ドーパミンに敏感なアデニルサイクラゼ:シナプス伝達における潜在的な役割
Science (New York, N.Y.)
|December 24, 1971
まとめ
研究者らは,上部頸部交感性ギャングリアのドーパミン活性化アデニルサイクラスを発見した. この酵素は,シナプス活動中にアデノシン3',5'-モノフォスファート (cAMP) を増加させることで,ドーパミンの生理学的効果を媒介する可能性があります.
科学分野:
- 神経科学は神経科学である.
- バイオケミストリー バイオケミストリー
- 細胞生物学 細胞生物学
背景:
- ドーパミンは,中枢神経系と外周神経系における重要な神経伝達物質である.
- ガングリアのシナプス活動は,細胞内シグナル伝達分子の変化と関連しています.
- アデノシン3',5'-モノフォスファート (cAMP) は,様々な細胞プロセスに関与する重要な第2メッセンジャーです.
研究 の 目的:
- 哺乳類の上部頸部交感性ギャングリオンにおけるドーパミンの作用の基礎となる分子メカニズムを特定する.
- ドーパミナージック神経伝達を媒介するアデニルサイクラスの役割を調査する.
主な方法:
- バイオケミカルアッセイは,アデニルサイクラゼの活性性を検出するために使用されました.
- 酵素活性は,ドーパミンの濃度の変化に反応して測定されました.
- アデノシン3',5'-モノフォスファートのレベルは,シナプス刺激中に定量化されました.
主要な成果:
- ドーパミンの低濃度に対して敏感な新しいアデニルサイクラスが,上部頸部交感性ギャングリオンで特定されました.
- この酵素の存在は,シナプス活動中のcAMPレベルの増加と相関しています.
- ドーパミンは,このアデニルサイクラスを直接活性化し,cAMP合成の強化につながります.
結論:
- 特定されたアデニルサイクラスは,上部頸部交感性ギャングリオンにおけるシナプス活動中に観察されたcAMPの増加に起因する可能性があります.
- ドーパミンの生理学的効果は,このギャングリオンおよび潜在的に他の神経組織において,この酵素によるcAMP合成の刺激によって媒介されます.
関連する概念動画
01:24Intracellular Signaling Cascades
Once a ligand binds to a receptor, the signal is transmitted through the membrane and into the cytoplasm. The continuation of a signal in this manner is called signal transduction. Signal transduction only occurs with cell-surface receptors, which cannot interact with most components of the cell, such as DNA. Only internal receptors can interact directly with DNA in the nucleus to initiate protein synthesis. When a ligand binds to its receptor, conformational changes occur that affect the...
01:09GPCRs Regulate Adenylyl Cylase Activity
Some GPCRs transmit signals through adenylyl cyclase (AC), a transmembrane enzyme. AC helps synthesize second messenger cyclic adenosine monophosphate (cAMP). AC catalyzes cyclization reaction and converts ATP to cAMP by releasing a pyrophosphate. The pyrophosphate is further hydrolyzed to phosphate by the enzyme pyrophosphatase, which drives cAMP synthesis to completion. However, cAMP is rapidly degraded to 5′ AMP by the enzymes phosphodiesterase (PDE), preventing overstimulation of cells.
Two...
Two...
01:26Neurochemical Transmission: Sites of Drug Action
Neurochemical transmission, the conduction of electrical impulses between neurons mediated by neurotransmitters, plays a vital role in various physiological processes. Autonomic drugs exert their effects by modulating neurotransmission within the autonomic nervous system. For instance, drugs such as hemicholinium block the precursor uptake necessary for synthesizing acetylcholine, an essential autonomic neurotransmitter. Following synthesis, neurotransmitters are stored in vesicles. Metyrosine...
01:27Adrenergic Neurons: Neurotransmission
Postganglionic sympathetic fibers (except those supplying the sweat glands) releasing noradrenaline or norepinephrine are called noradrenergic or adrenergic neurons. Noradrenaline, dopamine, adrenaline, or epinephrine are collectively called "catecholamines" as they contain a catechol moiety and an amine side chain. The five stages of neurotransmitter release involve their synthesis, storage, release, reuptake and metabolism.
Synthesis: Catecholamine synthesis requires tyrosine, which is taken...
Synthesis: Catecholamine synthesis requires tyrosine, which is taken...
01:21Drugs Affecting Neurotransmitter Release or Uptake
Certain drugs can affect how neurotransmitters called catecholamines, are released or taken back up in the adrenergic neuron. They can have different effects on the body's sympathetic transmission. Reserpine, a natural compound found in the Rauwolfia shrub, blocks a transporter called vesicular monoamine transporter (VMAT), which leads to a buildup of catecholamines in the cell and reduces sympathetic transmission. Another drug called guanethidine works in multiple ways, including blocking...
01:29Drugs Affecting Neurotransmitter Synthesis
Drugs affecting neurotransmitter synthesis can impact the adrenergic neuron and the synthesis of neurotransmitters. For example, α-methyltyrosine and carbidopa target specific enzymes involved in catecholamine synthesis. α-methyltyrosine inhibits the enzyme tyrosine hydroxylase, which converts tyrosine into dopamine. By blocking this enzyme, α-methyltyrosine reduces dopamine production and other catecholamines. Carbidopa, on the other hand, inhibits the enzyme dopa decarboxylase, which converts...