Caenorhabditis elegans as an in vivo Model to Assess Amphetamine Tolerance

Long-Lasting Epigenetic Changes in the Dopamine Transporter in Adult Animals Exposed to Amphetamine during Embryogenesis: Investigating Behavioral Effects

The dopamine transporter (DAT) is an integral member of the dopaminergic system and is responsible for the release and reuptake of dopamine from the synaptic space into the dopaminergic neurons. DAT is also the major target of amphetamine (Amph). The effects of Amph on DAT have been intensively studied; however, the mechanisms underlying the long-term effects caused by embryonal exposure to addictive doses of Amph remain largely unexplored. As in mammals, in the nematode C. elegans Amph causes changes in locomotion which are largely mediated by the C. elegans DAT homologue, DAT-1. Here, we show that chronic embryonic exposures to Amph alter the expression of DAT-1 in adult C. elegans via long-lasting epigenetic modifications. These changes are correlated with an enhanced behavioral response to Amph in adult animals. Importantly, pharmacological and genetic intervention directed at preventing the Amph-induced epigenetic modifications occurring during embryogenesis inhibited the long-lasting behavioral effects observed in adult animals. Because many components of the dopaminergic system, as well as epigenetic mechanisms, are highly conserved between C. elegans and mammals, these results could be critical for our understanding of how drugs of abuse initiate predisposition to addiction.

Mitochondria in the Spotlight: C. elegans as a Model Organism to Evaluate Xenobiotic-Induced Dysfunction

Mitochondria play a crucial role in cellular respiration, ATP production, and the regulation of various cellular processes. Mitochondrial dysfunctions have been directly linked to pathophysiological conditions, making them a significant target of interest in toxicological research. In recent years, there has been a growing need to understand the intricate effects of xenobiotics on human health, necessitating the use of effective scientific research tools. Caenorhabditis elegans (C. elegans), a nonpathogenic nematode, has emerged as a powerful tool for investigating toxic mechanisms and mitochondrial dysfunction. With remarkable genetic homology to mammals, C. elegans has been used in studies to elucidate the impact of contaminants and drugs on mitochondrial function. This review focuses on the effects of several toxic metals and metalloids, drugs of abuse and pesticides on mitochondria, highlighting the utility of C. elegans as a model organism to investigate mitochondrial dysfunction induced by xenobiotics. Mitochondrial structure, function, and dynamics are discussed, emphasizing their essential role in cellular viability and the regulation of processes such as autophagy, apoptosis, and calcium homeostasis. Additionally, specific toxins and toxicants, such as arsenic, cadmium, and manganese are examined in the context of their impact on mitochondrial function and the utility of C. elegans in elucidating the underlying mechanisms. Furthermore, we demonstrate the utilization of C. elegans as an experimental model providing a promising platform for investigating the intricate relationships between xenobiotics and mitochondrial dysfunction. This knowledge could contribute to the development of strategies to mitigate the adverse effects of contaminants and drugs of abuse, ultimately enhancing our understanding of these complex processes and promoting human health.

Central Effects of the Designer Drug Mephedrone in Mice-Basic Studies

Mephedrone belongs to the "party drugs" thanks to its psychostimulant effects, similar to the ones observed after amphetamines. Though mephedrone is used worldwide by humans and in laboratory animals, not all properties of this drug have been discovered yet. Therefore, the main aim of this study was to expand the knowledge about mephedrone's activity in living organisms. A set of behavioral tests (i.e., measurement of the spontaneous locomotor activity, rotarod, chimney, elevated plus maze with its modification, novel object recognition, and pentylenetetrazol seizure tests) were carried out in male albino Swiss mice. Different dose ranges of mephedrone (0.05-5 mg/kg) were administered. We demonstrated that mephedrone at a dose of 5 mg/kg rapidly increased the spontaneous locomotor activity of the tested mice and its repeated administration led to the development of tolerance to these effects. Mephedrone showed the anxiolytic-like potential and improved spatial memory, but it did not affect recognition memory. Moreover, the drug seemed not to have any anticonvulsant or proconvulsant activity. In conclusion, mephedrone induces many central effects. It easily crosses the blood-brain barrier and peaks in the brain quickly after exposure. Our experiment on inducing a hyperlocomotion effect showed that mephedrone's effects are transient and lasted for a relatively short time.

Developmental exposure to methylmercury and ADHD, a literature review of epigenetic studies

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that affects the competence of academic performance and social wellness in children and adults. The causes of ADHD are unclear. Both genetic and environmental factors contribute to the development of ADHD. The behavioral impairments in ADHD are associated with epigenetic changes in genes that are important for neurodevelopment. Among environmental causes of ADHD, the neurotoxin methylmercury (MeHg) is associated with an increased risk for ADHD. Developing children are susceptible to neurotoxic effects of prenatal MeHg exposure. Human epidemiology studies have shown that prenatal MeHg exposure could invoke epigenetic changes in genes that are involved in ADHD. In addition, the pathogenesis of ADHD involves dopaminergic system, which is a target of developmental MeHg exposure. MeHg-induced alterations in the dopaminergic system have a profound impact on behavioral functions in adults. As a trace level of MeHg (around nM) can induce long-lasting behavioral alterations, potential mechanisms of MeHg-induced functional changes in the dopaminergic system may involve epigenetic mechanisms. Here, we review the relevant evidence on developmental MeHg exposures and the risk for ADHD. We also point out research gaps in understanding environmental causes of ADHD.