Transcriptomics and metabolomics reveal Ca2+ overload and osmotic imbalance-induced neurotoxicity in earthworms (Eisenia fetida) under tri-n-butyl phosphate exposure

Tri-n-butyl phosphate (TNBP) is mass-produced and widely utilized in many products, which has increasingly drawn concern about its potential environmental risks. However, little is known about the toxic mechanism on soil-dwelling organisms caused by TNBP. In this study, earthworms (Eisenia fetida) were exposed to environmentally relevant or higher concentrations of TNBP (0, 0.1, 1, and 10 mg/kg) in artificial soil for 14 days. Our results showed that TNBP accumulated in earthworm nervous tissue (cerebral ganglions). In addition, the content of glutamate in cerebral ganglions decreased compared to the control (p < 0.05). The concentration of Ca²⁺ in earthworm cerebral ganglions increased. However, both Na⁺/K⁺-ATPase and Ca²⁺-ATPase activities were significantly reduced compared to the control (p < 0.05), which led to neurotoxicity in earthworm nervous tissue. Furthermore, the transcriptome and metabolomics revealed the toxic mechanism in earthworm nervous tissue caused by TNBP. Results indicated that the main neurotoxicity mechanisms induced by TNBP were an osmotic imbalance and Ca²⁺ overload in cerebral ganglions. Our findings fill a gap in the literature on neurotoxicity mechanisms of earthworm response to TNBP exposure and contribute to a better understanding of the adverse effects of TNBP on soil-dwelling organisms in terrestrial ecological systems.

Counter effects of Asiaticosids-D through putative neurotransmission on rotenone induced cerebral ganglionic injury in Lumbricus terrestris

Asiaticoside-D (AD) was shown to efficacy of ganglionic degenerated Lumbricus terrestris as a pioneering observation in our earlier research. Though, extract molecular mechanisms of AD for degenerative diseases (DDs) remains largely unknown. We investigated the neuroprotective effects of AD against ROT in cerebral ganglions (CGs) of degenerative L. terrestris. Worms were exposed to 0.4 ppm ROT for 7 days were subjected to co- treatment with 15 ppm of AD. After, CGs was removed. The levels oxidant, non-antioxidant, antioxidant status, ganglioside, ceramide and ceramide glycanase (CGase) were estimated. The m-RNA levels of dopamine transporter (DAT), octopamine transporter (OAT), innexins-9 (inx-9), ionotropic glutamate receptor 3 (iGlu3), heat shock proteins (hsp70), XPRLamide neuropeptide precursor, tyramine beta-hydroxylase (tbh-1) and β- adrenergic receptor kinase-2 (β-ARK2-3) by semi-qRT- PCR. The expression pattern of tyramine beta hydroxylase (TBH), glutamate receptor (iGluR), serotonin transporter (SERT), dopamine transporters (DAT), nerve growth factors (NGF), cytochrome C oxidase (COC), NADH dehydogenase subunit-1 (ND-1), neurotrophin receptor p75 (p75NTR), neuronal nitric oxiside synthase (nNOs) interleukin 1- beta (IL1-β) and tumor necrosis factor alpha (TNF-α) by western blotting. Glutaminergic, serotogenic and dopaminergic toxicity variations were also performed. The levels of oxidant, non-antioxidant, antioxidant status, lipids, proteins and m-RNAs were significantly altered (p < 0.001) on ROT-induced (group II) and their levels were significantly changes (p < 0.05) by ROT+AD in CGs. The sensitive study plan concluded the neuroprotective effects of AD against ROT induced degeneration in worms and suggest that the AD deserves future studies for its use as an effective alternative medicine that could minimize the morbidity of ganglionic degenerative diseases patients.

Rotenone causing dysfunctional mitochondria and lysosomes in cerebral ganglions of Lumbricus terrestris degenerate giant fibers and neuromuscular junctions

Rotenone is well-documented to cause neurodegenerative condition such as Parkinson's, in the exposed systems. However, its detrimental effect on particular sites of neuronal pathway is still under investigation. We aimed at elucidating the impact of rotenone on cerebral ganglions (CG) of Lumbricus terrestris which control movement and behaviour of the worms. Worms were exposed to 0-0.4 ppm/mL of rotenone. Mitochondrial and lysosomal integrities were found to be affected beyond 0.2 ppm/mL of rotenone. Activities of cholinergic enzymes and the expression of tyrosine hydroxylase showed an impaired neuronal transmission in CGs at the dose of 0.2 ppm/mL of rotenone. Histopathological and immunoflourescent analyses showed neuronal apoptosis, reduced nucleic acid content and inhibited of neurosecretion at 0.3 ppm/mL. Electron microscopy showed that the neurons and neuromuscular junctions were affected at 0.2 ppm/mL. Dose-dependent changes were also observed in the motor function such as burrowing behaviours and locomotion. Conduction velocity (CV) and locomotion assessment showed that the CV of lateral giant fiber (LGF) was reduced while that of MGF remains unaffected at 0.2 ppm, the dose at which the burrowing behaviour was also not affected. LGF, cholinergic enzymes and tyrosine hydroxylase are primarily targeted by rotenone affecting locomotion at 0.2 ppm/mL while MGF, neuropile and the burrowing behaviour were affected at 0.3 ppm/mL. We demonstrate, in addition to dose-dependent effects, that the bioaccumulation factors range 0.28-0.32 ppm/μg of rotenone cause degenerative impact on giant fibers affecting neuronal behaviors/locomotion of worms. We also propose worms for studying mechanisms of neuronal pathology caused by chemicals prevailing in earth's atmosphere.