Pearce L B, Benishin C G, Cooper J R
Proc Natl Acad Sci U S A. 1986 Oct;83(20):7979-83. doi: 10.1073/pnas.83.20.7979.
Evidence is presented of the existence of a substance in brain (substance B) that reverses presynaptic inhibition of evoked acetylcholine (AcCho) release. Addition of guinea pig brain synaptosomal incubation medium or whole brain extracts to assays in which 1,1-dimethyl-4-phenylpiperazinium-evoked release of [3H]AcCho from guinea pig myenteric plexus synaptosomes reversed purinergic, muscarinic, and alpha 2-adrenergic agonist inhibition. However, the extracts did not increase basal or evoked release of AcCho. Results of chromatography on Bio-Gel P-2 of a concentrated whole brain extract suggest this factor has an Mr of 700. Substance B was resistant to boiling under acid or alkaline conditions as well as incubation with phospholipase C and various proteases; ashing, however, completely destroyed activity. This endogenous factor was also found to antagonize agonist-mediated inhibition of electrically evoked contractions of myenteric plexus-longitudinal muscle strips from the guinea pig ileum. The demonstration of substance B with its ability to reverse presynaptic inhibition of AcCho release reveals one mode of presynaptic modulation.
有证据表明大脑中存在一种物质（物质B），它能逆转对诱发乙酰胆碱（AcCho）释放的突触前抑制。将豚鼠脑突触体孵育培养基或全脑提取物添加到检测中，在这些检测中，1,1 - 二甲基 - 4 - 苯基哌嗪诱发的豚鼠肠肌丛突触体[3H]AcCho释放可逆转嘌呤能、毒蕈碱能和α2 - 肾上腺素能激动剂的抑制作用。然而，这些提取物并未增加AcCho的基础释放或诱发释放。对浓缩全脑提取物进行Bio - Gel P - 2柱层析的结果表明，该因子的相对分子质量为700。物质B在酸性或碱性条件下煮沸以及与磷脂酶C和各种蛋白酶孵育时具有抗性；然而，灰化会完全破坏其活性。还发现这种内源性因子能拮抗激动剂介导的豚鼠回肠肠肌丛 - 纵肌条电诱发收缩的抑制作用。物质B具有逆转AcCho释放的突触前抑制的能力，这揭示了一种突触前调节模式。
