皮質てんかんラットモデルでの視床背内側核刺激の効果 Efficacy of mediodorsal thalamic nucleus stimulation in a rat model of cortical seizure

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Abstract

背景:視床背内側核は前頭葉と辺縁系とに強く結合している.この研究では,前頭葉への電気刺激で励起されるてんかん発作に対し,視床背内側核電気刺激が影響を与えるか否かを検討した.対象と方法:生後28日目の成熟雄ラット(n=7)の脳表(両側前頭葉)にネジ電極を,両側視床背内側核に深部電極を埋め込み,10日間休ませた後38日目から1日1回前頭葉の電極に電気刺激を行い,全身けいれん発作を出現させた.刺激は明らかな後放電(前頭葉の脳表からのてんかん性放電)が出現するまで,徐々に上昇させ,後放電が出現した時点で刺激を終了した.また,一定の刺激電圧(0.1mA)で視床背内側核電気刺激を0Hz,1Hz,5Hz,10Hzの周波数で各ラットに前頭葉刺激と同時に1日おきに行った.それぞれの群で後放電の閾値と持続時間を計測し比較した.結果:けいれん発作は両側前頭葉の棘波とそれに伴う全身強直間代性けいれんであった.後放電の閾値には4群間で有意な差を認めなかった.持続時間に関しては10Hz刺激でコントロール群より軽度短かったものの,全体として有意差を認めなかった.結論:視床背内側核の電気刺激は,今回のような低頻度刺激ではてんかん発作を抑制することは難しいと思われる.今後視床刺激の部位や頻度を変更する必要がある.

Objective: The mediodorsal thalamic nucleus (MD) has strong connectivity to the limbic systems and frontal lobe. The aim of this study was to determine whether the mediodorsal thalamic nucleus influences seizure induction by electrical stimulation in the rat frontal cortex. Materials and Methods: Juvenile male rats (n = 7) were used in the experiment. At postnatal day 28 (P28), stainless steel skull screws were inserted for stimulating cortices. Depth-stimulating electrodes were stereotaxically inserted into the MD of the bilateral thalamus. Electrical stimulation, which produces afterdischarges, was applied to the frontal cortices once/day for four consecutive days from postnatal day 38. Additional conditioning electrical stimulation to the bilateral MD was fixed at 0.1 mA, and the stimulus frequency was increased from 0 Hz, 1 Hz, and 5 Hz to 10 Hz. All seven rats were stimulated with those frequencies by rotation every other day. The data of animals with 0Hz MD stimulation were defined as controls. Afterdischarge thresholds and durations were measured at each frequency. Results: Seizures were accompanied by bilateral tonic-clonic convulsions and cortical spikes. Seizure behaviors were not different among the groups and there were no statistically significant differences in the cortical afterdischarge (AD) thresholds between animals with MD stimulations and controls in all frequencies. In the cortical AD durations, there were also no statistically significant differences between animals with MD stimulation and controls although the mean duration at 10-Hz stimulation was less than the control animals. Conclusion: These results indicated that thalamic MD stimulation might not suppress epileptic seizure induction. Further studies are needed to analyze other stimulus parameters, altered stimulus locations, and different test paradigms.

Journal

  • Fukuoka acta medica

    Fukuoka acta medica 100(8), 274-280, 2009-08-25

    福岡医学会

Codes

  • NII Article ID (NAID)
    120001672650
  • NII NACSIS-CAT ID (NCID)
    AN00215478
  • Text Lang
    ENG
  • Article Type
    journal article
  • Journal Type
    大学紀要
  • ISSN
    0016254X
  • NDL Article ID
    10547430
  • NDL Source Classification
    ZS7(科学技術--医学)
  • NDL Call No.
    Z19-86
  • Data Source
    NDL  IR 
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