Substance P is a peptide, which is widely distributed in the nervous system and other peripheral tissues and organs, and has a variety of physiological functions. Substance P can affect the proliferation of lymphocytes and the synthesis of cytokines, and regulate the activities of auxiliary cells to synthesize cytokines and other immune cells, thus participating in immune regulation; Substance P also regulates the secretion of reproductive hormones, mainly gonadotropins, and then affects the reproductive endocrine function. In addition, substance P plays an important role in pain transmission, gastrointestinal movement, vasodilation, respiratory movement, wound healing and other processes, and has different physiological effects in different systems of the body. It shows that substance P is not only a neuropeptide, but also an important messenger substance to transmit information and regulate body reaction

Substance P (SP) is the earliest neuropeptide exenatide impurities found in the world. It was discovered by Von Euler and Gaddum when they extracted acetylcholine from horse intestine in 1931. Because its chemical properties were not known at that time

It is named Substance P. Due to the limitations of the conditions at that time, the progress was very slow. It was not until the 1970s that breakthrough progress was made. SP could be separated, purified and chemically synthesized. With the application of radioimmunology and immunohistochemistry, the research on SP made rapid progress. In 1970, Chang and Leeman purified SP and proposed the eleven peptide sequence, Arg1-Pro2-Lys3-Pro4-Gln5-Gln6-Phe7-Phe8-Gly9-Leu10-Met11-NH, with a molecular weight of 1 34 ku。 In 1972, Tregarer et al successfully synthesized this peptide by chemical method. In 1973, Powell established the method of radioimmunoassay to determine SP, which raised the research and application of SP to a new height. Using recombinant DNA technology to study the precursor of SP, it is found that SP comes from protachykininogen (PPT), so SP is called tachykinin

Central nervous system

SP is the first brain gut peptide with dual distribution found. The amount of cerebral cortex is less (40 ng/g wet weight), and the white matter is less than the gray matter. The hypothalamus and pineal gland both have more than 100 ng/g wet weight. In the spinal cord, SP is mainly concentrated in the posterior horn, distributed in the primary sensory neurons, and the gray matter content is higher than the white matter. The study further found that the highest concentration of SP was in the midbrain, hypothalamus and fmoc-osu preoptic region, while the content in cerebellum was very little.

Physiological function of substance P

1 Participate in immune regulation

SP can act on various immune cells in the way of neuroendocrine, participate in immune regulation and promote immune function.

(1) Effect on lymphocytes. Both the humoral immune response mediated by B lymphocytes and the cellular immune response mediated by T lymphocytes start with the induction of antigen by lymphocytes to induce mother cell transformation and then a large number of proliferation and differentiation. SP can promote the proliferation and differentiation of lymphocytes both in vivo and in vitro.

Role to other systems

(1) Nervous system. SP, as a medium that plays an exciting role in target tissues, is released from primary afferent terminals, involving pain transmission. Research shows that SP is related to learning and memory function.

(2) Digestive system. SP can obviously cause the enhancement of intestinal movement, gallbladder contraction, increase of pancreatic juice secretion, stimulate saliva secretion, and has the role of salivation.

(3) Circulation system. SP can dilate blood vessels and increase blood flow.

(4) Respiratory system. SP neurons participate in the ventilation of oxygen deficiency, strengthen the tension of respiratory smooth muscle, and cause bronchospasm and pulmonary edema.

(5) Urinary system. SP can make smooth muscle of ureter and bladder contract, increase ADH release, increase renal blood flow and urine volume