Feedback on LH in Testosterone-Clamped Men Depends on the Mode of Testosterone Administration and Body Composition

The Effect of Low-Molecular-Weight Allosteric Agonist of Luteinizing Hormone Receptor on Functional State of the Testes in Aging and Diabetic Rats

Human chorionic gonadotropin that is widely used for improving spermatogenesis. The effect of chorionic gonadotropin is mediated through luteinizing hormone receptor. Treatment with gonadotropin is associated with undesirable effects due to hyperactivation of testosterone production and luteinizing hormone receptor desensitization. A promising alternative could be low-molecular-weight agonists of luteinizing hormone receptors, but their effects on spermatogenesis have not been investigated. Here we analyzed the effect of a thieno[2,3-d]pyrimidines (TP), 4-((3-(5-amino-6-(tert-butylcarbamoyl)-2-(methylthio)thieno [2,3-d]pyrimidine-4-yl) phenyl)carbamoyl)pyridine 1-oxide (TP22), an allosteric agonist of luteinizing hormone receptors, on the seminiferous tubules and spermatogenic cells in 4- and 18-month-old male rats and in animals with diabetes mellitus. TP22 and gonadotropin were administered in daily doses of 15 mg/kg and 20 U/rat for 5 days. Blood testosterone level, morphology of the seminiferous tubules, and the number of germ cells in them were estimated. Being comparable by the efficiency to gonadotropin, TP22 increased the testosterone level in all the studied groups of rats and restored epithelium thickness in the seminiferous tubules and the number of spermatogonia and pachytenic spermatocytes that are reduced in aging and diabetes, but, unlike gonadotropin, did not suppress the expression of luteinizing hormone receptor. The efficacy of TP22 as a stimulator of testicular spermatogenesis has been demonstrated both under normal conditions and in age-related and diabetes-associated reproductive dysfunctions.

Age and time-of-day differences in the hypothalamo-pituitary-testicular, and adrenal, response to total overnight sleep deprivation

STUDY OBJECTIVES

In young men, sleep restriction decreases testosterone (Te) and increases afternoon cortisol (F), leading to anabolic-catabolic imbalance, insulin resistance, and other andrological health consequences. Age-related differences in the hypothalamo-pituitary-testicular/adrenal response to sleep restriction could expose older individuals to greater or lesser risk. We aimed to evaluate and compare the 24-h and time-of-day effect of sleep restriction on F, luteinizing hormone (LH), and Te in young and older men.

METHODS

Thirty-five healthy men, aged 18-30 (n = 17) and 60-80 (n =18) years, underwent overnight sleep deprivation (complete nighttime wakefulness) or nighttime sleep (10 pm to 6 am) with concurrent 10-min blood sampling in a prospectively randomized crossover study. F, LH, and Te secretion were calculated by deconvolution analysis.

RESULTS

Sleep deprivation had multiple effects on 24-h Te secretion with significant reductions in mean concentrations, basal, total and pulsatile secretion, and pulse frequency (each p < 0.05), in the absence of detectable changes in LH. These effects were most apparent in older men and differed according to age for some parameters: pulsatile Te secretion (p = 0.03) and Te pulse frequency (p = 0.02). Time-of-day analyses revealed that sleep restriction significantly reduced Te in the morning and afternoon, reduced LH in the morning in both age groups, and increased F in the afternoon in older men.

CONCLUSIONS

These data suggest a time-of-day dependent uncoupling of the regulatory control of the testicular axis and of F secretion. Future studies will need to directly verify these regulatory possibilities specifically and separately in young and older men.

CLINICAL TRIAL

Not applicable.