Cholinergic forebrain degeneration in the APPswe/PS1 [Delta] E9 transgenic mouse (original) (raw)
Related papers
Cholinergic forebrain degeneration in the APPswe/PS1ΔE9 transgenic mouse
Neurobiology of Disease, 2007
The impact of Aβ deposition upon cholinergic intrinsic cortical and striatal, as well as basal forebrain long projection neuronal systems was qualitatively and quantitatively evaluated in young (2-6 months) and middle-aged (10-16 months) APPswe/PS1ΔE9 transgenic (tg) mice. Cholinergic neuritic swellings occurred as early as 2-3 months of age in the cortex and hippocampus and 5-6 months in the striatum of tg mice. However, cholinergic neuron number or choline acetyltransferase (ChAT) optical density measurements remained unchanged in the forebrain structures with age in APPswe/PS1ΔE9 tg mice. ChAT enzyme activity decreased significantly in the cortex and hippocampus of middle-aged tg mice. These results suggest that Aβ deposition has age-dependent effects on cortical and hippocampal ChAT fiber networks and enzyme activity, but does not impact the survival of cholinergic intrinsic or long projection forebrain neurons in APPswe/PS1ΔE9 tg mice.
Aging is associated with a diffuse impairment of forebrain cholinergic neurons
Brain Research, 1990
The study evaluates whether any degenerative changes affect forebrain cholinergic systems during natural aging. The medial septal nucleus, the nuclei of the diagonal band, the neostriatum, and the basal nucleus were studied in adult and aged Wistar rats. Butcher's technique for acetylcholinesterase allowed us to identify neurons located in these forebrain nuclei, which stained intensely or moderately for the enzyme and were putatively cholinergic. The size of forebrain regions containing stained neurons, and the number and size of stained perikarya located therein, were measured. In aged rats, the size of forebrain cholinergic nuclei was reduced by an average of 26%. The density of neurons located in these regions was also significantly lower in aged rats than in controls: intensely stained neurons displayed a mean reduction of 27.81%, while intensely and moderately stained perikarya together were reduced by 25.43%. Cross-sectional area of the stained perikarya was also reduced in aged rats by 32.87%. These data show that the number of forebrain acetylcholinesterase-containing neurons is reduced in aged rats. They are consistent with the hypothesis that natural aging brings about a diffuse and homogeneous depletion of forcbrain cholinergic perikarya. Neurons which are viable, and can be selectively stained, show morphological alterations, which are likely to be related to a degenerative process.
Neuroreport, 2001
The basalo-cortical cholinergic system was characterized in mice expressing mutant human genes for presenilin-1 (PS1), amyloid precursor protein (APP), and combined PS/APP. Dual immunocytochemistry for ChAT and Aâ revealed swollen cholinergic processes within cortical plaques in both APP and PS/APP brains by 12 months, suggesting aberrant sprouting or redistribution of cholinergic processes in response to amyloid deposition. At 8 months, cortical and subcortical ChAT activity was normal (PS/APP) or elevated (PS, APP frontal cortex), while cholinergic cell counts (nBM/SI) and receptor binding were unchanged. ChAT mRNA was up-regulated in the nBM/SI of all three transgenic lines at 8 months. The data indicate that the basal forebrain cholinergic system does not degenerate in mice expressing AD-related transgenes, even in mice with extreme amyloid load. The PS1 or APP transgene appears to enhance the cholinergic phenotype in younger mice, but this involves aberrant sprouting and redistribution of cortical cholinergic processes. NeuroReport 12:1377±1384 & 2001
Neuronal amyloid-β accumulation within cholinergic basal forebrain in ageing and Alzheimer's disease
Brain : a journal of neurology, 2015
The mechanisms that contribute to selective vulnerability of the magnocellular basal forebrain cholinergic neurons in neurodegenerative diseases, such as Alzheimer's disease, are not fully understood. Because age is the primary risk factor for Alzheimer's disease, mechanisms of interest must include age-related alterations in protein expression, cell type-specific markers and pathology. The present study explored the extent and characteristics of intraneuronal amyloid-β accumulation, particularly of the fibrillogenic 42-amino acid isoform, within basal forebrain cholinergic neurons in normal young, normal aged and Alzheimer's disease brains as a potential contributor to the selective vulnerability of these neurons using immunohistochemistry and western blot analysis. Amyloid-β1-42 immunoreactivity was observed in the entire cholinergic neuronal population regardless of age or Alzheimer's disease diagnosis. The magnitude of this accumulation as revealed by optical den...
Age-related recurrence of basal forebrain lesion-induced cholinergic deficits
Neuroscience Letters, 1987
Lesions of basal forebrain cholinergic nuclei projecting to neocortex have recently been employed as an animal model for the cholinergic deficits in Alzheimer's desease. However, unlike Alzheimer's patients, whose deterioration appears to be progressive and irreversible, basalis lesioned rats usually recover both behaviorally and neurochemically within several months after the lesion. We now demonstrate that this recovery may be a function of the age of the rat and that cholinergic deficits re-occur in the aged rat. Choline acetyltransferase (CHAT) activity and [3H]hemicholinium-3 ([3H]HCh-3) binding are reduced in cortex ipsilateral to ibotenic acid lesions in the 12-month postlesion rat following an initial recovery to normal levels by about 3 months postlesion. The recurrence of decrease of cholinergic markers is not a consequence of a non-specific age-related decline since the activity of glutamic acid decarboxylase remains constant between 3 and 12 months postlesion.
Cholinergic Changes in the APP23 Transgenic Mouse Model of Cerebral Amyloidosis
2002
Alzheimer's Disease (AD) is a neurodegenerative disorder that is characterized by extracellular deposits of amyloid- peptide (A) and a severe depletion of the cholinergic system, although the relationship between these two events is poorly understood. In the neocortex, there is a loss of cholinergic fibers and receptors and a decrease of both choline acetyltransferase (ChAT) and acetylcholinesterase enzyme activities. The nucleus basalis of Meynert (NBM), which provides the major cholinergic input to the neocortex, undergoes profound neuron loss in AD. In the present study, we have examined the cholinergic alterations in amyloid precursor protein transgenic mice (APP23), a mouse model of cerebral -amyloidosis. In aged APP23 mice, our results reveal modest decreases in cortical cholinergic enzyme activity compared with age-matched wild-type mice. Total cholinergic fiber length was more severely affected, with 29 and 35% decreases in the neocortex of aged APP23 mice compared with age-matched wild-type mice and young transgenic mice, respectively. However, there was no loss of cholinergic basal forebrain neurons in these aged APP23 mice, suggesting that the cortical cholinergic deficit in APP23 mice is locally induced by the deposition of amyloid and is not caused by a loss of cholinergic basal forebrain neurons. To study the impact of cholinergic basal forebrain degeneration on cortical amyloid deposition, we performed unilateral NBM lesions in adult APP23 mice. Three to 8 months after lesioning, a 38% reduction in ChAT activity and significant cholinergic fiber loss were observed in the ipsilateral frontal cortex. There was a 19% decrease in A levels of the ipsilateral compared with contralateral frontal cortex with no change in the ratio of A40 to A42. We conclude that the severe cholinergic deficit in AD is caused by both the loss of cholinergic basal forebrain neurons and locally by cerebral amyloidosis in the neocortex. Moreover, our results suggest that disruption of the basal cholinergic forebrain system does not promote cerebral amyloidosis in APP23 transgenic mice.
Postnatal maturation of cholinergic markers in forebrain regions of C57BL/6 mice
Developmental Brain Research, 1991
The maturation of some neurochemical markers linked to cholinergic function (choline acetyltransferase, acetylcholinesterase, muscarinic binding sites) has been studied from 10 to 150 days of age in mice belonging to C57BL/6 strain. Previous studies had suggested that part of the cholinergic neurons of the basal forebrain undergo degeneration during juvenile stages of life in these rodents. Our data showed a delayed maturation of the cholinergic levels in the cortex and hippocampus, the main targets of the forebrain cholinergic neurons, but not in the striatum and superior colliculus. In none of these regions was any clear trend towards a decrement of cholinergic levels observed during the lifespan considered. In the medial septum-diagonal band area, an actual decrease of cholinergic levels was observed between 60 and 150 days of age. A side experiment based on daily administration of GM1 ganglioside during juvenile life, showed no effect of this treatment on the maturation of cholinergic markers.
The length of hippocampal cholinergic fibers is reduced in the aging brain
Neurobiology of Aging, 2008
Cholinergic deficits occur in the aged hippocampus and they are significant in Alzheimer's disease. Using stereological and biochemical approaches, we characterized the cholinergic septohippocampal pathway in old (24 months) and young adult (3 months) rats. The total length of choline acetyltransferase (ChAT)-positive fibers in the dorsal hippocampus was significantly decreased by 32% with aging (F (1,9) = 20.94, p = 0.0014), along with the levels of synaptophysin, a presynaptic marker. No significant changes were detected in ChAT activity or in the amounts of ChAT protein, nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), tropomyosin related kinase receptor (Trk) A, TrkB, or p75 neurotrophin receptor (p75 NTR ) in the aged dorsal hippocampus. The number and size of ChAT-positive neurons and the levels of ChAT activity, NGF and BDNF were not statistically different in the septum of aged and young adult rats. This study suggests that substantial synaptic loss and cholinergic axonal degeneration occurs during aging and reinforces the importance of therapies that can protect axons and promote their growth in order to restore cholinergic neurotransmission.