Name: pain signaling and inflammation
Uploaded: 2025-10-23T11:49:14.000Z
Duration: 1 min 44 s
Channel: JoVE

一般的に痛みと言われている侵害受容は 侵害刺激が末梢神経系と 中枢神経系を介して伝達され 潜在的危害や損傷を警告するプロセスです。有害なシグナルが確認されると 自由神経終末の侵害受容器が活性化します。近くのマスト細胞がヒスタミンなどの化学物質を放出し マクロファージが免疫シグナルにおいて非常に重要な 小さなタンパク質である サイトカインを分泌します。同時に侵害受容器の軸索が 主に２つの異なる痛みの繊維を介して 脊髄後角にシグナルを送ります。最初に活性化されるのは 薄くミエリン化されたAδ線維です。鋭い極めて限局した痛みを即座に 非常に速いスピードで伝達することで 体を有害な刺激から離します。もう一つの種類の軸索はC線維です。ミエリン鞘がないため、ゆっくりと伝達し 長引く、焼けるような痛みをもたらします。脊髄から痛みのシグナルがクロスオーバーし 脳幹へと移動します。続いて視床、そして体性感覚皮質へと移動して 痛みのシグナルが解釈され 傷害の場所を断定します。脳のその他の部位も痛みのプロセスを行います。扁桃体や前頭前野など 情動記憶や認識力などに関連する 皮質辺縁構造が顕著です。最終的には脳内での多重相互作用が 個人が感じる主観的知覚の 一因となります。

「侵害受容と神経因性疼痛の理解における進歩」 Journal of Neurology 265、no. 2 (2018): 231–38.[<a href="https://doi.org/10.1007/s00415-017-8641-6" target="__blank">ソース</a>]

Pinho-Ribeiro、Felipe A.、Waldiceu A. Verri、およびIsaac M. Chiu.「痛みと炎症における侵害受容器感覚ニューロン-免疫相互作用」 免疫学の動向 38、no. 1(2017年1月):5–19。[<a href="https://doi.org/10.1016/j.it.2016.10.001" target="__blank">ソース</a>]

侵害受容

Nociception

痛みを感じる能力である侵害受容（痛覚）は、生物の生存と健康維持に不可欠な機能です。鋭利な物体からの突き刺さるような痛み、直火による熱、腐食性の化学物質との接触などの有害な刺激は、まず神経末端にある侵害受容器と呼ばれる感覚受容器によって感知されます。侵害受容器は、有害な刺激を電気信号に変換するイオンチャネルを発現しています。この信号が感覚ニューロンを介して脳に到達すると、痛みとして認識されます。
 
 痛みの病態には、免疫系が重要な役割を果たしています。有害な刺激に遭遇すると、傷害部位に存在するマスト細胞（肥満細胞、顆粒細胞）やマクロファージなどの免疫細胞が、サイトカイン、ケモカイン、ヒスタミン、プロスタグランジンなどの炎症性化学物質を放出します。これらの化学物質は、単球やT細胞などの他の免疫細胞を損傷部位に引き寄せます。また、侵害受容器を刺激することで、痛覚過敏（以前に受けた痛みのある刺激に対して、より強い反応を示すこと）やアロディニア（普段は何でもない軽い刺激に対して、痛みのある反応を示すこと）を引き起こします。このような痛みの感覚化は、治癒の際に傷ついた部位を保護するのに役立ちます。
 
 感作が時間をかけても解消されない場合、痛みは急性の警告システムとしての役割を終えています。慢性的な痛みは、関節リウマチなどの炎症性疾患に伴うものが多く、3ヶ月以上続く持続的、反復的な痛みです。アスピリンやイブプロフェンなどの非ステロイド性抗炎症薬（NSAIDs）は、炎症分子であるプロスタグランジンの合成を阻害することで痛みを軽減します。しかし、現在、痛みの治療に用いられているNSAIDsやオピオイドには、重篤な副作用や依存症の可能性があります。そのため、痛みの病態のメカニズムを理解することで、より効果的で副作用の少ない、痛みの知覚を抑える薬を開発できるでしょう。

侵害受容(痛みを感じる能力)は、生物の生存と全体的な健康に不可欠です。ピアスなどの有害な刺激...

Education

JoVE Core

Biology

生物学

Human Biology

ヒト生物学

Musculoskeletal System

筋骨格系

KEY TERMS AND CONCEPTS

主要用語と概念

pain signaling and inflammation

Pain signaling begins when the body detects a harmful stimulus. Sharp objects, open flames, and corrosive chemicals can trigger this response. Sensory receptors called nociceptors, which sit on nerve endings, detect these noxious stimuli and use ion channels to turn them into electrical signals.

Those electrical signals travel through sensory neurons to the brain, where they are experienced as pain. This warning system helps an organism avoid damage and stay safe. Pain is therefore an important part of survival and overall well-being.

The immune system also shapes pain after an injury. Mast cells and macrophages at the injury site release inflammatory chemicals such as cytokines, chemokines, histamines, and prostaglandins. These signals attract more immune cells, including monocytes and T cells, and they also stimulate nociceptors.

This immune response can increase pain sensitivity. Hyperalgesia is a stronger response to a stimulus that was already painful. Allodynia is pain caused by something that is usually not painful, such as light touch. These changes help protect the injured area during healing.

Pain can become a problem when sensitization does not fade. Chronic pain is persistent or recurring pain that lasts longer than three months. It often occurs with inflammatory diseases such as rheumatoid arthritis. NSAIDs, including aspirin and ibuprofen, reduce pain by blocking the production of prostaglandins. However, NSAIDs and opioids can cause serious side effects and may lead to addiction, so researchers continue to study pain mechanisms to find safer drugs.

Pain Signaling and Inflammation

what is the skeletal system?

Human Skeleton: Bones, Cells, and Disease

The human skeleton is a living framework made of 206 bones in adults. Bones connect with cartilage, tendons, and ligaments. This system gives the body support, protects organs, and helps with movement and locomotion. The skeleton has two main parts: the axial skeleton and the appendicular skeleton. The axial skeleton has 80 bones and includes the skull, the vertebral column, and the rib cage. The cranium, or upper skull, has eight bones that enclose the brain, while the lower part of the skull...

bone structure

Inside a Long Bone

Inside a long bone, osseous tissue is organized into two main types: cortical bone and cancellous bone. A femur is a clear example of this structure. The bone also includes outer coverings and inner spaces that support growth, repair, and blood cell production. Cortical bone, also called compact bone, forms the dense outer layer along the diaphysis, or shaft. It is covered by the periosteum, a membrane with connective tissue, capillaries, and nerves. Beneath the cortical layer is the medullary...

joints

Types of Joints in the Human Body

Joints are the places where adjacent bones connect. They are also called articulations or articular surfaces. Joints help the body move and stay stable. Joints can be classified by structure or by function. Structural classification depends on the material that forms the joint and whether there is a space between the bones. By structure, joints are fibrous, cartilaginous, or synovial. Fibrous joints are connected by fibrous tissue and have no cavity between the bones. Because of this, they do...

bone remodeling

How Hormones Control Bone Turnover

Bone turnover is a continuous process in which old bone is broken down and new bone is built. Osteoclasts carry out bone resorption, and osteoblasts carry out bone formation. In adults, this balanced cycle helps maintain bone mass and calcium homeostasis. Mechanical stress can also stimulate turnover as part of normal maintenance and repair. Parathyroid hormone, or PTH, helps control blood calcium levels by increasing bone resorption when calcium is low. It is released from the parathyroid...

skeletal muscle anatomy

Muscle Fibers, Tendons, and Contraction

Skeletal muscle moves the body by pulling on bones through tendons. Tendons are the connective tissue that attaches skeletal muscle to bones. When skeletal muscles contract, they create voluntary movement. Skeletal muscle is wrapped in layers of connective tissue. The outer layer is the epimysium, which helps protect the muscle. Beneath it, the perimysium surrounds and groups fasciculi, which are bundles of skeletal muscle cells called myocytes. These cells are also called skeletal muscle...

classification of skeletal muscle fibers

Skeletal Muscle Fiber Speed and Energy

Skeletal muscle fibers can be grouped by how fast they contract and how they make ATP, the energy cells use for movement. These differences also shape their physical features. Most human muscles contain all three fiber types, but in different amounts. Slow oxidative fibers, also called slow-twitch fibers, appear red because they have many capillaries and high levels of myoglobin, an oxygen-storing protein. They also contain more mitochondria, which make ATP through oxidative phosphorylation,...

muscle contraction

Nerve Signals That Trigger Muscle Contraction

Nerve signals trigger muscle contraction in both skeletal and smooth muscle, but the two muscle types use different control systems. In skeletal muscle, the signal begins at the motor end plate, which is the synapse between a motor neuron and a muscle fiber. In smooth muscle, contraction is controlled by the autonomic nervous system and happens without conscious control. In skeletal muscle, motor nerve terminals release acetylcholine. This neurotransmitter binds to receptors on the sarcolemma,...

cross-bridge cycle

Calcium Control in Muscle Contraction

Calcium control in muscle contraction depends on ATP, motor neurons, and the sliding action of actin and myosin. As a muscle contracts, the thin and thick filaments overlap more, and the sarcomere, which is the contractile unit of the muscle, becomes shorter. This process uses energy from ATP and happens in a repeating cycle at the molecular level. Myosin drives the movement of actin through a cross-bridge cycle. When ATP attached to the myosin head is hydrolyzed to ADP, myosin shifts into a...

motor units

How Motor Units Control Muscle Movement

Motor units control skeletal muscle movement. A motor unit includes one efferent motor neuron, which carries signals away from the central nervous system, and all of the muscle fibers it innervates. A single motor neuron can connect with multiple muscle fibers, but each muscle fiber is innervated by only one motor neuron. Lower motor neurons are the efferent neurons that control skeletal muscle, the most abundant type of muscle in the body. Their cell bodies are found in the spinal cord or...

the spinal cord

Spinal Cord Structure and Dermatomes

The spinal cord is the main nerve pathway of the central nervous system. It carries sensory signals from the body to the brain and motor signals from the brain to the body. It begins at the foramen magnum, the opening at the base of the skull, and extends to the level of the first or second lumbar vertebra. In cross-section, the spinal cord is cylindrical and contains both gray matter and white matter. The central canal lies in the middle and is a remnant of the lumen of the primitive neural...

nociception

Pain signaling begins when the body detects a harmful stimulus. Sharp objects, open flames, and corrosive chemicals can trigger this response. Sensory receptors called nociceptors, which sit on nerve endings, detect these noxious stimuli and use ion channels to turn them into electrical signals. Those electrical signals travel through sensory neurons to the brain, where they are experienced as pain. This warning system helps an organism avoid damage and stay safe. Pain is therefore an...

key terms and concepts

Learn how nociceptors detect harmful stimuli, how inflammation boosts pain sensitivity, and why chronic pain can persist after injury.

Pain Signaling and Inflammation | JoVE K12

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

biology

JoVE Core シリーズは、生物学の重要な概念を説明する 300 を超える簡潔でわかりやすいアニメーション ビデオ レッスンに加え、今日の研究室で行われる実際の研究実験を示す 150 以上の科学者の活動ビデオを通じて、生物学に命を吹き込みます。

myJoVE Corporation

Pain Signaling and Inflammation

Description

Transcript

Tags