Modulatory action of oxytocin on electrical responses of the neurons in the snail Helix pomatia

Abstract

1. 1. We have studied the influence of 10–100 nM oxytocin (OXT) added to the extracellular solution on electrical responses in Helix pomatia snail neurons. 2. 2. Certain neuronal responses were found to increase in the OXT-containing solution (OXT-solution). The following responses were studied: (a) to the stimulation of excitatory interneuron; (b) to application of the endogenous peptide; (c) to the OXT application; (d) to the intracellular cAMP injection. 3. 3. We observed a decrease of neuronal response to acetylcholine application in the OXT-containing solution and during cAMP injection. 4. 4. The intracellular injection of OXT increased the amplitude of the current induced by intracellular cAMP injection (cAMP-current). 5. 5. The OXT-solution effect on the cAMP-current was abolished by tolbutamide, a cAMP-dependent protein kinase inhibitor, added to the external solution. 6. 6. According to our finding, we suggest the existence in the Helix pomatia neurons intracellular OXT receptors. These receptors, likely, modulate the cAMP-dependent protein kinase activity, that could be underlye for modulatory OXT effects.