Growth hormone induction of lactogenic receptors at intracellular sites in male rat liver
Male and female rat livers were fractionated by density gradient centrifugation into Golgi I (mainly secretory vesicles), Golgi II (mainly cisternal elements), and lysosomes. Estimations of fraction purity and representativity were made by marker enzyme and electron microscopic analyses. The binding of (/sup 125/I)iodo-human GH ( (/sup 125/I)iodo-hGH) to different subcellular liver fractions were studied. In Golgi I and II the binding specificity was similar in both sexes and indicated that (/sup 125/I) iodo-hGH binds to a lactogenic receptor. Scatchard analysis showed a larger number of binding sites in female Golgi I (5600 fmol/mg protein), Golgi II (3400 fmol/mg), and lysosomes (1300 fmol/mg) than in male Golgi I (240 fmol/mg), Golgi II (200 fmol/mg), and lysosomes (230 fmol/mg). The apparent dissociation constant was within a similar range (0.6-0.7 X 10(-9) M) in all fractions. Administration of hGH to male rats by continuous infusion (infusion rate, 5 micrograms/h) resulted, after 5 days of treatment, in an increase in the number of lactogenic binding sites in Golgi I and II to levels similar to the binding in the corresponding female Golgi fractions. When rat GH was given to hypophysectomized male rats (infusion rate, 10 micrograms/h) for 1 week, the binding of (/sup 125/I)iodo-hGH in lysosomal and Golgi fractions was increased to a female level. The present results suggest that lactogenic receptors are located in the Golgi complex as well as the lysosomal compartment and that these receptors can be induced at these intracellular sites with both a somatotropic-lactogenic hormone (human GH) and a pure somatotropic hormone (rat GH).
- Research Organization:
- Huddinge Univ. Hospital, Sweden
- OSTI ID:
- 6204420
- Journal Information:
- Endocrinology; (United States), Journal Name: Endocrinology; (United States) Vol. 115:2; ISSN ENDOA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BIOCHEMICAL REACTION KINETICS
BIOCHEMISTRY
BODY
CELL CONSTITUENTS
CELL MEMBRANES
CHEMISTRY
DIGESTIVE SYSTEM
ELECTRON MICROSCOPY
GLANDS
HORMONES
ISOTOPE APPLICATIONS
KINETICS
LIVER
LYSOSOMES
MAMMALS
MAN
MEMBRANES
MICROSCOPY
ORGANOIDS
ORGANS
PEPTIDE HORMONES
PITUITARY HORMONES
PRIMATES
RADIORECEPTOR ASSAY
RATS
REACTION KINETICS
RECEPTORS
RODENTS
SEX DEPENDENCE
STH
TRACER TECHNIQUES
VERTEBRATES