Tachykinins and other biologically active peptides from the skin of the Costa Rican phyllomedusid frog Agalychnis callidryas.

Peptides present in a methanol extract prepared from skin of the Costa Rican frog Agalychnis callidryas of the Phyllomedusinae subfamily were studied by sequence analysis and pharmacological tests. Members of five different peptide families-tachykinins, bradykinins, caerulein, opioid peptides and sauvagine-were found. In particular, the extract contained a number of tachykinins with the following sequences: Gly-Pro-Pro-Asp-Pro-Asn-Lys-Phe-Ile-Gly-Leu-Met-NH2, Gly-Pro-Pro-Asp-Pro-Asp-Arg(Lys)-Phe-Tyr-Pro-Gly-Met-NH2, pGlu-Pro-Asp-Pro-Asp-Arg-Phe-Tyr-Pro-Gly-Met-NH2, Gly-Pro-Pro-Asp-Pro-Asn-Lys-Phe-Tyr-Pro-Val-Met.

Choline esters and biogenic amines in the hypobranchial gland of 55 molluscan species of the neogastropod Muricoidea superfamily.

As many as 55 neogastropod molluscs, all belonging to the Muricoidea superfamily, have been investigated for occurrence and contents, in their hypobranchial gland (HG), of choline esters and, subordinately, biogenic amines. Very high amounts of esters, strictly localized in the median area of the HG, were found in all dye-secreting molluscs. The choline esters were represented by murexine, dihydromurexine and senecioylcholine.

Pharmacological studies of 'sapo' from the frog Phyllomedusa bicolor skin: a drug used by the Peruvian Matses Indians in shamanic hunting practices.

The dried skin secretion from Phyllomedusa bicolor, 'sapo', is used by the Matses Indians of the Northern Peru, in shamanic rites mainly designed to improve luck in hunting. When rubbed into burned, exposed areas of the skin, the drug causes the prompt appearance of violent peripheral gastrointestinal and cardiovascular effects soon followed by remarkable central effects (increase in physical strength, heightening of senses, resistance to hunger and thirst, exalted capacity to face stress situations). All the peripheral and most of the central effects of 'sapo' can be ascribed to the exceptionally high content of the drug (up to 7% of its weight) in potently active peptides, easily absorbed through the burned, inflamed areas of the skin.

Guinea-pig ileum (GPI) and mouse vas deferens (MVD) preparations in the discovery, discrimination and parallel bioassay of opioid peptides.

As many as 47 amphibian and mammalian, natural and non-natural opioid peptides have been examined in guinea-pig ileum (GPI) and mouse vas deferens (MVD) preparations. The great value of these extremely simple and accessible tissue models in the identification, isolation and purification of endogenous opioid peptides, in studying structure/activity relationships, and in determining selectivity of the peptide molecules for the various opioid receptors, especially delta- and mu-receptors, is emphasized.

Dermorphin-related peptides from the skin of Phyllomedusa bicolor and their amidated analogs activate two mu opioid receptor subtypes that modulate antinociception and catalepsy in the rat.

Three naturally occurring dermorphin-like peptides from the skin of the frog Phyllomedusa bicolor, the related carboxyl-terminal amides, and some substituted analogs were synthesized, their binding profiles to opioid receptors were determined, and their biological activities were studied in isolated organ preparations and intact animals. The opioid binding profile revealed a very high selectivity of these peptides for mu sites and suggested the existence of two receptor subtypes, of high and low affinity. The peptides tested acted as potent mu opioid agonists on isolated organ preparations.

Identification and characterization of two dermorphins from skin extracts of the Amazonian frog Phyllomedusa bicolor.

Skin extracts of South American hylid frogs of the subfamily Phyllomedusinae contain dermorphins and deltorphins, opioid heptapeptides highly selective for either mu or delta receptors. In all these peptides, a D-amino acid is present in the second position. The structure of the precursors for Ala-deltorphins was recently deduced from cloned cDNAs derived from skin of Phyllomedusa bicolor (Richter et al.

Purification and characterization of bioactive peptides from skin extracts of Rana esculenta.

The peptide fraction extracted by methanol from the skin of Rana esculenta, a species widely distributed in Western Europe, was investigated. The pharmacological activity found in the extract is attributable to the presence of authentic bradykinin, together with a shorter, partially active version of this molecule, des-Arg9-bradykinin. Also the bradykinin fragment 1-7 has been isolated, but it was inactive in our bioassay system.

Pumiliotoxin B-like alkaloid in extracts of the skin of the Australian myobatrachid frog Pseudophryne coriacea: effects on the systemic blood pressure of experimental animals and the rat heart.

Semi-purified extracts of the skin of the Australian myobatrachid frog Pseudophryne coriacea (PS)displayed striking, reversible and, in part, dose-dependent effects on the systemic blood pressure of the rat and other experimental animals, as well as on the rat heart. The blood pressure response in the rat consisted typically in an abrupt, short-lasting fall, followed by a conspicuous, more persistent rise. The fall in pressure was abolished by atropine and potentiated by physostigmine, indicating a cholinergic mechanism; rise was abolished by prazosin and guanethidine, suggesting a release of catecholamines from adrenergic nerve terminals in the vasculature.

Deltorphin, a novel amphibian skin peptide with high selectivity and affinity for delta opioid receptors.

With a cDNA library prepared from skin of Phyllomedusa sauvagei, the sequence of the precursor of dermorphin was elucidated recently. The sequence suggested the existence of another peptide, distantly related to dermorphin. Two variants of this peptide have now been synthesized containing either L- or D-methionine as the second amino acid.

Action of a semi-purified extract of Pseudophryne coriacea skin on the frog rectus abdominis muscle.

Extracts of the skin of the Australian frog Pseudophryne coriacea (PS) displayed a striking potentiating effect on contractions evoked in the isolated frog rectus abdominis muscle by direct electrical stimulation. There was both a conspicuous increase in twitch amplitude and a remarkable prolongation of twitch duration. High concentrations of PS also elicited an increase in tone.

Active peptides in the skins of one hundred amphibian species from Australia and Papua New Guinea.

Extracts prepared from the dried skins of approximately one hundred amphibian species from Australia and Papua New Guinea were subjected to biological screening in order to determine the nature and amounts of peptides active on smooth muscle preparations and systemic blood pressure present in these extracts. The most frequently and abundantly occurring peptides were those of the caerulein, bombesin and tachykinin peptide families represented, respectively, by caerulein; litorin, Glu(OMe)2-litorin and Glu(OEt)2-litorin; uperolein and Lys5-Thr6-physalaemin. Bradykinin-like peptides seem to have a rather diffuse distribution, in the species examined, but so far no peptide of this family has been isolated and sequenced.

Synthetic peptides related to the dermorphins. II. Synthesis and biological activities of new analogues.

A new series of analogues of the potent opiate-like peptides dermorphins (mainly tetra- and pentapeptides) were synthesized in order to better evaluate the structure-activity relationships. Relative potencies were referred to dermorphin (H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2), the prototype of this class of frog skin peptides. Peripheral opioid activity (guinea-pig ileum and mouse vas deferens) was determined for all the dermorphin analogues.

Radioimmunoassay of dermorphin-like peptides in mammalian and non-mammalian tissues.

A selective RIA for D-Ala2-Dermorphin (Der), a natural peptide extracted from amphibian skin, has been developed using an antibody raised in rabbits against Der which has been coupled to BSA through its phenolic hydroxyl groups of tyrosine residues with 2,4-Dichloro-6-methoxy-1,3,5-triazine. The cross-reactivity of this antibody with dermorphin analogs, C- and N-terminal fragments of dermorphin molecule, some opioid and gastrointestinal peptides was tested. Der-like immunoreactivity has been identified in tissue extracts of rats, frog and cephalopoda.

The brain-gut-skin triangle: new peptides.

New data on tachykinins and bombesins are displayed and the present situation of research on the novel amphibian skin peptides sauvagine and dermorphin is illustrated. The potent stimulant effect of sauvagine on ACTH and beta-endorphin release has been confirmed both in vivo and on columns of isolated and dispersed rat pituitary cells, and similarly the potent inhibitory effect on PRL and GH release, both in the rat and man. Particular emphasis is laid on the occurrence of sauvagine-like immunoreactivity in fish urophysis and in amphibian nervous structures, including the retina.

Sauvagine, a new polypeptide from Phyllomedusa sauvagei skin. Occurrence in various Phyllomedusa species and pharmacological actions on rat blood pressure and diuresis.

1. The occurrence of sauvagine, a new polypeptide from amphibian skin, and its actions on rat blood pressure and diuresis were studied. 2.

Parallel bioassay of physalaemin and kassinin, a tachykinin dodecapeptide from the skin of the African frog Kassina senegalensis.

1. Kassinin, a tachykinin dodecapeptide isolated from the skin of the African frog Kassina senegalensis was submitted to parallel bioassay with physalaemin, eledoisin and substance P, three major representatives of the tachykinin peptide family. Bioassay was carried out on blood pressure, salivary secretion and isolated or in situ smooth muscle preparations.

Occurrence and polymorphism of bombesin-like peptides in the gastrointestinal tract of birds and mammals.

The gastrointestinal tract of mammals and birds, especially stomach and upper small intestine, contains bombesin-like peptides. This has been unequivocally demonstrated by radioimmunoassay and bioassay. Concentrations of bombesin-like activity may range from a few ng to 500-600 ng per g fresh tissue.

Occurrence of Hyp3-bradykinin in methanol extracts of the skin of the South African leptodactylid frog Heleophryne purcelli.

Methanol extracts of the skin of the South African amphibians belonging to the genus Heleophryne (H. purcelli purcelli, H. purcelli depressa, H.

Uperolein and other active peptides in the skin of the Australian leptodactylid frogs Uperoleia and Taudactylus.

Methanol extracts of the skin of the Australian leptodactylid frogs Uperoleia rugosa, Uperoleia marmorata and Taudactylus acutirostris contain several highly active polypeptides belonging to different peptide families. The most abundant peptide was uperolein, a tachykinin closely related to physalaemin and possessing the same spectrum of biological activity. Uperolein was present in the three species examined.

Occurrence of bombesin and alytesin in extracts of the skin of three European discoglossid frogs and pharmacological actions of bombesin on extravascular smooth muscle.

1. Methanol extracts of the skin of Bombina bombina and Bombina variegata variegata, two European discoglossid frogs, contain an active tetradecapeptide, bombesin. Alytesin, a tetradecapeptide strictly related to bombesin is present in extracts of the skin of Alytes obstetricans, another European discoglossid frog.