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PubMed1997

[The effects of zinc deficiency and testosterone supplement on testosterone synthesis and skeletal muscle of rats].

The effects of zinc deficiency and testosterone (T) supplement on T synthesis and skeletal muscle were investigated in zinc-deficient and zinc-replenished rats. The results showed that there were significantly lower weights of body, testes and musculus extensor digitorum longus, lower contents of T in testes and serum and total RNA in the profundus muscularis of quadriceps femoris of zinc-deficient rats. T supplement had no favourable effects on the decreased indices mentioned above. On the contrary, T supplement inhibited the endogenous synthesis of T and caused further atrophy of testes in zinc-deficient rats. The concentrations of actins, DNA and total protein in skeletal muscle were not influenced markedly by zinc deficiency and/or T supplement. It suggested that the decrease of anabolism in skeletal muscle is not related to the low level of T in the rats under the condition of zinc deficiency.

Animals↗

PubMedDate not supplied

[Circadian rhythm of plasm testosterone levels. II. Testosterone levels during the 1st and 2d half-day].

Testosterone in plasma is measured in 50 young males in the morning and in the evening by radioimmunoassay. Peaks are found in the morning. At 07,00 h and 10,00 h the values lie on a plateau: 91,77% at 07.00 h and 90,59% at 10.00 h. The difference is not significant. Significant differences however can be noted in comparison between values in the first and second half-day. The difference between the 07.00 h value and the 16.00 h value amounts to 17,08%; between the 07.00 h value and the 19.00 h value, to 22,6%.

Adolescent↗

PubMed1983

LH receptor in testosterone-producing ovarian tumor. In vivo and in vitro HCG-stimulated testosterone production.

The aim of the present work is to report in vivo and in vitro hormonal studies performed on a 71 year old virilized woman due to a Leydig cell tumor of the ovary. Testosterone (T), Cortisol, DHEA(s) and ACTH concentrations were determined in blood samples taken every 4 h throughout 24 h previous to surgery. T average concentration from the 6 samples was 3.3 ng/ml (range: 2.5-4.2 ng/ml). DHEA(s) was normal; Cortisol and ACTH levels were normal and their circadian rhythms were present. T value obtained during Dexamethasone administration (2 mg daily/3 days) was 2.4 ng/ml. This value was significantly higher than those obtained from postcorticoid normal women (0.3 +/- 0.1 ng/ml), suggesting an extraadrenal source. T concentration was 5.4, 6.0 and 6.6 ng/ml at 24, 48 and 72 h after hCG injection (5000 IU). After tumor removal, T values decreased progressively up to 6.0 ng/ml values, 5 days later, and remained steady on the following days. The studies performed in vitro were: determination of T in the tumor cytosol, specific binding of LH to ovarian tumor cell membrane fraction and T production in tissue culture in both with and without added hCG conditions. Normal ovarian tissue from the same patient under similar experimental conditions was used as control. The T concentration expressed as ng/mg of protein in the tumor and normal ovarian cytosol was 9.1 and 1.1, respectively. Scatchard analysis of specific 125I-hCG binding to tumor and normal ovarian cells indicated 53 pg and 28 pg of labeled hCG bound/mg of membrane protein, respectively, suggesting that this Leydig cell tumor of the ovary contained LH (hCG) receptors. The amounts of T, expressed as ng/mg of tissue/6 days, generated by tumoral and normal tissue ere 4.1 and 0.3, respectively. The addition of hCG elicited a response of 6.3 and 0.6 ng/mg protein/6 days in both preparation, respectively. These results demonstrate in vivo and in vitro hCG-stimulated T production in this particularly masculinizing ovarian tumor and suggest tumoral LH dependence.

Aged↗

PubMed1963