Distribution of [³H]QNB and [¹²⁵I]α‐bungarotoxin binding and acetylcholinesterase activity in visual system and hippocampal structures of eleven mammalian species

Abstract

This study assessed interspecies differences in regional brain distribution of [3H]QNB binding, [125I]alpha-bungarotoxin binding and acetylcholinesterase activity, by autoradiographic and histochemical methods. Eleven mammalian species were examined, including carnivores (cat, dog), a lagomorph (rabbit), and rodents (squirrel, guinea pig, gerbil, hamster, vole, lemming, rat, mouse). Comparisons were based on primary visual system structures (superior colliculus, lateral geniculate nucleus, primary visual cortex) and the hippocampal formation. The two radioligands differed greatly in the degree of interspecies variation: while the pattern of [3H]QNB binding was quite similar across species, [125I]alpha-bungarotoxin showed striking interspecies diversity. This contrast was most obvious in laminar patterns of the visual cortex and hippocampal formation. Regional distributions of acetylcholinesterase staining were fairly diverse, and were unlike the patterns of either [3H]QNB or [125I]alpha-bungarotoxin. The two ligands showed more consistency in overall levels across species than did acetylcholinesterase. Possible correlates of the differences in interspecies diversity are discussed.

Kappa opioid receptor-like immunoreactivity is present in substance P-containing subcortical afferents in guinea pig dentate gyrus

“…2A). This pattern resembles that which has been previously described for AChE staining in the guinea pig (Fuchs and Schwark, 1993). Ipsilateral to the fornix transection, AChE staining was reduced in all lamina of the dentate gyrus, with the decrease in the diffuse bands of staining noticeably larger than in the scattered labeled processes (Fig.…”

“…In the first set of experiments, the light microscopic distribution of KT-immunolabeling was compared in dentate gyrus ipsilateral and contralateral to a fornix transection. The distributions of SP immunolabeling and AChE staining in the fornix-transected animals were also analyzed, because the SUM afferents in guinea pig contain immunoreactivity for substance P (SP; Gall and Selawski, 1984), and AChE has been reported to be present in afferents from the SUM (Harley et al, 1983;Fuchs and Schwark, 1993) and other sources which enter through the fimbria (Kuhar, 1975;Butcher, 1977). The second set of experiments, conducted in normal animals, used dual-labeling electron microscopy to determine whether KT-LI is colocalized with SP-labeling in the dentate gyrus, and if so, to analyze the cellular relationships of such terminals.…”

Expression of neuronal nicotinic acetylcholine receptor subunit mRNAs in rat hippocampal GABAergic interneurons

“…These findings suggest the presence of mainly homomeric nAChRs but very limited expression of the major heteromeric nAChR subtypes in the hippocampus. This is supported by receptor autoradiographic studies demonstrating that in rodent hippocampus, the major nAChR subtype is the α7 homomeric receptor, exhibiting strong binding throughout the hippocampal formation including interneurons (Clarke et al,1985; Fuchs and Schwark,1993; Freedman et al,1993; Tribollet et al,2004). In contrast, the number of binding sites for heteromeric receptors, detected with radiolabeled ligands such as nicotine, epibatidine, or cytosine, are very low (Clarke et al,1985; Pauly et al,1989; Perry and Kellar,1995; Happe et al, 1995; Tribollet et al,2004).…”

Cholinergic innervation in adult rat cerebral cortex: A quantitative immunocytochemical description

“…More recently, fast excitatory actions mediated by nicotinic receptors have also been described, in ferret, rat, and human neocortical tissue (Roerig et al, 1997;Xiang et al, 1998;Porter et al, 1999;Alkondon et al, 2000). (Clarke et al, 1985;Quirion et al, 1989;Fuchs and Schwark, 1993;Séguéla et al, 1993;Aubert et al, 1996). According to immunocytochemical descriptions carried out with specific antibodies against nicotinic subunits or muscarinic receptor subtypes, the closest match with the ACh innervation is probably that of the ␣4 and ␤2 nicotinic subunits, the coassembly of which forms the predominant nicotinic receptor in the CNS (Sargent, 1993).…”