Reversible and irreversible labeling and autoradiographic localization of the cerebral histamine H2 receptor using ( sup 125 I)iodinated probes

Journal Article · Thu Mar 01 00:00:00 EST 1990 · Proceedings of the National Academy of Sciences of the United States of America; (USA)

DOI:https://doi.org/10.1073/pnas.87.5.1658· OSTI ID:6921477

Ruat, M; Traiffort, E; Bouthenet, M L; Schwartz, J C; Hirschfeld, J; Buschauer, A; Schunack, W ^[1]

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1. l'Institut National de la Sante et de la Recherche, Paris (France)

Iodoaminopotentidine (I-APT)--i.e., N-(2-(4-amino-3-iodobenzamido)ethyl)-N'-cyano-N''-(3-(3- (1-piperidinylmethyl)phenoxy)propyl)guanidine--represents one of the most potent H2-receptor antagonists known so far. In membranes of guinea pig brain 125I-APT bound reversibly, selectively, and with high affinity (Kd = 0.3 nM) to a homogeneous population of sites unambiguously identified as H2 receptors by inhibition studies conducted with a large panel of antagonists. 125I-APT binding was also inhibited by histamine, and the effect was modulated by a guanyl nucleotide, which is consistent with the association of the H2 receptor with a guanine nucleotide binding regulatory protein. The low nonspecific binding of 125I-APT generated high contrast autoradiographic pictures in brain sections and established the precise distribution of H2 receptors. Their highly heterogeneous distribution and laminated pattern in some areas suggest their major association with neuronal elements. These localizations were more consistent than those of H1 receptors with the distribution of histaminergic projections, indicating that H2 receptors mediate a larger number of postsynaptic actions of histamine--e.g., in striatum. Colocalizations of H1 and H2 receptors in some areas account for their known synergistic interactions in cAMP formation induced by histamine. The distribution of 125I-APT binding sites did not strictly parallel that of the H2-receptor-linked adenylate cyclase activity, which may reflect heterogeneity among H2 receptors. After UV irradiation and SDS/PAGE analysis, (125I)iodoazidopotentidine (125I-AZPT), a photoaffinity probe derived from 125I-APT, was covalently incorporated in several peptides, among which the labeling of two peptides of 59 and 32 kDa was prevented by H2 antagonists, suggesting that they correspond to H2-receptor binding peptides or proteolysis products of the latter.

• OSTI ID: 6921477
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (USA), Vol. 87:5; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
GUANIDINES
BIOCHEMICAL REACTION KINETICS
HISTAMINE
RECEPTORS
BIOLOGICAL LOCALIZATION
AFFINITY
AUTORADIOGRAPHY
BRAIN
CELL MEMBRANES
CYCLASES
GUINEA PIGS
IODINE 125
LABELLING
AMINES
ANIMALS
AZOLES
BETA DECAY RADIOISOTOPES
BODY
CARBONIC ACID DERIVATIVES
CELL CONSTITUENTS
CENTRAL NERVOUS SYSTEM
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ENZYMES
HETEROCYCLIC COMPOUNDS
IMIDAZOLES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPES
KINETICS
LYASES
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
NERVOUS SYSTEM
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RODENTS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques