Binding and internalization in vivo of (/sup 125/I)hCG in Leydig cells of the rat

Journal Article · Thu Dec 31 23:00:00 EST 1987 · J. Androl.; (United States)

DOI:https://doi.org/10.1002/j.1939-4640.1988.tb01000.x· OSTI ID:5175848

Hermo, L; Lalli, M

The present study was performed to demonstrate the binding, mode of uptake, pathway and fate of iodinated human chorionic gonadotropin ((/sup 125/I)hCG) by Leydig cells in vivo using electron microscope radioautography. Following a single injection of (/sup 125/I)hCG into the interstitial space of the testis, the animals were fixed by perfusion with glutaraldehyde at 20 minutes, 1, 3, 6 and 24 hours. The electron microscope radioautographs demonstrated a prominent and qualitatively similar binding of the labeled hCG on the microvillar processes of the Leydig cells at 20 minutes, 1, 3, and 6 hours. The specificity of the (/sup 125/I)hCG binding was determined by injecting a 100-fold excess of unlabeled hormone concurrently with the labeled hormone. Under these conditions, the surface, including the microvillar processes of Leydig cells, was virtually unlabeled, indicating that the binding was specific and receptor-mediated. In animals injected with labeled hCG and sacrificed 20 minutes later, silver grains were also seen overlying the limiting membrane of large, uncoated surface invaginations and large subsurface vacuoles with an electron-lucent content referred to as endosomes. A radioautographic reaction was also seen within multivesicular bodies with a pale stained matrix. At 1 hour, silver grains appeared over dense multivesicular bodies and occasionally over secondary lysosomes, in addition to the structures mentioned above, while at 3 and 6 hours, an increasing number of secondary lysosomes became labeled. At 24 hours, binding of (/sup 125/I)hCG to the microvillar processes of Leydig cells persisted but was diminished, although a few endosomes, multivesicular bodies and secondary lysosomes still showed a radioautographic reaction. No membranous tubules that were seen in close proximity to, or in continuity with, endosomes and multivesicular bodies were observed to be labeled at any time interval.

• Research Organization: McGill Univ., Montreal (Canada)
• OSTI ID: 5175848
• Journal Information: J. Androl.; (United States), Journal Name: J. Androl.; (United States) Vol. 9:1; ISSN JOAND
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMAL CELLS
ANIMALS
AUTORADIOGRAPHY
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL PATHWAYS
BODY
CELL CONSTITUENTS
CELL MEMBRANES
CYTOPLASM
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
GONADOTROPINS
GONADS
HORMONES
IN VIVO
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPES
KINETICS
LYSOSOMES
MALE GENITALS
MAMMALS
MEMBRANES
NUCLEI
ODD-EVEN NUCLEI
ORGANOIDS
ORGANS
PEPTIDE HORMONES
PITUITARY HORMONES
RADIOISOTOPES
RATS
REACTION KINETICS
RODENTS
SPECIFICITY
TESTES
VERTEBRATES