Aim: This study is to better understand how the transient ion transport activity of touch receptors could change the graded potential to stimulate an action potential firing. Methods: The latest transmembrane-electrostatically localized protons/cations charges (TELC) theory is employed for numerical analysis to calculate the neural touch signal transduction responding time required to fire an action potential spike. Results: A neural action potential spike was constructed successfully using newly developed time-dependent TELC-based neural transmembrane potential integral equations (Equations 5, 6, and 7). The results explicated that the TELC curve has an inverse relationship with neural transmembrane potential since its curve appears as an inverse mirror image to the action potential spike. Based on the TELC density at resting membrane potential of –70 mV calculated to be 3,900 (excess protons + cations) per μm2 and that at the stimulation threshold level (–55 mV) calculated to be 3,100 (excess protons + cations) per μm2 on extracellular membrane surface, the neural touch signal transduction responding time from PIEZO channel ion conduction to reduce the TELC density to the stimulation level of 3,100 TELC per μm2 has now, for the first time, been calculated for action potential firing. Conclusions: The activity of a single or a few PIEZO channels may be sufficient to generate a “graded potential” to trigger an action potential spike firing. With a high number (200–300) of PIEZO channels activated by touch, it can generate the required “graded potential” to reach the stimulation threshold level (–55 mV) within a neural touch signal transduction time as fast as 0.3 ms. The calculated neural touch signal transduction responding time (e.g., 0.3 ms) may have fundamental implications not only for neuroscience but also for other science and technology fields such as bioengineering and sports physiology.

The SAR-CoV-2 virus has evolved to co-exist with human hosts, albeit at a substantial energetic cost resulting in post-infection neurological manifestations [Neuro-post-acute sequelae of SARS-CoV-2 infection (PASC)] that significantly impact public health and economic productivity on a global scale. One of the main molecular mechanisms responsible for the development of Neuro-PASC, in individuals of all ages, is the formation and inadequate proteolysis/clearance of phase-separated amyloid crystalline aggregates—a hallmark feature of aging-related neurodegenerative disorders. Amyloidogenesis during viral infection and persistence is a natural, inevitable, protective defense response that is exacerbated by SARS-CoV-2. Acting as chemical catalyst, SARS-CoV-2 accelerates hydrophobic collapse and the heterogeneous nucleation of amorphous amyloids into stable β-sheet aggregates. The clearance of amyloid aggregates is most effective during slow wave sleep, when high levels of adenosine triphosphate (ATP)—a biphasic modulator of biomolecular condensates—and melatonin are available to solubilize amyloid aggregates for removal. The dysregulation of mitochondrial dynamics by SARS-CoV-2, in particular fusion and fission homeostasis, impairs the proper formation of distinct mitochondrial subpopulations that can remedy challenges created by the diversion of substrates away from oxidative phosphorylation towards glycolysis to support viral replication and maintenance. The subsequent reduction of ATP and inhibition of melatonin synthesis during slow wave sleep results in incomplete brain clearance of amyloid aggregates, leading to the development of neurological manifestations commonly associated with age-related neurodegenerative disorders. Exogenous melatonin not only prevents mitochondrial dysfunction but also elevates ATP production, effectively augmenting the solubilizing effect of the adenosine moiety to ensure the timely, optimal disaggregation and clearance of pathogenic amyloid aggregates in the prevention and attenuation of Neuro-PASC.

Aim: Patients with tuberous sclerosis complex (TSC) which is caused by hyperactivation of mechanistic target of rapamycin complex 1 (mTORC1) often show giant cells in the brain. These giant cells are thought to be involved in epileptogenesis, but the underlying mechanisms are unknown. In this study, we focused on mTORC1 activation and γ-amino butyric acid (GABA)ergic signaling in somatostatin-expressing inhibitory neurons (SST-INs) using TSC-related epilepsy model mice. Methods: We analyzed the 8-week-old Tsc2 conditional knockout (Tsc2 cKO) mice, which have epileptic seizures that are cured by sirolimus, an mTORC1 inhibitor. After the occurrence of epileptic seizures was confirmed, Tsc2 cKO mice were treated with vehicle or sirolimus. Then, their brains were investigated by hematoxylin and eosin staining, immunohistochemical staining and immunoblotting assay. Results: As in TSC patients, giant cells with hyperactivation of mTORC1 were found in the cerebral cortex of Tsc2 cKO mice. These giant cells were mainly SST-INs in the cortical layers 4/5. Giant cells showed decreased expression of GABA type A receptor subunit α1 (GABAAR-α1) compared with normal size cells in control mice and Tsc2 cKO mice. In addition, decreased GABAAR-α1 expression was also confirmed by immunoblotting assay of the whole cerebral cortex. In the cerebral cortex of sirolimus-treated Tsc2 cKO mice, whose epileptic seizures were cured, decreased GABAAR-α1 expression was recovered to the same level as in control mice. Conclusions: These results suggest that the epileptic seizures in Tsc2 cKO mice are caused by the deregulation of GABAergic signaling through mTORC1 activation of SST-INs localized in cortical layers 4/5.