title: Hypoalgesic behaviors of P/Q-type voltage-gated Ca2+ channel mutant mouse, rolling mouse Nagoya.
abstract: Rolling mouse Nagoya (tg(rol)) is a spontaneously occurring P/Q-type voltage-gated Ca2+ channel (VGCC) mutant mouse. A P/Q-type VGCC with the tg(rol) mutation has lower voltage sensitivity of activation, and mice with a homozygous genotype (tg(rol)/tg(rol)) but not with a heterozygous genotype (tg(rol)/+) show impaired motor coordination of the hind limbs. To investigate the roles of P/Q-type VGCC in pain sensing mechanisms, behavioral responses of adult tg(rol) mice to thermal, mechanical and chemical nociceptive stimuli were examined by the plantar, tail-flick, von Frey and formalin tests. The latency of the withdrawal response to thermal stimuli in the plantar or tail-flick tests was significantly longer in tg(rol)/tg(rol) mice than in tg(rol)/+ and wild-type (+/+) mice, and in tg(rol)/+ mice than in +/+ mice. The withdrawal response to mechanical stimuli in the von Frey test was lower in tg(rol)/tg(rol) mice than in +/+ mice. Although the licking time during the first 5 min after the formalin injection was similar among all of the three genotypes, that during 5-60 min was significantly shorter in tg(rol)/tg(rol) mice than in tg(rol)/+ and +/+ mice, and in tg(rol)/+ mice than in +/+ mice. Artificial inflammation induced by injection of complete Freund's adjuvant (CFA) into a hind paw significantly enhanced the withdrawal response recorded in the plantar and von Frey tests regardless of the mouse genotype. The CFA-enhanced response in the tg(rol)/tg(rol) mice was similar to the response in +/+ mice without the CFA injection. These results suggest that tg(rol) mutant mice show hypoalgesic responses caused by a lower sensitivity to nociceptive thermal, mechanical and chemical stimuli. It is concluded that the P/Q-type VGCC has a pro-nociceptive role and that the tg(rol) mutant mouse may be a useful tool to investigate the role of the P/Q-type VGCC in pain sensing mechanisms.
authors.affiliation: Department of Veterinary Physiology, Faculty of Agriculture, Tottori University, 101, South 4th, Koyama, Tottori 6808553, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Fukumoto
authors.forename: Y
authors.initials: Y
authors.lastname: Obama
authors.forename: N
authors.initials: N
authors.lastname: Kitamura
authors.forename: K
authors.initials: K
authors.lastname: Niimi
authors.forename: E
authors.initials: E
authors.lastname: Takahashi
authors.forename: C
authors.initials: C
authors.lastname: Itakura
authors.forename: I
authors.initials: I
authors.lastname: Shibuya
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D020864:Calcium Channels, N-Type / Q000235:genetics*; D005620:Freund's Adjuvant; D005838:Genotype; D006614:Hindlimb; D006358:Hot Temperature; D007249:Inflammation / Q000139:chemically induced; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D009154:Mutation; D010146:Pain / Q000139:chemically induced / Q000503:physiopathology*; D010147:Pain Measurement; D017288:Pain Threshold; D010812:Physical Stimulation; D013997:Time Factors
chemical_list: D020864:Calcium Channels, N-Type; D005620:Freund's Adjuvant