Presence of α7 nicotinic acetylcholine receptors on dorsal root ganglion neurons proved using knockout mice and selective α-neurotoxins in histochemistry

2009 ◽  
Vol 109 (4) ◽  
pp. 1087-1095 ◽  
Author(s):  
Irina V. Shelukhina ◽  
Elena V. Kryukova ◽  
Katrin Susanne Lips ◽  
Victor I. Tsetlin ◽  
Wolfgang Kummer
2004 ◽  
Vol 113 (1-2) ◽  
pp. 32-42 ◽  
Author(s):  
Rainer Viktor Haberberger ◽  
Nadia Bernardini ◽  
Michaela Kress ◽  
Petra Hartmann ◽  
Katrin Susanne Lips ◽  
...  

2018 ◽  
Vol 293 (46) ◽  
pp. 17838-17852 ◽  
Author(s):  
Arik J. Hone ◽  
Todd T. Talley ◽  
Janet Bobango ◽  
Cesar Huidobro Melo ◽  
Fuaad Hararah ◽  
...  

Nicotinic acetylcholine receptors (nAChRs) containing α6 and β4 subunits are expressed by dorsal root ganglion neurons and have been implicated in neuropathic pain. Rodent models are often used to evaluate the efficacy of analgesic compounds, but species differences may affect the activity of some nAChR ligands. A previous candidate α-conotoxin-based therapeutic yielded promising results in rodent models, but failed in human clinical trials, emphasizing the importance of understanding species differences in ligand activity. Here, we show that human and rat α6/α3β4 nAChRs expressed in Xenopus laevis oocytes exhibit differential sensitivity to α-conotoxins. Sequence homology comparisons of human and rat α6β4 nAChR subunits indicated that α6 residues forming the ligand-binding pocket are highly conserved between the two species, but several residues of β4 differed, including a Leu–Gln difference at position 119. X-ray crystallography of α-conotoxin PeIA complexed with the Aplysia californica acetylcholine-binding protein (AChBP) revealed that binding of PeIA orients Pro13 in close proximity to residue 119 of the AChBP complementary subunit. Site-directed mutagenesis studies revealed that Leu119 of human β4 contributes to higher sensitivity of human α6/α3β4 nAChRs to α-conotoxins, and structure–activity studies indicated that PeIA Pro13 is critical for high potency. Human and rat α6/α3β4 nAChRs displayed differential sensitivities to perturbations of the interaction between PeIA Pro13 and residue 119 of the β4 subunit. These results highlight the potential significance of species differences in α6β4 nAChR pharmacology that should be taken into consideration when evaluating the activity of candidate human therapeutics in rodent models.


2001 ◽  
Vol 86 (4) ◽  
pp. 1773-1782 ◽  
Author(s):  
Jonathan R. Genzen ◽  
William Van Cleve ◽  
Daniel S. McGehee

Although nicotinic agonists can modulate sensory transmission, particularly nociceptive signaling, remarkably little is known about the functional expression of nicotinic acetylcholine receptors (nAChRs) on primary sensory neurons. We have utilized molecular and electrophysiological techniques to characterize the functional diversity of nAChR expression on mammalian dorsal root ganglion (DRG) neurons. RT-PCR analysis of subunit mRNA in DRG tissue revealed the presence of nAChR subunits α2–7 and β2–β4. Using whole cell patch-clamp recording and rapid application of nicotinic agonists, four pharmacologically distinct categories of nicotinic responses were identified in cultured DRG neurons. Capacitance measurements were used to divide neurons into populations of large and small cells, and the prevalence of nicotinic responses was compared between groups. Category I (α7-like) responses were seen in 77% of large neurons and 32% of small neurons and were antagonized by 10 nM methyllycaconitine citrate (MLA) or or 50 nM α-bungarotoxin (α-BTX). Category II (α3β4-like) responses were seen in 16% of large neurons and 9% of small neurons and were antagonized by 20 μM mecamylamine but not 10 nM MLA or 1 μM DHβE. Category II responses had a higher sensitivity to cytisine than nicotine. Two other types of responses were identified in a much smaller percentage of neurons and were classified as either category III (α4β2-like) or category IV (subtype unknown) responses. Both the α7-like and α3β4-like responses could be desensitized by prolonged applications of the analgesic epibatidine.


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