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Clomiphene Studies:
J Clin Endocrinol Metab 1985 Nov;61(5):842-5
Evidence for a role of endogenous estrogen in the hypothalamic control of gonadotropin secretion in men.
Winters SJ, Troen P.
To examine the mechanism by which endogenous estrogens inhibit gonadotropin secretion in men, blood samples were drawn every 10 min for 12 h in five men before and at the completion of 3 weeks of treatment with the estrogen antagonist clomiphene citrate (50 mg twice daily). Samples were analyzed for LH and alpha-subunit by RIA. Clomiphene produced a 3-fold rise in circulating LH levels, which was associated with a 80% increase in pulse frequency and a 70% increase in pulse amplitude. Immunoreactive alpha-subunit secretion was also pulsatile before and after clomiphene treatment. Mean alpha-levels rose 70%, together with a 39% increase in pulse frequency and a 41% increase in pulse amplitude. Circulating testosterone and estradiol levels increased 2-fold and FSH levels increased 3-fold after clomiphene treatment. Insofar as each LH and uncombined alpha-subunit pulse reflects a LHRH secretory episode, our data indicate that endogenous estrogens tonically restrain the hypothalamic release of LHRH. From these results and those of previous studies, we conclude that estrogens as well as androgens are important in the testicular feedback inhibition of the hypothalamic oscillator that governs pulsatile gonadotropin secretion.
J Androl 1991 Jul-Aug;12(4):258-63
The effects of normal aging on the response of the pituitary-gonadal axis to chronic clomiphene administration in men.
Tenover JS, Bremner WJ.
Department of Medicine, University of Washington School of Medicine, Seattle.
Serum androgens decline with age in normal men, despite normal or elevated bioactive serum gonadotropins, suggesting that primary testicular dysfunction occurs with aging. The authors further assessed the question of age-related testicular dysfunction by evaluating whether raising serum gonadotropins above the normal serum range for an extended time in healthy elderly men might result in bringing their gonadal function to a level similar to that found in young adult men. Five elderly (65 to 85 years old) and five young adult men (26 to 33 years old) were given 50 mg of clomiphene citrate (CC) twice a day for 8 weeks to stimulate gonadotropin production. During that time, testosterone (T), non-sex hormone-binding globulin bound T, and estradiol increased significantly in both age groups, while serum inhibin increased significantly only in the young adult men. The increases in serum androgens with CC administration were significantly greater in the young adult men than in the elderly men. These hormone changes occurred in the setting of serum gonadotropins that increased significantly in both age groups, although there was a tendency for the elderly men to have a smaller increase in luteinizing hormone. Despite 8 weeks of stimulation of the pituitary-gonadal axis by CC administration, the elderly men demonstrated significantly diminished testicular responses compared with the young adult men. Sertoli cell function, as determined by inhibin production, was more diminished in the elderly men than was Leydig cell function. These data strengthen the hypothesis that normal aging in men is accompanied by a decline in testicular function.
Urology 1991 Oct;38(4):317-22
Possible hypothalamic impotence. Male counterpart to hypothalamic amenorrhea?
Guay AT, Bansal S, Hodge MB.
Section of Endocrinology, Lahey Clinic Medical Center, Burlington, Massachusetts.
Twenty-one men with erectile complaints who were found to have a low level of serum testosterone without a reciprocal elevation of the serum levels of luteinizing hormone were evaluated to identify whether the defect was of hypothalamic or of pituitary origin. Patients underwent a luteinizing hormone (LH)-follicle-stimulating hormone (FSH)-releasing hormone stimulation test that showed a normal but sluggish increase in LH and FSH levels, thus ruling out a pituitary defect and suggesting a suprapituitary abnormality. This was confirmed when, in response to clomiphene, patients had a normal increase in gonadotropin and testosterone levels. Although the basal as well as clomiphene and gonadotropin releasing hormone-stimulated levels of total testosterone and gonadotropins were identical in men less than and more than fifty years old, the elevation of free testosterone levels in response to clomiphene was higher in patients younger than fifty. This suggested that although the primary abnormality found in these patients is altered secretion of gonadotropin hormone-releasing hormone from the hypothalamus, an age-related decline in the responsivity of Leydig cells to LH may make it more manifest in older patients. Elevation of testosterone levels from a subnormal to a normal range in response to clomiphene administered for seven days suggests that the defect is functional and reversible and that the drug may be useful in treatment of sexual dysfunction in this group of patients.
Nephron 1993;63(4):390-4
Effect of clomiphene citrate on hormonal profile in male hemodialysis and kidney transplant patients.
Martin-Malo A, Benito P, Castillo D, Espinosa M, Burdiel LG, Perez R, Aljama P.
Department of Nephrology, Hospital Universitario Reina Sofia, Cordoba, Spain.
The aim of this study was to evaluate the role of clomiphene citrate (CC) therapy in the hypothalamus-pituitary-gonadal axis of male uremic subjects. Thirty-four patients on hemodialysis (HD) and 8 successful kidney transplant subjects (RT) were evaluated. Nine healthy males were used as controls (C). At baseline, zinc, testosterone (TEST), prolactin (PRL), FSH, LH and estradiol plasma concentrations were measured. All subjects were treated with CC (100 mg/day) for a week. The aforementioned parameters were determined again on the seventh day of CC therapy, and 3 days after drug withdrawal. Following CC, there was a rise in FSH, LH and TEST levels in all subjects (p < 0.05); it is interesting to stress that TEST became normal in HD. In addition, we observed a decrease of PRL after CC only in HD patients (p < 0.01). In summary, CC was able to partially correct most of the hormonal disturbances of the gonadal axis in uremic patients.
J Clin Endocrinol Metab 1985 Nov;61(5):842-5
Evidence for a role of endogenous estrogen in the hypothalamic control of gonadotropin secretion in men.
Winters SJ, Troen P.
To examine the mechanism by which endogenous estrogens inhibit gonadotropin secretion in men, blood samples were drawn every 10 min for 12 h in five men before and at the completion of 3 weeks of treatment with the estrogen antagonist clomiphene citrate (50 mg twice daily). Samples were analyzed for LH and alpha-subunit by RIA. Clomiphene produced a 3-fold rise in circulating LH levels, which was associated with a 80% increase in pulse frequency and a 70% increase in pulse amplitude. Immunoreactive alpha-subunit secretion was also pulsatile before and after clomiphene treatment. Mean alpha-levels rose 70%, together with a 39% increase in pulse frequency and a 41% increase in pulse amplitude. Circulating testosterone and estradiol levels increased 2-fold and FSH levels increased 3-fold after clomiphene treatment. Insofar as each LH and uncombined alpha-subunit pulse reflects a LHRH secretory episode, our data indicate that endogenous estrogens tonically restrain the hypothalamic release of LHRH. From these results and those of previous studies, we conclude that estrogens as well as androgens are important in the testicular feedback inhibition of the hypothalamic oscillator that governs pulsatile gonadotropin secretion.
J Androl 1991 Jul-Aug;12(4):258-63
The effects of normal aging on the response of the pituitary-gonadal axis to chronic clomiphene administration in men.
Tenover JS, Bremner WJ.
Department of Medicine, University of Washington School of Medicine, Seattle.
Serum androgens decline with age in normal men, despite normal or elevated bioactive serum gonadotropins, suggesting that primary testicular dysfunction occurs with aging. The authors further assessed the question of age-related testicular dysfunction by evaluating whether raising serum gonadotropins above the normal serum range for an extended time in healthy elderly men might result in bringing their gonadal function to a level similar to that found in young adult men. Five elderly (65 to 85 years old) and five young adult men (26 to 33 years old) were given 50 mg of clomiphene citrate (CC) twice a day for 8 weeks to stimulate gonadotropin production. During that time, testosterone (T), non-sex hormone-binding globulin bound T, and estradiol increased significantly in both age groups, while serum inhibin increased significantly only in the young adult men. The increases in serum androgens with CC administration were significantly greater in the young adult men than in the elderly men. These hormone changes occurred in the setting of serum gonadotropins that increased significantly in both age groups, although there was a tendency for the elderly men to have a smaller increase in luteinizing hormone. Despite 8 weeks of stimulation of the pituitary-gonadal axis by CC administration, the elderly men demonstrated significantly diminished testicular responses compared with the young adult men. Sertoli cell function, as determined by inhibin production, was more diminished in the elderly men than was Leydig cell function. These data strengthen the hypothesis that normal aging in men is accompanied by a decline in testicular function.
Urology 1991 Oct;38(4):317-22
Possible hypothalamic impotence. Male counterpart to hypothalamic amenorrhea?
Guay AT, Bansal S, Hodge MB.
Section of Endocrinology, Lahey Clinic Medical Center, Burlington, Massachusetts.
Twenty-one men with erectile complaints who were found to have a low level of serum testosterone without a reciprocal elevation of the serum levels of luteinizing hormone were evaluated to identify whether the defect was of hypothalamic or of pituitary origin. Patients underwent a luteinizing hormone (LH)-follicle-stimulating hormone (FSH)-releasing hormone stimulation test that showed a normal but sluggish increase in LH and FSH levels, thus ruling out a pituitary defect and suggesting a suprapituitary abnormality. This was confirmed when, in response to clomiphene, patients had a normal increase in gonadotropin and testosterone levels. Although the basal as well as clomiphene and gonadotropin releasing hormone-stimulated levels of total testosterone and gonadotropins were identical in men less than and more than fifty years old, the elevation of free testosterone levels in response to clomiphene was higher in patients younger than fifty. This suggested that although the primary abnormality found in these patients is altered secretion of gonadotropin hormone-releasing hormone from the hypothalamus, an age-related decline in the responsivity of Leydig cells to LH may make it more manifest in older patients. Elevation of testosterone levels from a subnormal to a normal range in response to clomiphene administered for seven days suggests that the defect is functional and reversible and that the drug may be useful in treatment of sexual dysfunction in this group of patients.
Nephron 1993;63(4):390-4
Effect of clomiphene citrate on hormonal profile in male hemodialysis and kidney transplant patients.
Martin-Malo A, Benito P, Castillo D, Espinosa M, Burdiel LG, Perez R, Aljama P.
Department of Nephrology, Hospital Universitario Reina Sofia, Cordoba, Spain.
The aim of this study was to evaluate the role of clomiphene citrate (CC) therapy in the hypothalamus-pituitary-gonadal axis of male uremic subjects. Thirty-four patients on hemodialysis (HD) and 8 successful kidney transplant subjects (RT) were evaluated. Nine healthy males were used as controls (C). At baseline, zinc, testosterone (TEST), prolactin (PRL), FSH, LH and estradiol plasma concentrations were measured. All subjects were treated with CC (100 mg/day) for a week. The aforementioned parameters were determined again on the seventh day of CC therapy, and 3 days after drug withdrawal. Following CC, there was a rise in FSH, LH and TEST levels in all subjects (p < 0.05); it is interesting to stress that TEST became normal in HD. In addition, we observed a decrease of PRL after CC only in HD patients (p < 0.01). In summary, CC was able to partially correct most of the hormonal disturbances of the gonadal axis in uremic patients.
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