Estrogen-2-hydroxylase in the brain of the male African catfish, Clarias gariepinus

Journal Article · Tue Nov 01 00:00:00 EST 1988 · Gen. Comp. Endocrinol.; (United States)

DOI:https://doi.org/10.1016/0016-6480(88)90202-X· OSTI ID:6786635

Timmers, R J; Granneman, J C; Lambert, J G; van Oordt, P G

Estrogen-2-hydroxylase activity, involved in the biosynthesis of catecholestrogens, was localized in the brain of the male African catfish, Clarias gariepinus, by means of a radiometric assay using (2-TH)estradiol as substrate. Fore- and midbrain were divided in 18, 500-microns thick, transverse sections from which small defined areas were punched out and assayed. The estrogen-2-hydroxylase activity was calculated from the release of tritium during hydroxylation, and expressed in femtomole catecholestradiol.milligram-1 tissue.hour-1. The enzyme could be demonstrated throughout the brain. A high activity (greater than 350 fmol) was observed in the telencephalon, in particularly the rostral part and the area ventralis pars dorsalis; in the diencephalon in the preoptic region, including the magnocellular part of the preoptic nucleus and the rostral part of the anterior periventricular nucleus; and in the area tuberalis, including the nucleus lateralis tuberis, the rostral part of the nucleus anterior tuberis, the caudal part of the nucleus posterior periventricularis, and in the nucleus recessus posterioris. Also a high activity was detected in the mesencephalic tectum opticum and the dorsolateral part of the torus semicircularis. The ventral mesencephalon showed a moderate (200-350 fmol) to low (less than 200 fmol) activity, whereas the lowest activity was found in the hindbrain (118 fmol). The significance of the biosynthesis of catecholestrogens in the brain is discussed in light of the negative feedback mechanism of gonadal steroids on gonadotropin release.

• Research Organization: Univ., of Utrecht (Netherlands)
• OSTI ID: 6786635
• Journal Information: Gen. Comp. Endocrinol.; (United States), Vol. 72:2
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ESTROGENS
BIOSYNTHESIS
HYDROXYLASES
ENZYME ACTIVITY
BRAIN
ESTRADIOL
FISHES
RADIOASSAY
TISSUE DISTRIBUTION
TRITIUM COMPOUNDS
ANIMALS
AQUATIC ORGANISMS
BODY
CENTRAL NERVOUS SYSTEM
DISTRIBUTION
ENZYMES
ESTRANES
HORMONES
HYDROXY COMPOUNDS
LABELLED COMPOUNDS
NERVOUS SYSTEM
ORGANIC COMPOUNDS
ORGANS
OXIDOREDUCTASES
STEROID HORMONES
STEROIDS
SYNTHESIS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques