The depolarization induced by Cav2 decreases and pain threshold increases with aging. To characterize strain dependence of age-related changes in nociception and spinal expression of Cav2 in mice, we evaluated nociceptive sensitivity and Cav2α1 mRNA expression in 2-month-old and 20-month-old mice of seven inbred strains (A/J, AKR/N, BALB/c, C3H/HeJ, C57BL6/J, DBA/2, 129/SvJ). In the hot plate test, 20-month-old C3H/HeJ showed reduced thermal nociceptive thresholds relative to 2-month-old mice, but no difference was observed between 2-month-old and 20-month-old mice of other strains. In the formalin paw test, there was no difference in licking/biting time in phase 1 between 2-month-old and 20-month-old animals of any strain, but the phase 2 responses in 20-month-old C3H/HeJ and DBA/2 were decreased compared with those of 2-month-old mice. Cav2.1α1 mRNA was expressed at lower level in spinal cord of 20-month-old C3H/HeJ than in 2-month-old mice. Cav2.2α1 mRNA was expressed at lower level in spinal cord of 20-month-old C3H/HeJ and DBA/2 than in 2-month-old mice. These findings suggest that age-related changes in nociceptive transmission differ in different strains, and may be associated with impairment of spinal synaptic neurotransmission owing to deterioration of depolarization-induced Ca2+ currents caused by age-related Cav2.1 or Cav2.2 channel dysfunction.
|出版社||Nova Science Publishers, Inc.|
|出版ステータス||出版済み - 8月 2012|
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