Tityus serrulatus scorpion venom as a potential drug source for Chagas' disease: Trypanocidal and immunomodulatory activity.

Current chemical therapies for Chagas Disease (CD) lack ability to clear Trypanosoma cruzi (Tc) parasites and cause severe side effects, making search for new strategies extremely necessary. We evaluated the action of Tityus serrulatus venom (TsV) components during Tc infection. TsV treatment increased nitric oxide and pro-inflammatory cytokine production by Tc-infected macrophages (MØ), decreased intracellular parasite replication and trypomastigotes release, also triggering ERK1/2, JNK1/2 and p38 activation. Ts7 demonstrated the highest anti-Tc activity, inducing high levels of TNF and IL-6 in infected MØ. TsV/Ts7 presented synergistic effect on p38 activation when incubated with Tc antigen. KPP-treatment of MØ also decreased trypomastigotes releasing, partially due to p38 activation. TsV/Ts7-pre-incubation of Tc demonstrated a direct effect on parasite decreasing MØ-trypomastigotes releasing. In vivo KPP-treatment of Tc-infected mice resulted in decreased parasitemia. Summarizing, this study opens perspectives for new bioactive molecules as CD-therapeutic treatment, demonstrating the TsV/Ts7/KPP-trypanocidal and immunomodulatory activity during Tc infection.

Phα1ß, a peptide from the venom of the spider Phoneutria nigriventer shows antinociceptive effects after continuous infusion in a neuropathic pain model in rats.

BACKGROUND: Neuropathic pain is a severe painful pathology that is difficult to treat. One option for its management is the continuous intrathecal (i.t.) infusion of ziconotide (the Conus magnus peptide ω-conotoxin MVIIA), which, in addition to being effective, produces serious adverse effects at analgesic doses. Single i.t. administration of Phα1ß, a peptide purified from the venom of the spider Phoneutria nigriventer, has antinociceptive effects with a greater therapeutic window than ziconotide in rodents. To further evaluate its analgesic potential, we investigated the antinociceptive and toxic effects of Phα1ß after single or continuous i.t. infusion in a rat model of neuropathic pain. METHODS: Adult male Wistar rats (200-300 g) bred in-house were used. Chronic constriction injury (CCI) of the sciatic nerve was used as the neuropathic pain model. Nociception was assessed by detecting mechanical hyperalgesia, considering a significant reduction in 50% paw withdrawal threshold values after CCI compared with baseline values. First, we assessed the antinociceptive effect of a single i.t. injection of Phα1ß (10, 30, or 100 pmol/site) in a model of neuropathic pain 8 days after nerve injury. In a different experiment, we delivered Phα1ß (60 pmol/µL/h) or vehicle (phosphate-buffered saline, 1.0 µL/h) through continuous infusion using an osmotic pump by spinal catheterization for 7 days in rats submitted to nerve injury. Behavioral adverse effects were evaluated after single or continuous Phα1ß i.t. administration, and histopathological analysis of spinal cord, brainstem, and encephalon was performed after continuous Phα1ß i.t. injection. RESULTS: We observed that CCI of the sciatic nerve but not sham surgery caused intense (reduction of approximately 2.5 times in mechanical withdrawal threshold) and persistent (up to 14 days) nociception in rats. The single i.t. injection of Phα1ß (30 or 100 pmol/site) reduced neuropathic nociception from 1 to 6 hours after administration, without showing detectable side effects. Similarly, the continuous infusion of Phα1ß (60 pmol/µL/h for 7 days) was also able to reverse nerve injury-induced nociception from 1 to 7 days, but did not cause either behavioral side effects or histopathological changes in the central nervous system. CONCLUSIONS: Thus, we have shown for the first time that the continuous i.t. delivery of Phα1ß produces analgesia disconnected from toxicity in a relevant model of neuropathic pain, indicating that it is an effective and safe drug with a great potential to treat pain.

Phoneutria spider toxins block ischemia-induced glutamate release and neuronal death of cell layers of the retina.

PURPOSE: To investigate the effect of calcium channel blockers, spider toxins, on cell viability and the glutamate content of ischemic retinal slices. METHODS: Rat retinal slices were subjected to ischemia via exposure to oxygen-deprived low-glucose medium for 45 minutes. Slices were either treated or not treated with the toxins PhTx3, Tx3-3, and Tx3-4. After oxygen-deprived low-glucose insult, glutamate content and cell viability were assessed in the slices by confocal and optical microscopy. RESULTS: In the retinal ischemic slices that were treated with PhTx3, Tx3-3, and Tx3-4, confocal imaging showed a decrease in cell death of 79.5 ± 3.1%, 75.5 ± 5.8%, and 61 ± 3.8%, respectively. Neuroprotective effects were also observed 15, 30, 60, and 90 minutes after the onset of the retinal ischemic injury. As a result of the ischemia, glutamate increased from 6.2 ± 1.0 nMol/mg protein to 13.2 ± 1.0 nMol/mg protein and was inhibited by PhTx3, Tx3-3, and Tx3-4 to 8.6 ± 0.7, 8.8 ± 0.9, and 7.4 ± 0.8 nMol/mg protein, respectively. Histologic analysis of the live cells in the outer, inner, and ganglion cell layers of the ischemic slices showed a considerable reduction in cell death by the toxin treatment. CONCLUSION: Spider toxins reduced glutamate content and cell death of retinal ischemic slices.

Phoneutria nigriventer Tx3-3 peptide toxin reduces fibromyalgia symptoms in mice.

Fibromyalgia is characterized by the amplification of central nervous system pain with concomitant fatigue, sleep, mood disorders, depression, and anxiety. It needs extensive pharmacological therapy. In the present study, Swiss mice were treated with reserpine (0.25 mg/kg, s.c.) over three consecutive days, in order to reproduce the pathogenic process of fibromyalgia. On day 4, the administrations of the Tx3-3 toxin produced significant antinociception in the mechanical allodynia (87.16% ±12.7%) and thermal hyperalgesia (49.46% ± 10.6%) tests when compared with the PBS group. The effects produced by the classical analgesics (duloxetine 30 mg/kg, pramipexole 1 mg/kg, and pregabalin 30 mg/kg, p.o., respectively) in both of the tests also demonstrated antinociception. The administrations were able to increase the levels of the biogenic amines (5-HTP and DE) in the brain. The treatments with pramipexole and pregabalin, but not duloxetine, decreased the immobility time in the FM-induced animals that were submitted to the forced swimming test; however, the Tx3-3 toxin (87.45% ± 4.3%) showed better results. Taken together, the data has provided novel evidence of the ability of the Tx3-3 toxin to reduce painful and depressive symptoms, indicating that it may have significant potential in the treatment of FM.

The inhibitory effect of Phα1ß toxin on diabetic neuropathic pain involves the CXCR4 chemokine receptor.

BACKGROUND: Diabetic neuropathy is a common cause of painful diabetic neuropathy (PDN). C-X-C chemokine receptor type 4 (CXCR4) expression is increased in peripheral nerve samples from diabetes patients, suggesting a role for CXCR4 in PDN. Therefore, we evaluated the effects of Phα1ß, ω-conotoxin MVIIA, and AMD3100 in a model of streptozotocin (STZ)-induced PDN in rodents and naïve model of rats with the activation of the CXCR4/stromal cell-derived factor 1 (SDF-1) signal. METHODS: Diabetic neuropathy was induced by intraperitoneal (ip) injection of STZ in Wistar rats. Naïve rats were intrathecally injected with SDF-1 to test the CXCR4/SDF-1 signal. The effects of Phα1ß intrathecal (it), ω-conotoxin MVIIA intrathecal (it), and AMD3100 intraperitoneal (ip) on rat hypersensitivity, IL-6, and the intracellular calcium [Ca2+]i content of diabetic synaptosomes were studied. RESULTS: The drugs reduced the hypersensitivity in diabetic rats. SDF-1 (1.0 µg/it) administration in naïve rats induced hypersensitivity. Phα1ß (100 pmol/it) or AMD3100 (2.5 µg/ip) reduced this hypersensitivity after 2 h treatments, while ω-conotoxin MVIIA did not have an effect. IL-6 and [Ca2+]i content increased in the spinal cord synaptosomes in diabetic rats. The drug treatments reduced IL-6 and the calcium influx in diabetic synaptosomes. CONCLUSIONS: Phα1ß, ω-conotoxin MVIIA, and AMD3100, after 2 h of treatment of STZ-induced PDN, reduced hypersensitivity in diabetic rats. In naïve rats with CXCR4/SDF-1 activation, the induced hypersensitivity decreased after 2 h treatments with Phα1ß or AMD-3100, while ω-conotoxin MVIIA did not affect. The inhibitory effects of Phα1ß on PDN may involve voltage-dependent calcium channels.

Antinociceptive effect of Brazilian armed spider venom toxin Tx3-3 in animal models of neuropathic pain.

Venoms peptides have produced exceptional sources for drug development to treat pain. In this study we examined the antinociceptive and side effects of Tx3-3, a peptide toxin isolated from Phoneutria nigriventer venom, which inhibits high-voltage-dependent calcium channels (VDCC), preferentially P/Q and R-type VDCC. We tested the effects of Tx3-3 in animal models of nociceptive (tail-flick test), neuropathic (partial sciatic nerve ligation and streptozotocin-induced diabetic neuropathy), and inflammatory (intraplantar complete Freund's adjuvant) pain. In the tail-flick test, both intrathecal (i.t.) and intracerebroventricular (i.c.v.) injection of Tx3-3 in mice caused a short-lasting effect (ED(50) and 95% confidence intervals of 8.8 [4.1-18.8] and 3.7 [1.6-8.4] pmol/site for i.t. and i.c.v. injection, respectively), without impairing motor functions, at least at doses 10-30 times higher than the effective dose. By comparison, ω-conotoxin MVIIC, a P/Q and N-type VDCC blocker derived from Conus magus venom, caused significant motor impairment at doses close to efficacious dose in tail flick test. Tx3-3 showed a long-lasting antinociceptive effect in neuropathic pain models. Intrathecal injection of Tx3-3 (30 pmol/site) decreased both mechanical allodynia produced by sciatic nerve injury in mice and streptozotocin-induced allodynia in mice and rats. On the other hand, i.t. injection of Tx3-3 did not alter inflammatory pain. Taken together, our data show that Tx3-3 shows prevalent antinociceptive effects in the neuropathic pain models and does not cause adverse motor effects at antinociceptive efficacious doses, suggesting that this peptide toxin holds promise as a novel therapeutic agent for the control of neuropathic pain. The Brazilian armed spider Tx3-3, a new P/Q and R-type calcium channel blocker, effectively alleviates allodynia in animal neuropathic pain models.