Brain sites mediating corticosteroid feedback inhibition of stimulated ACTH secretion

Miscellaneous · Sun Jan 01 00:00:00 EST 1989

OSTI ID:5673993

Jacobson, L

There is substantial evidence that the brain mediates stress-induced and circadian increases in ACTH secretion and that corticosteroid concentrations which normalize basal plasma ACTH are insufficient to normalize ACTH responses to circadian or stressful stimuli in adrenalectomized rats. To identify brain sites mediating corticosteroid inhibition of stimulated ACTH secretion, two approaches were used. The first compared brain ({sup 14}C)-2-deoxyglucose uptake in rats with differential ACTH responses to stress. Relative to sham-adrenalectomized (SHAM) rats, adrenalectomized rats replaced with low, constant corticosterone levels via a subcutaneous corticosterone pellet (B-PELLET) exhibited elevated and prolonged ACTH responses to a variety of stimuli. Adrenalectomized rate given a circadian corticosterone rhythm via corticosterone in their drinking water exhibited elevated ACTH levels immediately after stress, but unlike B-PELLET rats, terminated stress induced ACTH secretion normally relative to SHAMS. Therefore, the abnormal ACTH responses to stress in B-PELLET rats were due to the lack of both circadian variations and stress-induced increases in corticosterone. Hypoxia was selected as a standardized stimulus for correlating brain ({sup 14}C)-2-deoxyglucose uptake with ACTH secretion. In intact rats, increases in plasma ACTH and decreases in arterial PO{sub 2} correlated with the severity of hypoxia at arterial PCO{sub 2} below 60 mm Hg. Hypoxia PELLET vs. SHAM rats. However, in preliminary experiments, although hypoxia increased brain 2-deoxyglucose uptake in most brain regions, plasma ACTH correlated poorly with 2-deoxyglucose uptake at 12% and 10% O{sub 2}.

• Research Organization: California Univ., San Francisco, CA (USA)
• OSTI ID: 5673993
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
BRAIN
BIOCHEMISTRY
CORTICOSTEROIDS
SECRETION
GLUCOSE
UPTAKE
ADRENALECTOMY
ANOXIA
BIOLOGICAL STRESS
CARBON 14 COMPOUNDS
RATS
TRACER TECHNIQUES
ADRENAL HORMONES
ALDEHYDES
ANIMALS
BODY
CARBOHYDRATES
CENTRAL NERVOUS SYSTEM
CHEMISTRY
HEXOSES
HORMONES
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
KETONES
LABELLED COMPOUNDS
MAMMALS
MEDICINE
MONOSACCHARIDES
NERVOUS SYSTEM
ORGANIC COMPOUNDS
ORGANS
PREGNANES
RODENTS
SACCHARIDES
STEROIDS
SURGERY
VERTEBRATES
550201* - Biochemistry- Tracer Techniques