Catechol estrogen formation by brain tissue: a comparison of the release of tritium from (2-3H)estradiol with (6,7-3H)2-hydroxyestradiol formation from (6,7-3H)estradiol by rabbit hypothalami in vitro

Journal Article · Tue Dec 01 04:00:00 EST 1981 · Endocrinology; (United States)

DOI:https://doi.org/10.1210/endo-109-6-1902· OSTI ID:5476201

Hersey, R M; Gunsalus, P; Lloyd, T; Weisz, J

A detailed comparison was made between the formation of tritiated water (3H2O) and (6,7-3H)2-hydroxyestradiol (2-OHE2) by rabbit hypothalami in vitro from 2-3H- and 6,7-3H-labeled estradiol, respectively. Maximum activity for both functions was associated with the soluble fractions (S2, 17,500 X g supernatant, for tritium release; S3, 100,000 X g supernatant, for 2-OHE2 formation). In contrast, maximal 3H2O formation by rat liver was associated with the microsomal (P3, 100,000 X g pellet) fraction and was virtually abolished by Tween-80. The amount of 3H2O formed exceeded, up to severalfold, the amount of 2-OHE2 produced under all conditions examined and in all subcellular fractions. The bulk of the excess 3H2O formation, unrelated to the production of 2-OHE2, could be eliminated by adding ascorbic acid (10 mM) to the incubation medium. However, a second, smaller component of spurious 3H2O release could not be suppressed. This component was responsible for a persistent lack of stoichiometry between the formation of 3H2O and 2-OHE2, with the former exceeding the latter by up to 2-fold. This discrepancy was unaffected by ascorbic acid (up to 20 mM), unlabeled 2-OHE2 (up to 10 microM), and reducing the temperature of incubation from 37 to 30 C, measures that prolonged the t1/2 of 2-OHE2 during incubation with hypothalamic tissue from under 3 min to over 100 min.

• Research Organization: Department of Obstetrics and Gynecology, The Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey
• OSTI ID: 5476201
• Journal Information: Endocrinology; (United States), Journal Name: Endocrinology; (United States) Vol. 109:6; ISSN ENDOA
• Country of Publication: United States
• Language: English

Related Subjects

550201 -- Biochemistry-- Tracer Techniques
551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADDITIVES
ANIMALS
ASCORBIC ACID
BODY
BRAIN
CELL CONSTITUENTS
CENTRAL NERVOUS SYSTEM
CENTRIFUGATION
CHALCOGENIDES
DETERGENTS
EMULSIFIERS
ENZYME ACTIVITY
ENZYMES
ESTRADIOL
ESTRANES
ESTROGENS
HORMONES
HYDROXY COMPOUNDS
HYDROXYLASES
HYPOTHALAMUS
IN VITRO
LABELLED COMPOUNDS
MAMMALS
METABOLISM
MICROSOMES
NERVOUS SYSTEM
ORGANIC COMPOUNDS
ORGANOIDS
ORGANS
OXIDES
OXIDOREDUCTASES
OXYGEN COMPOUNDS
RABBITS
SEPARATION PROCESSES
STEROID HORMONES
STEROIDS
SURFACTANTS
TRITIUM COMPOUNDS
TRITIUM OXIDES
ULTRACENTRIFUGATION
VERTEBRATES
VITAMINS
WETTING AGENTS