Neuroendocrine control of glycogen mobilization in the freshwater snail Lymnaea stagnalis

Abstract

In the freshwater snail Lymnaea stagnalis the anterior mantle region, which mainly consists of large numbers of special glycogen-storing cells, is an important depot for the energy reserves of this snail. In organ culture experiments the central nervous system (CNS), in contrast to other tissues, both inhibits glycogen synthesis (measured as incorporation of [ 14C]glucose into glycogen) and stimulates glycogen breakdown in anterior mantle tissue (measured as a decreased retention of prelabeled glycogen). These effects are dose dependent, with saturation at the highest doses tested. High-potassium Ringer solution stimulates the secretion of a CNS factor which induces glucose release by anterior mantle tissue. This glucose-release-stimulating effect of the CNS is also dose dependent, but saturation of the response was not achieved. It is concluded that inhibition of glycogen synthesis and stimulation of glycogen breakdown and glucose release are probably effects of a single neurohormone which controls glycogen mobilization from the storage cells in the mantle. Like similar factors in other animal phyla, this putative neurohormone is referred to as a hyperglycemic factor.