Role of calcium in gonadotropin releasing hormone-induced luteinizing hormone secretion from the bovine pituitary
Thesis/Dissertation
·
OSTI ID:7063506
The hypothesis was tested that GnRH acts to release LH by increasing calcium uptake by gonadotroph which in turn stimulates calcium-calmodulin activity and results in LH release from bovine pituitary cells as it does in the rat. Pituitary glands of calves (4-10 months of age) were enzymatically dispersed (0.2% collagenase) and grown for 5 days to confluency in multiwell plates (3 x 10/sup 5//well). Cells treated with GnRH Ca/sup + +/ ionophore A23187, and ouabain all produced significant releases of LH release in a pronounced all or none fashion, while thorough washing of the cells with 0.5 mM EGTA in Ca/sup + +/-free media prevented the action of GnRH. GnRH caused a rapid efflux of /sup 45/Ca/sup + +/. Both GnRH-stimulated /sup 45/Ca efflux and LH release could be partially blocked by verapamil GnRH-induced LH release could also be blocked by nifedipine and tetrodotoxin, although these agents did not affect /sup 45/Ca efflux. The calmodulin antagonists calmidazolium and W7 were found to block GnRH induced LH release, as well as LH release induced by theophylline, KC PGE/sub 2/ and estradiol. These data indicated that: (1) calcium is required for GnRH action, but extracellular Ca/sup + +/ does not regulate LH release; (2) GnRH elevates intracellular Ca/sup + +/ by opening both voltage sensitive and receptor mediated Ca/sup + +/ channels; (3) activation of calmodulin is one mechanism involved in GnRH-induced LH release.
- Research Organization:
- Texas A and M Univ., College Station (USA)
- OSTI ID:
- 7063506
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CALCIUM 45
CALCIUM COMPOUNDS
CALCIUM ISOTOPES
CALVES
CATTLE
CHEMICAL ACTIVATION
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
ENDOCRINE GLANDS
EVEN-ODD NUCLEI
GLANDS
GONADOTROPINS
HORMONES
INTERMEDIATE MASS NUCLEI
ISOTOPES
LH
LIBERINS
MAMMALS
NUCLEI
ORGANS
PEPTIDE HORMONES
PITUITARY GLAND
PITUITARY HORMONES
RADIOISOTOPES
RUMINANTS
SECRETION
UPTAKE
VERTEBRATES
59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CALCIUM 45
CALCIUM COMPOUNDS
CALCIUM ISOTOPES
CALVES
CATTLE
CHEMICAL ACTIVATION
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
ENDOCRINE GLANDS
EVEN-ODD NUCLEI
GLANDS
GONADOTROPINS
HORMONES
INTERMEDIATE MASS NUCLEI
ISOTOPES
LH
LIBERINS
MAMMALS
NUCLEI
ORGANS
PEPTIDE HORMONES
PITUITARY GLAND
PITUITARY HORMONES
RADIOISOTOPES
RUMINANTS
SECRETION
UPTAKE
VERTEBRATES