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Nieraad H, de Bruin N, Arne O, Hofmann MCJ, Pannwitz N, Resch E, Luckhardt S, Schneider AK, Trautmann S, Schreiber Y, Gurke R, Parnham MJ, Till U, Geisslinger G. The Roles of Long-Term Hyperhomocysteinemia and Micronutrient Supplementation in the AppNL–G–F Model of Alzheimer’s Disease. Front Aging Neurosci 2022; 14:876826. [PMID: 35572151 PMCID: PMC9094364 DOI: 10.3389/fnagi.2022.876826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 04/01/2022] [Indexed: 11/16/2022] Open
Abstract
A causal contribution of hyperhomocysteinemia to cognitive decline and Alzheimer’s disease (AD), as well as potential prevention or mitigation of the pathology by dietary intervention, have frequently been subjects of controversy. In the present in vivo study, we attempted to further elucidate the impact of elevated homocysteine (HCys) and homocysteic acid (HCA) levels, induced by dietary B-vitamin deficiency, and micronutrient supplementation on AD-like pathology, which was simulated using the amyloid-based AppNL–G–F knock-in mouse model. For this purpose, cognitive assessment was complemented by analyses of ex vivo parameters in whole blood, serum, CSF, and brain tissues from the mice. Furthermore, neurotoxicity of HCys and HCA was assessed in a separate in vitro assay. In confirmation of our previous study, older AppNL–G–F mice also exhibited subtle phenotypic impairment and extensive cerebral amyloidosis, whereas dietary manipulations did not result in significant effects. As revealed by proximity extension assay-based proteome analysis, the AppNL–G–F genotype led to an upregulation of AD-characteristic neuronal markers. Hyperhomocysteinemia, in contrast, indicated mainly vascular effects. Overall, since there was an absence of a distinct phenotype despite both a significant amyloid-β burden and serum HCys elevation, the results in this study did not corroborate the pathological role of amyloid-β according to the “amyloid hypothesis,” nor of hyperhomocysteinemia on cognitive performance. Nevertheless, this study aided in further characterizing the AppNL–G–F model and in elucidating the role of HCys in diverse biological processes. The idea of AD prevention with the investigated micronutrients, however, was not supported, at least in this mouse model of the disease.
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Affiliation(s)
- Hendrik Nieraad
- Fraunhofer Institute for Translational Medicine and Pharmacology, Frankfurt am Main, Germany
| | - Natasja de Bruin
- Fraunhofer Institute for Translational Medicine and Pharmacology, Frankfurt am Main, Germany
- *Correspondence: Natasja de Bruin,
| | - Olga Arne
- Fraunhofer Institute for Translational Medicine and Pharmacology, Frankfurt am Main, Germany
| | - Martine C. J. Hofmann
- Fraunhofer Institute for Translational Medicine and Pharmacology, Frankfurt am Main, Germany
| | - Nina Pannwitz
- Fraunhofer Institute for Translational Medicine and Pharmacology, Frankfurt am Main, Germany
| | - Eduard Resch
- Fraunhofer Institute for Translational Medicine and Pharmacology, Frankfurt am Main, Germany
| | - Sonja Luckhardt
- Fraunhofer Institute for Translational Medicine and Pharmacology, Frankfurt am Main, Germany
| | - Ann-Kathrin Schneider
- Fraunhofer Institute for Translational Medicine and Pharmacology, Frankfurt am Main, Germany
| | - Sandra Trautmann
- Pharmazentrum Frankfurt/ZAFES, Institute of Clinical Pharmacology, Goethe University, Frankfurt am Main, Germany
| | - Yannick Schreiber
- Fraunhofer Institute for Translational Medicine and Pharmacology, Frankfurt am Main, Germany
| | - Robert Gurke
- Fraunhofer Institute for Translational Medicine and Pharmacology, Frankfurt am Main, Germany
- Pharmazentrum Frankfurt/ZAFES, Institute of Clinical Pharmacology, Goethe University, Frankfurt am Main, Germany
| | - Michael J. Parnham
- Fraunhofer Institute for Translational Medicine and Pharmacology, Frankfurt am Main, Germany
- EpiEndo Pharmaceuticals, Reykjavík, Iceland
| | - Uwe Till
- Former Institute of Pathobiochemistry, Friedrich-Schiller-Universität Jena, Jena, Germany
| | - Gerd Geisslinger
- Fraunhofer Institute for Translational Medicine and Pharmacology, Frankfurt am Main, Germany
- Pharmazentrum Frankfurt/ZAFES, Institute of Clinical Pharmacology, Goethe University, Frankfurt am Main, Germany
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Tanase S, Mamiya T, Nagata S, Ikawa Y, Tang YP, Hiramatsu M, Nabeshima T. Effects of galantamine on social interaction impairments in cholecystokinin receptor-2 overexpression mice. J Pharmacol Sci 2022; 148:364-368. [DOI: 10.1016/j.jphs.2022.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 02/09/2022] [Accepted: 02/15/2022] [Indexed: 11/29/2022] Open
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Klemz A, Wildner F, Tütüncü E, Gerevich Z. Regulation of Hippocampal Gamma Oscillations by Modulation of Intrinsic Neuronal Excitability. Front Neural Circuits 2022; 15:778022. [PMID: 35177966 PMCID: PMC8845518 DOI: 10.3389/fncir.2021.778022] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 12/21/2021] [Indexed: 11/16/2022] Open
Abstract
Ion channels activated around the subthreshold membrane potential determine the likelihood of neuronal firing in response to synaptic inputs, a process described as intrinsic neuronal excitability. Long-term plasticity of chemical synaptic transmission is traditionally considered the main cellular mechanism of information storage in the brain; however, voltage- and calcium-activated channels modulating the inputs or outputs of neurons are also subjects of plastic changes and play a major role in learning and memory formation. Gamma oscillations are associated with numerous higher cognitive functions such as learning and memory, but our knowledge of their dependence on intrinsic plasticity is by far limited. Here we investigated the roles of potassium and calcium channels activated at near subthreshold membrane potentials in cholinergically induced persistent gamma oscillations measured in the CA3 area of rat hippocampal slices. Among potassium channels, which are responsible for the afterhyperpolarization in CA3 pyramidal cells, we found that blockers of SK (KCa2) and KV7.2/7.3 (KCNQ2/3), but not the BK (KCa1.1) and IK (KCa3.1) channels, increased the power of gamma oscillations. On the contrary, activators of these channels had an attenuating effect without affecting the frequency. Pharmacological blockade of the low voltage-activated T-type calcium channels (CaV3.1–3.3) reduced gamma power and increased the oscillation peak frequency. Enhancement of these channels also inhibited the peak power without altering the frequency of the oscillations. The presented data suggest that voltage- and calcium-activated ion channels involved in intrinsic excitability strongly regulate the power of hippocampal gamma oscillations. Targeting these channels could represent a valuable pharmacological strategy against cognitive impairment.
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Rajkumar RP. Physician-Assisted Suicide in Dementia: Paradoxes, Pitfalls and the Need for Prudence. FRONTIERS IN SOCIOLOGY 2021; 6:815233. [PMID: 35004941 PMCID: PMC8727695 DOI: 10.3389/fsoc.2021.815233] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 12/07/2021] [Indexed: 06/14/2023]
Abstract
There has been an increasing drive towards the legalization of physician-assisted suicide (PAS) in patients with dementia, particularly in patients with advanced disease and severe cognitive impairment. Advocacy for this position is often based on utilitarian philosophical principles, on appeals to the quality of life of the patient and their caregiver(s), or on economic constraints faced by caregivers as well as healthcare systems. In this paper, two lines of evidence against this position are presented. First, data on attitudes towards euthanasia for twenty-eight countries, obtained from the World Values Survey, is analyzed. An examination of this data shows that, paradoxically, positive attitudes towards this procedure are found in more economically advanced countries, and are strongly associated with specific cultural factors. Second, the literature on existing attitudes towards PAS in cases of dementia, along with ethical arguments for and against the practice, is reviewed and specific hazards for patients, caregivers and healthcare professionals are identified. On the basis of these findings, the author suggests that the practice of PAS in dementia is not one that can be widely or safely endorsed, on both cultural and ethical grounds. Instead, the medical field should work in collaboration with governmental, social welfare and patient advocacy services to ensure optimal physical, emotional and financial support to this group of patients and their caregivers.
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