Sonoda H, Ikenoue K, Yokota T
Brain Res. 1986 Mar 26;369(1-2):91-102. doi: 10.1016/0006-8993(86)90516-0.
In adult cats anesthetized with urethan-chloralose, effects of descending volleys from the mesencephalic periaqueductal gray (PAG) upon the viscerointercostal and galvanic skin reflexes were studied. The viscerointercostal reflex (VIR) was evoked by electrical stimulation of the greater splanchnic nerve and was recorded from the 11th, 12th or 13th intercostal nerve. Conditioning stimuli applied to the PAG inhibited the VIR. The inhibition was particularly marked when the nucleus raphe dorsalis (NRD) or its immediately adjacent ventromedial PAG was stimulated. A train of pulses was required in order to produce a recognizable PAG/NRD inhibition of the VIR. When the PAG/NRD was stimulated at 300-500 Hz, stimulation-produced inhibition became more pronounced in parallel with increase in number of pulses in each train and levelled off at about 5 pulses. The most effective frequency of PAG/NRD stimulation was found within this frequency range. Degree of PAG/NRD stimulation-produced inhibition of the VIR was dependent upon the strength of the test stimulus applied to the splanchnic nerve; the weaker the test stimulus, the more marked the inhibition. PAG/NRD stimulation-produced inhibition of the VIR was completely eliminated by bilateral section of the dorsolateral funiculi. The same section enhanced the VIR per se. It was suggested that PAG/NRD stimulation-produced inhibition of the VIR is mediated by descending pathways in the ipsi- as well as contralateral dorsolateral funiculi, and that the VIR per se is tonically inhibited by descending impulses in these pathways. PAG/NRD stimulation inhibited the segmental polysynaptic reflex in the intercostal nerve, but had little effect on the segmental monosynaptic reflex in the same nerve. Intravenous administration of morphine suppressed the VIR. The suppression was antagonized by intravenous naloxone. In contrast, PAG/NRD stimulation-produced inhibition of the VIR was unaffected by intravenous naloxone. Electrical stimulation of the splanchnic nerve evoked the galvanic skin reflex (GSR) from the forepaw pad. The GSR was inhibited by electrical stimulation of the PAG/NRD. The PAG/NRD stimulation-produced inhibition of the GSR was completely eliminated by intravenous administration of naloxone (0.4 mg/kg).
在使用氨基甲酸乙酯-氯醛糖麻醉的成年猫中，研究了中脑导水管周围灰质（PAG）下行冲动对内脏肋间反射和皮肤电反射的影响。通过电刺激内脏大神经诱发内脏肋间反射（VIR），并在第11、12或13肋间神经记录。施加于PAG的条件刺激抑制VIR。当刺激中缝背核（NRD）或其紧邻的腹内侧PAG时，这种抑制尤为明显。为了产生可识别的PAG/NRD对VIR的抑制，需要一串脉冲。当以300 - 500 Hz刺激PAG/NRD时，刺激产生的抑制随着每串脉冲数量的增加而变得更加明显，并在约5个脉冲时趋于平稳。在此频率范围内发现了PAG/NRD刺激的最有效频率。PAG/NRD刺激产生的对VIR的抑制程度取决于施加于内脏神经的测试刺激的强度；测试刺激越弱，抑制越明显。双侧切断背外侧索可完全消除PAG/NRD刺激产生的对VIR的抑制。同样的切断增强了VIR本身。提示PAG/NRD刺激产生的对VIR的抑制是通过同侧和对侧背外侧索中的下行通路介导的，并且VIR本身受到这些通路中下行冲动的紧张性抑制。PAG/NRD刺激抑制肋间神经节段性多突触反射，但对同一神经的节段性单突触反射影响很小。静脉注射吗啡抑制VIR。这种抑制被静脉注射纳洛酮所拮抗。相反，PAG/NRD刺激产生的对VIR的抑制不受静脉注射纳洛酮的影响。电刺激内脏神经从前爪垫诱发皮肤电反射（GSR）。GSR被PAG/NRD的电刺激所抑制。静脉注射纳洛酮（0.4 mg/kg）可完全消除PAG/NRD刺激产生的对GSR的抑制。
