intensity of an excitotoxic insult. Rather, it progresses continuously after the insult. Because these two situations involve different mechanisms, short-term paradigms are inappropriate for interpreting the pathogenic mechanisms responsible for long-term neurodegenerative processes.

Drug abuse, brain calcification and glutamate-induced neurodegeneration.

Positive and negative reinforcing systems are part of the mechanism of drug dependence. Drugs with abuse potential may change the manner of response to negative emotional stimuli, activate positive emotional reactions and possess primary reinforcing properties. Catecholaminergic and peptidergic processes are of importance in these mechanisms. Current research needs to understand the types of adaptations that underlie the particularly long-lived aspects of addiction. Presently, glutamate is candidate to play a role in the enduring effects of drugs of abuse. For example, it participates in the chronic pathological changes of corticostriatal terminals produced by methamphetamine. At the synaptic level, a link between over-activation of glutamate receptors, [C(a2+)](i) increase and neuronal damage has been clearly established leading to neurodegeneration. Thus, neurodegeneration can start after an acute over-stimulation whose immediate effects depend on a diversity of calcium-activated mechanisms. If sufficient, the initial insult results in calcification and activation of a chronic on-going process with a progressive loss of neurons. At present, long-term effects of drug dependence underlie an excitotoxicity process linked to a polysynaptic pathway that dynamically regulates synaptic glutamate. Retaliatory mechanisms include energy capability of the neurons, inhibitory systems and cytoplasmic calcium precipitation as part of the neuron-glia interactions. This paper presents an integrated view of these molecular and cellular mechanisms to help understand their relationship and interdependence in a chronic pathological process that suggest new targets for therapeutic intervention.

Nimodipine inhibits TMB-8 potentiation of AMPA-induced hippocampal neurodegeneration.

Human cerebral calcification has been related to deregulation of intracellular calcium homeostasis. In rat basal ganglia, nimodipine and TMB-8, two commonly used calcium antagonists, worsen the chronic AMPA-induced lesion, whereas only nimodipine potentiates calcification. To investigate whether similar effects are present in the hippocampus, AMPA dose-response and calcium movement blockade were performed. A dose-related increase of both hippocampal lesion and calcification was evident in a saturable mode, mostly different from the continuous globus pallidus response previously observed. The value of 2.7 nmol AMPA, selected as yielding 60% of maximum calcification, was coinjected with nimodipine or/and TMB-8 to determine their influence on tissue damage. TMB-8 increased the AMPA lesion in terms of calcified area, and nimodipine reversed this increase, with no effect alone. These results, divergent from those for the globus pallidus, reveal differences in extra- and intracellular calcium movement between the two neurodegenerative processes. Future work focused on other brain areas is required to understand how control of calcium stores may influence neurodegenerative disease evolution.

Canine cognitive dysfunction and the cerebellum: acetylcholinesterase reduction, neuronal and glial changes.

The specific functional and pathological alterations observed in Alzheimer's disease are less severe in the cerebellum than in other brain areas, particularly the entorhinal cortex and hippocampus. Since dense core amyloid-beta plaque formation has been associated with an acetylcholinesterase heterogeneous nucleator action, we examined if an acetylcholinesterase imbalance was involved in cerebellum plaque deposition. By using the canine counterpart of senile dementia of the Alzheimer's type, a promising model of human brain aging and early phases of Alzheimer's disease, we investigated how cerebellar pathology and acetylcholinesterase density could be related with cognitive dysfunction. As in Alzheimer's disease, the late affectation of the cerebellum was evidenced by its lack of amyloid-beta plaque and the presence of diffuse deposition throughout all cortical grey matter layers. The highest acetylcholinesterase optic density corresponded to cerebellar islands of the granular layer and was predominantly associated with synaptic glomeruli and the somata of Golgi cells. Its reduction correlated with aging and loss of granule cells, whereas cognitive deficit only correlated with loss of Purkinje cells. The observed Bergmann glia alterations may correspond to a reactive response to the loss and damage of the Purkinje cells, their specific neuronal partner. Regarding the role of acetylcholinesterase mediation in amyloid-beta deposition, our data argue against an interaction between these two proteins because acetylcholinesterase reduction correlates with aging but not with cognitive deficit. Finally, our data support the use of companion dogs of all breeds to study aging and early phases of Alzheimer's disease.