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  • 1
    ISSN: 1432-1912
    Keywords: Tachykinins ; Calcitonin gene related peptide ; Neutrophils ; Monocytes ; Chemotaxis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Polymorphonuclear leukocytes (PMNL) are a component of the inflammatory response to neurogenic mediators. Using the micropore filter approach, the authors studied the chemoattracting properties of tachykinins, including substance P (SP), neurokinin A (NKA) and neurokinin B (NKB), and that of calcitonin gene-related peptide (CGRP) for human PMNL in vitro and now show that SP in near nanomolar concentrations stimulates locomotion of human PMNL. Locomotion of PMNL is induced by SP, aminoterminal SP (1–9) and the SP receptor antagonist [d-pro2, d-trp7,9]-SP (DPDT) but not by carboxyterminal SP (3–11), NKA, NKB, or CGRP suggesting that the aminoterminal amino acids arginine and proline, are essential residues of SP in activation of PMNL locomotion. In contrast, the migratory effect of SP on monocytes resides in the carboxyterminal SP amino acid sequence, which is in agreement with carboxyterminal, SP receptor-mediated chemotaxis of human monocytes previously shown by others. From the known structure-activity relationships for SP receptors it is concluded that induction of PMNL migration by SP does not involve neurokinin-1 (NK-1), NK-2 or NK-3 receptors. “Checkerboard” analysis reveals that PMNL locomotion by SP is not dependent on concentration gradients and thus represents chemokinesis, which is enhancement of speed and/or frequency of locomotion. One cannot exclude that this action of SP on PMNL is mediated by the aminoterminal sequence via yet unknown SP “receptors”. Since structure-activity relationships appear to be similar to the mast cell degranulating actions of tachykinins, which also critically depend on the aminoterminal sequence, it may correspondingly be regarded as non-receptorial mechanism, due to membrane interaction of the basic groups in the N-terminal region of the peptide.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1912
    Keywords: Somatostatin ; Octreotide ; Neutrophils ; Raspiratory burst ; Chemotaxis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Growth hormone, prolactin and somatostatin are polypeptide hormones of the neuroendocrine and peripheral nervous systems. In vitro, these have opposing effects on cells of the immune system. We compared the effects of these peptides on activation of neutrophils using a recombinant preparation of human growth hormone, human prolactin and octreotide, a long acting analog of somatostatin. In the absence of growth hormone, octreotide did not affect either neutrophil locomotion or respiratory burst. Octreotide, however, significantly antagonized growth hormone-induced activation of neutrophils for enhanced respiratory burst as well as growth hormone-induced inhibition of stimulated migration. As the effect of growth hormone on neutrophils is mediated by the prolactin receptor, its inhibition by octreotide was also tested using prolactin as priming agent. Data indicate comparable effects of octreotide on priming of neutrophils by prolactin. The effect of octreotide was dose-dependent and appeared to be selective, as activation of neutrophil respiration burst by γ-interferon, and inhibition of stimulated migration by tumor necrosis factor-α were unaffected by octreotide. The present study suggests that octreotide may act on neutrophils directly by antagonizing growth hormone or prolactin at the cellular level.
    Type of Medium: Electronic Resource
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