1,721,120 research outputs found
Vittorio Erspamer (1909-1999)
No full textVittorio Erspamer's scientific achievements are highlighted by illustrating his long-life commitment to research and to truth, as well as his untiring rhythm of work, both in Italy and abroad--in the scientific expeditions organized to gather amphibians all around the world. His life and career are set against the background of Italian political and cultural life in the Novecento
Satiety and scratching; effects of bombesin-like peptides.
No full textTwo novel amphibian peptides, [Ser7]litorin-like peptide (Ser-LIT) and [Ser7]bombesin-like peptide (Ser-BN), recently isolated from the skin of the South American frog Phyllomedusa sauvagei, are characterized by the occurrence of a Ser residue in place of His7 in the C-terminal tripeptide. For testing on food intake in fasted rats the peptides were injected intraperitoneally (i.p.) and intracerebroventricularly (i.c.v.) and their activity compared with that of bombesin (BN) and litorin (LIT). Ser-LIT was completely ineffective on food intake while Ser-BN was about ten times less potent than LIT by i.p. injection; given i.c.v., Ser-BN inhibited food intake in the first 15 min after injection but its effect faded within 60 min. The i.c.v. administration of both [Ser7]-substituted peptides, elicited intense scratching with a potency equal to or higher than that of BN or LIT. The existence of two different kinds of receptors for BN-like peptides may be hypothesized: the first, specific for the C-terminal tripeptide sequence, is apparently involved in the inhibition of feeding; the second, responsible for the stimulating activity on the urinary bladder and for scratching, shows higher affinity for the N-terminal portion of the biological active sequence
Action of sauvagine on the mesenteric vascular bed of the dog.
No full textSauvagine, a linear peptide of 40 amino acids, produced hypotension when administered intravenously to anesthetized dogs. Diastolic pressure was always more affected than systolic pressure. Aortic blood flow and venous return both increased to the same extent. The mechanism of the hypotensive response was mainly, if not exclusively, due to dilatation of the superior and inferior mesenteric arteries. Intravenous infusion of sauvagine in doses ranging from 3 to 10 ng . kg-1 . min-1 produced a dose-related increase of mesenteric blood flow up to 400% control values. Mucosal-submucosal blood flow of ileum and colon was increased, while blood flow in muscle was unaffected or slight decreased. The mesenteric vasodilator response was not prevented by adrenergic or muscarinic receptor blockade. The hypotensive response was more marked and sustained in dibenamine-propranolol treated dogs
Nonmammalian tachykinins: their contribution to the discovery and biological characterization of the mammalian neurokinin system
No full textThe dermorphin peptide family
No full text1. In 1980, the skin of certain frogs belonging to the genus Phyllomedusinae was found to contain two new peptides that proved to be selective mu-opioid agonists. Given the name dermorphins, these were the first members of a peptide family that in the past 15 years has grown to reach a total of seven naturally occurring peptides and nearly 30 synthetic analogs. 2. Dermorphin peptides are potent analgesics in rodents and primates, including man. Some dermorphins can enter the blood-brain barrier and produce central antinociception after peripheral administration. 3. The dermorphin family also includes mu(1)-opioid receptor selective agonists that produce intense opioid analgesia, but stimulate pulmonary ventilation. 4. Experiments in rats and mice chronically exposed to dermorphins have shown that not only do they have higher antinociceptive efficacy and potency than morphine, but they are also less likely than morphine to produce tolerance, dependence and opiate side effects. Copyright (C) 1996 Elsevier Science Inc
Action of caerulein and caerulein-like peptides on "short-circuit current" and acid secretion in the isolated gastric mucosa of amphibians
No full textCaerulein produced an increase of the short-circuit current in the isolated gastric mucosa of Rana esculenta and Bufo viridis. Threshold concentrations were of the order of 10–10 M and 3×10–11 M, respectively. A dose-response relationship was observed for concentrations of the polypeptide up to 10 to 20 times the threshold. At the same time, the polypeptide also caused an increase in the secretion of hydrochloric acid by the isolated mucosa, as measured by a direct titrimetric method. The effects of caerulein were atropine-resistant, and hence not mediated through a cholinergic mechanism. The action of caerulein on short-circuit current was compared to that of a number of synhtetic caerulein-like peptides and to that of other miscellaneous stimulants of gastric acid secretion. This study allows some conclusions to be drawn as to the relationship between chemical structure and biological activity, and largely confirms results obtained with other test preparations. With the exception of some caerulein-like peptides, no other compound could compete with caerulein in its stimulant action on the isolated amphibian gastric mucosa: cholecystokinin possessed 3% of the activity of caerulein, histamine approximately 0.1%, human gastrin I, pentagastrin and carbachol barely 0.01%
Distribution and metabolism of dermorphin in rats
No full textDermorphin distribution and metabolism were studied in rats injected with high doses of the peptide and with 125I-dermorphin, using RIA methods, HPLC extraction and γ-counting. Dermorphin rapidly disappeared from plasma (half-life: 1.3 min). In vivo and in vitro experiments demonstrated that the peptide was destroyed in liver and kidney. The highest percent (11%) of injected dermorphin has been found in the bile collected over 1 hour. HPLC analysis showed that bile contained also breakdown products (di, tri, and tetra N-terminal peptide fragments). Reported data suggested that intact dermorphin can be eliminated more slowly than breakdown products
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