Histochemistry of acetylcholinesterase and immunocytochemistry of an acetylcholine receptor‐like antigen in the brain of the honeybee

Abstract

A histochemical staining method for acetylcholinesterase (AChE) and an antiserum raised against nicotinic acetylcholine receptors (AChR) of locust nervous tissue were applied in order to reveal certain candidates of cholinergic pathways in the brain of the honeybee. The AChE staining marked layers in the optic lobes, fibers connecting the two brain hemispheres, and fiber tracts as well as soma clusters within the protocerebrum. The calycal input regions of the mushroom bodies were labelled, whereas the intrinsic Kenyon cells showed no staining. Although the antennal afferents projecting into the dorsal lobe showed strong AChE activity, projections into the antennal lobe showed rather weak staining. Application of the antiserum against the AChR showed immunoreactivity in neuropiles, tracts, somata, and the antennal nerve. The immunoreactivity of the optic lobes coincided with the banding pattern of the AChE staining. A particularly striking overlap of AChR immunoreactivity and AChE staining was found in the lip neuropile of the mushroom bodies, which would suggest a cholinergic input into this neuropile via fibers of the median antennoglomerular tract. Because the antiserum against locust AChR binds in neuropiles displaying AChE activity, we conclude that this antiserum also cross-reacts with the bee's receptor. This interpretation is supported by experiments showing alpha-bungarotoxin (alpha-BTX) binding sites in some areas of strong immunoreactivity.

The Processing of Color, Motion, and Stimulus Timing Are Anatomically Segregated in the Bumblebee Brain

“…issl and Bicker, 1989;Bicker, 1999;Sinakevitch et al, 2005). The increased amount of serotonergic branching in layers 1-4 implies that their activity is modulated by localized serotonergic inputs.…”

Critical roles of mecamylamine-sensitive mushroom body neurons in insect olfactory learning

“…In insects, many neurons in neural pathways mediating olfactory signals, including olfactory receptor neurons on antennae, are cholinergic (Frontali, Piazza, & Scopelli, 1971;Kreissl and Bicker, 1989;Sanes & Hildebrand, 1976). Axons of olfactory receptor neurons project to the antennal lobe (AL, primary olfactory center) and make synaptic connections with local interneurons and projection neurons (Barbara, Grünewald, Paute, Gauthier, & Raymond-Delpech, 2008;Bicker, 1999;Moreaux & Gilles, 2007;Watanabe, Nishino, Nishikawa, Mizunami & Yokohari, 2010).…”

Fast Synaptic Currents inDrosophilaMushroom Body Kenyon Cells Are Mediated by α-Bungarotoxin-Sensitive Nicotinic Acetylcholine Receptors and Picrotoxin-Sensitive GABA Receptors

“…GABAergic lateral horn neurons, activated by odors, provide inhibitory input to the Kenyon cells. Although there are no reports of in vivo intracellular recordings from Drosophila or honeybee Kenyon cells, anatomical studies indicate that axons from antennal lobe PNs are the primary source of cholinergic input to the mushroom body neurons in these insects as well (Kreissl and Bicker, 1989;Bicker, 1999;Yusuyama et al, 2002). In addition, ultrastructural analyses have identified GABA-positive boutons on Kenyon cell dendrites in Drosophila (Yusuyama et al, 2002) and honeybees (Ganeshina and Menzel, 2001).…”