Binding of bovine thyrotropin to specific sites in thyroid tissue from control and hemithyroidectomized rats

Journal Article · Sun Dec 01 04:00:00 EST 1985 · J. Surg. Res.; (United States)

DOI:https://doi.org/10.1016/0022-4804(85)90117-9· OSTI ID:5617463

Clark, O H; Lambert, W R; Amir, S M; Ingbar, S H

The binding of 125I-bovine thyrotropin to thyroid particulate fractions from sham-operated (control) and hemithyroidectomized rats was compared to determine if a change in either the number of bovine thyroid-stimulating hormone (bTSH) binding sites or their affinity for bTSH occurs in physiological situations that evoke changes in the intensity of thyroid stimulation. Following hemithyroidectomy serum TSH levels increase and the remnant thyroid lobe enlarges. Because of compensatory thyroid hypertrophy the concentration of TSH binding sites in the thyroid glands from hemithyroidectomized and control rats was related to particulate protein concentration, to the degree of thyroid cellularity as indicated by DNA concentration, and to the concentration of the plasma membrane markers, 5'-nucleotidase and magnesium-dependent ATPase. In each of four experiments, saturation studies revealed that the maximum specific binding of TSH per unit particulate protein and per thyroid lobe was greater in particulates from remnant than from control thyroid lobes. When related to DNA concentration, the concentration of TSH binding sites in remnant lobes was approximately twice that in control lobes. Because of an increase in plasma membrane markers per lobe after hemithyroidectomy, however, there was no difference in the number of TSH binding sites when related to the concentrations of the membrane marker enzymes in the particulate fractions. As judged from Scatchard analysis, the affinity of TSH binding was lower in remnant than in control lobes. This was partially but not completely due to the increased concentration of particulate protein in the remnant thyroid. These experiments demonstrate that the increase in serum TSH levels after hemithyroidectomy in the rat is associated with alterations in TSH receptor capacity and affinity.

• OSTI ID: 5617463
• Journal Information: J. Surg. Res.; (United States), Journal Name: J. Surg. Res.; (United States) Vol. 6; ISSN JSGRA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BETA DECAY RADIOISOTOPES
BODY
CATTLE
CHEMICAL BONDS
DAYS LIVING RADIOISOTOPES
DNA
DOMESTIC ANIMALS
ELECTRON CAPTURE RADIOISOTOPES
ENDOCRINE GLANDS
ENZYMES
ESTERASES
GLANDS
HORMONES
HYDROLASES
HYPERTROPHY
IN VITRO
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
MAMMALS
MEDICINE
MEMBRANE PROTEINS
NUCLEI
NUCLEIC ACIDS
NUCLEOTIDASES
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PATHOLOGICAL CHANGES
PEPTIDE HORMONES
PHOSPHATASES
PITUITARY HORMONES
PROTEINS
RADIOISOTOPES
RATS
RECEPTORS
RODENTS
RUMINANTS
SURGERY
THYROID
THYROIDECTOMY
TRACER TECHNIQUES
TSH
VERTEBRATES