Telford S, Wang S, Redgrave P
Department of Psychology, University of Sheffield, United Kingdom.
J Comp Neurol. 1996 Nov 25;375(4):601-17. doi: 10.1002/(SICI)1096-9861(19961125)375:4<601::AID-CNE4>3.0.CO;2-5.
The superior colliculus (SC) has an established role in the sensory guidance of motor commands required to orient an animal towards novel stimuli. In addition to the representations of visual, auditory, and somatosensory stimuli, the SC also contains a large population of nociceptive neurones. The purpose of the present investigation was to see if nociceptive neurones in the SC can be characterised with c-fos immunohistochemistry as a prelude to establishing anatomical connectivity with specific target regions in the brainstem. To ensure comparability with previous electrophysiological investigations, the present study was conducted in animals anaesthetised with urethane. A series of independent issue relating to basic aspects of experimental protocol were investigated. The principal findings were: (i) Despite minimising the exposure of animals to extraneous stimuli, basal levels of immunostaining were observed. (ii) Urethane anaesthesia induced an increase in Fos-like immunoreactivity (FLI) over the basal condition. (iii) No additional labelling was induced by non-noxious tactile stimulation of the hindpaw. (iv) Unilateral noxious mechanical stimulation elicited a reliable increase in FLI over all control conditions. (v) This increase in FLI was expressed bilaterally and restricted largely to the intermediate white layer. (vi) The induction of FLI was related to noxious stimulation intensity. (vii) No reliable differences in the spatial topography of FLI expression were observed when unilateral noxious mechanical stimulation was administered to the face or hind foot. (vii) A higher level of urethane anaesthesia had a generally suppressive effect on FLI expression. (ix) There were no differences in the distribution of FLI induced by noxious mechanical or noxious chemical stimulation. (x) The increase in FLI induced by noxious pinch was abolished by a naloxone reversible pre-treatment with morphine. These data confirm that c-fos immunohistochemistry can be used to characterise nociceptive cells in the rat superior colliculus, and generally complement recent electrophysiological data. The identification of nociceptive cells in the stratum album intermediale, the source of collicular input to regions of the contralateral brainstem involved in orienting, suggests the SC may play a significant role in the localisation of pain.
上丘（SC）在引导动物朝向新刺激定向所需的运动指令的感觉引导中具有既定作用。除了视觉、听觉和体感刺激的表征外，上丘还包含大量伤害性神经元。本研究的目的是看看是否可以用c-fos免疫组织化学来表征上丘中的伤害性神经元，以此作为建立与脑干中特定靶区域的解剖学连接的前奏。为确保与先前的电生理研究具有可比性，本研究在氨基甲酸乙酯麻醉的动物中进行。对与实验方案基本方面相关的一系列独立问题进行了研究。主要发现如下：（i）尽管尽量减少动物对外源刺激的暴露，但仍观察到基础免疫染色水平。（ii）氨基甲酸乙酯麻醉导致Fos样免疫反应性（FLI）较基础状态增加。（iii）后爪的非伤害性触觉刺激未诱导额外的标记。（iv）单侧伤害性机械刺激在所有对照条件下均引起FLI可靠增加。（v）这种FLI增加双侧表达，且主要局限于中间白层。（vi）FLI的诱导与伤害性刺激强度有关。（vii）当对面部或后足进行单侧伤害性机械刺激时，未观察到FLI表达空间拓扑结构的可靠差异。（viii）较高水平的氨基甲酸乙酯麻醉对FLI表达通常具有抑制作用。（ix）伤害性机械刺激或伤害性化学刺激诱导的FLI分布无差异。（x）伤害性夹捏诱导的FLI增加被纳洛酮可逆性吗啡预处理所消除。这些数据证实，c-fos免疫组织化学可用于表征大鼠上丘中的伤害性细胞，并且总体上补充了最近的电生理数据。中间白层中伤害性细胞的鉴定，即上丘向对侧脑干参与定向的区域输入的来源，表明上丘可能在疼痛定位中起重要作用。
