A diurnal variation in testicular hormone production is maintained following gonadotrophin suppression in normal men

Walton, Matthew; Anderson, Richard A.; Kicman, Andrew T.; Elton, R. A.; Ossowska, Karolina; Baird, D. T.

doi:10.1111/j.1365-2265.2006.02696.x

Cited by 17 publications

(18 citation statements)

References 42 publications

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“…It is known that the diurnal variation of E is comparable to the serum T level . As expected we noted a correlation between serum T and urinary E levels, both at baseline and after the administration of T. Luigi et al also found a correlation between serum total T and urinary E, and they suggested a possible peripheral conversion of exogenous T into E .…”

Section: Discussionsupporting

confidence: 89%

“…It is known that the diurnal variation of E is comparable to the serum T level. [26] As expected we noted a correlation between serum T and urinary E levels, both at baseline and after the administration of T. Luigi et al also found a correlation between serum total T and urinary E, and they suggested a possible peripheral conversion of exogenous T into E. [27] However, the main part of E synthesis is believed to be via a direct pathway from pregnenolone to 5α-androstane-3β,17α-diol catalyzed by CYP17. [18,28] In accordance with previous studies, we show that exogenous T administration represses the excretion rate of E. It has been assumed that this is due to an inhibition of LH secretion, but a correlation between LH and urinary E levels has only been verified in hypergonadotropic hypogonadal men (n=5).…”

Section: Discussionsupporting

confidence: 77%

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Dose‐dependent testosterone sensitivity of the steroidal passport and GC‐C‐IRMS analysis in relation to the UGT2B17 deletion polymorphism

Strahm

Mullen

Gårevik

et al. 2015

Drug Testing and Analysis

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The newly implemented Steroid Module of the Athlete Biological Passport has improved doping tests for steroids. A biomarker included in this passport is the urinary testosterone glucuronide to epitestosterone glucuronide (T/E) ratio, a ratio greatly affected by a deletion polymorphism in UGT2B17. Suspect urine doping tests are further analyzed with gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) to determine the origin of the androgen. In this study, we investigated the sensitivity of the steroidal module and the IRMS analysis, in subjects administered with three doses of testosterone enanthate (500, 250, and 125 mg), in relation to the UGT2B17 polymorphism. All subjects carrying the UGT2B17 enzyme reached the traditionally used threshold, a T/E ratio of 4, after all three administered doses, whereas none of the subjects devoid of this enzyme reached a T/E of 4. On the other hand, using the athlete biological passport and IRMS analysis, all three doses could be detected to a high degree of sensitivity. The concentrations of all steroids included in the steroidal module were dose dependently increased, except for epitestosterone which decreased independent of dose. The decrease in epitestosterone was significantly associated with circulatory levels of testosterone post dose (rs =0.60 and p=0.007). In conclusion, these results demonstrate that administration of a single dose of 125-500 mg testosterone enanthate could be detected using the athlete biological passport, together with IRMS. Since IRMS is sensitive to testosterone doping independent of UGT2B17 genotype, also very small changes in the steroidal passport should be investigated with IRMS.

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Section: Discussionsupporting

confidence: 89%

Section: Discussionsupporting

confidence: 77%

Dose‐dependent testosterone sensitivity of the steroidal passport and GC‐C‐IRMS analysis in relation to the UGT2B17 deletion polymorphism

Strahm

Mullen

Gårevik

et al. 2015

Drug Testing and Analysis

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“…1–5 Other factors, such as nutrient-sensitive hormones (such as insulin and adipokines) vary their circulating levels in part in response to the environment/behaviors, such as light/dark and feeding/fasting cycles, that typically occur in time-of-day-dependent patterns. 6, 7 Figure 1 and Table 1 summarize what is known regarding time-of-day-dependent oscillations in these and other endocrine factors, while below we provide additional detail for several of these factors.…”

Section: Circadian Rhythms In Stimulus-response Couplingmentioning

confidence: 99%

Circadian clock control of endocrine factors

et al. 2014

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Organisms experience dramatic fluctuations in demands/stresses over the course of the day. In order to maintain biological processes within physiologic boundaries, it is imperative that mechanisms have evolved for anticipation of, and adaptation to, these daily fluctuations. Endocrine factors undoubtedly play an integral role in homeostasis. Not only do circulating levels of various endocrine factors oscillate over the 24 period, but so too does responsiveness of target tissues to these signals/stimuli. Emerging evidence suggests that these daily oscillations do not occur solely in response to behavioral fluctuations associated with sleep/wake and feeding/fasting cycles, but are orchestrated in part by an intrinsic timekeeping mechanism known as the circadian clock. Disruption of circadian clocks, through genetic and/or environmental means, appears to precipitate numerous common disorders, including cardiometabolic diseases and cancer. Collectively, these observations, which are reviewed within the current article, have led to suggestion that strategies designed to realign normal circadian rhythmicities hold a therapeutic potential for the treatment of various endocrine-related disorders.

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“…Additionally, there are circadian and seasonal rhythms to T concentrations [44-47]} and several types of social experiences can modulate plasma T profiles in both sexes, including sexual arousal, winning/losing sports competitions, exposure to an infant’s cries and providing nurturing care [48-57]. T concentrations can be modulated by social experiences as well as by exogenous drugs in both males [58,59] and females [60].…”

Section: Introductionmentioning

confidence: 99%

Sex differences in the neural mechanisms mediating addiction: a new synthesis and hypothesis

2012

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In this review we propose that there are sex differences in how men and women enter onto the path that can lead to addiction. Males are more likely than females to engage in risky behaviors that include experimenting with drugs of abuse, and in susceptible individuals, they are drawn into the spiral that can eventually lead to addiction. Women and girls are more likely to begin taking drugs as self-medication to reduce stress or alleviate depression. For this reason women enter into the downward spiral further along the path to addiction, and so transition to addiction more rapidly. We propose that this sex difference is due, at least in part, to sex differences in the organization of the neural systems responsible for motivation and addiction. Additionally, we suggest that sex differences in these systems and their functioning are accentuated with addiction. In the current review we discuss historical, cultural, social and biological bases for sex differences in addiction with an emphasis on sex differences in the neurotransmitter systems that are implicated.

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A diurnal variation in testicular hormone production is maintained following gonadotrophin suppression in normal men

Abstract: The diurnal variation of testosterone in normal men is due to a change in secretion rather than in clearance and is largely LH driven. An endogenous rhythm in both testicular steroidogenesis (epitestosterone) and Sertoli cell function (inhibin B) is also present.

Cited by 17 publications

References 42 publications

Dose‐dependent testosterone sensitivity of the steroidal passport and GC‐C‐IRMS analysis in relation to the UGT2B17 deletion polymorphism

Dose‐dependent testosterone sensitivity of the steroidal passport and GC‐C‐IRMS analysis in relation to the UGT2B17 deletion polymorphism

Circadian clock control of endocrine factors

Sex differences in the neural mechanisms mediating addiction: a new synthesis and hypothesis

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