Ikeda H, Akiyama G, Matsuzaki S, Sato M, Koshikawa N, Cools A R
Department of Pharmacology, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan.
Neuroscience. 2004;125(3):553-62. doi: 10.1016/j.neuroscience.2004.02.021.
The role of GABA(A) receptors in the pedunculopontine tegmental nucleus in turning behaviour of rats was studied. Unilateral injection of the GABA(A) receptor agonist, muscimol (25-100 ng), into the pedunculopontine tegmental nucleus dose-dependently produced contraversive pivoting, namely tight head-to-tail turning marked by abnormal hindlimb backward stepping. This effect was GABA(A) receptor specific, since it was prevented by the GABA(A) receptor antagonist, bicuculline (50 ng), which alone did not elicit turning behaviour. Unilateral injection of a mixture of dopamine D(1) ((+/-)-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-7,8-diol [SKF 38393], 5 microg) and D(2) (quinpirole, 10 microg) receptor agonists into the nucleus accumbens shell has been found to elicit contraversive pivoting, whilst unilateral injection of the acetylcholine receptor agonist (carbachol, 5 microg) into the same site is known to elicit contraversive circling, namely turning marked by normal stepping. The pivoting induced by a mixture of SKF 38393 (5 microg) and quinpirole (10 microg) injected into the nucleus accumbens shell was significantly inhibited by bicuculline (50 ng) injected into the pedunculopontine tegmental nucleus, whereas muscimol (25 ng) had no effect. Neither muscimol (25 ng) nor bicuculline (50 ng) modulated the contraversive circling induced by carbachol (5 microg) injected into the nucleus accumbens shell. It is therefore concluded that unilateral stimulation of GABA(A) receptors in the pedunculopontine tegmental nucleus can elicit contraversive pivoting and that the pedunculopontine tegmental nucleus is one of the output stations of the accumbens region that mediates shell-specific, dopaminergic pivoting, but not of the accumbens region that mediates shell-specific, cholinergic circling.
研究了GABA(A)受体在大鼠脚桥被盖核中对其转向行为的作用。向脚桥被盖核单侧注射GABA(A)受体激动剂蝇蕈醇（25 - 100纳克），剂量依赖性地产生对侧枢转，即头部到尾部紧密转动，其特征为后肢异常向后迈步。这种效应具有GABA(A)受体特异性，因为它可被GABA(A)受体拮抗剂荷包牡丹碱（50纳克）阻断，而荷包牡丹碱单独注射不会引发转向行为。已发现向伏隔核壳单侧注射多巴胺D(1)（(+/-)-1-苯基-2,3,4,5-四氢-1H-3-苯并氮杂卓-7,8-二醇[SKF 38393]，5微克）和D(2)（喹吡罗，10微克）受体激动剂混合物会引发对侧枢转，而向同一部位单侧注射乙酰胆碱受体激动剂（卡巴胆碱，5微克）已知会引发对侧转圈，即正常迈步的转动。向伏隔核壳注射SKF 38393（5微克）和喹吡罗（10微克）混合物所诱导的枢转，被向脚桥被盖核注射的荷包牡丹碱（50纳克）显著抑制，而蝇蕈醇（25纳克）则无作用。蝇蕈醇（25纳克）和荷包牡丹碱（50纳克）均未调节向伏隔核壳注射卡巴胆碱（5微克）所诱导的对侧转圈。因此得出结论，单侧刺激脚桥被盖核中的GABA(A)受体可引发对侧枢转，并且脚桥被盖核是伏隔核区域的输出站之一，该区域介导壳特异性的多巴胺能枢转，但不介导壳特异性的胆碱能转圈。
