Radical triads, not pairs, may explain effects of hypomagnetic fields on neurogenesis
Abstract
Radical triads, not pairs, may explain effects of hypomagnetic fields on neurogenesis Ramsay J, Kattnig DR. Radical triads, not pairs, may explain effects of hypomagnetic fields on neurogenesis. PLoS Comput Biol. 2022 Sep 15;18(9):e1010519. doi: 10.1371/journal.pcbi.1010519. Abstract Adult hippocampal neurogenesis and hippocampus-dependent cognition in mice have been found to be adversely affected by hypomagnetic field exposure. The effect concurred with a reduction of reactive oxygen species in the absence of the geomagnetic field. A recent theoretical study suggests a mechanistic interpretation of this phenomenon in the framework of the Radical Pair Mechanism. According to this model, a flavin- superoxide radical pair, born in the singlet spin configuration, undergoes magnetic field-dependent spin dynamics such that the pair's recombination is enhanced as the applied magnetic field is reduced. This model has two ostensible weaknesses: a) the assumption of a singlet initial state is irreconcilable with known reaction pathways generating such radical pairs, and b) the model neglects the swift spin relaxation of free superoxide, which abolishes any magnetic sensitivity in geomagnetic/hypomagnetic fields. We here suggest that a model based on a radical triad and the assumption of a secondary radical scavenging reaction can, in principle, explain the phenomenon without unnatural assumptions, thus providing a coherent explanation of hypomagnetic field effects in biology. Author Summary The hippocampal region of the brain plays a major role in learning and memory functionality. In male mice, shielding of the Earth’s magnetic field was found to decrease hippocampal neurogenesis, i.e. the formation of new neurons, following from a decrease in levels of reactive oxygen species. In this study, we suggest an explanation in terms of spin dynamics of a three radical system composed of flavin-semiquinone, superoxide and ascorbyl radical. This model agrees with the experimental data whilst retaining realistic parameters for a biological system, unlike the Radical Pair Mechanism. Open access paper: journals.plos.org
AI evidence extraction
Main findings
The paper proposes a theoretical radical-triad model (involving flavin-semiquinone, superoxide, and ascorbyl radical) to explain reported adverse effects of hypomagnetic field exposure on mouse hippocampal neurogenesis and associated reductions in reactive oxygen species. The authors argue this triad-based mechanism can account for the phenomenon without assumptions they consider unrealistic in prior radical-pair models (e.g., singlet initial state and neglect of rapid superoxide spin relaxation).
Outcomes measured
- Adult hippocampal neurogenesis
- Hippocampus-dependent cognition
- Reactive oxygen species (ROS) levels
- Proposed spin-dynamics mechanism (radical triad vs radical pair)
Limitations
- The abstract describes a theoretical/mechanistic model rather than new experimental outcome data.
- Details of exposure conditions, experimental protocols, and quantitative fit to data are not provided in the abstract.
- Findings about neurogenesis and cognition are referenced from prior mouse studies rather than reported as new results here.
View raw extracted JSON
{
"publication_year": 2022,
"study_type": "other",
"exposure": {
"band": "static",
"source": "hypomagnetic field (shielding of Earth's geomagnetic field)",
"frequency_mhz": null,
"sar_wkg": null,
"duration": null
},
"population": "male mice (referenced experimental findings)",
"sample_size": null,
"outcomes": [
"Adult hippocampal neurogenesis",
"Hippocampus-dependent cognition",
"Reactive oxygen species (ROS) levels",
"Proposed spin-dynamics mechanism (radical triad vs radical pair)"
],
"main_findings": "The paper proposes a theoretical radical-triad model (involving flavin-semiquinone, superoxide, and ascorbyl radical) to explain reported adverse effects of hypomagnetic field exposure on mouse hippocampal neurogenesis and associated reductions in reactive oxygen species. The authors argue this triad-based mechanism can account for the phenomenon without assumptions they consider unrealistic in prior radical-pair models (e.g., singlet initial state and neglect of rapid superoxide spin relaxation).",
"effect_direction": "unclear",
"limitations": [
"The abstract describes a theoretical/mechanistic model rather than new experimental outcome data.",
"Details of exposure conditions, experimental protocols, and quantitative fit to data are not provided in the abstract.",
"Findings about neurogenesis and cognition are referenced from prior mouse studies rather than reported as new results here."
],
"evidence_strength": "low",
"confidence": 0.7399999999999999911182158029987476766109466552734375,
"peer_reviewed_likely": "yes",
"stance": "neutral",
"stance_confidence": 0.66000000000000003108624468950438313186168670654296875,
"summary": "This paper presents a theoretical mechanism to explain previously reported hypomagnetic-field effects on adult hippocampal neurogenesis in mice and associated reductions in reactive oxygen species. The authors critique a prior radical-pair interpretation and propose that a radical triad with a secondary radical scavenging reaction could reproduce the phenomenon using more realistic assumptions. The work is mechanistic and does not report new animal or human exposure outcomes in the abstract.",
"key_points": [
"Prior mouse studies are described as finding reduced hippocampal neurogenesis and cognition under hypomagnetic field exposure.",
"Those reported effects coincided with reduced reactive oxygen species in the absence of the geomagnetic field.",
"The authors identify two weaknesses in a prior radical-pair model: an implausible singlet initial state and loss of magnetic sensitivity due to rapid superoxide spin relaxation.",
"A radical-triad model is proposed involving flavin-semiquinone, superoxide, and ascorbyl radical.",
"The proposed triad mechanism is suggested to explain hypomagnetic-field biological effects without the criticized assumptions.",
"The paper is primarily a theoretical/mechanistic contribution rather than a new exposure experiment."
],
"categories": [
"Mechanisms",
"Animal studies",
"Static magnetic fields"
],
"tags": [
"Hypomagnetic Fields",
"Geomagnetic Field Shielding",
"Adult Hippocampal Neurogenesis",
"Reactive Oxygen Species",
"Radical Pair Mechanism",
"Radical Triad",
"Spin Dynamics",
"Flavin Semiquinone",
"Superoxide",
"Ascorbyl Radical",
"Mouse Hippocampus",
"Theoretical Model"
],
"keywords": [
"hypomagnetic field",
"geomagnetic field",
"neurogenesis",
"hippocampus",
"reactive oxygen species",
"radical pair mechanism",
"radical triad",
"spin dynamics",
"flavin-semiquinone",
"superoxide",
"ascorbyl radical"
],
"suggested_hubs": [],
"social": {
"tweet": "New theoretical work in PLOS Comp Biol proposes a radical-triad (not radical-pair) spin-dynamics mechanism that could explain reported hypomagnetic-field effects on mouse hippocampal neurogenesis and ROS levels. doi:10.1371/journal.pcbi.1010519",
"facebook": "A PLOS Computational Biology paper proposes a radical-triad spin-dynamics model that may explain previously reported reductions in mouse hippocampal neurogenesis and reactive oxygen species under hypomagnetic-field (geomagnetic shielding) conditions. doi:10.1371/journal.pcbi.1010519",
"linkedin": "PLOS Computational Biology (2022) presents a mechanistic model suggesting radical triads could account for reported hypomagnetic-field effects on mouse hippocampal neurogenesis and ROS, addressing limitations of earlier radical-pair interpretations. doi:10.1371/journal.pcbi.1010519"
}
}
AI can be wrong. Always verify against the paper.
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