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Digitale Medien

Sites of action of testosterone in the brain of the female primate (1986)

Rees, H. D. ; Bonsall, R. W. ; Michael, R. P.

Springer

Experimental brain research 63 (1986), S. 67-75

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ISSN: 1432-1106

Schlagwort(e): Testosterone ; Dihydrotestosterone ; 3H-estradiol uptake ; Rhesus monkey ; Autoradiography

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Summary Thaw-mount autoradiography was used to map target neurons for tritiated steroids in the brains of ovariectomized rhesus monkeys. In five females, studies were performed 60 min after the administration of 3H-estradiol. Of these, two females were pretreated for five days with daily injections of 2 mg testosterone propionate, one female was pretreated with daily injections of 2 mg dihydrotestosterone propionate, and two females were pretreated with oil vehicle. For comparison, two additional females were administered 3H-testosterone and were killed 30 min later. Following 3H-estradiol administration in females pretreated with oil, there were numerous labeled neurons in the medial preoptic nucleus (n.), anterior hypothalamic area, ventromedial hypothalamic n., arcuate n., bed n. of stria terminalis, lateral septal n., and regions of the amygdala. In females pretreated with testosterone propionate, labeling was virtually abolished in all these areas with the exceptions of the lateral septal n. and arcuate n., presumably because estradiol formed from testosterone competed with 3H-estradiol for estrogen-binding sites. Pretreatment with dihydrotestosterone propionate had no effect on the labeling following the administration of 3H-estradiol. Areas where labeling was blocked, therefore, represent regions where testosterone acted as an estrogen, and it would appear that regional differences in the activity of aromatizing enzymes determine which estrogen target sites in the brain can interact with estrogenic metabolites of testoterone in female primates.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00235647

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Digitale Medien

Absence of phytosterol dealkylation and identification of the major ecdysteroid as makisterone A in Dysdercus fasciatus (Heteroptera, Pyrrhocoridae) (1983)

Gibson, J. M. ; Majumder, M. S. I. ; Mendis, A. H. W. ; [weitere]

New York, NY [u.a.] : Wiley-Blackwell

Archives of Insect Biochemistry and Physiology 1 (1983), S. 105-120

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ISSN: 0739-4462

Schlagwort(e): phytosterol dealkylation ; ecdysteroids ; makisterone A ; Heteroptera ; Dysdercus ; gas-liquid chromatography/mass spectrometry ; cotton stainer bug ; ecdysone ; 20-hydroxyecdysone ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Biologie

Notizen: The absence of phytosterol dealkylation in the cotton stainer bug, Dysdercus fasciatus, has been established and the major ecdysteroid in the fifth-stage larvae identified. The demonstration that the free and esterified sterols in D fasciatus consisted of 95-96% sitosterol and 4-5% campesterol, a similar composition to the cottonseed diet, together with the lack of conversion of [14C]sitosterol into cholesterol, establishes that phytosterol dealkylation does not occur in this insect species. The ecdysteroid titer determined by radioimmunoassay in the fifth instar of D fasciatus shows a distinct peak at day 6, the instar lasting for 7 days. Makisterone A was purified by HPLC from insects at a time of high ecdysteroid titer and identified as a major component by both fast atom bombardment and electron impact mass spectrometry. Gas-liquid chromatography/mass spectrometry (selected ion monitoring) confirmed the occurrence of makisterone A and revealed the presence of two unidentified compounds. One of these occurs in a similar amount to makisterone A and may be 26-hydroxymakisterone A, whereas only a minute amount of the other compound, which may be 20-deoxymakisterone A, was present; further identification of the latter compounds is necessary. C27 ecdysteroids (eg, ecdysone and 20-hydroxyecdysone) and C29 ecdysteroids (eg, podecdysone A) were undetectable. The specificity of the enzymes of ecdysteroid biosynthesis is discussed.

Zusätzliches Material: 8 Ill.