de Brito Sanchez María Gabriela, Kaissling Karl-Ernst
Laboratorio de Fisiología de Insectos, FCEyN, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina.
Chem Senses. 2005 Jun;30(5):435-42. doi: 10.1093/chemse/bji038. Epub 2005 May 18.
As shown in single-sensillum recordings, iodobenzene has a bimodal effect on the receptor cell tuned to benzoic acid (BA) of the female silk moth Bombyx mori. Exposure to iodobenzene causes an inhibition of the response to BA. With stimulation by iodobenzene alone, a reduction of basic nerve impulse firing during exposure is followed by a transient post-stimulus excitation (rebound). We suggest that inhibition suppresses excitation during exposure but fades afterwards more rapidly than excitation. Due to the spatial equivalence of the iodine and the acid residue, these effects might indicate opposing interactions of iodobenzene with the specific site for the key compound BA. This is supported by the fact that substitutions by smaller halogens are less effective in both inhibition and rebound. The inhibitory effect but not the rebound with iodobenzene alone was also observed in receptor cells tuned to key compounds other than benzoic acid, e.g. in the cell most sensitive to 2,6-dimethyl-5-heptene-2-ol (DMH-cell) occurring in the same sensillum as the BA-cell, or in the bombykol- and bombykal-cells of the male. At least in these cells the inhibitory effect might reflect the action of iodobenzene on a general site, e.g. the lipid matrix of the plasma membrane of the receptor cells.
如单感器记录所示，碘苯对家蚕雌蛾中调谐至苯甲酸（BA）的受体细胞具有双峰效应。接触碘苯会抑制对BA的反应。仅用碘苯刺激时，接触期间基本神经冲动发放减少，随后是刺激后的短暂兴奋（反弹）。我们认为，抑制作用在接触期间抑制兴奋，但之后比兴奋更快消退。由于碘和酸残基在空间上等效，这些效应可能表明碘苯与关键化合物BA的特定位点存在相反的相互作用。较小卤素取代在抑制和反弹方面效果较差这一事实支持了这一点。在调谐至除苯甲酸以外的关键化合物的受体细胞中，例如在与BA细胞位于同一感器中的对2,6 - 二甲基 - 5 - 庚烯 - 2 - 醇最敏感的细胞（DMH细胞）中，或在雄蛾的蚕蛾醇和蚕蛾醛细胞中，也观察到仅碘苯的抑制作用而非反弹作用。至少在这些细胞中，抑制作用可能反映了碘苯对一个通用位点的作用，例如受体细胞质膜的脂质基质。
