Wang W H, Lovick T A
Department of Physiology, Medical School, Birmingham, UK.
Exp Brain Res. 1993;94(2):295-300. doi: 10.1007/BF00230299.
Experiments were carried out in urethane-anaesthetised rats to determine whether the inhibition of neurones in the rostral ventrolateral medulla (RVLM) induced by stimulation in the ventrolateral periaqueductal grey matter (PAG), is mediated via a relay in the medullary raphe nuclei. Electrical stimulation in the ventrolateral part of the PAG (20-ms trains, 7 pulses, 5-100 microA) inhibited ongoing activity of neurones in the RVLM for periods of 10-120 ms (mean 43.6 ms). The duration of the inhibition was reduced by 51.1% after microinjection of GABA (40-160 nmol in volumes of 200-400 nl, 9/12 sites), but not 165 mM NaCl (8/8 sites) in nucleus raphe magnus (NRM) and the rostral half of nucleus raphe obscurus (NRO). In a further series of experiments, activation of neuronal perikarya at 17 sites in NRM or NRO by microinjection of d,l-homocysteic acid (5-40 nmol in volumes of 50-400 nl) inhibited ongoing activity of 9 out of 14 neurones in the RVLM, the other 5 being excited. We suggest that the inhibitory effect on neurones in the RVLM, which can be evoked by stimulation in the ventrolateral PAG, is mediated indirectly by activation of an inhibitory projection to the RVLM from NRM and the rostral half of NRO.
在氨基甲酸乙酯麻醉的大鼠中进行了实验，以确定腹外侧导水管周围灰质（PAG）刺激所诱导的延髓头端腹外侧区（RVLM）神经元抑制是否通过延髓中缝核团的中继介导。PAG腹外侧部分的电刺激（20毫秒串刺激，7个脉冲，5 - 100微安）抑制RVLM中神经元的持续活动达10 - 120毫秒（平均43.6毫秒）。在中缝大核（NRM）和中缝隐核头端半区（NRO）微量注射GABA（40 - 160纳摩尔，体积200 - 400纳升，9/12个位点）后，抑制持续时间减少了51.1%，但注射165 mM NaCl（8/8个位点）则没有这种效果。在另一系列实验中，通过微量注射d，l - 高半胱氨酸（5 - 40纳摩尔，体积50 - 400纳升）激活NRM或NRO中17个位点的神经元胞体，抑制了RVLM中14个神经元中的9个的持续活动，另外5个被兴奋。我们认为，腹外侧PAG刺激所诱发的对RVLM中神经元的抑制作用是由NRM和NRO头端半区对RVLM的抑制性投射激活间接介导的。
