Publications by authors named "Ivo Lebrun"

Although proteins in snake venoms have been extensively studied and characterized, low-mass molecules remain relatively unexplored, mainly due to their low abundance, secondary role in envenomation, and some analytical technique limitations. However, these small molecules can provide new important data related to venom toxins' molecular structure, functions, and evolutionary relationships. This research aimed to characterize molecules below 10 kDa in the venoms of snakes from the Viperidae families (Bothrops, Agkistrodon, and Bitis) and compare two chromatographic approaches: reverse-phase chromatography (RP), a classic technique, and hydrophilic interaction liquid chromatography (HILIC), an alternative technique, both coupled with high-resolution mass spectrometry (HRMS).

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Article Synopsis
  • Body temperature regulation is managed by the hypothalamus, and envenomation can cause various symptoms related to thermoregulation, such as hypothermia and hyperthermia.
  • This study explores the effects of venom on thermoregulation using rats and identifies specific venom components responsible for these effects through various laboratory techniques.
  • The findings suggest that certain venom molecules can affect temperature regulation and may lead to the discovery of new drugs, but more research is needed to fully understand these toxins.
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Ketamine is an anesthetic drug that also has antidepressant properties, with quick action. Despite the great number of studies showing its effectiveness as a treatment for major depression, there is little information about its effects on postpartum depression, as pharmacological treatments bring risks to the health of both mother and child. Thus, this study aimed to evaluate the effects of prolonged treatment with subanesthetic doses of ketamine in a rat model of postpartum depression.

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Background: The tremor mutant mice present motor impairments comprised of whole-body tremors, ataxia, decreased exploratory behavior, and audiogenic seizures.

Objectives: This study aims to investigate the development of motor dysfunction in this mutant mouse and the relationships with cortical, striatal, and cerebellar levels of GABA, glutamate, glycine, dopamine (DA), serotonin (5-HT), noradrenaline (NOR), and its metabolites. The serum cytokines levels, myelin content, and the astrocytic expression of the glial fibrillary acidic protein (GFAP) investigated the possible influence of inflammation in motor dysfunction.

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Posterior hypothalamic-deep brain stimulation (pHyp-DBS) has been reported as a successful treatment for reducing refractory aggressive behaviors in patients with distinct primary diagnoses. Here, we report on a patient with cri du chat syndrome presenting severe self-injury and aggressive behaviors toward others, who was treated with pHyp-DBS. Positive results were observed at long-term follow-up in aggressive behavior and quality of life.

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Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is considered the gold-standard treatment for PD; however, underlying therapeutic mechanisms need to be comprehensively elucidated, especially in relation to glial cells. We aimed to understand the effects of STN-microlesions and STN-DBS on striatal glial cells, inflammation, and extracellular glutamate/GABAergic concentration in a 6-hydroxydopamine (6-OHDA)-induced PD rat model. Rats with unilateral striatal 6-OHDA and electrodes implanted in the STN were divided into two groups: DBS OFF and DBS ON (5 days/2 h/day).

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Postpartum depression is a mentally disabling disease with multifactorial etiology that affects women worldwide. It can also influence child development and lead to behavioral and cognitive alterations. Despite the high prevalence, the disease is underdiagnosed and poorly studied.

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Tb II-I isolated from venom causes epileptic-discharges when injected into the hippocampus of rats. The involvement of neurotransmitters in this activity was investigated. Our results demonstrated that Tb II-I increases the concentrations of dopamine metabolite but does not alter other neurotransmitters.

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Patients bitten by snakes consistently manifest a bleeding tendency, in which thrombocytopenia, consumption coagulopathy, mucous bleeding, and, more rarely, thrombotic microangiopathy, are observed. Von Willebrand factor (VWF) is required for primary hemostasis, and some venom proteins, such as botrocetin (a C-type lectin-like protein) and snake venom metalloproteinases (SVMP), disturb the normal interaction between platelets and VWF, possibly contributing to snakebite-induced bleedings. To understand the relationship among plasma VWF, platelets, botrocetin and SVMP from Bothrops jararaca snake venom (BjV) in the development of thrombocytopenia, we used (a) Wistar rats injected s.

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Background: Intermittent explosive disorder (IED) is a psychiatric disorder characterized by recurrent outbursts of aggressive behavior. Deep brain stimulation (DBS) in the posteromedial nucleus of the hypothalamus (pHyp) is an alternative therapy for extreme cases and shows promising results. Intraoperative microdialysis can help elucidate the neurobiological mechanism of pHyp-DBS.

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The insula has emerged as a critical target for electrical stimulation since it influences pathological pain states. We investigated the effects of repetitive electrical stimulation of the insular cortex (ESI) on mechanical nociception, and general locomotor activity in rats subjected to chronic constriction injury (CCI) of the sciatic nerve. We also studied neuroplastic changes in central pain areas and the involvement of GABAergic signaling on ESI effects.

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The tremor mutant phenotype results from an autosomal recessive spontaneous mutation arisen in a Swiss-Webster mouse colony. The mutant mice displayed normal development until three weeks of age when they began to present motor impairment comprised by whole body tremor, ataxia, and decreased exploratory behavior. These features increased in severity with aging suggesting a neurodegenerative profile.

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Secreted autotransporter toxin (Sat) is a 107-kDa serine protease autotransporter of Enterobacteriaceae (SPATE) presenting cytotoxic activity in renal and bladder cells. Further studies have detected the Sat-encoding gene (sat) in enteroaggregative Escherichia coli (EAEC) and in E. coli strains isolated from neonatal septicemia and meningitis.

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Background: Here, we described the presence of a neurotoxin with phospholipase A activity isolated from venom (Mlx-8) with affinity for muscarinic acetylcholine receptors (mAChRs).

Methods: The purification, molecular mass determination, partial amino acid sequencing, phospholipase A activity determination, inhibition of the binding of the selective muscarinic ligand [H]QNB and inhibition of the total [H]inositol phosphate accumulation in rat hippocampus of the Mlx-8 were determined.

Results: Thirty-one fractions were collected from HPLC chromatography, and the Mlx-8 toxin was used in this work.

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Here, we report the neurotoxic effects aroused by the intracerebral injection (in rats) of Tb1, which is a neurotoxin isolated from scorpion venom. Biochemical analyses have demonstrated that this toxin is similar to the gamma toxin from , which is a β-scorpion toxin that acts on sodium channels, causing the activation process to occur at more hyperpolarized membrane voltages. Male Wistar rats were stereotaxically implanted with intrahippocampal electrodes and cannulas for electroencephalographic recording and the evaluation of amino acid neurotransmitters levels.

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Varenicline is a drug used for smoking addiction cessation treatment and acts as a partial agonist of nicotinic cholinergic receptors. Recent clinical trial data support use of varenicline for treatment of conditions/addictions that are not related to smoking cessation. Considering the importance of this issue and the need for new studies on its effects, especially on behavior, more studies using animal models are necessary.

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Objective: Motor cortex stimulation (MCS) is a neurosurgical technique used to treat patients with refractory neuropathic pain syndromes. MCS activates the periaqueductal gray (PAG) matter, which is one of the major centers of the descending pain inhibitory system. However, the neurochemical mechanisms in the PAG that underlie the analgesic effect of MCS have not yet been described.

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Studies of scorpion venoms have used different venom drying methods: lyophilization, desiccation, lyophilization after mixing with 0.9% saline or purified water and centrifugation. The aim of this study was to see if these different approaches cause some alteration in the composition of the venom or interfere with its biological effects.

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Estrogen and phytoestrogens, mainly isoflavones (SIF) treatment has been suggested to improve mood, behavior, and cognitive function in postmenopausal women. However, there is a lack of information on the mechanism of such treatment on the central nervous system. We used rats to investigate the effects of long-term treatment with commercial isoflavones on behavior, hormones, and brain neurotransmitter levels.

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The venom of Micrurus lemniscatus, a coral snake of wide geographical distribution in South America, was fractionated by reverse-phase HPLC and the fractions screened for phospholipase A2 (PLA2) activity. The major component of the venom, a PLA2, here referred to as 'Lemnitoxin', was isolated and characterized biochemically and toxicologically. It induces myotoxicity upon intramuscular or intravenous injection into mice.

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Article Synopsis
  • TsTX-I, derived from Tityus serrulatus scorpion venom, triggers seizure-like activity in the central nervous system.
  • The study focused on how excitatory amino acids and cytokines, particularly IFN-γ, were involved in this process.
  • Results showed that while TsTX-I boosts IFN-γ release, it doesn't affect the levels of excitatory amino acids, suggesting IFN-γ plays a more crucial role in convulsions than glutamate.
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  • Mastoparan is a peptide from wasp venom that demonstrates various biological effects, such as antimicrobial properties and the ability to induce cell death.
  • In studies using B16F10-Nex2 melanoma cells, mastoparan triggered cell death through the mitochondrial apoptosis pathway, confirmed by methods like the Annexin V-FITC/PI assay and DNA degradation.
  • Additionally, mastoparan showed promising results in vivo by reducing melanoma growth and improving survival rates in mice, indicating its potential as a therapeutic agent against this type of cancer.
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The neurotoxicity of two secreted Phospholipases A2 from Brazilian coral snake venom in rat primary hippocampal cell culture was investigated. Following exposure to Mlx-8 or Mlx-9 toxins, an increase in free cytosolic Ca(2+) and a reduction in mitochondrial transmembrane potential (ΔΨm) became evident and occurred prior to the morphological changes and cytotoxicity. Exposure of hippocampal neurons to Mlx-8 or Mlx-9 caused a decrease in the cell viability as assessed by MTT and LDH assays.

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Breast cancer is the world's leading cause of death among women. This situation imposes an urgent development of more selective and less toxic agents. The use of natural molecular fingerprints as sources for new bioactive chemical entities has proven to be a quite promising and efficient method.

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Serogroup B outer membrane vesicles (OMV) with iron regulated proteins (IRP) from Neisseria meningitidis constitute the antigen for the vaccine against the disease caused by this bacterium. Aiming to enhance final OMV concentration, seven batch experiments were carried out under four different conditions: (i) with original Catlin medium; (ii) with original Catlin medium and lactate and amino acids pulse at the 6th cultivation hour; (iii) with Catlin medium with double initial concentrations of lactate and amino acids and (iv) Catlin medium without glycerol and with double initial concentrations of lactate and amino acids. The cultivation experiments were carried out in a 7-L bioreactor under the following conditions: 36°C, 0.

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