Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa 769-2193, Japan.
J Exp Biol. 2010 Sep 15;213(Pt 18):3144-9. doi: 10.1242/jeb.046938.
The tentacles of pulmonates regenerate spontaneously following amputation. The regenerated tentacle is equipped with all the elements necessary for normal olfactory functioning, and the slugs can behave as well as they did before the tentacle amputation. However, it is not known what changes occur to the olfactory center procerebrum in the brain at the morphological and physiological levels. Here, we investigated the innervation of tentacular nerves into the procerebrum by examining the size of the terminal mass (input layer from tentacular nerves) of the procerebrum and also by staining afferent nerves immunohistochemically at 15, 58 and 75 days following unilateral amputation of the superior and inferior tentacles. The size of the terminal mass was significantly decreased, and the Phe-Met-Arg-Phe-NH(2)ergic (FMRFamidergic) afferent nerves disappeared by 15 days following the tentacle amputation. However, the size of the terminal mass had recovered substantially by 58 days, as the tentacle regenerated. The FMRFamidergic innervation into the cerebral ganglion was also restored by this time. An extended recovery (75 days), however, did not result in any further increase in the size of the terminal mass. We also recorded the local field potential (LFP) oscillation in the procerebrum. We found that the oscillatory frequency of the LFP had decreased at 15 days following the tentacle amputation but had recovered at 58 and 75 days. These results suggest that the amputation and regrowth of the tentacle are accompanied by the respective degeneration and re-innervation of olfactory nerves, and these changes in the innervation status affect the basal state of LFP oscillation.
肺螺类的触角在截肢后会自发再生。再生的触角配备了正常嗅觉功能所需的所有元素，而蛞蝓的行为表现可以与触角未截肢前一样好。然而，目前尚不清楚在形态和生理水平上，大脑中的前脑 procerebrum 的嗅觉中枢会发生什么变化。在这里，我们通过检查前脑 procerebrum 的终末质量（来自触角神经的输入层）的大小，以及在单侧上、下触角截肢后 15、58 和 75 天用免疫组织化学染色法染色传入神经，研究了触角神经对前脑 procerebrum 的神经支配。终末质量显著减小，并且在触角截肢后 15 天，Phe-Met-Arg-Phe-NH2 能（FMRFamidergic）传入神经消失。然而，随着触角再生，终末质量已经恢复了相当大的一部分。到此时，FMRFamidergic 传入神经也已经恢复到大脑神经节。然而，一个扩展的恢复（75 天）并没有导致终末质量的进一步增加。我们还记录了前脑 procerebrum 中的局部场电位（LFP）振荡。我们发现，在触角截肢后 15 天，LFP 的振荡频率降低，但在 58 天和 75 天恢复。这些结果表明，触角的截肢和再生伴随着嗅觉神经的各自退化和再支配，这种支配状态的变化会影响 LFP 振荡的基础状态。
