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Paying attention with a compromised cholinergic system: Attenuated activation of cholinergic neurotransmission in attentional task-performing CHT+/- mice.
Mallory CS, Paolone G, Koshy Cherian A, Blakely RD, Sarter M (2012) Paying attention with a compromised cholinergic system: Attenuated activation of cholinergic neurotransmission in attentional task-performing CHT+/- mice. Neuroscience 2012 Abstracts 536.08. Society for Neuroscience, New Orleans, LA.
Summary: Prefrontal cholinergic neurotransmission is necessary for sustained attentional performance. In rats, prefrontal acetylcholine (ACh) release reaches 140% over baseline during the performance of a sustained attention task (SAT; St. Peters et al., 2011a). SAT performance also increases the density of choline transporters (CHT) in synaptic plasma membranes (Apparsundaram et al., 2005), which we hypothesize is needed to sustain elevations of cholinergic activity and behavioral responses. Here we employed the SAT recently adapted for use in mice (St. Peters et al., 2011b) and developed new techniques that permit monitoring of ACh release via microdialysis of mice performing the SAT in order to determine the impact of genetically manipulated levels of choline transporter capacity. First, reverse dialysis of atropine (50 µM) increased ACh release levels in naive WT mice. In contrast, CHT+/- mice could not sustain these increases, consistent with changes observed in levels of muscarinic receptors in the CHT +/- mice (Bazalakova et al., 2007). However, SAT performance did not differ significantly between WT controls and CHT+/- mice. Furthermore, basal (absolute) levels of ACh release were comparable between strains. However, performance-associated increases in ACh release were strikingly attenuated in CHT+/- mice, reaching 40% over basal levels versus 130% in WT. Performance-associated increases in ACh release in CHT+/- mice were TTX-sensitive, similar to release monitored in WT mice (1 µM via reversed dialysis). To determine whether cholinergic activity was necessary for SAT performance in CHT+/- mice we then removed basal forebrain cholinergic neurons by infusing murine-p75NTR-saporin obtaining similar impairment on SAT performance in both strains. Finally, and because cholinergic activity modulates cortical circuitry primarily via nAChR, mecamylamine (MEC; 50 µM) was reverse dialyzed during SAT performance. WT mice were only moderately impaired in the SAT task, whereas the performance of CHT+/- mice rapidly declined and the performance-associated ACh levels rapidly returned to the pre-task levels. In summary CHT+/- mice are able to perform the basic SAT, despite attenuated levels of cholinergic neurotransmission, likely as a result of compensatory postsynaptic mechanisms. However, their attentional performance and underlying cholinergic signaling exhibit heightened sensitivity to behavioral and pharmacological challenges. Together, these findings suggest that CHT+/- mice are an important model for the impaired cognitive control of attentional performance that is a common symptom of ADHD, schizophrenia and other cognitive disorders.
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Emerging roles of pathogens in alzheimer’s and moderate magnetic field therapy: dc emf 0.5 tesla
Nichols TW (2012) Emerging roles of pathogens in alzheimer’s and moderate magnetic field therapy: dc emf 0.5 tesla. Neuroscience 2012 Abstracts 438.10. Society for Neuroscience, New Orleans, LA.
Summary: Chronic spirochetal infection can cause slowly progressive dementia, cortical atrophy and amyloid deposition in the atrophic form of general paresis. There is a significant association between Alzheimer disease (AD) and various types of spirochete (including the periodontal pathogen Treponemas and Borrelia burgdorferi), and other pathogens such as Chlamydophyla pneumoniae and herpes simplex virus type-1 (HSV-1). (Miklossy 2011 Exp Rev Mol Med) Miklossy’s lab exposed mammalian glia & neuronal cells in vitro to Borrelia burgdorferi spirochetes and bacterial lipopolysaccharides (LPS). Morphological changes analogous to amyloid deposits were observed at 2-8 wks exposure. Increased levels of ß-amyloid precursor protein and hyperphosphorylated tau were detected by WB.The frequency of spirochetes is significantly higher in the brains of Alzheimer patients compared to controls.The statistical analysis is based on the cumulative data of the literature. (P=1.5×10-17,OR=20, 95%CI=8-60! Seven out of ten brains from the Harvard McLean Brain bank were positive for Borrelia DNA. Alan Mac Donald MD. “Borrelia Infection is the root cause of at least 70% of Alzheimer’s disease, based on the detection of positive In situ DNA hybridization results in the cytoplasic GVB sites of hippocampal neurons ( with no positive signals detected in the nucleus) for flagellin B DNA sequences of Borrelia burgdorferi.” Antibiotics in Alzheimer’s disease: A randomized controlled trial of doxycycline and rifampin for patients with Alzheimer’s disease 2004. Cognitive decline was statically improved in treatment over placebo. Minocycline protects basal forebrain cholinergic neurons from mu p 75-saporin immunotoxic lesioning 2004 in animal model. Minocycline attenuates neuronal cell death and improves cognitive impairment in Alzheimer’s disease models 2007. Minocycline does not affect amyloid ß phagocytosis by human microglia cells. (Minocycline attenuates the release of TNF-α by human microglia upon exposure to Abeta, SAP and C1q) 2007. Moderate Magnetic Field Therapy (0.5 Tesla) in 15 Alzheimer’s patients. Results; Cognition Improved: group average hours = 184.Mechanism hypothesis: Overview of crosstalk between SMF & IL-6.Wang, Z, Sarje A, Che PL, Yarema K. Moderate strength (0.23-0.28T) static magnetic fields (SMF) modulate signaling and differentiation in human embryonic cells. BMC Genomic 2009;10:356
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Combined loss of entorhinal and basal forebrain cholinergic hippocampal inputs deeply impairs spatial navigation memory in C57BL/6J and hAPPxapoE mice.
Mathis C, Moreau P-H, Zerbinatti C, Goutagny R, Cosquer B, Geiger K, Kelche C, Cassel J-C (2012) Combined loss of entorhinal and basal forebrain cholinergic hippocampal inputs deeply impairs spatial navigation memory in C57BL/6J and hAPPxapoE mice. Neuroscience 2012 Abstracts 203.28. Society for Neuroscience, New Orleans, LA.
Summary: The hippocampus plays a key role in spatial learning and memory. Major inputs provided by the cholinergic basal forebrain (CBF) and the entorhinal cortex (EC) neurons are expected to modulate hippocampal functions. Surprisingly, the selective lesion of one or the other produces only moderate performance degradation in spatial navigation tasks, suggesting possible compensation provided by other hippocampal inputs. We therefore assessed the effects of single versus combined lesions of the EC (NMDA excitotoxin) and the CBF (mu-p75 saporin immunotoxin) on several forms of memory in C57BL/6 mice. Single lesions had moderate or no effects, while the combined lesions completely abolished long-term spatial memory retention in the water-maze and the Barnes-maze navigation tasks. Object recognition memory was selectively and profoundly affected by the loss of cholinergic neurons, whereas object location memory was only marginally affected by the lesions. These results suggest that the integrity of both the CBF and the EC is critical to establish an enduring spatial navigation memory. The synergistic interaction between the two lesions is particularly relevant to Alzheimer’s disease (AD) since both structures undergo severe degeneration in parallel to dramatic impairments in spatial navigation tasks. The apolipoprotein E4 (apoE4) allele, a major genetic risk factor for AD, has been proposed as a cholinergic deficit predictor and has been associated with larger EC atrophy in AD patients. Thus, the effects of single and combined EC and CBF lesions were evaluated on Barnes maze navigation performance in hAPPxapoE mice knocked-in for the human apoE3 or apoE4 gene allele on a (normal) human APP YAC transgenic background. Long-term spatial memory performances of hAPPxapoE3 and hAPPxapoE4 mice were dramatically affected by the CBF lesion and the combined lesions, but not by the EC lesion. A similar pattern of deficit was observed on learning performances in apoE4 not in apoE3 mice; the latter were only affected by the combined lesions. In conclusion, the apoE4 genotype had no effect on the consequences of EC and combined lesions, but it worsened the outcome of CBF lesions compared to the apoE3 genotype. Since the mice of the two genotypes showed similar loss of cholinergic neurons, our data may reflect a deleterious impact of apoE4 on the activity of the few surviving neurons (about 20%). Alternatively, our findings would also be consistent with impaired compensatory mechanisms following cholinergic loss which could depend on other hippocampal inputs such as the entorhinal cortex. Further analyses are underway to clarify this issue.
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Featured Article: Partial basal forebrain cholinergic depletion leaves working memory susceptible to the effects of systemic inflammation
Cunningham C (2012) Featured Article: Partial basal forebrain cholinergic depletion leaves working memory susceptible to the effects of systemic inflammation. Targeting Trends 13(4)
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Read the featured article in Targeting Trends.
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Cholinergic denervation exacerbates amyloid pathology and induces hippocampal atrophy in Tg2576 mice.
Gil-Bea FJ, Gerenu G, Aisa B, Kirazov LP, Schliebs R, Ramirez MJ (2012) Cholinergic denervation exacerbates amyloid pathology and induces hippocampal atrophy in Tg2576 mice. Neurobiol Dis 48(3):439-446. doi: 10.1016/j.nbd.2012.06.020
Summary: The hallmarks of Alzheimer’s disease (AD) include hippocampal cell loss, cholinergic dysfunction, amyloid plaques, and neurofibrillary tangles, among other things. This work sought to examine the interaction between cholinergic denervation, amyloid precursor protein (APP) processing, and hippocampal integrity. Tg2576 transgenic mice received 2 μg of mu p75-SAP (Cat. #IT-16) injected into the third ventricle. These mice overexpress a version of human APP. Lesioned animals displayed various aspects of AD such as hippocampal synaptic pathology and neurodegeneration, indicating that immunolesions in this mouse line produce a viable model for AD.
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Prior pathology in the basal forebrain cholinergic system predisposes to inflammation-induced working memory deficits: Reconciling inflammatory and cholinergic hypotheses of delirium.
Field RH, Gossen A, Cunningham C (2012) Prior pathology in the basal forebrain cholinergic system predisposes to inflammation-induced working memory deficits: Reconciling inflammatory and cholinergic hypotheses of delirium. J Neurosci 32(18):6288-6294. doi: 10.1523/JNEUROSCI.4673-11.2012
Summary: The authors lesioned the basal forebrain of mice with 0.08 μg or 0.4 μg icv injections of mu p75-SAP (Cat. #IT-16) to establish an early dementia-associated cholinergic loss model. The mice were then challenged with systemic inflammation using low-dose lipopolysaccharide (LPS). The mu p75-SAP lesion left hippocampal-dependent reference and working memory relatively intact. LPS-induced inflammation created acute working memory deficits; an aceytlcholinesterase inhibitor protected against this deficit.
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CXB-909 attenuates cognitive deficits in the mu-p-75 saporin mouse model of Alzheimer’s disease.
Lowrance S, Matchynski J, Rossignol J, Dekorver N, Sandstrom M, Dunbar G (2012) CXB-909 attenuates cognitive deficits in the mu-p-75 saporin mouse model of Alzheimer’s disease. Neuroscience & Medicine 3(1):65-68. doi: 10.4236/nm.2012.31010
Summary: CXB-909 is a small molecule NGF amplifier that has been shown to enhance neurite outgrowth in various neuronal cell lines. This type of molecule has potential therapeutic use in disorders such as Alzheimer’s disease. In this work the authors lesioned cholinergic cells in the basal forebrain of mice with bilateral 0.8 μg intracerebroventricular injections of mup75-SAP (Cat. #IT-16). Lesioned animals performed significantly worse than controls in a water maze task. Lesioned animals subsequently treated with CXB-909 displayed improved performance, indicating that CXB-909 can attenuate memory deficits caused by loss of cholinergic input.
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Subplate neurons promote spindle bursts and thalamocortical patterning in the neonatal rat somatosensory cortex.
Tolner EA, Sheikh A, Yukin AY, Kaila K, Kanold PO (2012) Subplate neurons promote spindle bursts and thalamocortical patterning in the neonatal rat somatosensory cortex. J Neurosci 32(2):692-702. doi: 10.1523/JNEUROSCI.1538-11.2012
Summary: Immature cortices in both human and rat have spontaneous activity associated with the maturation of cortical synapses and neuronal circuits. In order to investigate what cells are controlling these events the authors administered 400 ng of 192-IgG-SAP (Cat. #IT-01) to the S1 cortex hindlimb/forelimb area of rats. mu p75-SAP (Cat. #IT-16) and mouse-IgG-SAP (Cat. #IT-18) were used as controls. This lesion eliminates subplate neurons which results in a significant loss of evoked spindle burst activity.
Related Products: 192-IgG-SAP (Cat. #IT-01), mu p75-SAP (Cat. #IT-16), Mouse IgG-SAP (Cat. #IT-18)
Rapid beta-amyloid deposition and behavioural impairment after cholinergic denervation in APPswe/PS1dE9
Pacheco-Herrero M, Thyssen D, Ramos-Rodriguez J, Berrocoso E, Bacskai B, Garcia-Alloza M (2011) Rapid beta-amyloid deposition and behavioural impairment after cholinergic denervation in APPswe/PS1dE9. Neuroscience 2011 Abstracts 47.02. Society for Neuroscience, Washington, DC.
Summary: Alzheimer’s disease (AD) is the most common cause of dementia. Although the ultimate neurotoxic mechanisms are not known, extensive evidence supports the role of amyloid-beta (Aβ) deposition as senile plaques (SP) in the disease. On the other hand, neuronal loss is the pathological feature that best correlates with the duration and severity of the illness and specifically, cholinergic denervation of the basal forebrain seems to be a good predictor of clinical dementia in AD. A close relationship has been documented between Aβ deposition and neurodegeneration, however, whether specific neurodegeneration may lead to senile plaque deposition remains unclear. We addressed this by inducing selective cholinergic lesions in APPswe/PS1dE9 mice with murine p-75 saporin, an inmunotoxin that selectively removes cholinergic innervation. We performed intracerebroventricular murine p-75 lesions in animals with an incipient (~3 months) and robust (~7 months of age) Aβ deposition and removed ~50% of basal forebrain cholinergic innervation to cortex and hippocampus. Immediately after injections, cranial windows were implanted and Aβ deposition was monitored in vivo and in real time in the cortex using methoxy-XO4 and multiphoton microscopy. We observed increased SP deposition as soon as 1 week after the lesion. We further corroborated our in vivo data post-mortem, using anti- Aβ and anti-fibrils antibodies as well as thioflavin S staining, both in the cortex and the hippocampus. 7 days after the surgery, when the lesion is established, animals were tested in the new object discrimination and Morris water maze tests. We observed an early memory impairment in young lesioned mice (~3 months) and this effect worsened with age (~7 months of age), when Aβ deposition is more robust. Altogether, our data suggest that cholinergic denervation may contribute to the deposition of Aβ and synergistically contribute to the cognitive impairment observed in AD.
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Acetylcholine and attention.
Klinkenberg I, Sambeth A, Blokland A (2011) Acetylcholine and attention. Behav Brain Res 221(2):430-442. doi: 10.1016/j.bbr.2010.11.033
Summary: This review article summarizes studies investigating the role of acetylcholine in attention and cognition. The roles of 192-IgG-SAP (Cat. #IT-01) and mu p75-SAP (Cat. #IT-16) in these experiments is discussed. Acetylcholine is thought to play a top-down role in the prefrontal, parietal, and somatosensory regions; playing an important role in the control of attentional orienting and stimulus discrimination.
Related Products: 192-IgG-SAP (Cat. #IT-01), mu p75-SAP (Cat. #IT-16)