刺激猫中缝核对海马内脏伤害性单位放电的影响

EFFECTS OF ELECTRICAL STIMULATION OF NUCLEUS RAPHE ON RESPONSES OF HIPPOCAMPAL UNITS TO VISCERAL A-DELTA OR C AFFERENT VOLLEYS IN CATS

实验在氯醛糖和氨基甲酸乙酯麻醉猫上进行,用箭毒制动。以玻璃微电极记录背海马CA1区神经元放电。观察刺激中缝核(NR)对伤害性刺激内脏大神经引起的海马单位放电的影响。在记录的104个单位中,对伤害性刺激发生显著反应的82个。其中伤害性兴奋单位(NEU)38个;伤害性抑制单位(NIU)44个。伤害性无关单位(NUU)22个。刺激NR后,检测了63个单位,其中NEU的自发放电和伤害性放电出现抑制效应的,分别占单位数的40％和60％。26个NIU出现抑制加强的占60％;出现脱抑制的占25％。12个NUU,有的转变为NEU,有的转变为NIU,有的则维持原状。结果表明,海马CA1区存在内脏伤害性相关单位,该神经元分为NEU和NIU两类,刺激NR对它们中的多数均起抑制作用,并对其机制进行了讨论。

Experiments were performed on 14 male cats anesthetized with chloralose and urethane. The animals were immobilized wivh d-tubocurarine. Single unit discharge of the dorsal hippocampus (HPC) CA1 area was recorded extracellularly by the glass microelectrode. fn this study an attempt was made to observe the effects of stimulation of nucleus raphe (NR) on responses of HPC units to visceral A-Delta or C afferent volleys. 104 units were observed. 82 units showed significant changes after stimulation of nervi splanchnicus major, among which nociceptive excitatory units (NEU) and nociceptive inhibitory units (NIU) were 38 (36.5%) and 44 (42.3%) respectively. 22 units (21.2%) were nociceptive unrelated units (NUU). 63 units were tested for the effect of stimulation of NR. The changes in the forms of unit discharge were recorded after electrical stimulation of NR. Of 25 NEUs, 40 % and 60% showed depression of spontaneous discharge and depression of nociceptive discharge respectively. Of 26 NIUs, 60% exhibited an inhibitory effect whereas 40% showed a disinhibitory effect. Among 12 NUUs, some units turned into NEUs or NIUs and the others showed no change. These results suggest that there are visceral-pain-related neurons in the HPC of the cat. The neurons can be divided into NEUs and NIUs. The effects of electrical stimulation of NR on responses of HPC units to visceral A-Delta or C afferent volleys were mainly inhibitory which were probably due to the release of serotonin and other transmitters from the ascending serotonergic terminals originating in NR.