Algogenic auction of melittin ; bee venom

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Honeybee venom produces pain and accompanying inflammation. Bee venom contains many physiologically active substances ; i.e. apamin, melittin and others. The aim of the present study was to investigate whether melittin can be used in the study of pain in humans and rats. Intradermal melittin into the forearm in healthy humans temporally produced a severe pain and a subsequent skin temperature increase monitored by thermograph. Topical application of lidocaine inhibited the temperature increase. Patients with postherpetic neuralgia (PHN) were classified into 2 subgroups. In allodynia group, intradermal melittin into the PHN skin produced a significant pain, although less marked than in the normal skin. Melittin-induced temperature increase in the PHN skin was lower than in the normal skin. In non-allodynia group, intradermal melittin injection into the PHN skin produced little pain and did not elicit any significant temperature increase. These data suggest that C fibers are decreased in … More the PHN skin. This melittin test can be used to assess impairment of C fibers in PHN.The intradermal melittin into the forearm decreased the skin temperature of both palms immediately after the injection, and then increased well above the control level prior to the injection. The duration of the initial decrease was comparable to the duration of pain sensation. The initial decrease was interpreted as sympathetic vasoconstrictor reflex, and the later increase as inhibition of sympathetic vasomotor activity induced by noxious stimulation.Subcutaneous melittin into the hindpaw of pentobarbital-anesthetized rat induced a local skin temperature increase. Subcutaneous bee venom produced a comparable skin temperature increase, but apamin didn't. Melittin injected into the L4 or L5 dorsal root ganglion or sciatic nerve increased the skin temperature. These data suggest that melittin is the algogenic substance and that the melittin-induced skin temperature increase involves neurogenic mechanisms including axon reflexes and dorsal root reflexes. Less