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KMID : 0378119790060020418
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Chungnam Medical Journal
1979 Volume.6 No. 2 p.418 ~ p.428
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Effect of Constant Illumination on Plasma Testosterone Level of Female Rat
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Abstract
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Effect of constant illumination on plasma testosterone concentration was studied in adult female rats. Effects on HCG induced changes were also observed. Cyclic changes of plasma concentration of testosterone and estradiol during cycle 2 in constant illuminati￢on were measured in rats having a regular 5 day-cycle.
The observations in constant illumination were also made in the rats stimulated with HCG on the day of proestrus and the rats stimulated with HCG continuously during the entire estrous cycle.
Values observed in constant illumination were compared with the values obtained in the rats kept on a light-dark environment.
Followings were the results
1. There was no significant variation in plasma testosterone concentration during estr￢ous cycle of both the control rats and the rats exposed to constant illumination, although the levels of the rats in constant illumination slightly tended to be low.
2. Plasma testosterone levels effected by single stimulation of HCG during estrous cycle of all rats exposed to either photoperiod resembled those obtained in each control rats. But the level of diestrus shown in constant illumination was lower than that of light-da￢rk environment: the difference was borderline significant.
3. Promoting effcet of continual HCG stimulation on plasma testosterone rise during latter half of the cycle was abolished by constant illumination; the levels on the day of metaestrus and diestrus shown in the rats kept in constant illumination were significantly lower than those of light-dark environment.
4. Exposing rats to constant illumination for 2 estrous cycles failed to alter the cycle changes of plasma estrogen concentration in all rats with or without HCG stimulation.
Although the estradiol levels of rats kept in constant illumination appeared to be lower than those of light-dark environment, differences were not significant.
5. From the result of absence of a change in plasma estradiol pattern, author discussed that diminished stimulatory action of HCG on testosterone release caused by constant illumination could not be connected with altered estrous cycle.
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KEYWORD
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