Enhanced cholinergic transmission promotes recall in honeybees

• Published in: Journal of insect physiology Vol. 56; no. 9; pp. 1341 - 1348
• Main Authors: Guez, D., Zhu, H., Zhang, S.W., Srinivasan, M.V.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.09.2010
• Subjects: Acetylcholine receptors (muscarinic); acetylcholinesterase; Animals; Anticholinesterase; Apis mellifera; Associative learning; Bees - drug effects; Bees - physiology; biochemical pathways; cholinergic agents; cholinergic receptors; Cholinergic system; Cholinesterase Inhibitors - toxicity; Conditioning (Psychology); Discrimination learning; Discrimination Learning - drug effects; Discrimination Learning - physiology; Ecotoxicology; enzyme inhibitors; honey bees; Insecticides - toxicity; learning; Maze Learning - drug effects; memory; Memory - drug effects; Memory - physiology; memory acquisition; memory recall; Methyl Parathion; Muscarinic; muscarinic-like effects; Nicotinic; nicotinic-like effects; Non-target species; Organo-phosphates; parathion-methyl; Pesticide; Receptors, Cholinergic - drug effects; Receptors, Cholinergic - physiology; signal transduction; smell; Smell - drug effects; Smell - physiology; Statistics, Nonparametric; vision; Vision, Ocular - drug effects; Vision, Ocular - physiology; Apis mellifera; Nicotinic; Muscarinic; Pesticide; Ecotoxicology; Non-target species; Organo-phosphates; Anticholinesterase; Discrimination learning; Associative learning; Cholinergic system
• ISSN: 0022-1910; 1879-1611
• DOI: 10.1016/j.jinsphys.2010.04.022

The involvement of the cholinergic system in learning and memory in honeybees has been well established using olfactory conditioning. We examined the effect of Methyl Parathion (MeP), an acetylcholinesterase inhibitor of the organo-phosphate family, on the learning and recall of visual and olfactory discrimination tasks in honeybees. One of our expectations was to observe the effects induced by both the nicotinic and muscarinic systems, as the blocking of acetylcholinesterase should induce an increase in the activity of both systems. We were also interested in knowing whether the type of tasks could influence the results. The visual tasks involved learning to discriminate the orientation of gratings in a Y-maze; the olfactory task involved learning to discriminate odours in a proboscis extension reflex (PER) paradigm. The results indicate that MeP treatment enhances recall of learned tasks in the visual and olfactory domains, but it does not affect the acquisition phase in either domain. Surprisingly, MeP treatment led to muscarinic-like effects but failed to mimic the nicotinic-like effects already described in relation to learning phases in honeybees. Implications for the role of cholinergic pathways in learning and memory and the nature of their involvement are discussed, and a hypothesis relating to the organisation of the cholinergic system and the relationship between the nicotinic and muscarinic systems in honeybees is proposed. The results are also discussed in terms of their ecotoxicological consequences.