scholarly journals Plasma Testosterone Correlates with Morph Type across Breeding Substages in Male White‐Throated Sparrows

2009 ◽  
Vol 82 (5) ◽  
pp. 572-579 ◽  
Author(s):  
M. B. Swett ◽  
C. W. Breuner
Keyword(s):  
Plasma Testosterone ◽  
Morph Type

INFLUENCE OF METYRAPONE ON PLASMA CONCENTRATIONS OF TESTOSTERONE AND ANDROSTENEDIONE IN MAN

1971 ◽  
Vol 68 (3) ◽  
pp. 576-584 ◽  
Author(s):  
K. O. Nilsson ◽  
B. Hökfelt
Keyword(s):  
Body Weight ◽  
Male Patient ◽  
Gradual Increase ◽  
Plasma Concentrations ◽  
Plasma Testosterone ◽  
Testosterone Levels ◽  
Basal Plasma ◽  
Normal Males ◽  
A Minor ◽  
Secondary Hypogonadism

ABSTRACT Metyrapone was administered either orally, 750 mg every four h, in a total of six doses, or intravenously 30 mg per kg body weight as a four h infusion. In three males with normal endocrine functions, metyrapone given orally or intravenously induced a fall in plasma testosterone and an elevation of androstenedione within 2–8 h. When metyrapone was administered to a patient given dexamethasone to suppress endogenous ACTH production, the androstenedione levels did not alter whereas the testosterone levels showed a slight, transient decrease. In two normal females metyrapone administration was followed by a marked increase in plasma androstenedione whereas testosterone showed only a minor, gradual increase. In one male patient with Addison's disease the basal plasma testosterone was normal whereas the level of androstenedione was low. Following metyrapone intravenously, there was a slight suppression of plasma testosterone but no change in the androstenedione concentration. In one patient with primary hypogonadism, two with secondary hypogonadism and two with Klinefelter's syndrome the plasma testosterone was low under basal conditions and did not change following metyrapone. Basal plasma androstenedione was within the range for normal males and increased markedly following metyrapone in all the cases.

SUPRESSION OF ANDROGEN AND OESTROGEN PRODUCTION IN NORMAL MEN

1972 ◽  
Vol 70 (2) ◽  
pp. 342-350 ◽  
Author(s):  
M. A. Kirschner ◽  
D. W. R. Knorr
Keyword(s):  
Urine Sample ◽  
Plasma Testosterone ◽  
Low Level ◽  
Normal Men

ABSTRACT An attempt was made to suppress production of androgens and oestrogens in normal men by administering large doses of exogenous androgens and corticoids. After 5 days of 40 mg fluoxymesterone qd, plasma testosterone concentrations decreased from 509 to 73 ng/100 ml (85%); on adding 8 mg qd of dexamethasone, there was a further decrease to 45 ng/100 ml. Androstenedione concentrations were decreased equally by fluoxymesterone and corticoids. To monitor the suppressive effects of exogenous steroids, urinary LH was followed serially by radioimmunoassay, and decreased to only 40% of control levels after 5 days of fluoxymesterone, with no further suppression noted on adding dexamethasone. Nanogram quantities of steroidal metabolites were not adsorbed by kaolin extraction of urine, thus enabling gonadotrophins (kaolin extract) and low-level steroids (supernate) to be measured in the same urine sample. Urinary oestrone and oestradiol excretion decreased during 5 days of fluoxymesterone, and continued to fall when dexamethasone was added. In no case was oestrone or oestradiol excretion, urinary LH or plasma androgens completely suppressed by large doses of fluoxymesterone alone, or in combination with large doses of dexamethasone.

Effects of oestradiol benzoate (OeB) and human chorionic gonadotrophin (hCG) on the testes and accessory sex glands of the rat

1981 ◽  
Vol 96 (2) ◽  
pp. 273-280 ◽  
Author(s):  
Mridula Chowdhury ◽  
Robert Tcholakian ◽  
Emil Steinberger
Keyword(s):  
Treated Group ◽  
Inhibitory Effect ◽  
Male Rats ◽  
Plasma Testosterone ◽  
Control Group ◽  
Intact Male ◽  
Intact Control ◽  
Testosterone Levels ◽  
Oestradiol Benzoate ◽  
Direct Inhibitory Effect

Abstract. It has been suggested that treatment of intact male rats with oestradiol benzoate (OeB) causes an interference with testosterone (T) production by the testes by a direct inhibitory effect on steroidogenesis. To test this hypothesis, different doses (5, 10 or 25 IU) of hCG were administered concomitantly with 50 μg of OeB to adult intact or hypophysectomized male rats. The testicular and plasma testosterone, and serum hCG levels were determined. The sex accessory weights were recorded. In the intact OeB-treated group of animals, hCG stimulated both the secondary sex organs and plasma testosterone levels above the intact control group. However, in hypophysectomized animals, although plasma testosterone levels increased above that of intact controls, their secondary sex organ weights did not. Moreover, inspite of high circulating hCG levels, the testicular testosterone content and concentration remained suppressed in OeB-treated animals. The reason for such dichotomy of hCG action on OeB-treated animals is not clear at present.

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