The synthesis of analogs of the C-terminal tridecapeptide of gastrin is described. These pseudopeptide analogs were obtained either by replacing the C-terminal phenylalanine amide with 2-phenylethylalcohol or with 2-phenylethylamine, or by replacing the peptide bond between Trp and Leu, or between Leu and Asp with an aminomethylene (CH2NH). The ability of these compounds to stimulate gastric acid secretion in anesthetized rats and to inhibit binding of labeled CCK-8 to isolated cells from rabbit fundic mucosa was tested. [desPhe(13), Leu(11)]-HG-12-I-beta-phenylethylester 33, [desPhe(13), Leu(11)]-HG-12-II-beta-phenylethylester 38,[desPhe(13), Leu(11)]-HG-12-I-beta-phenylethylamide 32, and [desPhe(13), Leu(11)]-HG-12-II-beta-phenylethylamide 37 acted as gastrin receptor antagonists, while [Trp (10)-Psi(CH2NH)-Leu(11)]-HG-13-I 31 and [Trp(10)-Psi(CH2NH)-Leu(11)]-HG-13-II 36 acted as agonists. Unexpectedly, [Leu(11)-Psi(CH2NH)-Asp(12)]-HG-13-I 30 and [Leu(11)-Psi(CH2NH)-Asp(12)]-HG-13-II 35 were almost devoid of affinity for the gastrin receptor.

We have shown that gastrin and cholecystokinin octapeptide (CCK-8) are differently coupled to G protein (GTP-binding protein) through type B cholecystokinin receptors in guinea-pig brain membranes and Jurkat cells. Indeed, the gastrin-13 binding affinity is strongly reduced by stable guanyl nucleotides, whereas CCK-8 binding is only slightly affected. In order to determine the structural requirements regulating such coupling, we have synthesized several gastrin and cholecystokinin fragments (sulphated or unsulphated) elongated at the N-terminus of the common C-terminal tetrapeptide. We investigated their interaction with CCKB receptors in guinea pig brain membranes and Jurkat cells and their involvement in the G protein coupling. Their apparent binding affinities to CCKB receptors were measured by inhibition of [125I]Bolton Hunter-CCK-8 (3-[125I]iodo-4-hydroxyphenyl)propionyl-CCK-8) binding in the presence or absence of GTPγS (guanosine 5′-O-(3-thio)triphosphate) or aluminium tetrafluoride (AlF4−). Activation of the G proteins by GTPγS or AlF4− led to a decrease in binding affinity for the gastrin related peptides, the common CCK-gastrin C-terminal forms, the cholecystokinin hexapeptide and the unsulphated cholecystokinin heptapeptide. Sulphated CCK-7, CCK-8, and cionin apparent binding affinities were not affected. These finding indicated that the sulphated tyrosine in position 7 in CCK (as counted from the C-terminus), provides the cholecystokinin selectivity for the CCKB receptor compared to gastrin. The results are discussed with the aim to better clarify the physiological relevance of gastrin and cholecystokinin toward CCKB receptors and their related intracellular events.

In the present study we compared various CCKB receptor antagonists and tried to detect a difference in biological activity between the C-terminal octapeptides of cholecystokinin (CCK-8) and [Leu11]gastrin-(5–17) in isolated rabbit gastric glands. Binding experiments showed that different CCKB/gastrin receptor agonists bound with high affinity and that antagonists inhibited this binding in accordance with a CCKB/gastrin pharmacological profile. [Leu11]Gastrin-(5–17), CCK-8 and cionin were found to induce [14C]aminopyrine accumulation to 25% above the basal level. Under the same experimental conditions, histamine induced a response twice as great as the response obtained with [Leu11]gastrin-(5–17) or CCK-8. [Leu11]Gastrin-(5–17) (10−7 M), CCK-8 (10−8 M) and cionin (10−8 M) appeared to be full agonists. CCKB/gastrin receptor antagonists including L-365,260 (3R-(+)-N-(2,3-dihydro-1-methyl-2-oxo-5-phenyl-1H-1,4-benzodiazepin-3-yl)-N-(3-methylphenyl) urea), L-364,718 (3S-(−)-N-(2,3-dihydro-1-methyl-2-oxo-5-phenyl-1H-1,4-benzodiazepin-3-yl)-1H-indole-2-carboximide) (a selective CCKA receptor ant (4([2-[[3-(1H-indol-3-yl)-2-methyl-1-oxo-2-[[[1.7.7-trimethyl-bicyclo[2.2.1]hept-2-yl)oxy]carbonyl]amino]propyl]amino]-1-phenylethyl] amino-4-oxo-[1S-1α.2β[S∗(S∗)]4α]]-butanoate N-methyl-d-glucamine) (bicyclo system 1S-endo), YM-022 ((R)-1-[2,3-dihydro-1-(2′-methylphenacyl)-2-oxo-5-phenyl-1H-1,4-benzodiazepin-3-yl]-3-(3-methylphenyl)urea) and JMV-180 (Boc-Tyr(SO3H)-Nle-Gly-Trp-Nle-Asp-O-CH2-CH2-C6H5) exhibited the same profile for inhibition of [Leu11]gastrin-(5–17) or CCK-8-induced [14C]aminopyrine accumulation in rabbit gastric glands. These results suggested that [Leu11]gastrin-(5–17) and CCK-8 induced [14C]aminopyrine accumulation by the same mechanism. [Leu11]Gastrin-(5–17)- or CCK-8-induced [14C]aminopyrine accumulation was inhibited by about 40% by the histamine H2 receptor blocker cimetidine. These results are consistent with there being cooperativity between [Leu11]gastrin-(5–17) (or CCK-8) and histamine in the acid secretory pathway. Similarly, the CCKB/gastrin receptor antagonists were tested against histamine-induced [14C]aminopyrine accumulation and surprisingly, only compound L-365,260 appeared active and even more potent than cimetidine.

The synthesis of chiral N-protected tetramic acid derivatives which are important precursors of β-hydroxy γ-amino acid under mild conditions is described. Reaction of urethane-N-carboxyanhydrides (UNCAs) with Meldrum's acid in the presence of a tertiary amine, followed by subsequent cyclisation produced tetramic acid derivatives. This procedure is applicable to Boc-, Fmoc- and Z- N-carboxyanhydrides.

In the course of our study concerning gastrin and cholecystokinin (CCK) receptors, we have synthesized and characterized a new labeled gastrin ligand, 125I-BH-[Leu15]-gastrin-(5-17) [(3-[125I]iodo-4-hydroxyphenyl)-propionyl-[Leu15]-gastrin-(5-17)]. Binding of 125I-BH-[Leu15]-gastrin-(5-17) to isolated canine fundic mucosal cells was specific, saturable and of high affinity. 125I-BH-[Leu15]-gastrin- (5-17) and 125I-BH-CCK-8[(3-[125I]iodo-4-hydroxyphenyl)-propionyl-CCK-8] interact with isolated canine fundic mucosal cells with small differences in maximal binding capacities and affinities, 3800 +/- 900 binding sites/cell (Kd = 0.52 +/- 0.23 nM) and 6200 +/- 1100 binding sites/cell (Kd = 0.31 +/- 0.18 nM), respectively. The relative order of potencies for gastrin and CCK analogs in displacing 125I-BH-[Leu15]-gastrin-(5-17) binding correlated well with those obtained using 125I-BH-CCK-8. Selective CCK/gastrin antagonists L-364,718 (MK-329) and L-365,260 also inhibited 125I-BH-[Leu15]-gastrin-(5-17) binding. These results indicate that 125I-BH-[Leu15]-gastrin-(5-17) binds to gastrin receptors in isolated canine fundic mucosal cells. We have also characterized 125I-BH-[Leu15]-gastrin-(5-17) binding to the human Jurkat lymphoblastic cell line (Jurkat cells) known to express the CCK-B/gastrin receptor. Saturation experiments have shown that both 125I-BH-[Leu15]-gastrin-(5-17) and 125I-BH-CCK-8 interact with a single class of high-affinity binding sites in the Jurkat cell line.(ABSTRACT TRUNCATED AT 250 WORDS)

Annals of the New York Academy of SciencesVolume 713, Issue 1 p. 346-349 Gastrin13 Binds to CCKB Brain Membrane Receptors Coupled to G Protein in Guinea Pig Brain Membranes J. C. LALLEMENT, J. C. LALLEMENT Chimie et Pharmacologie de Molécules d'Intérět Biologique EP CNRS 51 Faculté de Pharmacie 15 Av. Charles Flahault 34060 Montpellier, FranceSearch for more papers by this authorJ. C. GALLEYRAND, J. C. GALLEYRAND Chimie et Pharmacologie de Molécules d'Intérět Biologique EP CNRS 51 Faculté de Pharmacie 15 Av. Charles Flahault 34060 Montpellier, FranceSearch for more papers by this authorA. C. LIMA-LEITE, A. C. LIMA-LEITE Chimie et Pharmacologie de Molécules d'Intérět Biologique EP CNRS 51 Faculté de Pharmacie 15 Av. Charles Flahault 34060 Montpellier, FranceSearch for more papers by this authorP. FULCRAND, P. FULCRAND Chimie et Pharmacologie de Molécules d'Intérět Biologique EP CNRS 51 Faculté de Pharmacie 15 Av. Charles Flahault 34060 Montpellier, FranceSearch for more papers by this authorJ. MARTINEZ, J. MARTINEZ Chimie et Pharmacologie de Molécules d'Intérět Biologique EP CNRS 51 Faculté de Pharmacie 15 Av. Charles Flahault 34060 Montpellier, FranceSearch for more papers by this author J. C. LALLEMENT, J. C. LALLEMENT Chimie et Pharmacologie de Molécules d'Intérět Biologique EP CNRS 51 Faculté de Pharmacie 15 Av. Charles Flahault 34060 Montpellier, FranceSearch for more papers by this authorJ. C. GALLEYRAND, J. C. GALLEYRAND Chimie et Pharmacologie de Molécules d'Intérět Biologique EP CNRS 51 Faculté de Pharmacie 15 Av. Charles Flahault 34060 Montpellier, FranceSearch for more papers by this authorA. C. LIMA-LEITE, A. C. LIMA-LEITE Chimie et Pharmacologie de Molécules d'Intérět Biologique EP CNRS 51 Faculté de Pharmacie 15 Av. Charles Flahault 34060 Montpellier, FranceSearch for more papers by this authorP. FULCRAND, P. FULCRAND Chimie et Pharmacologie de Molécules d'Intérět Biologique EP CNRS 51 Faculté de Pharmacie 15 Av. Charles Flahault 34060 Montpellier, FranceSearch for more papers by this authorJ. MARTINEZ, J. MARTINEZ Chimie et Pharmacologie de Molécules d'Intérět Biologique EP CNRS 51 Faculté de Pharmacie 15 Av. Charles Flahault 34060 Montpellier, FranceSearch for more papers by this author First published: March 1994 https://doi.org/10.1111/j.1749-6632.1994.tb44088.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Volume713, Issue1CholecystokininMarch 1994Pages 346-349 RelatedInformation