Simultaneous measurement of hormone release and secretagogue binding by individual pituitary cells

Journal Article · Sat Aug 01 00:00:00 EDT 1987 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.84.15.5501· OSTI ID:5294028

Smith, P F; Neill, J D

The quantitative relationship between receptor binding and hormone secretion at the single-cell level was investigated in the present study by combining a reverse hemolytic plaque assay for measurement of luteinizing hormone (LH) secretion from individual pituitary cells with an autoradiographic assay of /sup 125/I-labeled gonadontropin-releasing hormone (GnRH) agonist binding to the same cells. In the plaque assay, LH secretion induces complement-mediated lysis of the LH-antibody-coated erythrocytes around the gonadotropes, resulting in areas of lysis (plaques). LH release from individual gonadotropes was quantified by comparing radioimmunoassayable LH release to hemolytic area in similarly treated cohort groups of cells; plaque area was linearly related to the amount of LH secreted. Receptor autoradiography was performed using /sup 125/I-labeled GnRH-A (a superagonist analog of GnRH) both as the ligand and as the stimulant for LH release in the plaque assay. The grains appeared to represent specific and high-affinity receptors for GnRH because (i) no pituitary cells other than gonadotropes bound the labeled ligand and (ii) grain development was progressively inhibited by coincubation with increasing doses of unlabeled GnRH-A. The authors conclude that GnRH receptor number for any individual gonadotrope is a weak determinant of the amount of LH it can secrete; nevertheless, full occupancy of all its GnRH receptors is required for any gonadotrope to reach its full LH-secretory capacity. Apparently the levels of other factors comprising the steps along the secretory pathway determine the secretory capacity of an individual cell.

• Research Organization: Univ. of Alabama, Birmingham (USA)
• OSTI ID: 5294028
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 84:15
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
LH
RADIOIMMUNOASSAY
SECRETION
LIBERINS
AUTORADIOGRAPHY
RECEPTORS
IODINE 125
LIGANDS
PITUITARY GLAND
SOMATIC CELLS
ANIMAL CELLS
BETA DECAY RADIOISOTOPES
BODY
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ENDOCRINE GLANDS
GLANDS
GONADOTROPINS
HORMONES
IMMUNOASSAY
IMMUNOLOGY
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MEMBRANE PROTEINS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HORMONES
PITUITARY HORMONES
PROTEINS
RADIOASSAY
RADIOIMMUNOLOGY
RADIOISOTOPES
TRACER TECHNIQUES
550601* - Medicine- Unsealed Radionuclides in Diagnostics