Walter J. Greenleaf

1 Hormonal replacement and sexuality in men

Summary Only in the last few years has the scientific study of hormonal replacement therapy for hyposexuality begun in earnest with the advent of appropriately controlled experimental studies. Dose-response relationships can be demonstrated between testosterone (T) and sexual measures, but these have not yet been investigated in detail. Some aspects of sexual function are maintained in the presence of androgen levels well below the normal range, but preliminary evidence suggests that within a normal population high levels of T are correlated with more vigorous responses to visual erotic stimuli. Though T (and to a greater extent free T) declines with aging in parallel with the decline of sexual function, these hormonal changes contribute only to a minor extent to the behavioural change. Some non-aromatizable androgens may be less effective in stimulating sexual behaviour than T, but initial data on effects of dihydrotestosterone suggests that the capacity of an androgen to be aromatized (converted to oestrogen) is not a requirement for its sexual action. While T apparently increases the incidence of all types of male sexual activity, recent data contradict the belief that it directly facilitates the erectile mechanism in men, even though erection frequency is greatly reduced in untreated hypogonadal men. At the present juncture, it appears that the initial action of T may be on libido factors which lead in turn to the stimulation of other aspects of sexuality. Specifically, we propose that androgen acts through stimulating genital sensations and/or other pleasurable awareness of sexual response rather than directly through cognitive processes such as sexual imagery.

Aging and sexual function in men

Sexual function, and in particular erectile capacity, declines with age in men. The present study attempted to identify possible sensory/neural and autonomic factors related to this decline. Data on self-reported sexual activity and functioning, as well as erectile response to visual erotic stimulation, were gathered from 39 healthy, sexually functional men ranging in age from 21 to 82. In addition, four parameters of putative significance to sexual functioning were measured: penile electrical and vibrotactile thresholds, pudendal somatosensory evoked potentials, penile autonomic response to ischemia, and blood testosterone. Results indicated significant age-related decreases in self-reported frequency of sexual activity and in erectile response to erotica. Furthermore, penile sensitivity, response to penile ischemia, and somatosensory evoked potentials showed age-related changes. In contrast, self-reported erectile capacity, ratings of overall sex life, and levels of testosterone did not change over age groups. These findings suggest that decreasing erectile capacity in aging men may be related to decreasing sensory/neural and autonomic functioning, but they also indicate that factors other than the frequency of and potency for sexual response are important to the overall rating of sex life.

Penile and finger sensory thresholds in young, aging, and diabetic males

AbstractTo investigate the possible role of sensory function in conditions affecting sexual function, sensory thresholds were compared between young healthy men (n = 14,

Plasma Oxytocin Increases in the Human Sexual Response

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The Nature of Androgen Action on Male Sexuality: A Combined Laboratory-Self-Report Study on Hypogonadal Men*

age =29.8) aging men(n = 15,

The ENGAGE study: Integrating neuroimaging, virtual reality and smartphone sensing to understand self-regulation for managing depression and obesity in a precision medicine model

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