Hormonal factors from the mammalian pineal gland interfere with cell development in Hydra.

A partially purified, melatonin-free low-molecular-weight extract from the ovine pineal gland with antitumor activity (YC05R), interferes with terminal differentiation in the interstitial cell line of Hydra. Nematoblasts developed into defective nematocytes that were subject to cell death and the tentacles eventually became devoid of nematocytes. In an attempt to identify the causative components of the extract, several known potential constituents were assayed. Two factors were found to have similar effects, although only in rather high concentrations: 1alpha, 25 dihydroxyvitamin D3 (>150 nM) and pinoline (>5 microM), a natural tryptophan-derived beta-carboline. The proliferative activity in the interstitial cell line was only slightly reduced by these factors. Two other beta-carbolines that occur in the mammalian brain, harmine (10 microM) and n-butyl-beta-carboline-3-carboxylate (beta-CCB), caused the premature death of epithelial cells and thus the development of dwarfish animals which, however, continued to generate new animals by budding. The pineal extract probably contains some more, still unidentified components that interfere more potently with cell development, in Hydra as well as in mammals.