Unveiling the Pain Relief Potential: Harnessing Analgesic Peptides from Animal Venoms.

The concept of pain encompasses a complex interplay of sensory and emotional experiences associated with actual or potential tissue damage. Accurately describing and localizing pain, whether acute or chronic, mild or severe, poses a challenge due to its diverse manifestations. Understanding the underlying origins and mechanisms of these pain variations is crucial for effective management and pharmacological interventions. Derived from a wide spectrum of species, including snakes, arthropods, mollusks, and vertebrates, animal venoms have emerged as abundant repositories of potential biomolecules exhibiting analgesic properties across a broad spectrum of pain models. This review focuses on highlighting the most promising venom-derived toxins investigated as potential prototypes for analgesic drugs. The discussion further encompasses research prospects, challenges in advancing analgesics, and the practical application of venom-derived toxins. As the field continues its evolution, tapping into the latent potential of these natural bioactive compounds holds the key to pioneering approaches in pain management and treatment. Therefore, animal toxins present countless possibilities for treating pain caused by different diseases. The development of new analgesic drugs from toxins is one of the directions that therapy must follow, and it seems to be moving forward by recommending the composition of multimodal therapy to combat pain.

Experimental Bothropsatrox Envenomation: Blood Plasma Proteome Effects after Local Tissue Damage and Perspectives on Thromboinflammation.

The clinical manifestations of Bothrops atrox envenoming involve local and systemic changes, among which edema requires substantial attention due to its ability to progress to compartmental syndromes and sometimes cause tissue loss and amputations. However, the impact of edema on the poisoned body's system has not been explored. Thus, the present study aimed to explore the systemic pathological and inflammatory events that are altered by intraplantar injection of B. atrox venom in a mouse model through hematologic, lipidic, and shotgun proteomics analysis. Plasma samples collected showed a greater abundance of proteins related to complement, coagulation, lipid system, platelet and neutrophil degranulation, and pathways related to cell death and ischemic tolerance. Interestingly, some proteins, in particular, Prdx2 (peroxiredoxin 2), Hba (hemoglobin subunit alpha), and F9 (Factor IX), increased according to the amount of venom injected. Our findings support that B. atrox venom activates multiple blood systems that are involved in thromboinflammation, an observation that may have implications for the pathophysiological progression of envenomations. Furthermore, we report for the first time a potential role of Prdx2, Hba, and F9 as potential markers of the severity of edema/inflammation in mice caused by B. atrox.

Blood plasma proteome alteration after local tissue damage induced by Bothrops erythromelas snake venom in mice.

Snakes of the genus Bothrops are responsible the most snakebites in the Brazil, causing a diverse and complex pathophysiological condition. Bothrops erythromelas is the main specie of medical relevance found in the Caatinga from the Brazilian Northeast region. The pathophysiological effects involving B. erythromelas snakebite as well as the organism reaction in response to this envenomation are not so explored. Thus, edema was induced in mice paws using 2.5 µg or 5.0 µg of B. erythromelas venom, and the percentage of edema was measured. Plasma was collected 30  minutes after the envenomation-induced in mice and analyzed by mass spectrometry. It was identified a total of 112 common plasma proteins differentially abundant among experimental groups, which are involved with the complement system and coagulation cascades, oxidative stress, neutrophil degranulation, platelets degranulation and inflammatory response. Apolipoprotein A1 (Apoa), serum amyloid protein A-4 (Saa4), adiponectin (Adipoq) showed up-regulated in mice plasma after injection of venom, while fibulin (Fbln1), factor XII (F12) and vitamin K-dependent protein Z (Proz) showed down-regulated. The results indicate a protein pattern of thrombo-inflammation to the B. erythromelas snakebite, evidencing potential biomarkers for monitoring this snakebite, new therapeutic targets and its correlations with the degree of envenomation once showed modulations in the abundance among the different groups according to the amount of venom injected into the mice.

Distinct Cell-specific Roles of NOX2 and MyD88 in Epileptogenesis.

It is well established that temporal lobe epilepsy (TLE) is often related to oxidative stress and neuroinflammation. Both processes subserve alterations observed in epileptogenesis and ultimately involve distinct classes of cells, including astrocytes, microglia, and specific neural subtypes. For this reason, molecules associated with oxidative stress response and neuroinflammation have been proposed as potential targets for therapeutic strategies. However, these molecules can participate in distinct intracellular pathways depending on the cell type. To illustrate this, we reviewed the potential role of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) and myeloid differentiation primary response 88 (MyD88) in astrocytes, microglia, and neurons in epileptogenesis. Furthermore, we presented approaches to study genes in different cells, employing single-cell RNA-sequencing (scRNAseq) transcriptomic analyses, transgenic technologies and viral serotypes carrying vectors with specific promoters. We discussed the importance of identifying particular roles of molecules depending on the cell type, endowing more effective therapeutic strategies to treat TLE.

A fingerprint of plasma proteome alteration after local tissue damage induced by Bothrops leucurus snake venom in mice.

Bothrops spp. is responsible for about 70% of snakebites in Brazil, causing a diverse and complex pathophysiological condition. Bothrops leucurus is the main species of medical relevance found in the Atlantic coast in the Brazilian Northeast region. The pathophysiological effects involved B. leucurus snakebite as well as the organism's reaction in response to this envenoming, it has not been explored yet. Thus, edema was induced in mice paw using 1.2, 2.5, and 5.0 µg of B. leucurus venom, the percentage of edema was measured 30 min after injection and the blood plasma was collected and analyzed by shotgun proteomic strategy. We identified 80 common plasma proteins with differential abundance among the experimental groups and we can understand the early aspects of this snake envenomation, regardless of the suggestive severity of an ophidian accident. The results showed B. leucurus venom triggers a thromboinflammation scenario where family's proteins of the Serpins, Apolipoproteins, Complement factors and Component subunits, Cathepsins, Kinases, Oxidoreductases, Proteases inhibitors, Proteases, Collagens, Growth factors are related to inflammation, complement and coagulation systems, modulators platelets and neutrophils, lipid and retinoid metabolism, oxidative stress and tissue repair. Our findings set precedents for future studies in the area of early diagnosis and/or treatment of snakebites. SIGNIFICANCE: The physiopathological effects that the snake venoms can cause have been investigated through classical and reductionist tools, which allowed, so far, the identification of action mechanisms of individual components associated with specific tissue damage. The currently incomplete limitations of this knowledge must be expanded through new approaches, such as proteomics, which may represent a big leap in understanding the venom-modulated pathological process. The exploration of the complete protein set that suffer modifications by the simultaneous action of multiple toxins, provides a map of the establishment of physiopathological phenotypes, which favors the identification of multiple toxin targets, that may or may not act in synergy, as well as favoring the discovery of biomarkers and therapeutic targets for manifestations that are not neutralized by the antivenom.

Pain modulated by Bothrops snake venoms: Mechanisms of nociceptive signaling and therapeutic perspectives.

Snake venoms are substances mostly composed by proteins and peptides with high biological activity. Local and systemic effects culminate in clinical manifestations induced by these substances. Pain is the most uncomfortable condition, but it has not been well investigated. This review discusses Bothrops snakebite-induced nociception, highlighting molecules involved in the mediation of this process and perspectives in treatment of pain induced by Bothrops snake venoms (B. alternatus, B. asper, B. atrox, B. insularis, B. jararaca, B. pirajai, B. jararacussu, B. lanceolatus, B. leucurus, B. mattogrossensis, B. moojeni). We highlight, the understanding of the nociceptive signaling, especially in snakebite, enables more efficient treatment approaches. Finally, future perspectives for pain treatment concerning snakebite patients are discussed.

Ryanodine receptors drive neuronal loss and regulate synaptic proteins during epileptogenesis.

Status epilepticus (SE) is a clinical emergency that can lead to the development of temporal lobe epilepsy (TLE). The development and maintenance of spontaneous seizures in TLE are linked to calcium (Ca+2)-dependent processes such as neuronal cell loss and pathological synaptic plasticity. It has been shown that SE produces an increase in ryanodine receptor-dependent intracellular Ca+2 levels in hippocampal neurons, which remain elevated during the progression of the disease. However, the participation of ryanodine receptors (RyRs) in the neuronal loss and circuitry rewiring that take place in the hippocampus after SE remains unknown. In this context, we first investigated the functional role of RyRs on the expression of synaptic and plasticity-related proteins during epileptogenesis induced by pilocarpine in Wistar rats. Intrahippocampal injection of dantrolene, a selective pharmacological blocker of RyRs, caused the increase of the presynaptic protein synapsin I (SYN) and synaptophysin (SYP) 48 h after SE induction. Specifically, we observed that SYN and SYP were regulated in hippocampal regions known to receive synaptic inputs, revealing that RyRs could be involved in network changes and/or neuronal protection after SE induction. In order to investigate whether the changes in SYN and SYP were related to neuroplastic changes that could contribute to pathological processes that occur after SE, we evaluated the levels of activity-regulated cytoskeleton-associated protein (ARC) and mossy fiber sprouting in the dentate gyrus (DG). Interestingly, we observed that although SE induced the appearance of intense ARC-positive cells, dantrolene treatment did not change the levels of ARC in both western blot and immunofluorescence analyses. Accordingly, in the same experimental conditions, we were not able to detect changes in the levels of both pre- and post-synaptic plasticity-related proteins, growth associated protein-43 (GAP-43) and postsynaptic density protein-95 (PSD-95), respectively. Additionally, the density of mossy fiber sprouting in the DG was not increased by dantrolene treatment. We next examined the effects of intrahippocampal injection of dantrolene on neurodegeneration. Notably, dantrolene promoted neuroprotective effects by decreasing neuronal cell loss in CA1 and CA3, which explains the increased levels of synaptic proteins, and the apparent lack of positive effect on pathological plasticity. Taken together, our results revealed that RyRs may have a major role in the hippocampal neurodegeneration associated to the development of acquired epilepsy.

Dynamic expression of glial fibrillary acidic protein and ionized calcium binding adaptor molecule 1 in the mouse spinal cord dorsal horn under pathological pain states.

Objective: Animal models of chronic pain have demonstrated that glial cells are promising target for development of analgesic drugs. However, preclinical studies on glial response under chronic pain conditions vary depending on the cellular markers, the species used, the experimental design and model. Therefore, we investigate the expression profile of GFAP and Iba-1 during the behavioral manifestation of sensory disorder in inflammatory and neuropathic pain models. Methods: the expression profile of fibrillary acidic protein (GFAP) and ionized calcium binding adaptor molecule-1 (Iba-1) were quantitated in the spinal dorsal horn of Balb/C mice submitted to six models of chronic pain. Protein analysis was performed by western blot and the results colligated with pain-related behavior. Results: Using the same method to quantitate proteins we observed that while GFAP is upregulated after axotomy, partial nerve injury and cutaneous inflammation, its expression is not changed during muscle inflammation, non-inflammatory muscle pain, and in a viral-associated pain. Differently, Iba-1 is downregulated after axotomy but upregulated after partial lesion of peripheral nerve as well as after virus inoculation and during non-inflammatory muscle pain. Cutaneous and muscle inflammation induced no change in Iba-1 expression in the dorsal horn.In spite of a marked time-dependent variation in protein expression, mechanical allodynia was present at any time of all the models investigated. Discussion: Under distinct pain conditions, GFAP and Iba-1 expression is dependent on the origin of the stimulus, disease progression and tissue affected. Moreover, their expression and is not necessarily associated to the behavior manifestation of pain.

Effect of swimming training on nerve morphological recovery after compressive injury.

OBJECTIVE: This study aims to investigate morphological alterations caused by partial sciatic nerve ligation (PNL) and the efficacy of a moderate-intensity swimming training as therapeutic strategy for nerve regeneration. METHODS: A number of 30 male adult mice were equally divided in control, 14 days after PNL (PNL 14 days), 42 days after PNL (PNL 42 days), 70 days after PNL (PNL 70 days) and 5-week exercise training after 7 days post-lesion (PNL trained 35 days) groups. PNL trained 35 days group began with a 10-min session for 3 days and this time was gradually increased by 10 min every three sessions until the animals had swum for 50 min per session. Morphoquantitative analysis was carried out to assess nerve regeneration in each group. RESULTS: PNL 14 days group exhibited less degenerating signs than PNL 42 days group, where most post-lesion alterations were visualized. Nerve area and minimum diameter were significantly lower (p < 0.05) than control group. PNL 70 days group showed a greater degree of regenerating fibers and similar morphometric parameters to control group. PNL trained 35 days demonstrated signs of regeneration, reaching control group values in the morphometric analysis. DISCUSSION: PNL promotes great histopathological changes, which became more visible at 42 post-injury days. A natural nerve-regeneration tendency was observed throughout time, as observed in PNL 70 days group; nevertheless, moderate swimming training was found to be a therapeutic resource for nerve regeneration, accelerating such process from a morphoquantitative perspective. ABBREVIATIONS: ANOVA: One-way analysis of variance; BDNF: Brain-derived neurotrophic factor; FGF-2: Fibroblast growth factor 2; GDNF: Glial cell line derived neurotrophic factor; IGF: Insulin-link growth factor; IL-1ß: Interleukin-1ß; NGF: Neural growth factor; PBS: Phosphate-buffered saline; PNL: Partial sciatic nerve ligation.

The experimental model of nephrotic syndrome induced by Doxorubicin in rodents: an update.

Nephrotic syndrome (NS) is characterized by proteinuria, hypoalbuminemia, generalized edema, and hyperlipidemia. It begins by changes in the glomerular filtration barrier, with increased permeability to plasma proteins. It affects all age groups and can progress to end-stage renal disease. NS pathophysiology is still unknown. However, the critical role of the immune system is well recognized. Animal models are useful tools for the investigation of NS. Among different experimental models proposed in the literature, disease induced by Doxorubicin has been considered helpful to the purpose of many studies. The aim of this review article is to describe the animal model of NS induced by the injection of Doxorubicin in rodents, with emphasis on action of the drug, potential mechanisms of renal injury, as well biochemical, histological, and corporal changes obtained with this model.

Exercise therapy normalizes BDNF upregulation and glial hyperactivity in a mouse model of neuropathic pain.

Treatment of neuropathic pain is a clinical challenge likely because of the time-dependent changes in many neurotransmitter systems, growth factors, ionic channels, membrane receptors, transcription factors, and recruitment of different cell types. Conversely, an increasing number of reports have shown the ability of extended and regular physical exercise in alleviating neuropathic pain throughout a wide range of mechanisms. In this study, we investigate the effect of swim exercise on molecules associated with initiation and maintenance of nerve injury-induced neuropathic pain. BALB/c mice were submitted to partial ligation of the sciatic nerve followed by a 5-week aerobic exercise program. Physical training reversed mechanical hypersensitivity, which lasted for an additional 4 weeks after exercise interruption. Swim exercise normalized nerve injury-induced nerve growth factor, and brain-derived neurotrophic factor (BDNF) enhanced expression in the dorsal root ganglion, but had no effect on the glial-derived neurotrophic factor. However, only BDNF remained at low levels after exercise interruption. In addition, exercise training significantly reduced the phosphorylation status of PLCγ-1, but not CREB, in the spinal cord dorsal horn in response to nerve injury. Finally, prolonged swim exercise reversed astrocyte and microglia hyperactivity in the dorsal horn after nerve lesion, which remained normalized after training cessation. Together, these results demonstrate that exercise therapy induces long-lasting analgesia through various mechanisms associated with the onset and advanced stages of neuropathy. Moreover, the data support further studies to clarify whether appropriate exercise intensity, volume, and duration can also cause long-lasting pain relief in patients with neuropathic pain.