Morphometric analysis of progressive changes in hereditary cerebellar cortical degenerative disease (abiotrophy) in rabbits caused by abnormal synaptogenesis

We previously investigated rabbit hereditary cerebellar cortical degenerative disease, called cerebellar cortical abiotrophy in the veterinary field, and determined that the pathogenesis of this disease is the result of failed synaptogenesis between parallel fibers and Purkinje cells. In this study, longitudinal changes in the development and atrophy of the cerebellum of rabbits with hereditary abiotrophy after birth were morphometrically examined (postnatal day [PD] 15 and 42) using image analysis. Although development of the cerebellum in rabbits with abiotrophy was observed from PD 15 to PD 42, the growth rate of the cerebellum was less than that in normal rabbits. In rabbits with abiotrophy, the number of granular cells undergoing apoptosis was significantly higher at PD 15 and dramatically decreased at PD 42. The number of granular cells did not increase from PD 15 to 42. The synaptogenesis peak at PD 15 occurred when the largest number of apoptotic granular cells in rabbits with abiotrophy was observed. Although 26% to 36% of parallel fiber terminals formed synaptic junctions with Purkinje cell spines, the remainder did not at PD 15 and 42. The rate of failure of synaptogenesis in the present study might be specific to this case of abiotrophy. Morphometric analysis revealed detailed changes in development and atrophy in animals with postnatal cerebellar disease occurring soon after birth.     

Naturally occurring parvovirus-associated feline hypogranular cerebellar hypoplasia-- A comparison to experimentally-induced lesions using immunohistology

Three cases of feline cerebellar hypoplasia are presented. At the time of examination, the ages of the cats ranged from 2 months to 1 year. Necropsy revealed cerebellar and pons hypoplasia. Polymerase chain reaction for parvoviral deoxyribonucleic acid was positive in cerebellar tissue. Cell-specific immunolabeling was used to characterize the lesions, which were characterized into 2 types. In type 1 lesions, the cortex was nearly agranular, with an extremely thin molecular layer; the Purkinje cells were randomly placed and oriented, and their stunted main dendrite produced a thorn-covered atrophic dendritic tree; the basket cell axons ran randomly and had dysmorphic endings; and myelinated fibers were severely reduced in folia axes. In type 2 lesions, the cortex was hypogranular; the Purkinje cells were linearly organized, but their main dendrite extended too far in the molecular layer before giving up smooth, bent secondary dendrites; many basket cells were located along the cerebellar surface, and their axons ran at right angle to the surface; myelinated fibers were moderately reduced. Defects in climbing fiber synapse translocation and elimination were evident in both types of lesion. This immunohistologic study allowed a comparison between lesions in these spontaneous cerebellar hypoplasia cases with those documented when using silver impregnation studies after perinatal experimental cerebellar damage. Such a comparison is consistent with viral infection that occurs before birth in all 3 cases. Progress in parvovirus biology knowledge suggests that viral NS1 protein cytotoxicity might explain degenerative changes in the Purkinje cells that were present, in addition to the development defect.     

Cerebellar hypoplasia associated with an avian leukosis virus inducing fowl glioma

Fowl glioma-inducing virus (FGV), which belongs to subgroup A of avian leukosis virus (ALV), shows tumorigenicity and pathogenicity, mainly in the nervous system, and causes astrocytoma and perineurioma. Apart from these neoplasms, cerebellar anomaly was found in chickens infected with FGV in ovo. The study reported here describes the morphologic characteristics of the affected cerebellum. Specific-pathogen-free chickens (C/O) were inoculated with FGV through the yolk sac on the 7th day of incubation. The cerebellar anomaly included diffuse depletion of granular cells of the internal granular layer (IGL), remnants of the external granular layer (EGL), and disorganization of the Purkinje cell layer. These cerebellar changes were observed in all birds except one. In the infected embryos, the EGL was thicker and had an irregular arrangement with a thin molecular layer (ML) and IGL, compared with the control. The granular cells were immunohistochemically positive for ALV common antigen. Immunohistochemical analysis for vimentin revealed disarrangement and decreased number of Bergmann's fibers. Use of the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling method and electron microscopy indicated that apoptotic granular cells were frequently observed in the EGL and ML. These results suggested that the cerebellar anomaly was hypoplasia, principally resulting from the apoptosis of granular cells in the EGL and ML caused by FGV infection and that the cell loss induced obstruction of granular cell migration and disarrangement of Bergmann's fibers in the ML.     

Cerebellar abiotrophy in a family of Border Collie dogs

Cerebellar abiotrophies have a nonsex-linked, autosomal, recessively inherited basis in a number of species, and lesions typically reflect profound and progressive loss of Purkinje cells. In this report, an unusual form of abiotrophy is described for two sibling Border Collies. Extensive loss of the cerebellar granular cell layer was present with relative sparing of Purkinje cells of two female pups. The biochemical basis for this form of cerebellar abiotrophy is unknown, but the lack of disease in other siblings supports an autosomal recessive mode of inheritance.     

Cerebellar degeneration in a mature Staffordshire terrier

A 5-year-old Staffordshire terrier exhibited slowly progressive signs of cerebellar disease, including nystagmus and dysmetria. After a 30-month course, the dog was euthanized. Grossly, the cerebellum was small and comprised only 5% of the brain weight. Histopathological examination of the brain documented diffuse degeneration. Purkinje cells were most depleted, but granular cells and the molecular layer of cerebellum were also depleted. The history and necropsy examination were evidence of late-onset primary cerebellar degeneration.     

Cerebellar cortical abiotrophy in Lagotto Romagnolo dogs

This case report documents two pathological variations of potentially inherited, cerebellar cortical abiotrophy in two unrelated Lagotto Romagnolo breed dogs. The first dog had an atypical lesion in the cerebellar cortex with depletion of cerebellar granular cell layer and sparing of the Purkinje cell layer. The second case had degenerative changes in both Purkinje and granular cell layers. The clinical picture was similar in both cases presented, although the severity of the signs of cerebellar dysfunction varied.     

Diagnosis of cerebellar cortical degeneration in a Scottish terrier using magnetic resonance imaging

Primary cerebellar cortical degeneration (CCD), also termed abiotrophy, is the spontaneous premature degeneration of fully differentiated neurological tissue. Cerebellar hypoplasia shares many morphological features with primary CCD, both conditions being characterised by decreased cerebellar size, with reduced numbers of Purkinje and granular cells. CCD has been identified in many canine breeds. This is the first report of the syndrome in a Scottish terrier. The patient presented with mild, gradually progressive ataxia. Survey radiographs of the cervical spine and cerebrospinal fluid (CSF) analysis were normal. CSF distemper and Toxoplasma titres were negative. A diagnosis of cerebellar atrophy was made based on magnetic resonance imaging. The progressive clinical signs suggested cerebellar degeneration rather than hypoplasia. On necropsy, the cerebellum showed macroscopic and microscopic changes consistent with primary CCD.     

Progressive encephalomyelopathy and cerebellar degeneration in 10 captive-bred cheetahs

Progressive ataxia, with head tremor, developed in 10 captive-born cheetah cubs under six months of age. The condition was usually preceded by coryza and an ocular discharge. Initially the ataxia and weakness affected the hindquarters, then the forelegs, and head tremor developed later. Significant pathological changes were confined to the central nervous system. There was widespread Wallerian degeneration in the funiculi of the spinal cord (except those in the dorsal columns), in the medulla and in the cerebellum. In the cerebellum there was degeneration of Purkinje cells and of the molecular and granular cell layers. There was chromatolysis in the Purkinje cells, the ventral horn cells of the spinal cord and in the neurons of the lateral vestibular nucleus. The olivary nucleus was necrotic. There were foci of inflammatory cells in the molecular layer of the cerebellum and in the medulla. The cause of the disease remains unknown.     

Lysosomal storage disease caused by Sida carpinifolia poisoning in goats

A neurologic disease characterized by ataxia, hypermetria, hyperesthesia, and muscle tremors of the head and neck was observed for 2 years in a flock of 28 Anglo-Nubian and Saanen goats on a farm with 5 ha of pasture. Six newborns died during the first week of life, and five abortions were recorded. The predominant plant in the pasture was Sida carpinifolia. The disease was reproduced experimentally in two goats by administration of this plant. Three goats with spontaneous disease and the two experimental animals were euthanatized and necropsied. No significant gross lesions were observed. Fragments of several organs, including the central nervous system, were processed for histopathology. Small fragments of the cerebellar cortex, liver, and pancreas of two spontaneously poisoned goats and two experimentally poisoned goats were processed for electron microscopy. Multiple cytoplasm vacuoles in hepatocytes, acinar pancreatic cells, and neurons, especially Purkinje cells, were the most striking microscopic lesions in the five animals. Ultrastructural changes included membrane-bound vacuoles in hepatocytes, Kupffer cells, acinar pancreatic cells, Purkinje cells, and the small neurons of the granular cell layer of the cerebellum. Paraffin-embedded sections of the cerebellum and pancreas were submitted for lectin histochemical analysis. The vacuoles in different cerebellar and acinar pancreatic cells reacted strongly to the following lectins: Concanavalia ensiformis, Triticum vulgaris, and succinylated Triticum vulgaris. The pattern of staining, analyzed in Purkinje cells and acinar pancreatic cells coincides with results reported for both swainsonine toxicosis and inherited mannosidosis.     

Late onset cerebellar degeneration in a middle-aged cat

Cerebellar degeneration (abiotrophy) (CD) is a spontaneous and accelerated degeneration of one or several mature cerebellar neuronal cell populations and has been described in many domestic animals, especially in dogs, with numerous breed-related cases. In cats, CD is mentioned as a rare sporadic entity. Late onset CDs are exceptionally uncommon and only two cases are reported in young adults, both aged 18 months. This report describes clinical and pathological findings of a late onset feline CD in a 9-year-old male Persian cat. The cat was presented with a history of progressive ataxia lasting 2 years. Neurological examination revealed severe neurological deficits such as generalised and severe ataxia, hypermetria in all four limbs, and bilateral absence of menace response. The lesion was diffusely localised in cerebellum. On gross pathology, the cerebellum appeared of normal size and shape and kidneys were characterised by mild hyperaemia. Histologically, lesions were limited to the cerebellum and kidneys. In the cerebellum, all cerebellar folia of both hemispheres and the vermis were affected. Changes were characterised by severe and diffuse loss of Purkinje cells, loss of cellularity in the granular layer, mild astrogliosis associated with moderate hypertrophy of Bergmann's glia. Immunohistochemistry for feline parvovirus antigen revealed a negative result. Renal lesions consisted of chronic fibrosis associated with chronic interstitial nephritis. CD is a rare disease and occurs commonly in puppies or young animals, who are clinically normal at birth and usually develop neurological signs within a few weeks or months after birth. This report represents the first case of CD in a middle-aged cat.     

Cerebellar cortical abiotrophy in American Staffordshire terriers: clinical and pathological description of 3 cases

Three American Staffordshire Terriers were presented with gait abnormalities and loss of balance at the age of 4.5 (female) and 6 years (2 males). The onset varied between 3 and 5 years of age and the clinical signs were slowly progressive. The neurological examination revealed symmetrical generalized cerebellar ataxia with hypermetria, stiffness, and loss of balance with no evidence of paresis. The menace reflex was decreased in one dog and absent in another. A positional nystagmus was found in two dogs. The dogs were euthanized and a histopathological examination of each brain was performed. Pathological changes were confined to the cerebellum. The main finding was loss of Purkinje cells, as well as depletion of granular cell bodies and shrinkage of the granular and molecular cell layer. These findings are consistent with cerebellar cortical abiotrophy. A genetic basis is supposed, but the mode of inheritance is not determined yet. In contrast to some spinocerebellar ataxias in humans, the cause of Purkinje cell degeneration in cerebellar cortical abiotrophy of dogs is not known.     

Two cases of hereditary quadriplegia and amblyopia in a litter of Irish setters

Two, one-month-old male Irish setters from the same litter showed incoordination, rotary nystagmus and motor and visual impairment. No abnormalities were found in either the blood, urine or cerebrospinal fluid. Radiographs of the head, chest and abdomen were normal. Histopathology revealed degeneration and necrosis of the granular layer and Purkinje cells of the cerebellar cortex. On electron microscopic examination, the granular cells showed dilated endoplasmic reticulum and vacuolated mitochondrial cristae. There was also serious destruction of Purkinje cells.     

Neuronal apoptosis in the developing cerebellum

The following study analysed apoptosis in proliferative cells and migrating neurons of the developing cerebellum. The external granular layer, Purkinje cell layer and internal granular layer in the developing mouse cerebellar cortex were analysed by active caspase-3 immunohistochemistry, Hoechst 33258 staining and Western blot analysis. Immunocytochemistry results indicated that the peak of apoptosis appeared at postnatal days P8, P5 and P9 in the external granular layer, Purkinje cell layer and internal granular layer, respectively. Subsequently, in each region, the rate of apoptosis decreased with increasing age. In contrast, Western blot results demonstrated the highest expression of activated caspase-3 in the cerebellum at P5, followed by a subsequent decline and disappearance of expression by P14. Activated caspase-8 was expressed maximally at P10, and subsequently disappeared by P30. The results of this study suggest that the key period of neuronal apoptosis in the cerebellar cortex is between P0 and P14, indicating that this developmental period could be susceptible to treatment for congenital neurodegenerative diseases.     

Effect of methotrexate on cerebellar development in infant rats

Six-day-old rats were treated intraperitoneal injections with methotrexate 1 mg/kg, and the cerebellum was examined. Both the length and width of the vermis decreased in the methotrexate-treated group instead of the control from 4 day after treatment (DAT) onward. A significant reduction in the width of the external granular layer was detected on 2 and 3 DAT in the methotrexate group. By 4 DAT, the width of the external granular layer of the methotrexate group was indistinguishable from the control, and by 8 DAT, it was greater than that of the control. The molecular layer of methotrexate group on 8 and 15 DAT was thinner than that of the control. On 1 DAT, in the methotrexate group, there were many TUNEL and cleaved caspase-3-positive granular cells throughout the external granular layer, and they decreased time-dependently. On 1 DAT, in the methotrexate group, phospho-histone H3-positive cells in the external granular layer were fewer than in the control and tended to increase on 2–4 DAT. The p21-positive-rate of the external granule cells in the MTX group was higher than in the control on 1–4 DAT. These results suggested that methotrexate exposure on postnatal day 6 induces a delay, slowing in the migration of external granular cells to the inner granular layer, attributed to decrease or inhibition in the production of external granular cells that had arisen from apoptosis and the decrease in cell proliferative activity, resulting in cerebellar hypoplasia.     

Purkinje cell apoptosis in arabian horses with cerebellar abiotrophy

Purkinje cerebellar cells were studied in three Arabian horses aged between 6 and 8 months with clinical disorders in their movements, tremors and ataxia; the occurrence of apoptosis in this cell population was investigated by the (terminal deoxynucleotidyl transferase biotin-dUTP nick-end labelling (TUNEL) method. Both optical and electron microscopical images showed a scant number of Purkinje cells, most of them with morphological features of apoptosis such as condensation of the nucleus and cytoplasm as well as segregation and fragmentation of the nucleus into apoptotic bodies. The TUNEL technique revealed a substantial number (65%) of positive immunoreactive Purkinje cells.     

Cerebellar hypoplasia in three sibling cats after intrauterine or early postnatal parvovirus infection

The present report describes the case of an intrauterine or early postnatal parvovirus infection with subsequent cerebellar hypoplasia in three kittens from the same litter. Clinical examination of affected cats revealed neurologic signs indicative of cerebellar ataxia. Due to poor prognosis, animals were euthanised and submitted for necropsy. Post mortem examination demonstrated variable degrees of cerebellar hypoplasia. Histologically, brain lesions were characterised by segmental loss of the external and internal granular layer and decreased numbers of Purkinje cells. Reactive proliferation of astrocytes in the central nervous system was verified by the detection of GFAP-expressing glial cells in affected areas using immunohistochemistry. Furthermore, parvovirus antigen was detected immunohistochemically in neuronal cells of the cerebellum, but not in other parts of the brain and spinal cord or non-neuronal tissues. The present report demonstrates the usefulness of post mortem examination and detection of viral antigen by immunohistochemistry for the discrimination of neurologic disorders in feline species. Neurologic deficiencies due to cerebellar hypoplasia caused by in utero or perinatal feline parvovirus infection should be taken into consideration as differential diagnoses for ataxia in neonatal and juvenile cats.     

Multifocal cerebellar granular layer necrosis in traumatically head-injured lambs.

In a blunt, nonmissile, head impact model of traumatic brain injury in 4-5-week-old Merino lambs, multiple foci of internal granular layer necrosis were found in all 10 impacted animals. This lesion has not previously been reported after human or animal head injury. Temporal lobe impact contusions, predominantly microscopic (8/10) and contralateral contusions (2/10), parenchymal (10/10) and subarachnoid (10/10) hemorrhage, and widely distributed axonal injury were also observed. Although the precise pathogenesis of this focal granule cell necrosis and often attendant red cell change in Purkinje cells was unclear, an ischemic etiology due to trauma-related vascular damage is postulated.     

Late onset cerebellar cortical degeneration in a koala

A 10-year-old male koala started to fall from the tree while sleeping. Subsequently, the koala often fell down while walking and showed a gait abnormality, abnormal nystagmus and hypersalivation. At 12 years of age, the koala became ataxic and seemed blind. At 13 years of age, the koala exhibited signs of dysstasia and was euthanased. Necropsy revealed marked symmetrical atrophy of the cerebellum. Histopathologically, a severe loss of Purkinje and granule cells was evident in the cerebellum, while the molecular layer was more cellular than normal with cells resembling small neurons, which were positively stained with parvalbumin immunohistochemistry. Reactive Bergmann glial cells (astrocytes) were present adjacent to the depleted Purkinje cell zone. The very late onset and slow progression of the cerebellar cortical degeneration in this case is particularly interesting and appears to be the first report in the koala.     

Cerebellar cortical abiotrophy in two Portuguese Podenco littermates

Cerebellar cortical abiotrophy in two Portuguese Podenco littermates is reported and discussed. The disease is characterized by progressive cerebellar ataxia with an early onset of two to three weeks. Extensive loss, degeneration, and necrosis of Purkinje cells particularly involved the cerebellar hemispheres. An autosomal recessive pattern of inheritance is suspected.     

Inositol 1,4,5-triphosphate receptor protein immunohistochemistry of cerebellar Purkinje cells in two dogs with hypoglycemia

Immunohistochemical study was performed on cerebellar Purkinje cells of two dogs with hypoglycemia using an antibody against the inositol 1,4,5-triphosphate receptor that is identical to the cerebellar Purkinje cell glycoprotein P(400) (P(400)/InsP(3)R). In the cerebellar neocortex of an acute case of hypoglycemia, the P(400)/InsP(3)R staining of hypoglycemic Purkinje cells was heterogeneous: some peripheral dendrites, including spiny branchlets, were negative and others were stained with various intensities, although Purkinje cells were morphologically intact by hematoxylin and eosin (HE) stain. In a chronic case of hypoglycemia, almost all the dendrites of Purkinje cells of both the neo- and archicortex of the cerebellum were not stained with the P(400)/InsP(3)R antibody. This is in contrast to the normal dog where Purkinje cell bodies, axons, and dendrites, including spiny branchlets, are intensely stained by the P(400)/InsP(3)R antibody. These results suggest that P(400)/InsP(3)R immunolabeling of Purkinje cells decreased, despite their morphology being preserved by HE stain, and that the function of P(400)/InsP(3)R, especially in spiny branchlets that receive inputs originating from axon terminals of parallel fibers, may be impaired in hypoglycemia.