Low dose zinc supplementation beneficially affects seizure development in experimental seizure models in rats

Increased Total Antioxidant Capacity Value Improves Survival of Fat Grafts in Rat Model

BACKGROUND

Although studies aiming to increase fat graft survival continue, in this study, the authors aimed to investigate the effects of different antioxidants on total antioxidant capacity (TAC) and their effect on graft survival.

METHODS

Thirty-two male Wistar rats were divided into four equally sized groups, including a control group and three antioxidant groups receiving either melatonin (10 mg/kg), zinc (2 mg/kg), or vitamins E and C (100 mg/kg). Autologous fat grafts (1.7 ± 0.4 g) were transferred to the dorsal subcutaneous region, and total antioxidant capacity was measured on days 0 and 1, week 1, and monthly until the third month. Transferred graft volume and mass (1.3 ± 0.4 g) were measured using the liquid overflow method and precision scales at the end of the study. Routine hematoxylin and eosin staining and immunohistochemistry against perilipin were performed for semiqualitative analysis and H-score for viable adipose cells, respectively.

RESULTS

Collected fat grafts measured significantly less in weight and volume and the survival rate was lower in the control group ( P < 0.01). The control group exhibited a reduction in TAC, whereas all groups receiving antioxidants had an increase in TAC during the first week ( P = 0.02, P = 0.008, and P = 0.004 for melatonin, zinc, and vitamins, respectively). Immunohistochemistry of the antioxidant group demonstrated a statistically significant excess and reactivity of cells staining with perilipin antibodies.

CONCLUSION

In this animal study, the beneficial effect of antioxidants on fat graft survival can be related to the significant increase in TAC following the first week of their administration.

CLINICAL RELEVANCE STATEMENT

Antioxidants improve fat graft survival and quality in this rat model, by increasing total antioxidant capacity in the first week of administration.

From zinc homeostasis to disease progression: Unveiling the neurodegenerative puzzle

Zinc is a crucial trace element in the human body, playing a role in various physiological processes such as oxidative stress, neurotransmission, protein synthesis, and DNA repair. The zinc transporters (ZnTs) family members are responsible for exporting intracellular zinc, while Zrt- and Irt-like proteins (ZIPs) are involved in importing extracellular zinc. These processes are essential for maintaining cellular zinc homeostasis. Imbalances in zinc metabolism have been linked to the development of neurodegenerative diseases. Disruptions in zinc levels can impact the survival and activity of neurons, thereby contributing to the progression of neurodegenerative diseases through mechanisms like cell apoptosis regulation, protein phase separation, ferroptosis, oxidative stress, and neuroinflammation. Therefore, conducting a systematic review of the regulatory network of zinc and investigating the relationship between zinc dysmetabolism and neurodegenerative diseases can enhance our understanding of the pathogenesis of these diseases. Additionally, it may offer new insights and approaches for the treatment of neurodegenerative diseases.

Deciphering the role of metal and non-metals in the treatment of epilepsy

Metals and non-metals have known to play a significant role in various physiological roles in the body including the central nervous system (CNS). The alterations in their concentration in the CNS leads to abnormalities in the normal functions which may lead to various neurological conditions including epilepsy. Manganese is a cofactor required for antioxidant enzymes such as Superoxide dismutase, Glutamine synthetase, etc. The accumulation of iron leads to formation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) which have the potential to cause ferroptosis, one of the reasons for epileptogenesis. Zinc has biphasic response, both neurotoxic and neuroprotective, based on concentration levels in the CNS. Selenium is a main element for selenoproteins which is responsible for the regulation of oxidative state and antioxidant defence mechanism. The reduction in the phosphorous levels in the CNS is widely observed after generalised tonic clonic seizures (GTC), which can be a potential diagnostic biomarker. Copper acts in the CNS in an identical manner, i.e., by blocking both AMPA mediated and GABA mediated neuronal transmission. Magnesium blocks calcium channels in the NMDA receptor and prevents glutamatergic transmission, thus inhibiting excitotoxicity. Lithium acts as a proconvulsive agent and is used in combination with pilocarpine to induce seizures. The identified potential of metals and non-metals in epilepsy can be utilised in order to devise new adjuvant therapies for the management of epilepsy. The article summaries in depth the role of metals and non-metals in the treatment of epilepsy supported with special paragraph on author perspective on to the topic. Furthermore, an update of preclinical and clinical evidences are discussed in the review to give evidence on metal and non-metal based therapies in epilepsy.

Dietary Zinc Differentially Regulates the Effects of the GPR39 Receptor Agonist, TC-G 1008, in the Maximal Electroshock Seizure Test and Pentylenetetrazole-Kindling Model of Epilepsy

The G-protein coupled receptor 39 (GPR39) is gaining increasing attention as a target for future drugs, yet there are gaps in the understanding of its pharmacology. Zinc is an endogenous agonist or an allosteric modulator, while TC-G 1008 is a synthetic, small molecule agonist. Zinc is also a positive allosteric modulator for the activity of TC-G 1008 at GPR39. Activation of GPR39 by TC-G 1008 facilitated the development of epileptogenesis in the pentylenetetrazole (PTZ)-induced kindling model of epilepsy. Congruently, TC-G 1008 decreased the seizure threshold in the maximal electroshock seizure threshold (MEST) test. Here, we investigated the effects of TC-G 1008 under the condition of zinc deficiency. Mice were fed a zinc-adequate diet (ZnA, 50 mg Zn/kg) or a zinc-deficient diet (ZnD, 3 mg Zn/kg) for 4 weeks. Following 4 weeks of dietary zinc restriction, TC-G 1008 was administered as a single dose and the MEST test was performed. Additional groups of mice began the PTZ-kindling model during which TC-G 1008 was administered repeatedly and the diet was continued. TC-G 1008 administered acutely decreased the seizure threshold in the MEST test in mice fed the ZnD diet but not in mice fed the ZnA diet. TC-G 1008 administered chronically increased the maximal seizure severity and the percentage of fully kindled mice in those fed the ZnA diet, but not in mice fed the ZnD diet. Our data showed that the amount of zinc in a diet is a factor contributing to the effects of TC-G 1008 in vivo.

Insights into Potential Targets for Therapeutic Intervention in Epilepsy

Epilepsy is a chronic brain disease that affects approximately 65 million people worldwide. However, despite the continuous development of antiepileptic drugs, over 30% patients with epilepsy progress to drug-resistant epilepsy. For this reason, it is a high priority objective in preclinical research to find novel therapeutic targets and to develop effective drugs that prevent or reverse the molecular mechanisms underlying epilepsy progression. Among these potential therapeutic targets, we highlight currently available information involving signaling pathways (Wnt/β-catenin, Mammalian Target of Rapamycin (mTOR) signaling and zinc signaling), enzymes (carbonic anhydrase), proteins (erythropoietin, copine 6 and complement system), channels (Transient Receptor Potential Vanilloid Type 1 (TRPV1) channel) and receptors (galanin and melatonin receptors). All of them have demonstrated a certain degree of efficacy not only in controlling seizures but also in displaying neuroprotective activity and in modifying the progression of epilepsy. Although some research with these specific targets has been done in relation with epilepsy, they have not been fully explored as potential therapeutic targets that could help address the unsolved issue of drug-resistant epilepsy and develop new antiseizure therapies for the treatment of epilepsy.

Comparison of Serum Trace Nutrient Concentrations in Epileptics Compared to Healthy Dogs

Idiopathic epilepsy (IE) is a common cause of seizures in dogs. There are several investigations regarding serum concentrations of trace nutrients, including copper, selenium, zinc, manganese, and iron in human epileptics and animal models. However, research of this nature in dogs with epilepsy is lacking. The purpose of this prospective study was to compare serum concentrations of several trace nutrients in healthy dogs to dogs with idiopathic epilepsy. Healthy client-owned dogs (n = 50) and dogs with IE (n = 92) were enrolled and blood samples were collected for trace nutrient analysis. Epileptics were subdivided into three groups: controlled: n = 27, uncontrolled: n = 42, and untreated: n = 23. Serum was evaluated for concentrations of copper, selenium, zinc, cobalt, manganese, molybdenum, and iron using inductively coupled plasma mass spectroscopy. Uncontrolled epileptics had significantly higher manganese concentrations compared to normal dogs (p = 0.007). Untreated epileptics had higher iron levels than the other three groups (p = 0.04). Significantly higher levels of copper (p < 0.0001) were found in controlled and uncontrolled epileptics compared to normal or untreated dogs. Significantly higher levels of molybdenum (p = 0.01) were found in controlled epileptics compared to normal or untreated epileptics. Uncontrolled and controlled epileptics had significantly higher levels of selenium (p = 0.0003) vs. normal dogs, and uncontrolled epileptics had higher levels of zinc (p = 0.0002) than normal and untreated dogs. The significant difference in serum concentrations of several trace nutrients (manganese, selenium, and zinc) may suggest a role for these nutrients in the pathophysiology and/or treatment of epilepsy. Additionally, these results suggest that anti-convulsant therapy may affect copper and molybdenum metabolism.

Long-Term Effects of Zinc Deficiency and Zinc Supplementation on Developmental Seizure-Induced Brain Damage and the Underlying GPR39/ZnT-3 and MBP Expression in the Hippocampus

We previously illustrated that long-term upregulated expression of ZnT-3 in the hippocampus of rats that underwent neonatal seizures was restored by pretreatment with a ketogenic diet. It was recently demonstrated that upregulated expression of ZnT-3 was associated with increased concentrations of intracellular free zinc ions in an in vitro model of glutamate-induced hippocampal neuronal excitotoxic damage. However, there is still a lack of research on the effects of different concentrations of zinc in the diet on developmental convulsive brain injury. The aim of this study was to investigate the effects of different zinc concentrations in the diet on long-term neurobehavioral and seizure thresholds following lithium chloride-pilocarpine-induced developmental seizures. Sprague-Dawley rats (postnatal day 27, P27) were randomly assigned to one of six dietary groups for 4 weeks: normal zinc control group (Control group, 44 mg/kg Zn), Zn-deficient control group (ZD group, 2.7 mg/kg Zn), Zn supplemented control group (ZS group, 246 mg/kg Zn), pilocarpine-induced seizure plus regular zinc diet group (SE group, 44 mg/kg Zn), seizure plus low-zinc diet group (SE + ZD group, 2.7 mg/kg Zn), and seizure plus high-zinc diet group (SE + ZS group, 246 mg/kg Zn). Novel object recognition and passive avoidance tests were performed on rats at P42 and P56. After routine seizure threshold detection and Timm staining procedures at P57, expression of GPR39, ZnT-3, and MBP were detected in the hippocampus by Western blot analysis. The results revealed that the Zinc-deficient diet for 4 weeks aggravated the long-term adverse effects of developmental seizures, evidenced by weight, cognition, seizure threshold and serum zinc concentrations, which were paralleled by expression changes in hippocampal GPR39 and ZnT-3. In contrast, zinc supplementation for 4 weeks significantly improved damage-related changes described above and rescued the abnormal expression of GPR39, ZnT-3, and MBP in the hippocampus. Similar alterations between the expression pattern of MBP and aberrant sprouting of mossy fibers in the hippocampus may indicate that sprouting is a secondary pathological change caused by developmental brain damage rather than the cause of epileptogenesis. Up-regulation of MBP protein levels in the high zinc diet-treated seizure group as well as the corresponding improvement of cognitive impairment and reduced hippocampal mossy fiber regenerative sprouting, may represent a compensatory mechanism for neuronal membrane damage and repair.

Effects of enalapril and losartan alone and in combination with sodium valproate on seizures, memory, and cardiac changes in rats

PURPOSE

Cardiac changes accompanying seizures may be responsible for sudden unexpected death in epilepsy (SUDEP), and drugs with antiseizure and favorable cardiovascular profile could be beneficial. The effect of losartan and enalapril alone and in combination with sodium valproate on seizures, cognition, cardiac histopathology, and serum brain-derived neurotropic factor (BDNF) levels were determined.

METHODS

Male "Wistar" rats (200-250 g) were administered enalapril (20 mg/kg, intraperitoneally (i.p.)) and losartan (10 mg/kg, i.p.) daily and simultaneously subjected to pentylenetetrazole (PTZ)-kindling (PTZ 30 mg/kg, i.p., every alternate day). Enalapril and losartan were injected 45 & 120 min before seizure stimuli. In another set of experiments, sodium valproate (150 mg/kg, i.p.) alone or in combination with enalapril (20 mg/kg, i.p.) and losartan (10 mg/kg, i.p.) were administered daily during induction of kindling. The effect on seizures and behavior were noted; rats were sacrificed, and blood and hearts were collected for further analysis, i.e., BDNF levels, heart weight-body weight (HWBW) ratio, and cardiac histopathology.

RESULTS

Losartan, but not enalapril, suppressed the seizure score in PTZ kindling. Sodium valproate alone or in combination with losartan or enalapril prevented kindled seizures. Sodium valproate per se caused cognitive impairment, which was prevented on combining with losartan or enalapril. A decrease in HWBW ratio was observed only in enalapril group (p value = 0.02). Kindling led to cardiac ischemic changes, which could be prevented by losartan and sodium valproate. Serum BDNF level was decreased in PTZ (p value = 0.02) and sodium valproate per se group (p value = 0.04), but sodium valproate could reverse the PTZ-induced decrease in serum BDNF level.

CONCLUSION

The use of losartan with sodium valproate in epilepsy may prevent the cognitive and cardiac sequelae of seizures. The BDNF levels as a marker for cardiovascular risk in persons with epilepsy (PWE) needs to be explored further.

Cracking novel shared targets between epilepsy and Alzheimer's disease: need of the hour

Epilepsy and Alzheimer's disease (AD) are interconnected. It is well known that seizures are linked with cognitive impairment, and there are various shared etiologies between epilepsy and AD. The connection between hyperexcitability of neurons and cognitive dysfunction in the progression of AD or epileptogenesis plays a vital role for improving selection of treatment for both diseases. Traditionally, seizures occur less frequently and in later stages of age in patients with AD which in turn implies that neurodegeneration causes seizures. The role of seizures in early stages of pathogenesis of AD is still an issue to be resolved. So, it is well timed to analyze the common pathways involved in pathophysiology of AD and epilepsy. The present review focuses on similar potential underlying mechanisms which may be related to the causes of seizures in epilepsy and cognitive impairment in AD. The proposed review will focus on many possible newer targets like abnormal expression of various enzymes like GSK-3β, PP2A, PKC, tau hyperphosphorylation, MMPs, caspases, neuroinflammation and oxidative stress associated with number of neurodegenerative diseases linked with epilepsy. The brief about the prospective line of treatment of both diseases will also be discussed in the present review.

Zinc signaling and epilepsy

Evidence from both preclinical and clinical studies suggest the importance of zinc homeostasis in seizures/epilepsy. Undoubtedly, zinc, via modulation of a variety of targets, is necessary for maintaining the balance between neuronal excitation and inhibition, while an imbalance between excitation and inhibition underlies seizures. However, the relationship between zinc signaling and seizures/epilepsy is complex as both extracellular and intracellular zinc may produce either protective or detrimental effects. This review provides an overview of preclinical/behavioral, functional and molecular studies, as well as clinical data on the involvement of zinc in the pathophysiology and treatment of seizures/epilepsy. Furthermore, the potential of targeting elements associated with zinc signaling or homeostasis and zinc levels as a therapeutic strategy for epilepsy is discussed.

Investigating owner use of dietary supplements in dogs with idiopathic epilepsy

Epilepsy is the most common chronic neurological disorder in dogs. Some diets have been shown to have a positive impact upon the seizure activity in dogs with idiopathic epilepsy (IE), while other diets and dietary supplements (DS), although marketed as providing health benefits, lack conclusive scientific evidence on their actual beneficial effects. A web-based owner questionnaire was designed to assess how and why owners of dogs with IE use different dietary regimes and DS. The study cohort, with 297 valid responses, consisted mainly of pure-breed (82.5%) male neutered (52.9%) dogs. Over two-thirds of owners (67.7%) changed their dog's diet after their dog received a diagnosis of IE. Nearly half of the owners (45.8%) reported giving DS, the most common being coconut oil or derived medium-chain triglyceride oil (71.3%). Some owner justifications of DS use included improvement of seizure frequency (88.2%), seizure severity (61.8%) and protection from potential drug side effects (62.5%). Many owners give DS to their dog with IE. The pharmacokinetic properties of anti-epileptic drugs, such as efficacy, absorption and clearance can be influenced by other medications, diets and possibly by DS. We propose that use of DS should be considered and monitored by veterinary surgeons in epilepsy management.

In vitro effects of Zinc in soluble and homeopathic formulations on macrophages and astrocytes

Zinc is an important metal in body homeostasis. Zinc in soluble form (Zn2+) and homeopathic Zincum metallicum were tested in macrophages and astrocytes in order to investigate its potential toxic or therapeutic effects. We evaluated cell viability (WST assay), cytokine production such as tumour necrosis factor alpha (TNF-α) and interleukin 10 (IL-10) by enzyme-linked immunosorbent assay (ELISA) and nitric oxide release by Griess reaction. The effect of zinc-depletion and high zinc pre-treatments on the cell adaptation capability was also investigated. In THP-1 macrophage cell line and in human primary macrophages, Zn2+ at sub-toxic doses (30 μM) caused stimulation of TNF-α and IL-10 with different dynamics reaching the maximum peak at the zinc concentration 100 μM, before the cell death. Highest doses (300 μM) impaired dramatically cell vitality. Similar effects on cell viability were obtained also in C6 astrocytes, where Zn2+ slightly increased the nitric oxide release only in cells activated by one of the pro-inflammatory stimuli used in our cellular model (interferon gamma plus TNF-α). Zinc depletion markedly reduced IL-10 production and cell viability. Zincum metallicum did not cause toxicity in any cell type and showed some small stimulation in WST assay that was statistically significant in a few experimental conditions.