Glucocorticoid regulation of gonadotropin release from gonadotropes of ovine pituitary gland in vitro

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5735854

Nangalama, A W

In order to understand the role of glucocorticoids in the regulation of gonadotropin release by the pituitary gland, the short-term effects of cortisol perifusion (1.5 h to 8 hrs) on GnRH-induced LH secretion were investigated. To determine the biochemical mechanism(s) by which cortisol can act to modulate GnRH-induced LH release, the interactions of cortisol and arachidonic acid in GnRH-stimulated LH release were examined. Cortisol perifusion for 1.5 hr had no effect on GnRH-induced LH release, but longer treatment periods (4 hr-8 hrs) significantly reduced GnRH-stimulated LH release (4.0 hr, p < 0.01; 6.0 hr, p < 0.001; 8.0 hr, p < 0.01). Treatment and animal effects were highly significant (p < 0.001). There were significant interactions (p < 0.001) between treatment and animal as determined by a two-way ANOVA. Cortisol treatment also produced progressive increases in basal LH secretion with time (1.5 hr, p < 0.05; 4.0 hr, p < 0.01; 6.0 hr, p < 0.01; 8.0 hr, p < 0.001). Incubation of pituitary tissue with arachidonic acid (AA) resulted in a linear dose-response of LH (p < 0.001). Cortisol infusion failed to inhibit GnRH-induced LH release in which 10{sup {minus}4}M AA was administered for 20 min before a 10 min, 10{sup {minus}10}M GnRH pulse. Like cortisol, chloroquine also failed to inhibit AA-induced LH release. Perifusion with 10{sup {minus}6}M cortisol for 6.0 hours significantly (p < 0.001) blocked GnRH-stimulated (H{sup 3})AA release 24% below the basal (100%) ({sup 3}H)AA secretion. Reduction of ({sup 3}H)AA release was accompanied by decreased GnRH-stimulated LH secretion.

• Research Organization: California Univ., Davis, CA (United States)
• OSTI ID: 5735854
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADRENAL HORMONES
ANIMALS
ARACHIDONIC ACID
BIOLOGICAL FUNCTIONS
BIOSYNTHESIS
BODY
CARBOXYLIC ACIDS
CORTICOSTEROIDS
DOMESTIC ANIMALS
DOSE-RESPONSE RELATIONSHIPS
ENDOCRINE GLANDS
GLANDS
GLUCOCORTICOIDS
GONADOTROPINS
HORMONES
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
IN VITRO
ISOTOPE APPLICATIONS
KETONES
LH
MAMMALS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HORMONES
PITUITARY GLAND
PITUITARY HORMONES
PREGNANES
PROTEINS
RUMINANTS
SECRETION
SHEEP
STEROIDS
SYNTHESIS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES