Modulation of nicotinic acetylcholine and N-methyl-d-aspartate receptors by some Hymenopteran venoms

IgE cross-reactivity of phospholipase A2 and hyaluronidase of Apis dorsata (Giant Asian Honeybee) and Apis mellifera (Western Honeybee) venom: Possible use of A. mellifera venom for diagnosis of patients allergic to A. dorsata venom

Diagnostic and therapeutic reagents are unavailable for anaphylaxis arising from stings by Apis dorsata. Venom profiles and cross-reactivity of A. dorsata and Apis mellifera were compared, to ascertain whether venom of A. mellifera can be used for diagnosis in A. dorsata allergy. Both venom profiles were similar by High Performance Liquid Chromatography and SDS-PAGE. Sera of 29 of 30 (96.7%) patients with anaphylaxis to A. dorsata stings had IgE to the phospholipase-2 (PLA₂) doublet (15 and 16 kDa) of A. dorsata venom by immunoblot, compared to 26 of 30 (86.7%) with the PLA₂ of A. mellifera and a purified preparation of PLA₂. Twelve patients (40%) with severe anaphylaxis had IgE reactivity to a 39 kDa protein band of venom of both species, a third band, identified in immunoblot as hyaluronidase. The cross-reactivity of PLA₂ and hyaluronidase of A. dorsata and A. mellifera were further confirmed by immunoblot inhibition results. Twenty five of 30 (83.3%) of our patients had positive venom specific IgE (>0.35 KU_A/L) reactivity to Phadia ImmunoCAPs of A. mellifera venom. The observed IgE cross reactivity suggests the possibility of using A. mellifera venom as a diagnostic test for A. dorsata venom allergy.

N-(4-Trifluoromethylphenyl)amide group of the synthetic histamine receptor agonist inhibits nicotinic acetylcholine receptor-mediated catecholamine secretion

The therapeutic targeting of nicotinic receptors requires the identification of drugs that selectively activate or inhibit a limited range of nicotine acetylcholine receptors (nAChRs). In this study, we identified N-(4-trifluoromethylphenyl)amide group of the synthetic histamine receptor ligands, histamine-trifluoromethyltoluide, that act as potent inhibitors of nAChRs in bovine adrenal chromaffin cells. Catecholamine secretion induced by the nAChRs agonist, 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP), was significantly inhibited by histamine-trifluoromethyltoluide. Real time carbon-fiber amperometry confirmed the ability of histamine-trifluoromethyltoluide to inhibit DMPP-induced exocytosis in single chromaffin cells. We also found that histamine-trifluoromethyltoluide inhibited DMPP-induced [Ca(2+)](i) and [Na(+)](i) increases, as well as DMPP-induced inward currents in the absence of extracellular calcium. Histamine-trifluoromethyltoluide had no effect on [(3)H]nicotine binding or on calcium increases induced by high K(+), bradykinin, veratridine, histamine, and benzoylbenzoyl ATP. Among the synthetic histamine receptor ligands, clobenpropit exhibited similarity. In addition, 4'-nitroacetanilide also significantly attenuated nAChR-mediated catecholamine secretion. In conclusion, the N-(4-trifluoromethylphenyl)amide group of the histamine-trifluoromethyltoluide might be the critical moiety in the inhibition of nAChR-mediated CA secretion.