Thymoquinone abrogates methamphetamine-induced striatal neurotoxicity and hyperlocomotor activity in mice

Natural products as the therapeutic strategies for addiction

World Drug Report 2023 concluded that 296 million people abused drugs, 39.5 million became addiction and 494,000 died as a direct or indirect result of addiction. Addiction has become a growing problem that affects individuals, their families, societies, countries and even the world. However, treatment for addiction is only limited to some developed countries because of the high cost, difficult implementation, and time consuming. Therefore, there is an urgent need to develop a low-cost, effective drug for the development of addiction treatment in more countries, which is essential for the stability and sustainable development of the world. In this review, it provided an overview of the abuse of common addictive drugs, related disorders, and current therapeutic regimen worldwide, and summarized the mechanisms of drug addiction as reward circuits, neuroadaptation and plasticity, cognitive decision-making, genetics, and environment. According to their chemical structure, 43 natural products and 5 herbal combinations with potential to treat addiction were classified, and their sources, pharmacological effects and clinical trials were introduced. It was also found that mitragine, ibogine, L-tetrahydropalmatine and crocin had greater potential for anti-addiction.

Evaluating the Protective Effects of Thymoquinone on Methamphetamine-induced Toxicity in an In Vitro Model Based on Differentiated PC12 Cells

Methamphetamine (Meth) is a highly addictive stimulant. Its potential neurotoxic effects are mediated through various mechanisms, including oxidative stress and the initiation of the apoptotic process. Thymoquinone (TQ), obtained from Nigella sativa seed oil, has extensive antioxidant and anti-apoptotic properties. This study aimed to investigate the potential protective effects of TQ against Meth-induced toxicity by using an in vitro model based on nerve growth factor-differentiated PC12 cells. Cell differentiation was assessed by detecting the presence of a neuronal marker with flow cytometry. The effects of Meth exposure were evaluated in the in vitro neuronal cell-based model via the determination of cell viability (in an MTT assay) and apoptosis (by annexin/propidium iodide staining). The generation of reactive oxygen species (ROS), as well as the levels of glutathione (GSH) and dopamine, were also determined. The model was used to determine the protective effects of 0.5, 1 and 2 μM TQ against Meth-induced toxicity (at 1 mM). The results showed that TQ reduced Meth-induced neurotoxicity, possibly through the inhibition of ROS generation and apoptosis, and by helping to maintain GSH and dopamine levels. Thus, the impact of TQ treatment on Meth-induced neurotoxicity could warrant further investigation.

Chronic Treatment with Nigella sativa Oil Exerts Antimanic Properties and Reduces Brain Inflammation in Rats

Nigella sativa (NS) is a native herb consumed habitually in several countries worldwide, possessing manifold therapeutic properties. Among them, anti-inflammatory features have been reported, presumably relating to mechanisms involved in the nuclear factor kappa-B pathway, among others. Given the observed association between neuroimmune factors and mental illness, the primary aim of the present study was to examine the effects of chronic NS use on manic-like behavior in rats, as well as analyze levels of brain inflammatory mediators following NS intake. Using male and female rats, baseline tests were performed; thereafter, rats were fed either regular food (control) or NS-containing food (treatment) for four weeks. Following intervention, behavioral tests were induced (an open field test, sucrose consumption test, three-chamber sociality test, and amphetamine-induced hyperactivity test). Subsequently, brain samples were extracted, and inflammatory mediators were evaluated, including interleukin-6, leukotriene B4, prostaglandin E2, tumor necrosis factor-α, and nuclear phosphorylated-p65. Our findings show NS to result in a marked antimanic-like effect, in tandem with a positive modulation of select inflammatory mediators among male and female rats. The findings reinforce the proposed therapeutic advantages relating to NS ingestion.

Protective effects of alpha-lipoic acid on anxiety-like behavior, memory and prevention of hippocampal oxidative stress in methamphetamine-treated rats

RATIONALE

Alpha-lipoic acid is an essential cofactor for aerobic metabolism and acts as a potent antioxidant in the body. It has been shown that acute exposure to methamphetamine induces oxidative stress, which is responsible for severe cognitive deficits in animals. The hippocampus plays a crucial role in the processing of memory and anxiety-like behavior.

OBJECTIVES

In this study, preventive effect of the alpha-lipoic acid on memory impairment in methamphetamine-induced neurotoxicity was investigated.

METHODS

Wistar male rats (200-220 g) were allocated to five groups (seven rats in each group): (1) saline + saline, (2) saline + vehicle (sunflower oil as alpha-lipoic acid solvent), (3) methamphetamine + vehicle, (4) methamphetamine + alpha-lipoic acid 10 mg/kg, and (5) methamphetamine + alpha-lipoic acid 40 mg/kg. Rats received intraperitoneal methamphetamine repeatedly (2 × 20 mg/kg, 2 h interval). Alpha-lipoic acid was injected 30 min, 24 h, and 48 h after the last injection of methamphetamine. The passive avoidance test and open field were used for evaluation of memory retrieval and anxiety, respectively. After behavioral test, rats were anesthetized, their brains were extracted, and after preparing hippocampal homogenates, malondialdehyde (MDA) level, catalase, and superoxide dismutase (SOD) activities were evaluated.

RESULTS

Statistical analysis showed that injection of saline or sunflower oil had no significant effect on anxiety, memory, or oxidative stress markers. Methamphetamine induced memory impairment, increased anxiety-like behavior and MDA level, but it reduced catalase and SOD activity. Treatment with alpha-lipoic acid decreased MDA, increased catalase and SOD activity, and also prevented memory impairment and anxiety-like behavior. Our results showed that alpha-lipoic acid protected the hippocampus from oxidative stress by elevating SOD and CAT activities and reduced memory impairment following acute methamphetamine injection. These findings suggest that alpha-lipoic acid may have a protective effect against the adverse effects of methamphetamine exposure on the hippocampus. Therefore, the current data indicated that ALA can reduce oxidative stress predominantly by its antioxidant property.

Recent Advances in the Treatment of Spinal Cord Injury

Spinal cord injury (SCI) is a complex, multifaceted, progressive, and yet incurable complication that can cause irreversible damage to the individual, family, and society. In recent years strategies for the management and rehabilitation of SCI besides axonal regeneration, remyelination, and neuronal plasticity of the injured spinal cord have significantly improved. Although most of the current research and therapeutic advances have been made in animal models, so far, no specific and complete treatment has been reported for SCI in humans. The failure to treat this complication has been due to the inherent neurological complexity and the structural, cellular, molecular, and biochemical characteristics of spinal cord injury. In this review, in addition to elucidating the causes of spinal cord injury from a molecular and pathophysiological perspective, the complexity and drawbacks of neural regeneration that lead to the failure in SCI treatment are described. Also, recent advances and cutting-edge strategies in most areas of SCI treatment are presented.

Nanowired Delivery of Mesenchymal Stem Cells with Antioxidant Compound H-290/51 Reduces Exacerbation of Methamphetamine Neurotoxicity in Hot Environment

Military personnel are often exposed to hot environments either for combat operations or peacekeeping missions. Hot environment is a severe stressful situation leading to profound hyperthermia, fatigue and neurological impairments. To avoid stressful environment, some people frequently use methamphetamine (METH) or other psychostimulants to feel comfortable under adverse situations. Our studies show that heat stress alone induces breakdown of the blood-brain barrier (BBB) and edema formation associated with reduced cerebral blood flow (CBF). On the other hand, METH alone induces hyperthermia and neurotoxicity. These effects of METH are exacerbated at high ambient temperatures as seen with greater breakdown of the BBB and brain pathology. Thus, a combination of METH use at hot environment may further enhance the brain damage-associated behavioral dysfunctions. METH is well known to induce severe oxidative stress leading to brain pathology. In this investigation, METH intoxication at hot environment was examined on brain pathology and to explore suitable strategies to induce neuroprotection. Accordingly, TiO₂-nanowired delivery of H-290/51 (150 mg/kg, i.p.), a potent chain-breaking antioxidant in combination with mesenchymal stem cells (MSCs), is investigated in attenuating METH-induced brain damage at hot environment in model experiments. Our results show that nanodelivery of H-290/51 with MSCs significantly enhanced CBF and reduced BBB breakdown, edema formation and brain pathology following METH exposure at hot environment. These observations are the first to point out that METH exacerbated brain pathology at hot environment probably due to enhanced oxidative stress, and MSCs attenuate these adverse effects, not reported earlier.

Methamphetamine induced neurotoxic diseases, molecular mechanism, and current treatment strategies

Methamphetamine (MA) is a extremely addictive psychostimulant drug with a significant abuse potential. Long-term MA exposure can induce neurotoxic effects through oxidative stress, mitochondrial functional impairment, endoplasmic reticulum stress, the activation of astrocytes and microglial cells, axonal transport barriers, autophagy, and apoptosis. However, the molecular and cellular mechanisms underlying MA-induced neurotoxicity remain unclear. MA abuse increases the chances of developing neurotoxic conditions such as Parkinson's disease (PD), Alzheimer's disease (AD) and other neurotoxic diseases. MA increases the risk of PD by increasing the expression of alpha-synuclein (ASYN). Furthermore, MA abuse is linked to high chances of developing AD and subsequent neurodegeneration due to biological variations in the brain region or genetic and epigenetic variations. To date, there is no Food and Drug Administration (FDA)-approved therapy for MA-induced neurotoxicity, although many studies are being conducted to develop effective therapeutic strategies. Most current studies are now focused on developing therapies to diminish the neurotoxic effects of MA, based on the underlying mechanism of neurotoxicity. This review article highlights current research on several therapeutic techniques targeting multiple pathways to reduce the neurotoxic effects of MA in the brain, as well as the putative mechanism of MA-induced neurotoxicity.

A review of basic to clinical studies of the association between hyperammonemia, methamphetamine

Methamphetamine (METH), an addictive psychostimulant drug, is the second most widely used type of drug all around the world. METH abusers are more likely to develop a psycho-neurological complication. Hyperammonemia (HAM) causes neuropsychiatric illnesses such as mental state changes and episodes of acute encephalopathy. Recently, there are some shreds of evidence about the relationship between METH complication and HAM. Both METH intoxication and HAM could induce psychosis, agitation, memory impairment, and psycho-neuronal disorders. They also have similar mechanisms of neuronal damages, such as excitotoxicity, oxidative stress, mitochondrial impairments, and inflammation responses, which can subsequently increase the glutamate level of the brain. Hence, the basic to clinical studies of the association between HAM and METH are reviewed by monitoring six case studies and a good body of animal studies literature. All instances of METH-associated HAM had changes in mental state and some level of confusion that were improved when the ammonia serum level returned to the normal level. Furthermore, most of them had typical vital signs. Several studies suggested some sources for METH-associated HAM, including METH-induced liver and renal damages, muscular hyperactivity, gut bacterial overgrowth, co-abuse of other substances, and using some forms of NH3 in METH cooking. In conclusion, it seems that mental status changes in METH abusers may be related to ammonia intoxication or HAM; therefore, it is important to assess the serum level of ammonia in METH intoxicated patients and resolve it.

Thymoquinone: Review of Its Potential in the Treatment of Neurological Diseases

Thymoquinone (TQ) possesses anticonvulsant, antianxiety, antidepressant, and antipsychotic properties. It could be utilized to treat drug misuse or dependence, and those with memory and cognitive impairment. TQ protects brain cells from oxidative stress, which is especially pronounced in memory-related regions. TQ exhibits antineurotoxin characteristics, implying its role in preventing neurodegenerative disorders such as Alzheimer’s disease and Parkinson’s disease. TQ’s antioxidant and anti-inflammatory properties protect brain cells from damage and inflammation. Glutamate can trigger cell death by causing mitochondrial malfunction and the formation of reactive oxygen species (ROS). Reduction in ROS production can explain TQ effects in neuroinflammation. TQ can help prevent glutamate-induced apoptosis by suppressing mitochondrial malfunction. Several studies have demonstrated TQ’s role in inhibiting Toll-like receptors (TLRs) and some inflammatory mediators, leading to reduced inflammation and neurotoxicity. Several studies did not show any signs of dopaminergic neuron loss after TQ treatment in various animals. TQ has been shown in clinical studies to block acetylcholinesterase (AChE) activity, which increases acetylcholine (ACh). As a result, fresh memories are programmed to preserve the effects. Treatment with TQ has been linked to better outcomes and decreased side effects than other drugs.