madman
Super Moderator
* Samples of venous blood were obtained from 22 healthy adult males age 19-26 before and after the im injection of testosterone in aqueous suspension (Oreton©).
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* The administration of the 12.5 and 25.0 mg of testosterone daily was reflected by markedly higher levels of serum testosterone. After the third dose of 25.0 mg, this level reached a peak within 16 hr after im administration and remained above control levels for at least 24 hr after the higher doses were administered. The rate of decline and the magnitude and duration of depression below mean control levels in serum concentrations of both LH and FSH were related to the amount and duration of drug administration. This indicates that testosterone suppresses pituitary release of LH and FSH in a dose related fashion. The possibility that suppression of LH and FSH might so inhibit endogenous production of testosterone (11) that net serum concentration of testosterone would fall appears to have been eliminated. The three larger dosage levels are greater than the daily endogenous production rate in normal adult males (11).
* When administered in doses of 12.5 mg per day and above, testosterone suppressed adult male LH levels to prepubertal levels (2.80 ± 0.15) (13) in 11 out of 13 individuals. FSH levels in 17 of 18 individuals receiving at least 5 mg testosterone per day were at or below prepubertal levels (4.59± 0.17) (13)
* At no time were levels of LH and FSH higher after administration of testosterone than levels in the same individual before treatment. Thus, no evidence was obtainedt o indicate that testosterone in this dose range enhances release of LH or FSH. Moreover, except after 1 mg for 3 days, a suppressive influence of testosterone was observed regardless of dosage or duration of treatment.
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*A similar trend for serum concentrations of LH and FSH was observed, although at none of the testosterone levels was there an identical response of LH and FSH. LH tended to drop more rapidly and return toward control mean levels before FSH. The percentage decline of LH after a given dosage of testosterone tended to be greater thant he decline of FSH.
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* The present report shows a consistent depression of LH after 4 dose levels of testosterone in aqueous suspension. This confirms previous reports of LH suppression after administration of androgens (1-4).
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* In our study, FSH levels were depressed below controls at all dosages except 1 mg/day.
* The present study indicates that FSH, as well as LH, decreases as testosterone levels increase.
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ABSTRACT
Serum LH and FSH levels were measured by radioimmunoassay after exogenous testosterone was administered to four groups of adult males in dosages ranging from 1-2S mg per day. Serum testosterone concentrations, determined by radioimmunoassay, were elevated subsequent to the administration of the higher dosages. Dose-related depression of both LH and FSH was observed subsequent to administration of 5 or more mg of testosterone per day; the smallest dosage (1 mg) was not associated with any consistent changes in LH or FSH. The rate and extent of decline of the two gonadotropins differed. Serum LH values tended to drop and recover more rapidly than FSH following testosterone administration. These results indicate that testosterone suppresses serum levels of both LH and FSH in the human adult male. There was no evidence of stimulation of gonadotropin release at these doses.(/ Clin Endocrinol Metab 35: 636, 1972).
--------4
ALTHOUGH the role of testosterone in feedback inhibition of pituitary luteinizing hormone (LH, ICSH) in the adult male of various species is well established (1-8), reports on the influence of testosterone on serum FSH are varied. Thus, following testosterone administration to men,serum FSH levels were not altered significantly, although LH values fell (2-4). In contrast, pharmacologic doses of testosterone were found to suppress plasma FSH incastrate rats (8-10).
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The present study, using radioimmunoassay techniques to measure LH, FSH and testosterone, was designed to determine the effects of exogenous testosterone upon gonadotropin concentrations in sera from healthy adult males. Since exogenous testosterone has a dose related suppressive effect upon endogenous testosterone production rates (11), serum testosterone levels were measured to determine the resultant serum concentrations achieved.
--------4
Materials and Methods
Samples of venous blood were obtained from 22 healthy adult males age 19-26 before and after the im injection of testosterone in aqueous suspension (Oreton©). Blood samples were obtained 3 times a day during hormone administration and once or twice a day following administration.
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Four groups of five individuals each received a different dosage of testosterone. The dosages, given for three days at 8 AM were 1.0, 5.0, 12.5 and 25.0 mg per day. One individual received 50.0 mg daily for three days.
-----------4
Discussion
The administration of the 12.5 and 25.0 mg of testosterone daily was reflected by markedly higher levels of serum testosterone. After the third dose of 25.0 mg, this level reached a peak within 16 hr after im administration and remained above control levels for at least 24 hr after the higher doses were administered. The rate of decline and the magnitude and duration of depression below mean control levels in serum concentrations of both LH and FSH were related to the amount and duration of drug administration. This indicates that testosterone suppresses pituitary release of LH and FSH in a dose related fashion. The possibility that suppression of LH and FSH might so inhibit endogenous production of testosterone (11) that net serum concentration of testosterone would fall appears to have been eliminated. The three larger dosage levels are greater than the daily endogenous production rate in normal adult males (11).
------
When administered in doses of 12.5 mg per day and above, testosterone suppressed adult male LH levels to prepubertal levels (2.80 ± 0.15) (13) in 11 out of 13 individuals. FSH levels in 17 of 18 individuals receiving at least 5 mg testosterone per day were at or below prepubertal levels (4.59± 0.17) (13)
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At no time were levels of LH and FSH higher after administration of testosterone than levels in the same individual before treatment. Thus, no evidence was obtainedt o indicate that testosterone in this dose range enhances release of LH or FSH. Moreover, except after 1 mg for 3 days, a suppressive influence of testosterone was observed regardless of dosage or duration of treatment.
--------
A similar trend for serum concentrations of LH and FSH was observed, although at none of the testosterone levels was there an identical response of LH and FSH. LH tended to drop more rapidly and return toward control mean levels before FSH. The percentage decline of LH after a given dosage of testosterone tended to be greater thant he decline of FSH.
-----------
The present report shows a consistent depression of LH after 4 dose levels of testosterone in aqueous suspension. This confirms previous reports of LH suppression after administration of androgens (1-4). Serum concentrations determined by radioimmunoassay were consistently depressed in human males receiving testosterone propionate (1,2,4) as well as fluoxymesterone (3).
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In our study, FSH levels were depressed below controls at all dosages except 1 mg/day. This consistent influence of testosterone in aqueous suspension differs with previous reports of effects of testosterone propionate (1,2,4) and fluoxymesterone (3).The latter showed either no influence or no consistent effect upon FSH levels. The present study indicates that FSH, as well as LH, decreases as testosterone levels increase. Conversion of androstenedione and testosterone to estradiol has recently been reported to occur in the anterior hypothalamus, limbic system and pituitary gland (19,20). Aromatization of testosterone may have occurred in individuals in the current study and if so, may have partially mediated the suppression of LH and FSH. This may explain the discrepancy between the present study and the study using fluoxymesterone (3) where conversion to estradiol is unlikely. *** and Dever (8) also found similar responses of FSH and LH in orchidectomized male rats receiving testosterone benzoate and estradiol benzoate.
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* The administration of the 12.5 and 25.0 mg of testosterone daily was reflected by markedly higher levels of serum testosterone. After the third dose of 25.0 mg, this level reached a peak within 16 hr after im administration and remained above control levels for at least 24 hr after the higher doses were administered. The rate of decline and the magnitude and duration of depression below mean control levels in serum concentrations of both LH and FSH were related to the amount and duration of drug administration. This indicates that testosterone suppresses pituitary release of LH and FSH in a dose related fashion. The possibility that suppression of LH and FSH might so inhibit endogenous production of testosterone (11) that net serum concentration of testosterone would fall appears to have been eliminated. The three larger dosage levels are greater than the daily endogenous production rate in normal adult males (11).
* When administered in doses of 12.5 mg per day and above, testosterone suppressed adult male LH levels to prepubertal levels (2.80 ± 0.15) (13) in 11 out of 13 individuals. FSH levels in 17 of 18 individuals receiving at least 5 mg testosterone per day were at or below prepubertal levels (4.59± 0.17) (13)
* At no time were levels of LH and FSH higher after administration of testosterone than levels in the same individual before treatment. Thus, no evidence was obtainedt o indicate that testosterone in this dose range enhances release of LH or FSH. Moreover, except after 1 mg for 3 days, a suppressive influence of testosterone was observed regardless of dosage or duration of treatment.
------
*A similar trend for serum concentrations of LH and FSH was observed, although at none of the testosterone levels was there an identical response of LH and FSH. LH tended to drop more rapidly and return toward control mean levels before FSH. The percentage decline of LH after a given dosage of testosterone tended to be greater thant he decline of FSH.
----
* The present report shows a consistent depression of LH after 4 dose levels of testosterone in aqueous suspension. This confirms previous reports of LH suppression after administration of androgens (1-4).
--------
* In our study, FSH levels were depressed below controls at all dosages except 1 mg/day.
* The present study indicates that FSH, as well as LH, decreases as testosterone levels increase.
-------4
ABSTRACT
Serum LH and FSH levels were measured by radioimmunoassay after exogenous testosterone was administered to four groups of adult males in dosages ranging from 1-2S mg per day. Serum testosterone concentrations, determined by radioimmunoassay, were elevated subsequent to the administration of the higher dosages. Dose-related depression of both LH and FSH was observed subsequent to administration of 5 or more mg of testosterone per day; the smallest dosage (1 mg) was not associated with any consistent changes in LH or FSH. The rate and extent of decline of the two gonadotropins differed. Serum LH values tended to drop and recover more rapidly than FSH following testosterone administration. These results indicate that testosterone suppresses serum levels of both LH and FSH in the human adult male. There was no evidence of stimulation of gonadotropin release at these doses.(/ Clin Endocrinol Metab 35: 636, 1972).
--------4
ALTHOUGH the role of testosterone in feedback inhibition of pituitary luteinizing hormone (LH, ICSH) in the adult male of various species is well established (1-8), reports on the influence of testosterone on serum FSH are varied. Thus, following testosterone administration to men,serum FSH levels were not altered significantly, although LH values fell (2-4). In contrast, pharmacologic doses of testosterone were found to suppress plasma FSH incastrate rats (8-10).
---------
The present study, using radioimmunoassay techniques to measure LH, FSH and testosterone, was designed to determine the effects of exogenous testosterone upon gonadotropin concentrations in sera from healthy adult males. Since exogenous testosterone has a dose related suppressive effect upon endogenous testosterone production rates (11), serum testosterone levels were measured to determine the resultant serum concentrations achieved.
--------4
Materials and Methods
Samples of venous blood were obtained from 22 healthy adult males age 19-26 before and after the im injection of testosterone in aqueous suspension (Oreton©). Blood samples were obtained 3 times a day during hormone administration and once or twice a day following administration.
-------
Four groups of five individuals each received a different dosage of testosterone. The dosages, given for three days at 8 AM were 1.0, 5.0, 12.5 and 25.0 mg per day. One individual received 50.0 mg daily for three days.
-----------4
Discussion
The administration of the 12.5 and 25.0 mg of testosterone daily was reflected by markedly higher levels of serum testosterone. After the third dose of 25.0 mg, this level reached a peak within 16 hr after im administration and remained above control levels for at least 24 hr after the higher doses were administered. The rate of decline and the magnitude and duration of depression below mean control levels in serum concentrations of both LH and FSH were related to the amount and duration of drug administration. This indicates that testosterone suppresses pituitary release of LH and FSH in a dose related fashion. The possibility that suppression of LH and FSH might so inhibit endogenous production of testosterone (11) that net serum concentration of testosterone would fall appears to have been eliminated. The three larger dosage levels are greater than the daily endogenous production rate in normal adult males (11).
------
When administered in doses of 12.5 mg per day and above, testosterone suppressed adult male LH levels to prepubertal levels (2.80 ± 0.15) (13) in 11 out of 13 individuals. FSH levels in 17 of 18 individuals receiving at least 5 mg testosterone per day were at or below prepubertal levels (4.59± 0.17) (13)
---------
At no time were levels of LH and FSH higher after administration of testosterone than levels in the same individual before treatment. Thus, no evidence was obtainedt o indicate that testosterone in this dose range enhances release of LH or FSH. Moreover, except after 1 mg for 3 days, a suppressive influence of testosterone was observed regardless of dosage or duration of treatment.
--------
A similar trend for serum concentrations of LH and FSH was observed, although at none of the testosterone levels was there an identical response of LH and FSH. LH tended to drop more rapidly and return toward control mean levels before FSH. The percentage decline of LH after a given dosage of testosterone tended to be greater thant he decline of FSH.
-----------
The present report shows a consistent depression of LH after 4 dose levels of testosterone in aqueous suspension. This confirms previous reports of LH suppression after administration of androgens (1-4). Serum concentrations determined by radioimmunoassay were consistently depressed in human males receiving testosterone propionate (1,2,4) as well as fluoxymesterone (3).
---------
In our study, FSH levels were depressed below controls at all dosages except 1 mg/day. This consistent influence of testosterone in aqueous suspension differs with previous reports of effects of testosterone propionate (1,2,4) and fluoxymesterone (3).The latter showed either no influence or no consistent effect upon FSH levels. The present study indicates that FSH, as well as LH, decreases as testosterone levels increase. Conversion of androstenedione and testosterone to estradiol has recently been reported to occur in the anterior hypothalamus, limbic system and pituitary gland (19,20). Aromatization of testosterone may have occurred in individuals in the current study and if so, may have partially mediated the suppression of LH and FSH. This may explain the discrepancy between the present study and the study using fluoxymesterone (3) where conversion to estradiol is unlikely. *** and Dever (8) also found similar responses of FSH and LH in orchidectomized male rats receiving testosterone benzoate and estradiol benzoate.
