Muscarinic Antagonist Enhances One-Trial Food-Aversion Learning in the Mollusc Pleurobranchaea

摘要

One hour before training, in two replicate studies on the sea slug Pleurobranchaea californica, all animals (N=114) received body-cavity injections of scopolamine, oxotremorine, or the equivalent volume of the saline/seawater vehicle that was used to inject the drugs. The low drug doses (2 micromoles/kg) were near the threshold for generating observable neurophysiological responses, but did not affect feeding thresholds arising to a stimulus derived from beer (Sbr) and to one derived from squid (Ssq). By comparison to the other injection, scopolamine 1) increased the ability of the experimental animals to make the discrimination between Sbr and Ssq, and 2) prevented learning to avoid Sbr in the control animals. An accompanying paper provides a detailed characterization of muscarinic receptor pharmacology in Pleurobranchaea. Keywords: Muscarinic antagonist, Food-aversion, Mollusc, Electric shocks, Learning, Reprints. (KT)