Orexinergic projections to the cat midbrain mediate alternation of emotional behavioural states from locomotion to cataplexy
スポンサーリンク
概要
- 論文の詳細を見る
The definitive version is available at www.blackwell-synergy.com and www.jphysiol.org.Orexinergic neurones in the perifornical lateral hypothalamus project to structures of the midbrain, including the substantia nigra and the mesopontine tegmentum. These areas contain the mesencephalic locomotor region (MLR), and the pedunculopontine and laterodorsal tegmental nuclei (PPN/LDT), which regulate atonia during rapid eye movement (REM) sleep. Deficiencies of the orexinergic system result in narcolepsy, suggesting that these projections are concerned with switching between locomotor movements and muscular atonia. The present study characterizes the role of these orexinergic projections to the midbrain. In decerebrate cats, injecting orexin-A (60 μm to 1.0 mm, 0.20–0.25 μl) into the MLR reduced the intensity of the electrical stimulation required to induce locomotion on a treadmill (4 cats) or even elicit locomotor movements without electrical stimulation (2 cats). On the other hand, when orexin was injected into either the PPN (8 cats) or the substantia nigra pars reticulata (SNr, 4 cats), an increased stimulus intensity at the PPN was required to induce muscle atonia. The effects of orexin on the PPN and the SNr were reversed by subsequently injecting bicuculline (5 mm, 0.20–0.25 μl), a GABAA receptor antagonist, into the PPN. These findings indicate that excitatory orexinergic drive could maintain a higher level of locomotor activity by increasing the excitability of neurones in the MLR, while enhancing GABAergic effects on presumably cholinergic PPN neurones, to suppress muscle atonia. We conclude that orexinergic projections from the hypothalamus to the midbrain play an important role in regulating motor behaviour and controlling postural muscle tone and locomotor movements when awake and during sleep. Furthermore, as the excitability is attenuated in the absence of orexin, signals to the midbrain may induce locomotor behaviour when the orexinergic system functions normally but elicit atonia or narcolepsy when the orexinergic function is disturbed.
論文 | ランダム
- GPS観測による日本列島の地殻歪みの年変化
- Interview 益子修 三菱自動車工業社長 (特集 トヨタ「軽」参入が引き金をひく 自動車業界の地殻変動)
- 迎え撃つスズキは登録車シフト 「国内自動車8社体制」は終焉へ (特集 トヨタ「軽」参入が引き金をひく 自動車業界の地殻変動)
- 図解 多彩な進化を遂げた軽自動車市場 (特集 トヨタ「軽」参入が引き金をひく 自動車業界の地殻変動)
- ダイハツの主戦場へ進出する"親会社"トヨタの深謀遠慮 (特集 トヨタ「軽」参入が引き金をひく 自動車業界の地殻変動)