Regulation of pro-adrenocorticotropin-endorphin synthesis and secretion in cultured neonatal rat anterior pituitary
- Johns Hopkins Univ. School of Medicine, Baltimore, MD (USA)
Previous work demonstrated that newborn rat anterior pituitary corticotropes display processing patterns for pro-ACTH/endorphin that are different from the adult. The synthesis and release of beta-endorphin-related peptides was examined in dispersed cell and explant cultures of newborn anterior pituitary to investigate corticotrope development further. The temporal pattern of pro-ACTH/endorphin processing differed significantly from adult rat melanotropes and AtT-20 cells. While pro-ACTH/endorphin processing begins within 30 min of synthesis in adult melanotropes and AtT-20 cells, pulse-labeling of newborn corticotropes in culture indicated that pro-ACTH/endorphin remained uncleaved for at least 90 min after synthesis. With further incubation, there was a decrease in radioactivity associated with the precursor and an equivalent rise in the radioactivity associated with beta-endorphin and beta-lipotropin. However, unprocessed precursor still remained in the cultured newborn anterior pituitary cells after a 25-h chase. Although intact pro-ACTH/endorphin from newborn corticotropes was very long-lived, the precursor did undergo oligosaccharide maturation and became endoglycosidase H resistant within 1 h after synthesis. Similar to the adult, pro-ACTH/endorphin synthesis was doubled in cultures of newborn anterior pituitary chronically treated with 10 nM CRF resulting in a 3- to 4-fold stimulation of secretion over the basal rate. However, unlike the AtT-20 cell or adult rat corticotrope, the proteolytic processing of pro-ACTH/endorphin in the newborn corticotrope was altered by chronic secretagogue treatment; less pro-ACTH/endorphin was converted to beta-endorphin in secretagogue-treated corticotropes than in controls. Thus processing of pro-ACTH/endorphin in the corticotrope is not mature by birth and can be regulated by chronic CRF treatment.
- OSTI ID:
- 6276489
- Journal Information:
- Molecular Endocrinology; (USA), Vol. 1:8; ISSN 0888-8809
- Country of Publication:
- United States
- Language:
- English
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PEPTIDES
BIOSYNTHESIS
PITUITARY GLAND
BIOCHEMISTRY
AGE DEPENDENCE
CELL CULTURES
ENDORPHINS
POST-TRANSLATION MODIFICATION
PRECURSOR
RATS
SECRETION
SULFUR ISOTOPES
TRACER TECHNIQUES
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BODY
CHEMISTRY
DRUGS
ENDOCRINE GLANDS
GLANDS
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
NEUROREGULATORS
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RODENTS
SYNTHESIS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques