Effect of thyrotropin releasing factor on body weight of the pond snail Lymnaea stagnalis.

Earlier studies had demonstrated that in Lymnaea stagnalis thyrotropin releasing factor (TRF) may be the secretory product of the so-called dark green neurosecretory cells. The dark green cells are believed to serve an osmoregulatory function. If TRF is the secretory product of the dark green cells, it should be capable of controlling the salt and water balance in L. stagnalis. In this study, the effect and fate of synthetic TRF injected in vivo into L. stagnalis was assessed. It was found that TRF caused an increase in the rate of loss of body water which normally occurs after anaesthesia. TRF also increased the loss of body water when it was administered to unanaesthetized animals. The peptide was accumulated and degraded by the tissues of the foot, mantle, and head regions, tissues which are believed to be the targets of the hormone of the dark green cells. Our results support the hypothesis that TRF may be the secretory product of the dark green cells and may be involved in osmoregulation in L. stagnalis.