In vivo and in vitro evidence for the biosynthesis of testosterone in the telencephalon of the female frog.
Neurons and glial cells are capable of synthesizing various steroid hormones, but biosynthesis of testosterone in the CNS has never been reported. The aim of the present study was to demonstrate the synthesis of testosterone in the frog brain. The presence of 17beta-hydroxysteroid dehydrogenase (17beta-HSD)-like immunoreactivity was detected in a population of glial cells located in the telencephalon. Reversed-phase HPLC analysis of brain tissue extracts combined with radioimmunoassay detection revealed the presence of substantial amounts of testosterone and 5alpha-dihydrotestosterone (5alpha-DHT) in the telencephalon where 17beta-HSD-positive cells were visualized. In male frogs, castration totally suppressed testosterone and 5alpha-DHT in the blood and in the rhombencephalon but did not affect the concentration of these two steroids in the telencephalon. Chemical characterization of testosterone in female frog telencephalon extracts was performed by coupling HPLC analysis with gas chromatography-mass spectrometry. Using the pulse-chase technique with [3H]pregnenolone as a precursor, the formation of a series of metabolites was observed, including dehydroepiandrosterone, androstenedione, testosterone, 5alpha-DHT, and estradiol. These data demonstrate the existence of an active form of 17beta-HSD in the frog telencephalon, which is likely involved in testosterone biosynthesis within the brain.
Mensah-Nyagan
A G
AG
Laboratories of Cellular and Molecular Neuroendocrinology, INSERM, UA CNRS, Mont-Saint-Aignan, France.
Do-Rego
J L
JL
Feuilloley
M
M
Marcual
A
A
Lange
C
C
Pelletier
G
G
Vaudry
H
H
D015067:17-Hydroxysteroid Dehydrogenases / Q000032:analysis / Q000276:immunology / Q000378:metabolism; D000735:Androstenedione / Q000096:biosynthesis; D000818:Animals; D000918:Antibody Specificity; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid; D003687:Dehydroepiandrosterone / Q000096:biosynthesis; D013196:Dihydrotestosterone / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D008297:Male; D013058:Mass Spectrometry; D011863:Radioimmunoassay; D011895:Rana ridibunda / Q000378:metabolism*; D013687:Telencephalon / Q000737:chemistry* / Q000378:metabolism; D013739:Testosterone / Q000032:analysis / Q000096:biosynthesis*; D014316:Tritium / Q000378:metabolism
D013196:Dihydrotestosterone; D014316:Tritium; D013739:Testosterone; D000735:Androstenedione; D003687:Dehydroepiandrosterone; D015067:17-Hydroxysteroid Dehydrogenases