TY - JOUR
T1 - Ca 2+ channel currents in dorsal root ganglion neurons of P/Q-type voltage-gated Ca 2+ channel mutant mouse, rolling mouse Nagoya
AU - Fukumoto, Nao
AU - Kitamura, Naoki
AU - Niimi, Kimie
AU - Takahashi, Eiki
AU - Itakura, Chitoshi
AU - Shibuya, Izumi
N1 - Funding Information:
Male homozygous (tg rol /tg rol ), heterozygous (tg rol /+), and wild type (+/+) mice that are F1 progeny from a cross between tg rol /+ mice (C57BL/6J × SIII background) were produced at the RIKEN Brain Science Institute. The tg rol /+ mice were produced by mating C57BL/6J (Charles River Laboratories Japan Inc., Japan) with tg rol /tg rol (SIII background) provided by RIKEN BioResource Center with support from the National BioResource Project of the Ministry of Education, Culture, Sports, Science, and Technology, Japan. Genotyping of the +/+ and tg rol /+ mice was performed using PCR of DNA from tail biopsies at an age of 3 weeks. The primers used to screen the genotypes were NW-1 (5′-GCTACGACCTCTAAAGACCATCAAGC-3′) and NR-1 (5′-GAAGACGTTCTTGAGCGAGTTCAC-3′) for the wild type and NM-1 (5′-CGACCTCTAAAGACCATCAAGG-3′) and NR-1 for the mutant type. PCR was performed with an initial extension at 94 °C for 10 min, followed by seven cycles of 94 °C for 30 s and 68 °C for 40 s, 35 cycles of 94 °C for 30 s and 64 °C for 40 s, and a final extension at 64 °C for 4 min. PCR amplification yielded 600-bp fragments with the NM-1 and NR-1 primers and with the NW-1 and NR-1 primers in tg rol /+ mice and yielded 600-bp fragments with the NW-1 and NR-1 primers but no product with the NM-1 and NR-1 primers in +/+ mice. Because tg rol /tg rol mice exhibit overt ataxia at 2 weeks of age, it was not necessary to conduct genotyping with the PCR method. The mice were transferred to Tottori University, provided ad libitum access to water and food pellets (CE-2, Nihon Clea, Japan), and kept at room temperature (22 ± 2 °C) and 55 ± 5% humidity under a 12:12-h light–dark cycle (light from 7:00 am to 7:00 pm). Male mice between 12 and 20 weeks old were used in the following studies, after being housed at Tottori University for at least 2 weeks.
PY - 2012/7
Y1 - 2012/7
N2 - The role of the P/Q-type voltage-gated Ca 2+ channels (VGCCs) in release of neurotransmitters involved in nociception is not fully understood. Rolling mouse Nagoya (tg rol), a P/Q-type channel mutant mouse, expresses P/Q-type VGCC whose activation curve has a higher half activation potential and a smaller slope factor than the wild type channel. We previously reported that tg rol mice showed hypoalgesic responses to noxious stimuli. In this study, we examined the VGCC current in dorsal root ganglion (DRG) neurons by the whole-cell patch-clamp method. Both ω-agatoxin IVA (0.1μM) and ω-conotoxin GVIA (1μM) inhibited the VGCC current by about 40-50% in both the homozygous tg rol (tg rol/tg rol) and wild type (+/+) mice. The voltage-activation relationships of the total VGCC current and the ω-agatoxin IVA-sensitive component in the tg rol/tg rol mice shifted positively compared to the +/+ mice, whereas that sensitive to the ω-conotoxin GVIA was not different between the two genotypes. The time constant of activation of the VGCC current at -20mV was longer in the tg rol/tg rol mice than in the +/+ mice. These changes in the properties of the VGCC in the tg rol/tg rol mouse may reduce the amount of the released neurotransmitters and account for the hypoalgesic responses.
AB - The role of the P/Q-type voltage-gated Ca 2+ channels (VGCCs) in release of neurotransmitters involved in nociception is not fully understood. Rolling mouse Nagoya (tg rol), a P/Q-type channel mutant mouse, expresses P/Q-type VGCC whose activation curve has a higher half activation potential and a smaller slope factor than the wild type channel. We previously reported that tg rol mice showed hypoalgesic responses to noxious stimuli. In this study, we examined the VGCC current in dorsal root ganglion (DRG) neurons by the whole-cell patch-clamp method. Both ω-agatoxin IVA (0.1μM) and ω-conotoxin GVIA (1μM) inhibited the VGCC current by about 40-50% in both the homozygous tg rol (tg rol/tg rol) and wild type (+/+) mice. The voltage-activation relationships of the total VGCC current and the ω-agatoxin IVA-sensitive component in the tg rol/tg rol mice shifted positively compared to the +/+ mice, whereas that sensitive to the ω-conotoxin GVIA was not different between the two genotypes. The time constant of activation of the VGCC current at -20mV was longer in the tg rol/tg rol mice than in the +/+ mice. These changes in the properties of the VGCC in the tg rol/tg rol mouse may reduce the amount of the released neurotransmitters and account for the hypoalgesic responses.
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U2 - 10.1016/j.neures.2012.04.006
DO - 10.1016/j.neures.2012.04.006
M3 - Article
C2 - 22575052
AN - SCOPUS:84861579938
SN - 0168-0102
VL - 73
SP - 199
EP - 206
JO - Neuroscience Research
JF - Neuroscience Research
IS - 3
ER -