Developmental regulation of aromatase activity in the rat hypothalamus

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

OSTI ID:5614175

Lephart, E D

The brain of all mammalian species studied thus far contain an enzymatic activity (aromatase) that catalyzes the conversion of androgens to estrogens. The activity is highest during prenatal development and contributes to the establishment of sex differences which determine adult gonadotropin secretion patterns and reproductive behavior. The studies presented in this dissertation represent a systematic effort to elucidate the mechanism(s) that control the initiation of and contribute to maintaining rat hypothalamic aromatase activity during pre- and postnatal development. Aromatase enzyme activity was measured by the {sup 3}H{sub 2}O release assay or by traditional estrogen product isolation. Brain aromatase mRNA was detected by hybridization to a cDNA encoding rat aromatase cytochrome P-450. In both males and females the time of puberty was associated with a decline in hypothalamic aromatase activity. This decline may represent a factor underlying the peri-pubertal decrease in the sensitivity to gonadal steroid feedback that accompanies completion of puberty. The results also indicate that androgens regulate brain aromatase levels during both the prepubertal and peri-pubertal stages of sexual development and that this regulation is transiently lost in young adults. Utilizing a hypothalamic organotypic culture system, aromatase activity in vitro was maintained for as long as two days. The results of studies of a variety of hormonal and metabolic regulators suggest that prenatal aromatase activity is regulated by factor(s) that function independently from the classical cyclic AMP and protein kinase C trans-membrane signaling pathways.

• Research Organization: Texas Univ., Dallas, TX (USA). Southwestern Medical Center
• OSTI ID: 5614175
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
GONADOTROPINS
SECRETION
HYPOTHALAMUS
BIOCHEMISTRY
ISOMERASES
ENZYME ACTIVITY
ANDROGENS
BIOLOGICAL PATHWAYS
ESTROGENS
ONTOGENESIS
RATS
REPRODUCTION
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANDROSTANES
ANIMALS
BODY
BRAIN
CENTRAL NERVOUS SYSTEM
CHEMISTRY
ENZYMES
HORMONES
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
MAMMALS
NERVOUS SYSTEM
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HORMONES
PITUITARY HORMONES
PROTEINS
RODENTS
STEROID HORMONES
STEROIDS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques