Octopus arm regeneration: Role of acetylcholinesterase during morphological modification

Abstract

The ability to regenerate whole-body structures has been long studied in both vertebrate and invertebrate animal models. Due to this regeneration capability here we propose the use of the Cephalopod Octopus vulgaris as a model of regeneration. We investigated the involvement of acetylcholinesterase (AChE) in the octopus arm regeneration. AChE has been demonstrated to have non-cholinergic functions in various cell types and to be involved in the regulation of cell proliferation, differentiation and apoptosis. In order to follow cell replacement in the octopus arm, we first assessed the expression of specific markers involved in cellular proliferation (AgNOR and PCNA). We showed that the activity of the enzyme AChE is related to the proliferation stage of the arm regenerative process. In the very initial stages of regrowth when most of the proliferation activity was at the level of the ‘blastema’ the cholinesterase activity was very low. AChE activity climbed slowly during the subsequent phase of cellular multiplication and, by the onset of morphogenesis, the activity rose sharply and active myogenesis was observed. AChE activity decreased then till reaching basal level at the time when the process of histogenesis occurred and the reestablishment of all the structures became evident. Interestingly AgNOR and AChE assay showed a similar trend in particular during the stages when the morphogenesis was mostly dependent upon cell proliferation. We suggest that AChE protein may have an important influence in the process of regeneration and that it could be considered as a potential target to promote or regulate the regenerative process.