Authors:Magda Alania, Varya Dyakonova, and D. A. Sakharov
In the pond snail Lymnaea stagnalis, D-glucose action was investigated on electrical activity of identified central neurons. In the CNS preparations isolated from specimens that starved for 24-96 h, D-glucose added to a standard or HiDi saline at 500-700 mg/ml effectively hyperpolarized ca. 90% of feeding related neurons B1, SO and CGC. However, not all feeding-related neurons examined were responsive to glucose. Experiments on cells of the serotonergic Pedal A cluster have shown that hyperpolarizing action of D-glucose is retained following complete isolation of «hunger» neurons. Threshold concentration producing 1-3 mV hyperpolarization was ca. 50 mg/ml. The results suggest a direct glucose involvement in the mechanisms that control feeding behavior in Lymnaea.
Authors:Magda Alania, D. Vorontsov, and D. Sakharov
A novel excitatory higher-order input (named Input-HO) to the feeding network of the pond snail,
, as well as a reliable procedure that makes it possible to initiate and maintain the Input-HO, are described. The Input-HO is primarily targeted to two bilaterally symmetrical pairs of extrabuccal projecting interneurons, the serotonergic Cerebral Giant Cells (CGCs or C1) and FMRFamidergic Pleural-Buccal cells (PlBs). Judging from the results of transection experiments, Input-HO originates in the paired cerebral ganglia where its left and right sources coexist. These sources discharge independently or, sometimes, one after the other. Both inputs project to the ipsilateral CGC/PlB only. In turn, the activity of PlB decreases the frequency of Input-HO bouts. We suggest that the Input-HO represents a prominent part of the mechanism controlling feeding behavior in