Cysteamine, zinc, and thiols modify detectability of rat pituitary prolactin: a comparison with effects on bovine prolactin suggests differences in hormone storage

Journal Article · Sat Mar 01 04:00:00 EST 1986 · Metab., Clin. Exp.; (United States)

DOI:https://doi.org/10.1016/0026-0495(86)90203-9· OSTI ID:5527211

Jacobs, L S; Lorenson, M Y

Little is known about the structure of prolactin (PRL) within secretory granules. Evidence from our previous studies in bovine tissue preparations suggests that control of secretion may reside, in part, in the conversion of storage hormone to releasable PRL. The conversion can be monitored by measuring changes in immunodetectability since the oligomeric, storage form is poorly recognized by antisera raised against monomeric PRL. Since many investigators use rats to study the secretory process and changes in detectability of rat pituitary PRL occur during lactation (depletion-transformation), we undertook the present immunodetectability studies to gain insight into the storage structure of rat (r) PRL. Cysteamine and zinc inhibited tissue PRL immunoassayability in male rat pituitary homogenates and also in partially purified secretory granules as they had inhibited bovine (b) PRL; however, zinc inhibited the rodent hormone less potently than the bovine. In vitro incubation of rat tissue samples without additions resulted in increases in rPRL detectability of up to 84% after 180 minutes; such incubation of bovine samples had no significant effect. A striking additional difference between the species was that exposure to reduced glutathione (GSH), cysteine, homocysteine, mercaptoethanol, and dithiothreitol inhibited rPRL by up to 44%. This compared to thiol stimulation of bPRL by as much as 450%. The inhibitory GSH effect on rPRL was abolished when 0.5% sodium dodecyl sulfate (SDS) was included; in contrast, the stimulatory GSH effect on bPRL did not change with added SDS. SDS alone had no effect on rat homogenate PRL, and only increased rat granule rPRL by 23% compared to its ability to increase bPRL assayability by 44%.

• Research Organization: Univ. of Rochester School of Medicine and Denistry, NY
• OSTI ID: 5527211
• Journal Information: Metab., Clin. Exp.; (United States), Journal Name: Metab., Clin. Exp.; (United States) Vol. 3; ISSN METAA
• Country of Publication: United States
• Language: English

Related Subjects

550601 -- Medicine-- Unsealed Radionuclides in Diagnostics
560305* -- Chemicals Metabolism & Toxicology-- Vertebrates-- (-1987)
62 RADIOLOGY AND NUCLEAR MEDICINE
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AMIDES
AMINES
AMINO ACIDS
ANIMALS
BIOLOGICAL EFFECTS
CARBONIC ACID DERIVATIVES
CARBOXYLIC ACIDS
CATTLE
CHELATING AGENTS
DOMESTIC ANIMALS
DRUGS
EDTA
ELEMENTS
GLUTATHIONE
GONADOTROPINS
HORMONES
IMMUNOASSAY
IMMUNOLOGY
ISOTOPE APPLICATIONS
LACTATION
LTH
MAMMALS
MEA
METALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PEPTIDE HORMONES
PEPTIDES
PITUITARY HORMONES
POLYPEPTIDES
PROTEINS
RADIOASSAY
RADIOIMMUNOASSAY
RADIOIMMUNOLOGY
RADIOPROTECTIVE SUBSTANCES
RATS
RODENTS
RUMINANTS
SECRETION
THIOLS
TRACER TECHNIQUES
UREA
VERTEBRATES
ZINC