Somatostatin and calcitonin stimulate neurite regeneration of molluscan neurons in vitro.

Isolated neurons from the gastropod Physella heterostropha fail to regenerate their neurites if cultured in defined medium in the absence of growth factors. A significant number of cultured neurons extend neurites if they are cultured in brain-conditioned or hemocyte-conditioned medium. Synthetic somatostatin and salmon calcitonin also stimulate neurite regeneration in a dose-dependent manner. Thyrotropin-releasing hormone, arginine vasotocin, and eledoisin fail to promote neurite outgrowth. It is concluded that, like other molluscan neurons, isolated neurons from Physella require the presence of factors that are released by brain tissue or are present in the hemolymph, and that somatostatin and calcitonin can, in part, substitute for the endogenous neurite-regenerating activities.