Pain and pain relief Emailyuhuicnsdu edu cn Introduction

Pain and pain relief 神经生物学研究所 于卉 Email：yuhuicn@sdu. edu. cn

概述 Introduction v疼痛的概念 Concepts of pain Pain: pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage 疼痛是由实际造成或有可能造成组织损伤的各种 刺激引起的一种不愉快的感觉，常伴有痛苦的心 理、情绪的感受。 包括痛感觉和 痛感觉 痛反应

Definitions n Hyperalgesia: increased pain in response to a painful stimulus n Allodynia: pain in response to an innocuous stimulus

感受器和传入神经纤维 n n FIRST STEP-----Transduction: the conversion of the energy from a noxious thermal, mechanical, or chemical stimulus into electrical energy (nerve impulses) By one of the somatic sensory receptors called nociceptors （伤害性感受器） n 高阈机械痛感受器(HTM)及多觉型痛感受器（PMN) n Present in most body tissues, including skin, bone, muscle, most internal organs, blood vessels, and the heart, but not in the brain.

Nociceptors are the free endings of (primary afferent) nerve fibers distributed throughout the periphery.

Adequate Stimulation Temperature (>50℃ or <1 ℃) Mechanical damage：强机械刺激，针尖刺敏感 Chemicals (released from damaged tissue)

n SECOND STEP-----Transmitting：Nerve impulses generated in the periphery are transmitted to the spinal cord and brain in several phases. n 疼痛信号在脊髓中的传递Periphery to the spinal cord n 疼痛信号由脊髓传递入脑 Spinal cord to the brain （ Ascending pain pathways）

疼痛信号在脊髓中的传递 Periphery to the spinal cord

Primary afferents Unmyelinated C fibers Spread slowly Lightly myelinated Aδ fibers Spread rapidly

刺痛 灼痛 Dorsal root ganglia

Referred pain（牵涉痛） n Pain originating from organs perceived as coming from skin n Site of pain may be distant from organ 是指内脏疾病往往引起 身体远隔的体表部位发 生疼痛的现象

Secondary neurons Primary neurons X Glutamate and substance P

疼痛信号由脊髓传递入脑 Spinal cord to the brain （ Ascending pain pathways）

Spinothalamic tract(STT) Decussate and ascend

Cerebrum Thalamus Spinothalamic pathway Midbrain Pons Medulla Spinal cord

intralaminar nucleus Ventral posterior nucleus

Difference between touch and pain

n Before reach the thalamus, some of the nociceptive information are transmitted to the reticular formation, mesencephalon, and hypothalamus

来自于头部的 疼痛传递 trigeminal ganglion 三叉神经脑桥核 三叉神经脊束核 Spinal trigeminal nucleus

From brain SG T

跨皮电刺激神经仪 (transcutaneous electric nerve stimulation TENS)

脑高级中枢对背角伤害性信息传递的下行调制 • Torture victims who sustained horrible injuries but apparently felt no pain. Brain regions related with pain suppression.

Discovery aqueduct of midbrain Periaqueductal gray matter 邹冈 48

中脑导水管周围灰质 脑桥背外侧网状结构 nucleus ceruleus 蓝斑核 serotonin endogenous opioids, serotonin, norepinephrine - 中缝大核 SG

内源性痛觉调制系统 (+-) Endogenous pain modulating systerm 信号发射站 中继站 RVM PAG LRN LC… 线路 DLF 接收站 DH RVM: rostral ventromedial medulla 延髓头端腹内侧网状结构 LRN: lateral reticular nucleus延髓尾部外侧网状核 LC: Locus Coeruleus 蓝斑核 DLF: dorsal lateral funiculus 脊髓背外侧索 DH: dorsal horn 脊髓后柱

enkephalin Pain signal NA 5 -HT enkephalin r-GABA Inter neuron Opioid receptor

n 扭体实验 0. 9% Acetic Acid（乙酸） (10 ml/kg; intraperitoneal)

NSAIDs

• b. Opioid analgesics: opium, heroin, morphine, codeine

enkephalin Pain signal