Melittin-induced tonic pain model is characterized by local inflammation, edema, spontaneous flinchings, and sustained mechanical hypersensitivity. These nociceptive responses are mediated through selective activation of capsaicin-sensitive primary afferent fibers by melittin. The present study was undertaken to elucidate the role of peripheral 5-hydroxytryptamine (5-HT) receptors in the melittin-induced nociceptive responses. Changes in mechanical threshold, flinching behaviors and paw thickness were measured in rat intraplantarly injected with melittin (40microgram/paw) alone or treated together with melittin and 5-HT receptor antagonists. WAY-100635 (100microgram & 200microgram/paw), isamoltane hemifumarate (100microgram & 200microgram/paw), methysergide maleate (60microgram, 120microgram & 200microgram/paw) and ICS-205,930 (100microgram & 200microgram/paw) were intraplantarly injected 20 min before melittin injection. All 5-HT receptor antagonists tested in this experiment significantly attenuated the ability of melittin to reduce mechanical threshold and to induce flinching behaviors. 5-HT receptor antagonists, except ICS-205,930, had mild inhibitory effect on melittin-induced edema. These experimental findings suggest that multiple peripheral 5-HT receptors are involved in the melittin-induced nociceptive responses.
Animals ; Edema ; Hypersensitivity ; Inflammation ; Melitten ; Methysergide ; Rats* ; Receptors, Serotonin ; Serotonin*

Intraplantar injection of melittin has been known to induce sustained decrease of mechanical threshold and increase of spontaneous flinchings. The present study was undertaken to investigate how the melittin-induced nociceptive responses were modulated by changes of metabotropic glutamate receptor (mGluR) activity. Changes in paw withdrawal threshold (PWT), number of flinchings and paw thickness were measured at a given time point after injection of melittin (10microgram/paw) into the mid-plantar area of rat hindpaw. To observe the effects of mGluRs on the melittin-induced nociceptions, group I mGluR (AIDA, 100microgram and 200microgram), mGluR1 (LY367385, 50microgram and 100microgram) and mGluR5 (MPEP, 200microgram and 300microgram) antagonists, group II (APDC, 100microgram and 200microgram) and III (L-SOP, 100microgram and 200microgram) agonists were intrathecally administered 20 min before melittin injection. Intraplantar injection of melittin induced a sustained decrease of mechanical threshold, spontaneous flinchings and edema. The effects of melittin to reduce mechanical threshold and to induce spontaneous flinchings were significantly suppressed following intrathecal pre-administration of group I mGluR, mGluR1 and mGluR5 antagonists, group II and III mGluR agonists. Group I mGluR antagonists and group II and III mGluR agonists had no significant effect on melittin-induced edema. These experimental findings indicate that multiple spinal mGluRs are involved in the modulation of melittin-induced nociceptive responses.
Animals ; Edema ; Melitten ; Nociception ; Rats ; Receptors, Metabotropic Glutamate

BACKGROUND: Bee venom (BV) has been widely investigated for potential medical uses. Recent inadvertent uses of BV based products have shown to mitigate signs of fungal infections. However, the component mediating the antifungal effect has not been identified. OBJECTIVE: This investigation compares bee venom in its whole and partial forms to evaluate the possible component responsible for the antifungal effect. METHODS: Forty-eight plates inoculated with Trichophyton rubrum were allocated into four groups. The groups were treated with raw BV (RBV), melittin, apamin and BV based mist (BBM) respectively and each group was further allocated accordingly to three different concentrations. The areas were measured every other day for 14 days to evaluate the kinetic changes of the colonies. RESULTS: The interactions of ratio differences over interval were confirmed in groups treated with RBV and BBM. In RBV, the level of differences were achieved in groups treated with 10 mg/100 µl (p=0.026) and 40 mg/100 µl (p=0.000). The mean difference of ratio in groups treated with RBV was evident in day 3 and day 5. The groups that were treated with melittin or apamin did not show any significant interaction. In BBM groups, the significant levels of ratio differences over time intervals were achieved in groups treated with 200 µl/100 µl (p=0.000) and 300 µl/100 µl (p=0.030). CONCLUSION: The the bee venom in its whole form delivered a significant level of inhibition and we concluded that the venom in separated forms are not effective. Moreover, BV based products may exert as potential antifungal therapeutics.
Antifungal Agents ; Apamin ; Bee Venoms* ; Bees* ; Melitten ; Negotiating ; Trichophyton* ; Venoms

OBJECTIVETo investigate the anti-tumor effects of melittin against malignant human glioma cells in vitro.

METHODSTwo malignant human glioma cell lines (U87 and U251) were treated with melittin at various concentrations, and the cell growth inhibition and apoptosis were evaluated using MTT assay, flow cytometry and agarose gel electrophoresis.

RESULTSMelittin could obviously inhibit the proliferation of the two glioma cell lines (P<0.05). At the concentrations of 1, 10, 20, 40, 80, 160, 200 mg/L, melittin resulted in U87 cell apoptosis rates of 12.80%, 16.92%, 22.69%, 34.05%, 41.82%, 59.87%, and 80.25%, and in U251 cell apoptosis rate of 11.61%, 16.21%, 22.03%, 30.57%, 41.10%, 58.33%, and 79.12%, respectively, showing a dose-dependent effect in its action of inducing cell apoptosis.

CONCLUSIONMelittin inhibits the proliferation and induces apoptosis of malignant human glioma cell lines in vitro.

Apoptosis ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Glioma ; metabolism ; pathology ; Humans ; Melitten ; pharmacology

To retain the anti-rheumatoid arthritis activity of melittin and to reduce the hemolysis and hypersusceptibility caused by melittin, a deletion peptide of melittin was synthesized. Its ant-inflammation effect was observed . A hydrophile peptide fragment of melittin was synthesized by standard solid-phase method. The product was analyzed by HPLC and MS. The relevant hemolysis and hypersusceptibility were tested. The rabbits' model of immune arthritis were established and treated. The results showed that the hemolysis rate for peptide fragment was less than 5%, the hypersusceptibility rate was less than 8%. The hydrophile peptide fragment of melittin may retain anti-rheumatoid arthritis activity and reduce the melittin-induced hemolysis and hypersusceptibility.
Animals ; Arthritis, Rheumatoid ; therapy ; Melitten ; chemical synthesis ; therapeutic use ; Peptide Fragments ; chemical synthesis ; therapeutic use ; Rabbits

The study was aimed to investigate the possibility of enhancing transfection efficiency of branched polyethylenimine (BPEI) in HeLa cells by hydrophobic tail of bee venom peptide (melittin). Hydrophobic tail of melittin was synthesized and its membrane permeable activity was evaluated by hemolysis test. The peptide was mixed with BPEI and the transfection efficiency was determined in HeLa cells by using green fluorescent protein gene (GFP) as a reporter gene. The cytotoxicity of the mixture was analyzed by MTT assay at 24 hours after transfection. The results indicated that the synthesized peptide had permeable activity leading to hemolysis in both neutral and acidic solution. At optimal condition, the peptide could significantly improve the transfection efficiency of BPEI and the cytotoxicity of the mixture was lower than BPEI itself. It is concluded that hydrophobic tail of melittin may be a potential enhancer to improve transfection efficiency mediated by cationic polymers in difficult to transfect cells.
HeLa Cells ; Humans ; Hydrophobic and Hydrophilic Interactions ; Melitten ; chemistry ; genetics ; Peptides ; chemistry ; Polyethyleneimine ; pharmacology ; Transfection

The effects of extremely low frequency electromagnetic fields (EMF) on intracellular Ca2+ mobilization and cellular function in RBL 2H3 cells were investigated. Exposure to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h did not produce any cytotoxic effects in RBL 2H3 cells. Melittin, ionomycin and thapsigargin each dose-dependently increased the intracellular Ca2+ concentration. The increase of intracellular Ca2+ induced by these three agents was not affected by exposure to EMF (60 Hz, 1 mT) for 4 or 16 h in RBL 2H3 cells. To investigate the effect of EMF on exocytosis, we measured beta-hexosaminidase release in RBL 2H3 cells. Basal release of beta-hexosaminidase was 12.3+/-2.3% in RBL 2H3 cells. Exposure to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h did not affect the basal or 1 microM melittin-induced beta-hexosaminidase release in RBL 2H3 cells. This study suggests that exposure to EMF (60 Hz, 0.1 or 1 mT), which is the limit of occupational exposure, has no influence on intracellular Ca2+ mobilization and cellular function in RBL 2H3 cells.
beta-N-Acetylhexosaminidases ; Electromagnetic Fields ; Exocytosis ; Ionomycin ; Melitten ; Occupational Exposure ; Thapsigargin

The role of phospholipase A2 (PLA2) in tumor cell growth was investigated using SK-N-MC human neuroblastoma cells. 4-Bromophenacyl bromide (BPB) and mepacrine (Mep), known PLA2 inhibitors, suppressed growth of the tumor cells in a dose-dependent manner without a significant cytotoxicity. Melittin (Mel), a PLA2 activator, enhanced the cell growth in a concentration-dependent fashion. The growth-enhancing effects of Mel were significantly reversed by the co-treatment with PLA2 inhibitors. In addition, Mel induced intracellular Ca2+ release from internal stores like as did serum, a known intracellular Ca2+ agonist in the tumor cells. Intracellular Ca2+ release induced by these agonists was significantly blocked by PLA2 inhibitors at growth-inhibitory concentrations. Arachidonic acid (AA), a product of the PLA2-catalyzed reaction, induced cell growth enhancement and intracellular Ca2+ release. These effects of AA were significantly blocked by BAPTA/AM, an intracellular Ca2+ chelator. Taken together, these results suggest that the modulation of PLA2 activity may be one of the regulatory mechanisms of cell growth in human neuroblastoma cells. Intracellular Ca2+ may act as a key mediator in the PLA2-induced growth regulation.
Arachidonic Acid ; Cell Proliferation* ; Humans* ; Melitten ; Negotiating* ; Neuroblastoma* ; Phospholipases A2 ; Phospholipases* ; Quinacrine

The present study was undertaken to confirm whether melittin, a major constituent of whole bee venom (WBV), had the ability to produce the same nociceptive responses as those induced by WBV. In the behavioral experiment, changes in mechanical threshold, flinching behaviors and paw thickness (edema) were measured after intraplantar (i.pl.) injection of WBV (0.1 mg & 0.3 mg/paw) and melittin (0.05 mg & 0.15 mg/paw), and intrathecal (i.t.) injection of melittin (6microgram). Also studied were the effects of i.p. (2 mg & 4 mg/kg), i.t. (0.2microgram & 0.4microgram) or i.pl. (0.3 mg) administration of morphine on melittin- induced pain responses. I.pl. injection of melittin at half the dosage of WBV strongly reduced mechanical threshold, and increased flinchings and paw thickness to a similar extent as those induced by WBV. Melittin- and WBV-induced flinchings and changes in mechanical threshold were dose- dependent and had a rapid onset. Paw thickness increased maximally about 1 hr after melittin and WBV treatment. Time-courses of nociceptive responses induced by melittin and WBV were very similar. Melittin-induced decreases in mechanical threshold and flinchings were suppressed by i.p., i.t. or i.pl. injection of morphine. I.t. administration of melittin (6microgram) reduced mechanical threshold of peripheral receptive field and induced flinching behaviors, but did not cause any increase in paw thickness. In the electrophysiological study, i.pl. injection of melittin increased discharge rates of dorsal horn neurons only with C fiber inputs from the peripheral receptive field, which were almost completely blocked by topical application of lidocaine to the sciatic nerve. These findings suggest that pain behaviors induced by WBV are mediated by melittin-induced activation of C afferent fiber, that the melittin- induced pain model is a very useful model for the study of pain, and that melittin-induced nociceptive responses are sensitive to the widely used analgesics, morphine.
Analgesics ; Bee Venoms* ; Bees* ; Lidocaine ; Melitten* ; Morphine ; Nerve Fibers, Unmyelinated ; Nociception ; Posterior Horn Cells ; Sciatic Nerve

The stability of melittin in different solvents (water, deoxygenated water, physiological saline, PBS, 50% ethanol, ethanol, glycerol)was studied and the results showed that the stability of melittin is not influenced by light, temperature and pH in 50% ethanol, which melittin can be completed dissolved when compared with ethanol and glycerol, in such, 50% ethanol was chosen as solvent storage when measured content of melittin. Then the effect of different concentrations of PBS, the pH of PBS and rat skin ho- mogenates were tested, and the results showed that melittin was degraded rapidly at low concentration solution and low ionic strength. Increasing pH of PBS and rat skin homogenate can accelerate the degradation of melittin. These researches provide an experimental ba- sis for further study of melittin.
Animals ; Drug Stability ; Ethanol ; chemistry ; Hydrogen-Ion Concentration ; Melitten ; chemistry ; Rats ; Skin ; drug effects ; Solvents ; chemistry ; Temperature