Investigation of TRPV1 loss-of-function phenotypes in transgenic shRNA expressing and knockout mice.
The function of the transient receptor potential vanilloid 1 (TRPV1) cation channel was analyzed with RNA interference technologies and compared to TRPV1 knockout mice. Expression of shRNAs targeting TRPV1 in transgenic (tg) mice was proven by RNase protection assays, and TRPV1 downregulation was confirmed by reduced expression of TRPV1 mRNA and lack of receptor agonist binding in spinal cord membranes. Unexpectedly, TRPV3 mRNA expression was upregulated in shRNAtg but downregulated in knockout mice. Capsaicin-induced [Ca(2+)](i) changes in small diameter DRG neurons were significantly diminished in TRPV1 shRNAtg mice, and administration of capsaicin hardly induced hypothermia or nocifensive behaviour in vivo. Likewise, sensitivity towards noxious heat was reduced. Interestingly, spinal nerve injured TRPV1 knockout but not shRNAtg animals developed mechanical allodynia and hypersensitivity. The present study provides further evidence for the relevance of TRPV1 in neuropathic pain and characterizes RNA interference as valuable technique for drug target validation in pain research.
Christoph
Thomas
T
Preclinical Research and Development, Department of Pharmacology, Grünenthal, Zieglerstrasse 6, 52078 Aachen, Germany. thomas.christoph@grunenthal.com
Bahrenberg
Gregor
G
De Vry
Jean
J
Englberger
Werner
W
Erdmann
Volker A
VA
Frech
Moritz
M
Kögel
Babette
B
Röhl
Thomas
T
Schiene
Klaus
K
Schröder
Wolfgang
W
Seibler
Jost
J
Kurreck
Jens
J
D000818:Animals; D030801:Animals, Genetically Modified; D002118:Calcium / Q000378:metabolism; D002211:Capsaicin / Q000494:pharmacology; D004224:Diterpenes / Q000493:pharmacokinetics; D005727:Ganglia, Spinal / Q000166:cytology; D015870:Gene Expression / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008297:Male; D051379:Mice; D009474:Neurons / Q000187:drug effects; D010147:Pain Measurement / Q000379:methods; D010641:Phenotype; D011485:Protein Binding / Q000187:drug effects; D034622:RNA Interference / Q000502:physiology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D011930:Reaction Time / Q000187:drug effects / Q000235:genetics; D013116:Spinal Cord / Q000187:drug effects; D013119:Spinal Cord Injuries / Q000378:metabolism; D050916:TRPV Cation Channels / Q000172:deficiency*
D004224:Diterpenes; D034741:RNA, Small Interfering; D050916:TRPV Cation Channels; D049452:Green Fluorescent Proteins; C024353:resiniferatoxin; D002211:Capsaicin; D002118:Calcium