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Guanine nucleotide regulation of dopamine receptor agonist affinity states in rat estradiol-induced pituitary tumors

Journal Article · · Life Sci.; (United States)
;

The authors have investigated dopamine (DA) receptor agonist high- and low-affinity states in female rate estradiol-induced prolactin (PRL)-secreting pituitary tumors and intact pituitary tissue. Estradiol treatment increased the anterior pituitary weight 9-fold and plasma prolactin levels 74-fold and these measures are correlated (R = 0.745, n = 73, p < 0.001). Competition for (/sup 3/H)-spiperone binding to the DA receptor by apomorphine was compared in normal and adenomatous pituitary tissue. The inhibition constants (Ki) and the proportions of the two apomorphine sites are unchanged in tumors compared to intact pituitary tissue. Guanosine 5'-(..beta..-..gamma..-imino)triphosphate (Gpp(NH)p) causes complete conversion of the high into low affinity dopaminergic agonist site in normal pituitary and in tumors. These results suggest that rats with primary estradiol-induced pituitary tumors have normal and functional DA receptors. 9 references, 2 tables.

Research Organization:
Laval Univ., Quebec
OSTI ID:
6075755
Journal Information:
Life Sci.; (United States), Journal Name: Life Sci.; (United States) Vol. 41:9; ISSN LIFSA
Country of Publication:
United States
Language:
English

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Related Subjects

550201* -- Biochemistry-- Tracer Techniques
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59 BASIC BIOLOGICAL SCIENCES
AFFINITY
AMINES
ANIMALS
AROMATICS
AUTONOMIC NERVOUS SYSTEM AGENTS
AZAARENES
BIOCHEMICAL REACTION KINETICS
BODY
CARCINOGENESIS
CARDIOTONICS
CARDIOVASCULAR AGENTS
DISEASES
DOPAMINE
DRUGS
ENDOCRINE GLANDS
ESTRADIOL
ESTRANES
ESTROGENS
GLANDS
GONADOTROPINS
GUANINE
HETEROCYCLIC COMPOUNDS
HORMONES
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LTH
MAMMALS
MEMBRANE PROTEINS
NEOPLASMS
NEUROREGULATORS
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PATHOGENESIS
PEPTIDE HORMONES
PHENOLS
PITUITARY GLAND
PITUITARY HORMONES
POLYPHENOLS
PROTEINS
PURINES
RATS
REACTION KINETICS
RECEPTORS
RODENTS
SPIPERONE
STEROID HORMONES
STEROIDS
SYMPATHOMIMETICS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES