Comparative Study of Postmortem Concentrations of Benzodiazepines and Z-Hypnotics in Several Different Matrices

Exploring unified methods of killing and storing insect samples for forensic entomotoxicology using diazepam in Lucilia sericata (Meigen, 1826) (Diptera: Calliphoridae) larvae

Forensic entomologists use the maturity of necrophagous larvae to estimate the minimum post-mortem interval (PMImin), ideally taking account of effects that xenobiotics in the corpse may have on insect maturation. Forensic toxicologists may employ larvae to detect drugs in drug-related deaths when human samples are unavailable. Yet current pre-analytical practices of these two professions differ significantly, impeding the successful use of the same samples. Potential benefits of shared pre-analytical practices and opportunities for enhanced collaboration have yet to be fully explored. We employed Lucilia sericata (Meigen, 1826) (Diptera: Calliphoridae) larvae, raised in the presence of diazepam, to investigate the effects of two standard investigative practices on larvae for drug detection and for quantifying mass and length as proxies of age. Specimens were killed by either blanching or freezing and stored at -20℃ for either intermediate or long periods. Blanched larvae showed smaller changes in size and body integrity during storage, thereby producing the most reproducible estimates of PMImin. Consequently, data obtained from blanched larvae were used to evaluate the impact of diazepam on larval development. Diazepam exerted no significant effect on larval mass, and a weak effect on length. Diazepam recovery was significantly higher from blanched larvae, suggesting that freeze-killing causes drug loss. This model system demonstrates the value to forensic entomologists of the standard technique of blanching larvae, followed by storage at -20℃ for toxicological analysis. We recommend that forensic toxicologists consider blanching to kill larvae before storage at low temperatures, at least for certain drugs. This approach offers the dual benefit of high-quality specimens for both PMI estimation and drug detection.

Flunitrazepam and its metabolites induced brain toxicity: Insights from molecular dynamics simulation and transcriptomic analysis

Psychoactive drugs frequently contaminate aquatic environments after human consumption, raising concerns about their residues and ecological harm. This study investigates the effects of flunitrazepam (FLZ) and its metabolite 7-aminoflunitrazepam (7-FLZ), benzodiazepine-class psychoactive drugs, on brain accumulation, blood-brain barrier (BBB), and neuroinflammation of the model organism zebrafish. Molecular dynamics simulation and transcriptome sequencing were used to uncover their toxic mechanisms. Results demonstrate that both FLZ and 7-FLZ can accumulate in the brain, increasing Evans blue levels by 3.4 and 0.8 times, respectively. This increase results from abnormal expression of tight junction proteins, particularly ZO-1 and Occludin, leading to elevated BBB permeability. Furthermore, FLZ and 7-FLZ can also induce neuroinflammation, upregulating TNFα by 91% and 39%, respectively, leading to pathological changes and disrupted intracellular ion balance. Molecular dynamics simulation reveals conformational changes in ZO-1 and Occludin proteins, with FLZ exhibiting stronger binding forces and greater toxicity. Weighted gene co-expression network analysis identifies four modules correlated with BBB permeability and neuroinflammation. KEGG enrichment analysis of genes within these modules reveals pathways like protein processing in the endoplasmic reticulum, NOD-like receptor signaling pathway, and arginine and proline metabolism. This study enhances understanding of FLZ and 7-FLZ neurotoxicity and assesses environmental risks of psychoactive substances. ENVIRONMENTAL IMPLICATION: With the increasing prevalence of mental disorders and the discharge of psychoactive drugs into water, even low drug concentrations (ng/L-μg/L) can pose neurological risks. This study, utilizing molecular dynamic (MD) simulations and transcriptome sequencing, investigate the neurotoxicity and mechanisms of flunitrazepam and 7-aminoflunitrazepam. It reveals that they disrupt the blood-brain barrier in zebrafish and induce neuroinflammation primarily by inducing conformational changes in tight junction proteins. MD simulations are valuable for understanding pollutant-protein interactions. This research offers invaluable insights for the environmental risk assessment of psychoactive drugs and informs the development of strategies aimed at prevention and mitigation.