New Perspectives for Developing Therapeutic Bioconjugates of Metabolite-Depleting Enzymes: Lessons Learned Combating Glutamate Excitotoxicity

Cramp-Fasciculation Syndrome Associated with Natural and Added Chemicals in Popular Food Items

Cramp-fasciculation syndrome (CFS) is a rare and benign neuromuscular disorder that may initially masquerade as motor neuron disease/amyotrophic lateral sclerosis. While CFS may have a familial disposition, we report on cases associated with high consumption of popular food items. One set of patients reversibly experienced acute onset of headache, flushing, muscle stiffness and fasciculations following the consumption of umami-flavored food containing a large concentration of monosodium glutamate. A second group of patients consuming food derived from lupin seed developed acute cholinergic toxicity, CFS, and, with chronic intake, significant, self-limiting, but incompletely reversible upper and lower motor neuron deficits. While these cases may improve our knowledge about the possible causes of CFS, our series also demonstrates that excessive consumption of some popular foods is not harmless. This warrants further research on their safety at all stages of human development from a neurological point of view.

Multisite and multitimepoint proteomics reveal that patent foramen ovale closure improves migraine and epilepsy by reducing right-to-left shunt-induced hypoxia

Patent foramen ovale (PFO) is a congenital defect in the partition between two atria, which may cause right-to-left shunt (RLS), leading to neurological chronic diseases with episodic manifestations (NCDEMs), such as migraine and epilepsy. However, whether PFO closure was effective in improving NCDEMs and the mechanism were unclear. Twenty-eight patients with migraine or epilepsy who underwent PFO closure were recruited. Notably, approximately half of patients received 50% or more reduction in seizure or headache attacks. Meanwhile, the postoperative blood oxygen partial pressure and oxygen saturation were elevated after PFO closure. Multisite (peripheral, right, and left atrial) and multitimepoint (before and after surgery) plasma proteomics from patients showed that the levels of free hemoglobin and cell adhesion molecules (CAMs) were significantly increased after PFO closure, which may be related to the relief of the hypoxic state. Furtherly, the omics data from multiple brain regions of mice revealed that a large number of proteins were differentially expressed in the occipital region in response to PFO, including redox molecules and CAMs, suggesting PFO-caused hypoxia may have great impacts on occipital region. Collectively, PFO may cause NCDEMs due to RLS-induced hypoxia, and PFO closure could prevent RLS to improve migraine and epilepsy.

The molecular pathophysiology of depression and the new therapeutics

Major depressive disorder (MDD) is a highly prevalent and disabling disorder. Despite the many hypotheses proposed to understand the molecular pathophysiology of depression, it is still unclear. Current treatments for depression are inadequate for many individuals, because of limited effectiveness, delayed efficacy (usually two weeks), and side effects. Consequently, novel drugs with increased speed of action and effectiveness are required. Ketamine has shown to have rapid, reliable, and long-lasting antidepressant effects in treatment-resistant MDD patients and represent a breakthrough therapy for patients with MDD; however, concerns regarding its efficacy, potential misuse, and side effects remain. In this review, we aimed to summarize molecular mechanisms and pharmacological treatments for depression. We focused on the fast antidepressant treatment and clarified the safety, tolerability, and efficacy of ketamine and its metabolites for the MDD treatment, along with a review of the potential pharmacological mechanisms, research challenges, and future clinical prospects.

Excitatory Synaptic Transmission in Ischemic Stroke: A New Outlet for Classical Neuroprotective Strategies

Stroke is one of the leading causes of death and disability in the world, of which ischemia accounts for the majority. There is growing evidence of changes in synaptic connections and neural network functions in the brain of stroke patients. Currently, the studies on these neurobiological alterations mainly focus on the principle of glutamate excitotoxicity, and the corresponding neuroprotective strategies are limited to blocking the overactivation of ionic glutamate receptors. Nevertheless, it is disappointing that these treatments often fail because of the unspecificity and serious side effects of the tested drugs in clinical trials. Thus, in the prevention and treatment of stroke, finding and developing new targets of neuroprotective intervention is still the focus and goal of research in this field. In this review, we focus on the whole processes of glutamatergic synaptic transmission and highlight the pathological changes underlying each link to help develop potential therapeutic strategies for ischemic brain damage. These strategies include: (1) controlling the synaptic or extra-synaptic release of glutamate, (2) selectively blocking the action of the glutamate receptor NMDAR subunit, (3) increasing glutamate metabolism, and reuptake in the brain and blood, and (4) regulating the glutamate system by GABA receptors and the microbiota–gut–brain axis. Based on these latest findings, it is expected to promote a substantial understanding of the complex glutamate signal transduction mechanism, thereby providing excellent neuroprotection research direction for human ischemic stroke (IS).