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Biomedical subjects

V Mutt

Publications and source records attributed to V Mutt.

At least 127 records · Page 7Linked to original sources
PubMed1983

Evidence for the existence of receptor--receptor interactions in the central nervous system. Studies on the regulation of monoamine receptors by neuropeptides.

Substance P (SP) (10(-8) M) can rapidly reduce the affinity and increase the density of 3H-5-HT binding sites in spinal cord membranes. CCK-8 and CCK-4 (10(-8) M) can rapidly and differentially change the characteristics of 3H-spiperone striatal binding sites linked to DA receptors of the D2 type. CCK-4 increase and CCK-8 reduce the number of striatal binding sites for 3H-spiperone, indicating for the first time separate CCK-4 binding sites. CCK-4 (10(-8) M) but not CCK-8 (10(-8) M) can rapidly reduce the affinity and increase the number of the 3H-spiperone binding sites linked to 5-HT receptors of the dorsal cerebral cortex of rats. CCK-8 (10(-8) M) only produces a trend for a small increase in the Bmax values of these receptors. These results again imply the existence of separate CCK-4 binding sites in this case in the cerebral cortex. Glutamate (10(-6) M), but not N-methyl-D-aspartate (10(-6) M) can rapidly change the characteristics of the 3H-N-propylnorapomorphine (3H-NPA) binding sites in striatal membranes of rats. Glutamate (10(-6) M) increases the density and especially reduces the affinity of the 3H-NPA binding sites, which label D2 and D3 types of DA receptors. Taken together the present findings give evidence that neuropeptide receptors and glutamate receptors can in vitro rapidly modulate the characteristics of different types of DA and 5-HT receptors by way of receptor--receptor interactions at the comodulate level or at the local circuit level. It is hypothesized that these receptor--receptor interactions are of importance for the encoding of short-term memory.

Animals↗
PubMed1983

Inhibition of interdigestive contractile activity in the stomach by peptide YY in Heidenhain pouch dogs.

The inhibitory effect of peptide YY on contractile activity in the innervated main stomach and the vagally denervated fundic pouch in conscious Heidenhain pouch dogs was investigated. Peptide YY was given in i.v. bolus injections of doses between 12.5 and 100 pmol/kg body wt. During the digestive state, 2-3 h after feeding, peptide YY was found to have no effect on contractile activity in either the innervated or the vagally denervated stomach. In the interdigestive state, it was found that peptide YY inhibited the interdigestive migrating contractions in the innervated main stomach dose-dependently for 1.2 +/- 0.1 to 5.8 +/- 0.3 min, but did not affect pouch contractions at all. This peptide, however, did not influence the cycle of the interdigestive migrating contractions. Pentagastrin, on the other hand, suppressed the interdigestive migrating contractions in the innervated main stomach when the bolus doses were greater than 300 pmol/kg body wt, but did not inhibit pouch contractions completely with this dose. Atropine (0.05 mg/kg body wt) suppressed contractions in both the main stomach and the vagally denervated pouch. Peptide YY inhibits the interdigestive migrating contractions in the stomach through the extrinsic nerves.

Animals↗
PubMed1982

Isolation of glucagon-37 (bioactive enteroglucagon/oxyntomodulin) from porcine jejuno-ileum. Isolation of the peptide.

A 37 amino acid-peptide has been isolated from porcine jejuno-ileum on the basis of its glucagon-like activity in liver (interaction with glucagon-binding sites and activation of adenylate cyclase) using gel filtration, ion-exchange and high-performance liquid chromatography. Depending on the criteria chosen, this peptide is referred to as either 'bioactive enteroglucagon' (activity in liver), 'oxyntomodulin' (specific action in gastric oxyntic glands) or 'glucagon-37' (chemical structure).

Adenylyl Cyclases↗
PubMed1982

Isolation of glucagon-37 (bioactive enteroglucagon/oxyntomodulin) from porcine jejuno-ileum. Characterization of the peptide.

A peptide isolated from porcine gut according to its glucagon-like activity in liver (bioactive enteroglucagon) has been characterized immunologically, biologically and chemically: its potency relative to pancreatic glucagon in interacting with an antiglucagon antibody, hepatic glucagon-binding sites and hepatic adenylate cyclase was approximately 100%, 20% and 10%, respectively. In contrast, it is approximately 20-times more potent than glucagon in oxyntic glands, justifying the term 'oxyntomodulin'. Chemically, it consists in the 29 amino acid-peptide glucagon elongated at its C-terminal end by the octapeptide Lys-Arg-Asn-Lys-Asn-Asn-Ile-Ala; accordingly, it is called 'glucagon-37'.

Amino Acid Sequence↗
PubMed1982

Synthesis and some pharmacological properties of Z-Tyr(SO3H)-Met-Gly-Trp-Met-Asp(Phe-NH2)-OH, a 32-beta-aspartyl analogue of cholecystokinin (pancreozymin) 27-33.

The heptapeptide carbobenzoxy-L-tyrosyl(O-sulfate)-L-methionylglycyl-L-tryptophyl-L-methionyl-L- aspartyl-beta-L-phenylalanine amine (Z-32-beta-Asp-CCK-27-33) was synthesized and tested for its ability to stimulate secretion from dispersed pancreatic acini in vitro, to increase protein secretion from cat pancreas in vivo, and to cause contraction of guinea pig gallbladder in situ. In increasing amylase secretion in vitro, the Z-32-beta-Asp-CCK-27-33 was equal in efficacy with but approximatively one-third as potent as the Boc-CCK-27-33, and when tested in vivo its activity is approximately 10 Ivy dog units (Idu)/microgram. In stimulation of the contraction of the gallbladder, it showed an activity lower than 1 Idu/microgram. This analogue has more pancreozyminic activity than cholecystokin-like activity. This seems to indicate different affinities for the two receptors.

Amylases↗
PubMed1982

Localization of peptide YY (PYY) in gastrointestinal endocrine cells and effects on intestinal blood flow and motility.

In immunohistochemical studies using antisera to peptide YY (PYY), a 36 amino acid polypeptide isolated from porcine duodenum, it was found that PYY-like immunoreactivity occurred mainly in endocrine cells of the gastrointestinal mucosa. PYY-immunoreactive cells were particularly abundant in the distal intestine and have been observed in five species, including man. By radioimmunoassay it was found that, in the rat, the amount of PYY immunoreactivity was about 100-fold higher in the colon than in the duodenum. The chromatographic profiles of PYY immunoreactivity from the rat colon and porcine PYY on a SP-Sephadex ion exchanger were similar. Furthermore, serial dilutions of extracts from the rat colon and porcine PYY had parallel displacement curves in radioimmunoassay. Close intraarterial administration of PYY in cats caused an intestinal vasoconstriction and an inhibition of jejunal and colonic motility. Simultaneously there was a rise in systemic arterial blood pressure. These effects of PYY were also observed after pretreatment with adrenergic blocking agents. It is concluded that PYY is a gastrointestinal peptide that is present mainly in endocrine cells of distal intestine and that has effect on both intestinal motility and the cardiovascular system.

Animals↗
PubMed1982

Structural similarities among gastrointestinal hormones and related active peptides.

The amino acid sequences of gastrointestinal hormones were compared in fragments of variable spans. Similarities within each of three peptide groups are extensive, but non-unique alignments were also noticed in the glucagon group. Use of different spans demonstrated that structural similarities are unevenly distributed in the gastrin family. Correct phasing was detected even for proteins with few identities and multi-shifted alignments (alcohol dehydrogenases). Tests for alignments among different groups of peptides revealed similarities between bombesin and glucagon or secretin, as well as between caerulein and litorin. Recently determined extended structures suggested the presence of a few deletions/insertions close to the middle of the molecules (two such positions missing in the gastrin-releasing peptide in relation to glucagon). The alignments appear to structurally link large groups of peptide hormones and active peptides. Similarities concentrate in the C-terminal parts, and gaps in the middle. These facts are consistent with known correlations with bioactivities. They also suggest the possibility of evolutionary connections among different peptides as well as corresponding relationships among their receptors.

Amino Acid Sequence↗
PubMed1982

A porcine brain polypeptide is identical to the vasoactive intestinal polypeptide.

The polypeptide known as the "vasoactive intestinal polypeptide" has now been isolated from porcine brain. Determination of the structure shows that cerebral vasoactive intestinal polypeptide consists of 28 amino acid residues in the sequence: His-Ser-Asp-Ala-Val-Phe-Thr-Asp-Asn-Tyr-Thr-Arg-Leu-Arg-Lys-Gln-Met-Ala-Val-Lys -Lys-Tyr-Leu-Asn-Ser-Ile-Leu-Asn-NH2. This structure is identical to that of vasoactive intestinal polypeptide previously isolated from porcine and bovine upper intestine, and its amino acid composition is identical to that of human vasoactive intestinal polypeptide from colon. Although immunoreactive vasoactive intestinal polypeptide has been shown previously to be present in different tissues, this is the first time it has actually been isolated from cerebral tissue, or indeed from any nonintestinal tissue.

Amino Acid Sequence↗
PubMed1982

Reassessment of gastric acid inhibition by cholecystokinin and gastric inhibitory polypeptide in dogs.

The inhibition of gastrin 17-stimulated acid secretion by a partially purified cholecystokinin preparation (PcB) containing 1.2% cholecystokinin and 0.7% gastric inhibitory polypeptide immunoreactivity was compared with the inhibition produced by immunopurified cholecystokinin, cholecystokinin-depleted PcB, and gastric inhibitory polypeptide in 6 dogs with gastric fistulas. The dose-response curves for PcB and "pure" cholecystokinin were parallel and relative inhibitory potency of the pure peptide was 1.2. Dose-response curves of gastric inhibitory polypeptide and cholecystokinin-depleted PcB were similar, nonparallel to cholecystokinin dose response, and demonstrated potency significantly lower than that of PcB. When prepared without human albumin there were significantly higher losses of cholecystokinin-immunoreactivity by nonspecific adsorption from pure cholecystokinin solutions compared with PcB solutions. We conclude that inhibition of gastrin-stimulated acid secretion by partially pure cholecystokinin preparations can be explained by their cholecystokinin content and that previously reported differences in inhibitory potencies may be explained by nonspecific adsorption to glass from protein-free solutions.

Animals↗
PubMed1981

[Bioactive "enteroglucagon" (oxyntomodulin): evidence for a C-terminal extension of the glucagon molecule].

The bioactive fraction of "enteroglucagon" has been isolated from the porcine jejuno-ileum on the basis of its glucagon-like action in liver. High performance liquid chromatography analysis followed by Dansylation of peptide fragments obtained after enzymatic digestion of both this peptide and glucagon suggests that the bioactive "enteroglucagon" contains the glucagon molecule plus a C-terminal extension under the from of the octapeptide. Lys-Arg-Asn-Lys-Asn-Asn-Ile-Ala-COOH. The presence in the native molecular of a structural difference of modification as compared to glucagon in the 1-11 fragment is possible.

Amino Acid Sequence↗