Interface of Aging and Acute Peripheral Neuropathy Induced by Oxaliplatin in Mice: Target-Directed Approaches for Na+, K+-ATPase, Oxidative Stress, and 7-Chloro-4-(phenylselanyl) quinoline Therapy

Platinum Deposition in the Central Nervous System: A Novel Insight into Oxaliplatin-induced Peripheral Neuropathy in Young and Old Mice

Numerous factors can contribute to the incidence or exacerbation of peripheral neuropathy induced by oxaliplatin (OXA). Recently, platinum accumulation in the spinal cord of mice after OXA exposure, despite the efficient defenses of the central nervous system, has been demonstrated by our research group, expanding the knowledge about its toxicity. One hypothesis is platinum accumulation in the spinal cord causes oxidative damage to neurons and impairs mitochondrial function. Thus, the main aim of this study was to investigate the relationship between aging and OXA-induced neuropathic pain and its comorbidities, including anxious behavior and cognitive impairment. By using an OXA-induced peripheral neuropathy model, platinum and bioelement concentrations and their influence on oxidative damage, neuroprotection, and neuroplasticity pathways were evaluated in Swiss mice, and our findings showed that treatment with OXA exacerbated pain and anxious behavior, albeit not age-induced cognitive impairment. Platinum deposition in the spinal cord and, for the first time, in the brain of mice exposed to OXA, regardless of age, was identified. We found that alterations in bioelement concentration, oxidative damage, neuroprotection, and neuroplasticity pathways induced by aging contribute to OXA-induced peripheral neuropathy. Our results strive to supply a basis for therapeutic interventions for OXA-induced peripheral neuropathy considering age specificities.

Structure-Activity Relationship of 7-Chloro-4-(Phenylselanyl) Quinoline: Novel Antinociceptive and Anti-Inflammatory Effects in Mice

The 7-chloro-4-(phenylselanyl) quinoline (4-PSQ) shows promise for its antinociceptive and anti-inflammatory properties. Here, we explored the structure-activity relationship of 4-PSQ and its analogues: 7-chloro-4-[(4-fluorophenyl) selanyl]quinoline (a), 7-chloro-4-{[3-trifluoromethyl)phenyl] selanyl} quinoline (b), 4-((3,5-Bis(trifluoromethyl)phenyl) selanyl-7-chloroquinoline (c), 7-chloro-4-[(2,4,6-trimethyl)selanyl]quinolinic acid (d) and 7-chloroquinoline-4-selenium acid (e) in models of acute inflammation and chemical, thermal and mechanical nociception in mice, alongside in silico analysis. Compounds a (-F), b (-CF3), c (-Bis-CF3), d (-CH3), e (-OOH), and 4-PSQ exhibited antinociceptive effects in chemical and thermal nociception models, except d (-CH3) and e (-OOH) in the hot plate test. None induced locomotor changes. In silico, only c (-Bis-CF3) showed low gastrointestinal absorption, and c (-Bis-CF3) and e (-OOH) lacked blood-brain barrier penetration, suggesting e (-OOH) lacked central antinociceptive effect. These compounds had higher COX-2 affinity than COX-1. Our findings suggest substituent insertion alters 4-PSQ's efficacy as an antinociceptive and anti-inflammatory agent.

Insights into Vincristine-Induced Peripheral Neuropathy in Aged Rats: Wallerian Degeneration, Oxidative Damage, and Alterations in ATPase Enzymes

This study aimed to elucidate vincristine (VCR)-induced peripheral neuropathy in aged rats, a poorly understood neurotoxicity. Both young and old Wistar rats were administered VCR (0.1 mg/kg, intraperitoneally (i.p.)) and compared to age-matched controls (0.9% saline; 10 mg/mL, i.p.). Mechanical (MN) and thermal nociceptive (TN) responses were assessed on days 0, 6, 11, and 17. Locomotor response, cognitive ability, and anxious-like behavior were evaluated on days 14, 15, and 16. Results showed MN and TN responses in both young and old VCR-exposed rats. In old rats, VCR exacerbated MN (on days 6, 11, and 17) and TN (on days 6 and 17) responses. VCR also induced cognitive impairments and anxiety-like behavior. Histological analysis revealed Wallerian degeneration in the spinal cords of VCR-exposed rats accompanied by macrophage migration. Furthermore, VCR increased Ca2+-ATPase activity while inhibiting Na+, K+-ATPase activity in young and old rats. VCR altered the homeostasis of Mg2+-ATPase activity. Lipid peroxidation and nitrite and nitrate levels increased in young and old rats exposed to VCR. This study provides valuable insights into VCR's mechanistic pathways in aged rats, emphasizing the need for further research in this area.

Sex differences in PD-L1-induced analgesia in paclitaxel-induced peripheral neuropathy mice depend on TRPV1-based inhibition of CGRP

AIMS

Paclitaxel (PTX) is extensively utilized in the management of diverse solid tumors, frequently resulting in paclitaxel-induced peripheral neuropathy (PIPN). The present study aimed to investigate sex differences in the behavioral manifestations and underlying pathogenesis of PIPN and search for clinically efficacious interventions.

METHODS

Male and female C57BL/6 mice (5-6 weeks and 12 months, weighing 18-30 g) were intraperitoneally (i.p.) administered paclitaxel diluted in saline (NaCl 0.9%) at a dose of 2 mg/kg every other day for a total of 4 injections. Von Frey and hot plate tests were performed before and after administration to confirm the successful establishment of the PIPN model and also to evaluate the pain of PIPN and the analgesic effect of PD-L1. On day 14 after PTX administration, PD-L1 protein (10 ng/pc) was injected into the PIPN via the intrathecal (i.t.) route. To knock down TRPV1 in the spinal cord, adeno-associated virus 9 (AAV9)-Trpv1-RNAi (5 μL, 1 × 1013 vg/mL) was slowly injected via the i.t. route. Four weeks after AAV9 delivery, the downregulation of TRPV1 expression was verified by immunofluorescence staining and Western blotting. The levels of PD-L1, TRPV1 and CGRP were measured via Western blotting, RT-PCR, and immunofluorescence staining. The levels of TNF-α and IL-1β were measured via RT-PCR.

RESULTS

TRPV1 and CGRP protein and mRNA levels were higher in the spinal cords of control female mice than in those of control male mice. PTX-induced nociceptive behaviors in female PIPN mice were greater than those in male PIPN mice, as indicated by increased expression of TRPV1 and CGRP. The analgesic effects of PD-L1 on mechanical hyperalgesia and thermal sensitivity were significantly greater in female mice than in male mice, with calculated relative therapeutic levels increasing by approximately 2.717-fold and 2.303-fold, respectively. PD-L1 and CGRP were partly co-localized with TRPV1 in the dorsal horn of the mouse spinal cord. The analgesic effect of PD-L1 in PIPN mice was observed to be mediated through the downregulation of TRPV1 and CGRP expression following AAV9-mediated spinal cord specific decreased TRPV1 expression.

CONCLUSIONS

PTX-induced nociceptive behaviors and the analgesic effect of PD-L1 in PIPN mice were sexually dimorphic, highlighting the significance of incorporating sex as a crucial biological factor in forthcoming mechanistic studies of PIPN and providing insights for potential sex-specific therapeutic approaches.

The Therapeutic Potential of Antioxidants in Chemotherapy-Induced Peripheral Neuropathy: Evidence from Preclinical and Clinical Studies

As cancer therapies advance and patient survival improves, there has been growing concern about the long-term adverse effects that patients may experience following treatment, and concerns have been raised about such persistent, progressive, and often irreversible adverse effects. Chemotherapy is a potentially life-extending treatment, and chemotherapy-induced peripheral neuropathy (CIPN) is one of its most common long-term toxicities. At present, strategies for the prevention and treatment of CIPN are still an open problem faced by medicine, and there has been a large amount of previous evidence that oxidative damage is involved in the process of CIPN. In this review, we focus on the lines of defense involving antioxidants that exert the effect of inhibiting CIPN. We also provide an update on the targets and clinical prospects of different antioxidants (melatonin, N-acetylcysteine, vitamins, α-lipoic acid, mineral elements, phytochemicals, nutritional antioxidants, cytoprotectants and synthetic compounds) in the treatment of CIPN with the help of preclinical and clinical studies, emphasizing the great potential of antioxidants as adjuvant strategies to mitigate CIPN.

Evaluation of potential cardiotoxicity of ammonia: l-selenomethionine inhibits ammonia-induced cardiac autophagy by activating the PI3K/AKT/mTOR signaling pathway

Ammonia is a major harmful gas in the environment of livestock and poultry. Studies have shown that excessive ammonia inhalation has adverse effects in pig heart. However, the mechanism of ammonia-induced cardiac toxicity in pigs has not been reported. L-selenomethionine is a kind of organic selenium (Se) which is easily absorbed by the body. Therefore, in this study, twenty-four 125-day-old pigs were randomly divided into 4 groups: C (control) group, A (ammonia) group, Se group (Se content: 0.5 mg kg-1), and A (ammonia) + Se group. The mechanism of ammonia-induced cardiotoxicity and the alleviating effect of L-selenomethionine were examined. The results in the A group showed as follows: a large number of myocardial fiber edema and cytoplasmic bleakness were observed in the heart; a large number of mitochondrial autophagy were observed; ATP content, ATPase activities and hematological parameters decreased significantly; Endoplasmic reticulum stress (ERS) markers (GRP78, IRE1α, ATF4, ATF6, and CHOP) were significantly induced in the mRNA and protein levels; PI3K/AKT/mTOR signaling pathway was activated; and autophagy key genes and proteins (Beclin-1, LC3, ATG3, and ATG5) were significantly up-regulated. The results of comparison between the A + Se group and the A group were as follows: the degree of edema of cardiac muscle fiber in the A + Se group was somewhat relieved; the level of mitochondrial autophagy decreased; ATP content and ATPase activities increased significantly; the mRNA and protein levels of ERS markers were significantly down-regulated; the expression level of PI3K/AKT/mTOR signaling pathway was decreased; and the mRNA and protein levels of key autophagy genes were decreased. However, the changes of these indexes in the A + Se group were still significantly different from those in the C group. Our results indicated that L-selenomethionine supplementation inhibited ammonia-induced cardiac autophagy by activating the PI3K/AKT/mTOR signaling pathway, which confirmed that L-selenomethionine could alleviate the cardiac injury caused by excessive ammonia inhalation to a certain extent. This study aims to enrich the toxicological mechanism of ammonia and provide valuable reference for future intervention of ammonia toxicity.