Intrinsic structural vulnerability in the hydrophobic core induces species-specific aggregation of canine SOD1 with degenerative myelopathy-linked E40K mutation.

Canine degenerative myelopathy (DM), a fatal neurodegenerative disease in dogs, shares clinical and genetic features with amyotrophic lateral sclerosis, a human motor neuron disease. Mutations in the SOD1 gene encoding Cu/Zn superoxide dismutase (SOD1) cause canine DM and a subset of inherited human amyotrophic lateral sclerosis. The most frequent DM causative mutation is homozygous E40K mutation, which induces the aggregation of canine SOD1 but not of human SOD1. However, the mechanism through which canine E40K mutation induces species-specific aggregation of SOD1 remains unknown. By screening human/canine chimeric SOD1s, we identified that the humanized mutation of the 117th residue (M117L), encoded by exon 4, significantly reduced aggregation propensity of canine SOD1E40K. Conversely, introducing a mutation of leucine 117 to methionine, a residue homologous to canine, promoted E40K-dependent aggregation in human SOD1. M117L mutation improved protein stability and reduced cytotoxicity of canine SOD1E40K. Furthermore, crystal structural analysis of canine SOD1 proteins revealed that M117L increased the packing within the hydrophobic core of the ß-barrel structure, contributing to the increased protein stability. Our findings indicate that the structural vulnerability derived intrinsically from Met 117 in the hydrophobic core of the ß-barrel structure induces E40K-dependent species-specific aggregation in canine SOD1.

Pathologic characterization of canine multiple system degeneration in the Ibizan hound.

Canine multiple system degeneration (CMSD) is a progressive hereditary neurodegenerative disorder commonly characterized by neuronal degeneration and loss in the cerebellum, olivary nuclei, substantia nigra, and caudate nuclei. In this article, we describe 3 cases of CMSD in Ibizan hounds. All patients exhibited marked cerebellar ataxia and had cerebellar atrophy on magnetic resonance imaging. At necropsy, all cases showed varying degrees of cerebellar atrophy, and 2 cases had gross cavitation of the caudate nuclei. Histologic findings included severe degeneration and loss of all layers of the cerebellum and neuronal loss and degeneration within the olivary nuclei, substantia nigra, and caudate nuclei. Pedigree analysis indicated an autosomal recessive mode of inheritance, but the causative gene in this breed is yet to be identified. CMSD resembles human multiple system atrophy and warrants further investigation.

A novel pathogenic variant in the 3' end of the AGTPBP1 gene gives rise to neurodegeneration without cerebellar atrophy: an expansion of the disease phenotype?

Childhood-onset neurodegeneration with cerebellar atrophy (CONDCA) is a recently described form of the large group of infantile hereditary lower motor neuron diseases (Teoh et al. 2017), resulting from biallelic damaging variants in the AGTPBP1 gene, first described by Shashi et al. in EMBO J 37(23):e100540, 2018. AGTPBP-related neurodegeneration is a severe neurodevelopmental disorder that progresses with global developmental delay and intellectual disability, often accompanied with peripheral nerve damage and lower motor degeneration and a fatal course in the early years of life. The encoded protein is ATP/GTP-Binding Protein1, also known as cytosolic carboxypeptidase 1 (CCP1) or nervous system nuclear protein induced by axotomy (NNA1). Here we report a consanguineous family with four offspring, two of whom are affected. The index patient is a 21-month-old male with global developmental delay and hypotonia. The proband's 17-year-old sister, diagnosed with cerebral palsy, had severe hypotonia accompanied by motor and cognitive retardation. WES analysis revealed a novel homozygous c.3293G > A variant in the AGTPBP1 gene with high pathogenicity scores. Targeted Sanger sequencing confirmed the variant in both affected children and in heterozygous form in the parents. The affected siblings present with hypotonia and motor and cognitive retardation, in line with the studies previously reported. However, in our patients, no signs of cerebellar atrophy in cranial MRI were present, so the acronym CONDCA is not applicable; lower motor neuron findings were also absent. The matching and distinguishing aspects of our patients will add to the present literature and expand our understanding of this rare genetic neurodegenerative disease of early childhood.

In-frame deletion in canine PITRM1 is associated with a severe early-onset epilepsy, mitochondrial dysfunction and neurodegeneration.

We investigated the clinical, genetic, and pathological characteristics of a previously unknown severe juvenile brain disorder in several litters of Parson Russel Terriers. The disease started with epileptic seizures at 6-12 weeks of age and progressed rapidly to status epilepticus and death or euthanasia. Histopathological changes at autopsy were restricted to the brain. There was severe acute neuronal degeneration and necrosis diffusely affecting the grey matter throughout the brain with extensive intraneuronal mitochondrial crowding and accumulation of amyloid-ß (Aß). Combined homozygosity mapping and genome sequencing revealed an in-frame 6-bp deletion in the nuclear-encoded pitrilysin metallopeptidase 1 (PITRM1) encoding for a mitochondrial protease involved in mitochondrial targeting sequence processing and degradation. The 6-bp deletion results in the loss of two amino acid residues in the N-terminal part of PITRM1, potentially affecting protein folding and function. Assessment of the mitochondrial function in the affected brain tissue showed a significant deficiency in respiratory chain function. The functional consequences of the mutation were modeled in yeast and showed impaired growth in permissive conditions and an impaired respiration capacity. Loss-of-function variants in human PITRM1 result in a childhood-onset progressive amyloidotic neurological syndrome characterized by spinocerebellar ataxia with behavioral, psychiatric and cognitive abnormalities. Homozygous Pitrm1-knockout mice are embryonic lethal, while heterozygotes show a progressive, neurodegenerative phenotype characterized by impairment in motor coordination and Aß deposits. Our study describes a novel early-onset PITRM1-related neurodegenerative canine brain disorder with mitochondrial dysfunction, Aß accumulation, and lethal epilepsy. The findings highlight the essential role of PITRM1 in neuronal survival and strengthen the connection between mitochondrial dysfunction and neurodegeneration.

Feline Spongy Encephalopathy With a Mutation in the ASPA Gene.

Canavan disease is an autosomal recessive leukodystrophy caused by mutations in the gene encoding aspartoacylase (ASPA), which hydrolyses N-acetylaspartate (NAA) to acetate and aspartate. A similar feline neurodegenerative disease associated with a mutation in the ASPA gene is reported herein. Comprehensive clinical, genetic, and pathological analyses were performed on 4 affected cats. Gait disturbance and head tremors initially appeared at 1 to 19 months of age. These cats eventually exhibited dysstasia and seizures and died at 7 to 53 months of age. Magnetic resonance imaging of the brain revealed diffuse symmetrical intensity change of the cerebral cortex, brainstem, and cerebellum. Gas chromatography-mass spectrometry analysis of urine showed significant excretion of NAA. Genetic analysis of the 4 affected cats identified a missense mutation (c.859G>C) in exon 6 of the ASPA gene, which was not detected in 4 neurologically intact cats examined as controls. Postmortem analysis revealed vacuolar changes predominantly distributed in the gray matter of the cerebrum and brain stem as well as in the cerebellar Purkinje cell layer. Immunohistochemically, these vacuoles were surrounded by neurofilaments and sometimes contained MBP- and Olig2-positive cells. Ultrastructurally, a large number of intracytoplasmic vacuoles containing mitochondria and electron-dense granules were detected in the cerebral cortex. All 4 cats were diagnosed as spongy encephalopathy with a mutation in the ASPA gene, a syndrome analogous to human Canavan disease. The histopathological findings suggest that feline ASPA deficiency induces intracytoplasmic edema in neurons and oligodendrocytes, resulting in spongy degeneration of the central nervous system.

Diffusion tensor imaging of the visual pathway in dogs with primary angle-closure glaucoma.

OBJECTIVE: To describe measurements of in vivo structures of the visual pathway beyond the retina and optic nerve head associated with canine primary angle-closure glaucoma (PACG). METHODS: A prospective pilot study was conducted using magnetic resonance diffusion tensor imaging (DTI) to obtain quantitative measures of the optic nerve, chiasm, tract, and lateral geniculate nucleus (LGN) in dogs with and without PACG. 3-Tesla DTI was performed on six affected dogs and five breed, age- and sex-matched controls. DTI indices of the optic nerve, optic chiasm, optic tracts, and LGN were compared between normal, unilateral PACG, and bilateral PACG groups. Intra-class correlation coefficient (ICC) was calculated to assess intra-observer reliability. RESULTS: Quantitative measurements of the optic nerve, optic tract, optic chiasm, and LGN were obtained in all dogs. There was a trend for reduced fractional anisotropy (FA) associated with disease for all structures assessed. Compared to the same structure in normal dogs, FA, and radial diffusivity (RD) of the optic nerve was consistently higher in the unaffected eye in dogs with unilateral PACG. Intra-observer reliability was excellent for measurements of the optic nerve (ICC: 0.92), good for measurements of the optic tract (ICC: 0.89) and acceptable for measures of the optic chiasm (ICC: 0.71) and lateral geniculate nuclei (ICC: 0.76). CONCLUSION: Diffusivity and anisotropy measures provide a quantifiable means to evaluate the visual pathway in dogs. DTI has potential to provide in vivo measures of axonal and myelin injury and transsynaptic degeneration in canine PACG.

Evaluation of proteinase K-resistant prion protein (PrPres) in Korean native black goats carrying a potential scrapie-susceptible haplotype of the prion protein gene (PRNP).

Prion disease is a fatal neurodegenerative disease with a broad host range in humans and animals. It is caused by proteinase K-resistant prion protein (PrPres). In previous studies, a heterogeneous infection in Cervidae and Caprinae was reported. Chronic wasting disease (CWD) has been frequently reported as the only prion disease in Korea that occurs in livestock. Thus, there is a possibility of transmission of CWD to Korean native black goats. However, PrPres has not been investigated thus far in Korean native black goats. We found strong linkage disequilibrium between c.126G>A and c.414T>C (r2 = 1) and between c.718C>T and c.126G>A (r2 = 0.638). In addition, the haplotype GTGTAAAC (representing codons 42, 102, 127, 138, 143, 146, 218 and 240) showed the highest frequency with 45.1%. Among 41 Korean native black goats, 20 animals (48.78%) were homozygous for the susceptible haplotypes (histidine at codon 143, asparagine at codon 146 and arginine at codon 154). Interestingly, we did not detect PrPres bands in any of the tested animals, including the 20 animals carrying potential scrapie susceptible haplotypes.

Spontaneous Incidental Brain Lesions in C57BL/6J Mice.

Genetically engineered mouse lines on a C57BL/6J background are widely employed as preclinical models to study neurodegenerative human disorders and brain tumors. However, because of the lack of comprehensive data on the spontaneous background neuropathology of the C57BL/6J strain, discriminating between naturally occurring changes and lesions caused by experimental mutations can be challenging. In this context, this study aims at defining the spectrum and frequency of spontaneous brain changes in a large cohort of C57BL/6J mice and their association with specific biological variables, including age and sex. Brains from 203 experimentally naive and clinically unremarkable C57BL/6J mice were collected and analyzed by means of histopathology and immunohistochemistry. Mice ranged in age from 3 to 110 weeks with 89 females, 111 males, and 3 unknowns. Sixteen different spontaneous lesion categories were described in this cohort. Age-related neurodegenerative and/or neuroinflammatory findings represented the most common pathologic changes and included (1) Hirano-like inclusions in the thalamic neurons, (2) neuroaxonal dystrophy in the medulla oblongata, (3) periodic acid-Schiff-positive granular deposits in the neuropil of the hippocampus, and (4) progressive neuroinflammation characterized by microgliosis and astrogliosis. Neoplastic conditions, developmental abnormalities, and circulatory disorders were rarely observed incidental findings. In conclusion, this study describes spontaneous age-related brain lesions of the C57BL/6J mouse and provides a reference for evaluating and interpreting the neuropathological phenotype in genetically engineered mouse models developed and maintained on this congenic background.

Transfer of the Neurotoxin ß-N-methylamino-l-alanine (BMAA) in the Agro-Aqua Cycle.

The neurotoxic non-protein amino acid ß-N-methylamino-l-alanine (BMAA) is connected to the development of neurodegenerative diseases. BMAA has been shown to accumulate in aquatic ecosystems, and filter-feeding molluscs seem particularly susceptible to BMAA accumulation. The blue mussels farmed along the Swedish coastline in the Baltic Sea are, due to their small size, exclusively used to produce feed for chicken and fish in the agro-aqua cycle. We have investigated the possible biotransfer of BMAA from mussels, via mussel-based feed, into chickens. Chickens were divided into two groups, the control and the treatment. BMAA was extracted from the muscle, liver, brain, and eye tissues in both chicken groups; a UPLC-MS/MS method was subsequently used to quantify BMAA. The results indicate detectable concentrations of BMAA in both chicken groups. However, the BMAA concentration in chicken was 5.65 times higher in the treatment group than the control group, with the highest concentration found in muscle tissue extracted from the treatment group chickens. These data suggest that there is a BMAA transfer route within the agro-aqua cycle, so further investigation is recommended before using mussel-based feed in the chicken industry.

Ulk1 Governs Nerve Growth Factor/TrkA Signaling by Mediating Rab5 GTPase Activation in Porcine Hemagglutinating Encephalomyelitis Virus-Induced Neurodegenerative Disorders.

Porcine hemagglutinating encephalomyelitis virus (PHEV) is a highly neurovirulent coronavirus and causes neurological dysfunction in the central nervous system (CNS), but the neuropathological mechanism of PHEV remains poorly understood. We report that Unc51-like kinase 1 (Ulk1/Unc51.1) is a pivotal regulator of PHEV-induced neurological disorders and functions to selectively control the initiation of nerve growth factor (NGF)/TrkA endosome trafficking. We first identified the function of Ulk1 by histopathologic evaluation in a PHEV-infected mouse model in which neuronal loss was accompanied by the suppression of Ulk1 expression. Morphogenesis assessments in the primary cortical neurons revealed that overexpression or mutations of Ulk1 modulated neurite outgrowth, collateral sprouting, and endosomal transport. Likewise, Ulk1 expression was decreased following PHEV infection, suggesting that there was a correlation between the neurodegeneration and functional Ulk1 deficiency. We then showed that Ulk1 forms a multiprotein complex with TrkA and the early endosome marker Rab5 and that Ulk1 defects lead to either blocking of NGF/TrkA endocytosis or premature degradation of pTrkA via constitutive activation of the Rab5 GTPase. Further investigation determined that the ectopic expression of Rab5 mutants induces aberrant endosomal accumulation of activated pTrkA, proving that targeting of Ulk1-TrkA-NGF signaling to the retrograde transport route in the neurodegenerative process that underlies PHEV infection is dependent on Rab5 GTPase activity. Therefore, we described a long-distance signaling mechanism of PHEV-driven deficits in neurons and suggested that such Ulk1 repression may result in limited NGF/TrkA retrograde signaling within activated Rab5 endosomes, explaining the progressive failure of neurite outgrowth and survival.IMPORTANCE Porcine hemagglutinating encephalomyelitis virus (PHEV) is a neurotropic coronavirus and targets neurons in the nervous system for proliferation, frequently leaving behind grievous neurodegeneration. Structural plasticity disorders occur in the axons, dendrites, and dendritic spines of PHEV-infected neurons, and dysfunction of this neural process may contribute to neurologic pathologies, but the mechanisms remain undetermined. Further understanding of the neurological manifestations underlying PHEV infection in the CNS may provide insights into both neurodevelopmental and neurodegenerative diseases that may be conducive to targeted approaches for treatment. The significance of our research is in identifying an Ulk1-related neurodegenerative mechanism, focusing on the regulatory functions of Ulk1 in the transport of long-distance trophic signaling endosomes, thereby explaining the progressive failure of neurite outgrowth and survival associated with PHEV aggression. This is the first report to define a mechanistic link between alterations in signaling from endocytic pathways and the neuropathogenesis of PHEV-induced CNS disease.

First description of enhanced expression of transforming growth factor-alpha (TGF-α) and glia maturation factor-beta (GMF-ß) correlate with severity of neuropathology in border disease virus-infected small ruminants.

Border disease (BD) is caused by Pestivirus and characterized by severe neuropathology, and histopathologically observed severe hypomyelination. We have previously shown that small ruminants infected with border disease virus (BDV) play an important role for neuropathology and pathogenesis of severe oxidative damage in brain tissue, neuronal mtDNA; in the production of high pathologic levels of nitric oxide; in glial cell activation and stimulation of intrinsic apoptosis pathway. This study aimed to investigate the relationship between glia maturation factor beta (GMF-ß) and transforming growth factor alpha (TGF-α) expressions and the causes of BDV-induced neuropathology and to investigate their role in neuropathogenesis in a way that was not presented before. Expression levels of GMF-ß and TGF-α were investigated. Results of the study revealed that the levels of GMF-ß (P < 0.005) and TGF-α (P < 0.005) expression in the brain tissue markedly increased in the BDV-infected animals compared to the non-infected healthy control group. While TGF-α expressions were predominantly observed in neurons, GMF-ß expressions were found in astrocytes, glial cells and neurons. These results were reasonable to suggest that BDV-mediated increased GMF-ß might play a pivotal role neuropathogenesis and a different type of role in the mechanism of neurodegeneration/neuropathology in the process of BD. The results also indicated that increased levels of GMF up-regulation in glial cells and neurons causes neuronal destruction, suggesting pathological pathway involving GMF-mediated brain cell cytotoxicity. It is clearly indicated that the cause of astrogliosis is due to severe TGF-a expression. This is the first study to demonstrate the expression of GMF-ß and TGF-α in neurons and reactive glial cells and its association with neuropathology in BD.

Plasma microRNA miR-26b as a potential diagnostic biomarker of degenerative myelopathy in Pembroke welsh corgis.

BACKGROUND: Degenerative myelopathy (DM) is a progressive neurodegenerative disease frequently found in Pembroke Welsh Corgis (PWCs). Most DM-affected PWCs are homozygous for the mutant superoxide dismutase 1 (SOD1) allele; however, the genetic examination for the SOD1 mutation does not exclusively detect symptomatic dogs. In order to identify novel biomarkers, the plasma microRNA (miRNA) profiles of PWCs with DM were investigated. RESULTS: Quantification of the plasma levels of 277 miRNAs by an RT-qPCR array identified 11 up-regulated miRNAs and 7 down-regulated miRNAs in DM-affected PWCs from those in wild-type SOD1 PWCs. A pathway analysis identified 3 miRNAs: miR-26b, miR-181a, and miR-196a, which potentially regulate several genes associated with SOD1. In order to validate the diagnostic accuracy of the candidate miRNAs in the aged PWC population, candidate miRNAs in plasma were measured by RT-qPCR and a receiver operating characteristic (ROC) curve analysis was performed. miR-26b had the largest area under the ROC curve for distinguishing DM PWCs from healthy PWCs (sensitivity, 66.7%; specificity, 87.0%). The plasma level of miR-26b was significantly higher in the DM group than in the healthy control group. A positive correlation was observed between increases in the plasma level of miR-26b and disease progression. CONCLUSIONS: These results suggest that plasma miR-26b is a potential novel diagnostic biomarker of DM.

Cerebellar Abiotrophy Across Domestic Species.

Cerebellar abiotrophy (CA) is a neurodegenerative disorder affecting the cerebellum and occurs in multiple species. Although CA is well researched in humans and mice, domestic species such as the dog, cat, sheep, cow, and horse receive little recognition. This may be due to few studies addressing the mechanism of CA in these species. However, valuable information can still be extracted from these cases. A review of the clinicohistologic phenotype of CA in these species and determining the various etiologies of CA may aid in determining conserved and required pathways necessary for proper cerebellar development and function. This review outlines research approaches of studies of CA in domestic species, compared to the approaches used in mice, with the objective of comparing CA in domestic species while identifying areas for further research efforts.

The Pathology of Wobbly Hedgehog Syndrome.

Wobbly hedgehog syndrome (WHS) is a leading cause of neurologic disease in African pygmy hedgehogs (APHs; Atelerix albiventris). This study describes the signalment, clinical signs, gross, microscopic, and ultrastructural lesions of WHS in a cohort of 12 pet APHs. Microscopically, lesions consisted of status spongiosus of the white matter, typically bilateral and symmetrical, with myelin degeneration and loss that was accompanied by neuronal/axonal degeneration plus reactive microgliosis and mild, focal astrocytosis and astrogliosis. Lesions were most severe in the cerebellum and medulla oblongata, as well as cervical and thoracic spinal cord. Less affected areas were the corona radiata, corpus callosum, corpus striatum, internal capsule, and the mesencephalon. Ultrastructurally, the lesions consisted of splitting of the myelin sheath at the intraperiod line with subsequent focal expansion, resulting in status spongiosus, disruption, dilatation, rhexis, and phagocytosis. Based on these results, WHS is best described as a "spongy myelinopathy" with widespread central nervous system involvement.

A missense change in the ATG4D gene links aberrant autophagy to a neurodegenerative vacuolar storage disease.

Inherited neurodegenerative disorders are debilitating diseases that occur across different species. We have performed clinical, pathological and genetic studies to characterize a novel canine neurodegenerative disease present in the Lagotto Romagnolo dog breed. Affected dogs suffer from progressive cerebellar ataxia, sometimes accompanied by episodic nystagmus and behavioral changes. Histological examination revealed unique pathological changes, including profound neuronal cytoplasmic vacuolization in the nervous system, as well as spheroid formation and cytoplasmic aggregation of vacuoles in secretory epithelial tissues and mesenchymal cells. Genetic analyses uncovered a missense change, c.1288G>A; p.A430T, in the autophagy-related ATG4D gene on canine chromosome 20 with a highly significant disease association (p = 3.8 x 10-136) in a cohort of more than 2300 Lagotto Romagnolo dogs. ATG4D encodes a poorly characterized cysteine protease belonging to the macroautophagy pathway. Accordingly, our histological analyses indicated altered autophagic flux in affected tissues. The knockdown of the zebrafish homologue atg4da resulted in a widespread developmental disturbance and neurodegeneration in the central nervous system. Our study describes a previously unknown canine neurological disease with particular pathological features and implicates the ATG4D protein as an important autophagy mediator in neuronal homeostasis. The canine phenotype serves as a model to delineate the disease-causing pathological mechanism(s) and ATG4D function, and can also be used to explore treatment options. Furthermore, our results reveal a novel candidate gene for human neurodegeneration and enable the development of a genetic test for veterinary diagnostic and breeding purposes.

Evidence of a genomic insertion in intron 2 of SOD1 causing allelic drop-out during routine diagnostic testing for canine degenerative myelopathy.

Degenerative myelopathy is a severe and progressive neurodegenerative disease and, in the majority of breeds, is associated with the c.118G>A substitution in exon 2 of the canine superoxide dismutase 1 (SOD1) gene. Our laboratories have been engaged in determining the cause of many discordant findings between the parental and the offspring genotypes found by different laboratories. In both cases, the discordant findings refer to actual heterozygous dogs that had been typed as homozygous for the variant allele. To that aim, the genomic context of the causative variant was investigated in two Hovawart dogs. An insertion of 54 nucleotides composed of a poly-T stretch and 15 nucleotides containing the duplication of the exon 2-intron 2 junction was found. The insertion was responsible for the partial mismatch of the reverse primer used for a direct sequencing assay. The mismatch hampered the amplification of the corresponding allele and caused an evident drop-out effect. The insertion is in complete linkage disequilibrium with the c.118G allele. The allele containing the insertion was highly prevalent in Hovawart dogs, accounting for the 26.6% of allele frequency. The insertion was also found in other unrelated breeds such as Rough Collies and Standard Poodles. In conclusion, the study illustrates the importance of correctly designing the primers to avoid inaccurate genotyping of the degenerative myelopathy causative variant in exon 2 of the SOD1 gene.

Basal Autophagy Is Altered in Lagotto Romagnolo Dogs with an ATG4D Mutation.

A missense variant in the autophagy-related ATG4D-gene has been associated with a progressive degenerative neurological disease in Lagotto Romagnolo (LR) dogs. In addition to neural lesions, affected dogs show an extraneural histopathological phenotype characterized by severe cytoplasmic vacuolization, a finding not previously linked with disturbed autophagy in animals. Here we aimed at testing the hypothesis that autophagy is altered in the affected dogs, at reporting the histopathology of extraneural tissues and at excluding lysosomal storage diseases. Basal and starvation-induced autophagy were monitored by Western blotting and immunofluorescence of microtubule associated protein 1A/B light chain3 (LC3) in fibroblasts from 2 affected dogs. The extraneural findings of 9 euthanized LRs and skin biopsies from 4 living affected LRs were examined by light microscopy, electron microscopy, and immunohistochemistry (IHC), using antibodies against autophagosomal membranes (LC3), autophagic cargo (p62), and lysosomal membranes (LAMP2). Biochemical screening of urine and fibroblasts of 2 affected dogs was performed. Under basal conditions, the affected fibroblasts contained significantly more LC3-II and LC3-positive vesicles than did the controls. Morphologically, several cells, including serous secretory epithelium, endothelial cells, pericytes, plasma cells, and macrophages, contained cytoplasmic vacuoles with an ultrastructure resembling enlarged amphisomes, endosomes, or multivesicular bodies. IHC showed strong membranous LAMP2 positivity only in sweat glands. The results show that basal but not induced autophagy is altered in affected fibroblasts. The ultrastructure of affected cells is compatible with altered autophagic and endo-lysosomal vesicular traffic. The findings in this spontaneous disease provide insight into possible tissue-specific roles of basal autophagy.

Circadian Rhythm Neuropeptides in Drosophila: Signals for Normal Circadian Function and Circadian Neurodegenerative Disease.

Circadian rhythm is a ubiquitous phenomenon in many organisms ranging from prokaryotes to eukaryotes. During more than four decades, the intrinsic and exogenous regulations of circadian rhythm have been studied. This review summarizes the core endogenous oscillation in Drosophila and then focuses on the neuropeptides, neurotransmitters and hormones that mediate its outputs and integration in Drosophila and the links between several of these (pigment dispersing factor (PDF) and insulin-like peptides) and neurodegenerative disease. These signaling molecules convey important network connectivity and signaling information for normal circadian function, but PDF and insulin-like peptides can also convey signals that lead to apoptosis, enhanced neurodegeneration and cognitive decline in flies carrying circadian mutations or in a senescent state.

Evidence of the Primary Afferent Tracts Undergoing Neurodegeneration in Horses With Equine Degenerative Myeloencephalopathy Based on Calretinin Immunohistochemical Localization.

Equine degenerative myeloencephalopathy (EDM) is characterized by a symmetric general proprioceptive ataxia in young horses, and is likely underdiagnosed for 2 reasons: first, clinical signs overlap those of cervical vertebral compressive myelopathy; second, histologic lesions--including axonal spheroids in specific tracts of the somatosensory and motor systems--may be subtle. The purpose of this study was (1) to utilize immunohistochemical (IHC) markers to trace axons in the spinocuneocerebellar, dorsal column-medial lemniscal, and dorsospinocerebellar tracts in healthy horses and (2) to determine the IHC staining characteristics of the neurons and degenerated axons along the somatosensory tracts in EDM-affected horses. Examination of brain, spinal cord, and nerves was performed on 2 age-matched control horses, 3 EDM-affected horses, and 2 age-matched disease-control horses via IHC for calbindin, vesicular glutamate transporter 2, parvalbumin, calretinin, glutamic acid decarboxylase, and glial fibrillary acidic protein. Primary afferent axons of the spinocuneocerebellar, dorsal column-medial lemniscal, and dorsospinocerebellar tracts were successfully traced with calretinin. Calretinin-positive cell bodies were identified in a subset of neurons in the dorsal root ganglia, suggesting that calretinin IHC could be used to trace axonal projections from these cell bodies. Calretinin-immunoreactive spheroids were present in EDM-affected horses within the nuclei cuneatus medialis, cuneatus lateralis, and thoracicus. Neurons within those nuclei were calretinin negative. Cell bodies of degenerated axons in EDM-affected horses are likely located in the dorsal root ganglia. These findings support the role of sensory axonal degeneration in the pathogenesis of EDM and provide a method to highlight tracts with axonal spheroids to aid in the diagnosis of this neurodegenerative disease.

Pathology of the Aging Brain in Domestic and Laboratory Animals, and Animal Models of Human Neurodegenerative Diseases.

According to the WHO, the proportion of people over 60 years is increasing and expected to reach 22% of total world's population in 2050. In parallel, recent animal demographic studies have shown that the life expectancy of pet dogs and cats is increasing. Brain aging is associated not only with molecular and morphological changes but also leads to different degrees of behavioral and cognitive dysfunction. Common age-related brain lesions in humans include brain atrophy, neuronal loss, amyloid plaques, cerebrovascular amyloid angiopathy, vascular mineralization, neurofibrillary tangles, meningeal osseous metaplasia, and accumulation of lipofuscin. In aging humans, the most common neurodegenerative disorder is Alzheimer's disease (AD), which progressively impairs cognition, behavior, and quality of life. Pathologic changes comparable to the lesions of AD are described in several other animal species, although their clinical significance and effect on cognitive function are poorly documented. This review describes the commonly reported age-associated neurologic lesions in domestic and laboratory animals and the relationship of these lesions to cognitive dysfunction. Also described are the comparative interspecies similarities and differences to AD and other human neurodegenerative diseases including Parkinson's disease and progressive supranuclear palsy, and the spontaneous and transgenic animal models of these diseases.