sincalide and phenylalanyl-leucyl-phenylalanyl-glutaminyl-prolyl-glutaminyl-arginyl-phenylalaninamide

The effects of two recently isolated mammalian FMRFamide related peptides (A-18-F-amide and F-8-F-amide) on the encocrine and exocrine rat pancreas were investigated. A-18-F-amide (10, 100, 1000 pM) inhibited concentration dependently glucose (10 mM)- and arginine (10 mM)-induced insulin secretion from the isolated perfused rat pancreas during the first (controls: 100%; 10 pM: 114%; 100 pM: 63%, p less than 0.05; 1000 pM: 31%, p less than 0.05) and the second secretion phase (controls: 100%; 10 pM: 102%; 100 pM: 78%; 1000 pM: 27%, p less than 0.05). The inhibitory actions of A-18-F-amide on pancreatic D-cell secretion were more pronounced during the first than the second phase (first phase: controls: 100%; 10 pM: 95%; 100 pM: 37%, p less than 0.05; 1000 pM: 39%, p less than 0.05%; second phase: controls: 100%; 10 pM: 113%; 100 pM: 72%; 1000 pM: 59%, p less than 0.05). F-8-F-amide (at 1000 pM) inhibited stimulated insulin (controls: 100%; first phase: 26%, p less than 0.05%; second phase: 20%, p less than 0.05) and somatostatin release (controls: 100%; first phase: 14%, p less than 0.05; second phase: 29%, p less than 0.05). Both peptides were without effect on basal and CCK-8-stimulated amylase release from isolated incubated rat pancreatic acini.

Topics: Amino Acid Sequence; Amylases; Animals; Arginine; Glucose; Insulin; Insulin Secretion; Islets of Langerhans; Male; Molecular Sequence Data; Neuropeptides; Oligopeptides; Pancreas; Rats; Rats, Inbred Strains; Sincalide; Somatostatin

An in vivo preparation of the rat spinal cord was used to investigate the electrophysiological actions of two non-opioid peptides, cholecystokinin (CCK8) and FLFQPQRF-NH2 (FMRFamide-like peptide) applied intrathecally. These compounds were examined alone and as a pretreatment before DAGO, a mu opioid agonist, and DSTBULET, a delta opioid agonist, both which selectively reduce C-fibre evoked dorsal horn neurone activity elicited by transcutaneous electrical stimulation. Given alone, CCK8 (1 microgram) elicited a modest enhancement of C-fibre induced activity which returned to control levels after 20 min, while FLFQPQRF-NH2 (10 micrograms) had no significant effect on C-fibre evoked firing. As a pretreatment, however, both peptides selectively prevented the inhibition of C-fibre evoked activity normally resulting from intrathecal DAGO, while having no effect on that resulting from DSTBULET. Further, CCK8 enhanced the facilitation of C-fibre evoked firing normally observed with low doses of DAGO. These data indicate that the anti-opioid roles suggested for CCK8 and FLFQPQRF-NH2 may be specific for neural elements utilizing the mu opioid receptor.

Topics: Animals; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; Enkephalins; Evoked Potentials; Injections, Spinal; Male; Nerve Fibers; Neurons; Oligopeptides; Pain; Rats; Rats, Inbred Strains; Receptors, Opioid; Receptors, Opioid, delta; Receptors, Opioid, mu; Sincalide; Spinal Cord