Circadian rhythm of plasma testosterone, cortisol and gonadotropins in normal male subjects

Piró, C; Fraioli, F; Sciarra, P.; Conti, C

doi:10.1016/0022-4731(73)90056-3

Cited by 49 publications

(20 citation statements)

References 32 publications

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“…The lack of significant effect on serum testosterone levels is most probably due to the fact that its conversion to D H T represents a relatively minor metabolic pathway and that testosterone exerts a negative feedback on its formation. Changes in testosterone concentrations observed 4 h post dose are consistent with the known diurnal pattern in serum testosterone (Piro et al 1973).…”

Section: Tolerabilitysupporting

confidence: 83%

Plasma concentrations and effect on testosterone metabolism after single doses of MK-0434, a steroid 5 alpha-reductase inhibitor, in healthy subjects

Hecken

Depré

Schwartz

et al. 1994

Eur J Clin Pharmacol

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A four-period, two-panel, single-rising-dose study (0.1-100 mg) was conducted in healthy males to investigate the pharmacodynamics, tolerability and pharmacokinetics of MK-0434, a steroid 5 alpha-reductase inhibitor. MK-0434 was associated with a significant reduction in dihydrotestosterone, which was maximal at 24 h and maintained through 48 h post treatment. The maximum reduction was approximately 50% and occurred at all doses above 5 mg (10, 25, 50 and 100 mg). MK-0434 appeared to have no effect on serum testosterone at these single doses. Rising single doses of MK-0434 were associated with an increase in Cmax and AUC but the changes were less than proportional to dose, most likely due to nonlinear absorption. MK-0434 given in single doses up to 100 mg was without significant adverse effects in healthy male volunteers. In summary, MK-0434 is a well-tolerated, potent, orally active 5 alpha-reductase inhibitor in man.

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Section: Tolerabilitysupporting

confidence: 83%

Plasma concentrations and effect on testosterone metabolism after single doses of MK-0434, a steroid 5 alpha-reductase inhibitor, in healthy subjects

Hecken

Depré

Schwartz

et al. 1994

Eur J Clin Pharmacol

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“…Usually there was little temporal fluctuation in testosterone levels within individual males over the sampling period. The reason for the marked variation in testosterone amongst males is not precisely known, although the data suggest that diurnal variation in androgen secretion may exist, as in man (Piro, Fraioli, Sciarra & Conti, 1973) and pig (Ellicott, 1980). Temporal gland secretion of short duration occurs in immature and mature African elephants of both sexes throughout the year (Perry, 1953) and apparently is not correlated with reproductive activity (Short, 1966;Short et al, 1967).…”

Section: Discussionmentioning

confidence: 99%

Electroejaculation, semen characteristics and serum testosterone concentrations of free-ranging African elephants (Loxodonta africana)

Howard

Bush²,

Vos

et al. 1984

Reproduction

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Summary. A regimented electroejaculation protocol (120 electrical stimulations; 10\ x=r eq-\ 30 V) was used to collect semen and characterize ejaculate quality from 9 adult, free\x=req-\ ranging African elephants under anaesthesia. Eight of the 9 ejaculates contained high concentrations of progressively motile spermatozoa. The overall mean ejaculate volume, sperm concentration/ml ejaculate, sperm motility, sperm status and ejaculate pH were 93\m=.\3 ml, 2408\m=.\6\m=x\106 spermatozoa/ml, 70%, 3\m=.\9and 7\m=.\4, respectively. A high percentage (mean 77\m=.\5%) of spermatozoa within each ejaculate was morphologically normal. Of the aberrant spermatozoa, 72% had a cytoplasmic droplet defect. When sperm viability was tested in vitro at 37\x=deg\C,sperm motility rating declined by at least half of the initial assessment within 3\m=.\5h of semen collection. Generally, spermatozoa maintained motility in vitro for < 6 h. Serum testosterone ranged from 1\m=.\4to 8\m=.\2 ng/ml in 4 males evaluated in the morning (07 :30\p=n-\08:00 h). In 4 of the 5 bulls assessed in the afternoon (15 :00\p=n-\18 :00 h), testosterone levels were <0\m=.\9ng/ml. The remaining bull, evaluated at 16:00 h, had exceptionally high testosterone concentrations (peak 25\m=.\6 ng/ml) and a preputial discharge potentially indicative of 'musth'. The present study demonstrates that high quality semen can be collected consistently from the African elephant and that striking differences exist in serum testosterone amongst free-ranging males which may be due, in part, to a diurnal rhythm.

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“…Previous research has shown that there are daily variations in testosterone, with the highest concentrations being observed in the morning and the lowest concentrations observed in the evening (Baxendale et al 1980;Gooren et al 1984;Piro et al 1973). However, little is known concerning the impact of an acute resistance exercise stress on the normal circadian pattern of testosterone secretion.…”

Section: Introductionmentioning

confidence: 95%

The effect of heavy resistance exercise on the circadian rhythm of salivary testosterone in men

Kraemer

Loebel

Volek

et al. 2001

European Journal of Applied Physiology

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Circadian rhythms of serum testosterone concentrations in men have been shown, in general, to be highest in the morning and lowest in the evening. Thus, the purpose of this investigation was to determine the effects of acute resistance exercise upon the waking circadian rhythm of salivary testosterone over 2 days (with or without resistance exercise). The subjects included ten resistance-trained men (with at least 1 year of lifting experience) with the following characteristics [mean (SD)]: age 21.6 (1.1) years; height 177.8 (9.5) cm; body mass 80.5 (11.5) kg; percent body fat 7.9 (1.7)%. A matched, randomized, crossover study design was used such that each subject was tested under both the resistance exercise and control (no exercise) conditions. The resistance exercise protocol consisted of ten exercises performed for three sets of ten repetitions maximum with 2 min of rest between sets. Saliva sample 1 was collected at 0615 hours and resistance exercise began immediately afterwards at approximately 0620 hours, and sample 2 was collected at 0700 hours, which corresponded approximately to a mid-exercise (or control) time point. Saliva samples were then obtained every hour on the hour from 0800 hours until 2200 hours. No significant differences were observed between the exercise and resting conditions for salivary testosterone, with the exception of a significant decrease at 0700 hours during the resistance exercise protocol. The results of this investigation indicate that resistance exercise does not affect the circadian pattern of salivary testosterone secretion over a 16-h waking period in resistance-trained men.

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Circadian rhythm of plasma testosterone, cortisol and gonadotropins in normal male subjects

Cited by 49 publications

References 32 publications

Plasma concentrations and effect on testosterone metabolism after single doses of MK-0434, a steroid 5 alpha-reductase inhibitor, in healthy subjects

Plasma concentrations and effect on testosterone metabolism after single doses of MK-0434, a steroid 5 alpha-reductase inhibitor, in healthy subjects

Electroejaculation, semen characteristics and serum testosterone concentrations of free-ranging African elephants (Loxodonta africana)

The effect of heavy resistance exercise on the circadian rhythm of salivary testosterone in men

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