What role does aromatization of testosterone in the male brain play in male sexual arousal, and to what extent do comparable testosterone effects in the female depend on aromatization? This finding needs to be replicated. As yet, there are no comparative data on the distribution of aromatase activity in women or female primates, though in the rat greater amounts of aromatase activity are found in the male than the female, in all areas examined except the medial preoptic nucleus (Roselli & Resko 1993). with sexually inactive or sexually naive rats) may be relevant (Pfaus & Gorzalka 1987). American Journal of Obstetrics and Gynecology.
Psychosomatic Medicine 59 161171. British Journal of Psychiatry 148 7479. b. excitement, plateau, orgasm, resolution. By identifying brain areas where there was overlap in androgen- and oestrogen-concentrating neurons, they concluded that the medial pre-optic and ventromedial hypothalamic nuclei, the bed nucleus of the stria terminalis, and the cortical, medial and accessory amygdaloid nuclei were the main sites at which the effects of testosterone are mediated predominantly by oestradiol. A number of age-related changes may be relevant: altered negative feedback of testosterone and hence less increase in luteinizing hormone (LH) with falling testosterone levels, increased sex hormone binding globulin (SHBG) and hence relatively reduced free testosterone and the likelihood of an age-related decline in testosterone receptor sensitivity. Nishimori K, Young LJ, Guo Q, Wang Z, Insel TR & Matzuk MM 1996 Oxytocin is required for nursing but not essential for parturition or reproductive behavior. It is also noteworthy because it focused on the immediate post-operative period in women who were not reporting significant sexual or mood problems pre-operatively. In female rats, studies with OT antagonists indicate that OT facilitates lordosis, an effect apparently dependent on progesterone priming. This is the only study in which testosterone administration on its own has been evaluated. The evidence is fairly clear that in men who have gone through normal puberty and who have not yet been affected by aging, testosterone plays an important role in their sexual interest and associated sexual arousability. c. Women's body cells are more sensitive to testosterone than men's. Lorrain et al. Appetite, however, is not the same as intense pleasure, the origins of which, and of sexual orgasm also, remain obscure. In addition, factors such as body weight and insulin resistance influence this ovarian androgen production (for a brief review of the evidence see Bancroft & Cawood 1996). Caldwell (2002) has proposed that OT is a satiety hormone that acts by de-coupling the G-protein (see above) and hence reducing sexual arousability. 1999). But we should also keep in mind that these two techniques are looking at very different markers of brain activity steroid receptors and localized oxygen uptake.
This hypothesis is open to testing in various ways. Androgen receptor messenger ribonucleic acid in brains and pituitaries of male rhesus monkeys: studies on distribution, hormonal control, and relationship to luteinizing hormone secretion.
Addiction 95 (Suppl 2) S91S117. Possible consequences of such desensitization in the male include that (i) genetically determined variations in CNS receptor responsiveness to androgens, across individuals, are flattened out and hence less evident and (ii) much higher levels of testosterone from puberty onwards are possible without hyperstimulation of CNS mechanisms.
(1985) investigated women who were about to undergo hysterectomy and bilateral oophorectomy. A great deal of evidence indicates that regular use of opiates, such as heroin, morphine, and methadone, often produces a significant, and sometimes dramatic, ____. What hormonal and neurotransmitter factors are involved? Prolactin (PRL) and its receptor: actions, signal transduction pathways and phenotypes observed in PRL receptor knockout mice.
When asked by her boyfriend if she would like to watch an erotic film, Celia reports she is "just not into that." (1999) found an increase in OT 1 min after orgasm, but levels were close to baseline by 5 min post-orgasm.
Appelt H & Strauss B 1986 The psychoendocrinology of female sexuality: a research project.
Eds E Knobil & JD Neill. Fertility and Sterility 43 9094. This was not commented on in the paper. There was a substantial placebo response; however, there was significantly more improvement with the higher testosterone dose than with placebo on measures of frequency of sexual activity, and pleasure/orgasm, though not for sexual desire or arousal (the opposite pattern reported by Sherwin et al. In animal studies, centrally administered OT has induced erection, an effect which is apparently testosterone dependent, and OT receptor antagonists can prevent non-contact erections, considered an index of sexual arousal (Argiolas 1999).
Sexual practices are interwoven with the spiritual traditions of Hinduism, Buddhism, and Taoism in some Asian societies.
Which of the following drugs may eventually be shown to have aphrodisiac qualities for at least some people? Norwalk: Appleton & Lange. There is a lack of evidence of testosterone levels during the early cycles of post-menarcheal adolescents, which tend to be irregular and not predictably ovulatory.
The l.c.
Steroid hormones, the menopause, sexuality and well-being of women. Neuropeptides, stress and sexuality: towards a new psychopharmacology. Estrogen action in males: insights through mutations in aromatase and estrogen-receptor genes.
OCarroll R & Bancroft J 1984 Testosterone therapy for low sexual interest and erectile dysfunction in men: a controlled study. With this conceptual framework in mind, some key issues requiring further research are proposed. (1999) examined the interaction of OT and serotonin. Shifren et al. Pfaus JG & Gorzalka BB 1987 Opioids and sexual behavior. Studies of testosterone administration to women may also be informative.
The menopause and sexual functioning: a review of population based studies. A prospective study of the effects of oral contraceptives on sexuality and well-being and their relationship to discontinuation. This threshold concept does not appear to apply to women.
Intramuscular testosterone enanthate had no effect on sleep parameters, and did not affect frequency, degree or duration of NPT, when assessed as penile circumference, but did increase, modestly but significantly, penile rigidity during NPT. Frequency of masturbation tends to follow the level of sexual interest, although cultural factors may influence this pattern of sexual expression (Anderson et al.
Journal of Endocrinology 154 5762. Fertility and Sterility 65 721723. This has focused attention on the negative sexual effects of PRL. d. At this time, research findings are contradictory. The most substantial evidence of the relationship between testosterone and emerging sexual arousability in females comes again from Udry et al.(1986). The evidence points mainly to the effects of testosterone on central arousal mechanisms; the peripheral effects of testosterone in the human male, relevant to sexual arousal, are as yet unclear. New York, NY: Greenwood Press. Although Arnold's doctor has told him he has a normal level of testosterone, Arnold believes his sexual performance will increase if he takes additional testosterone, which he buys on the Internet. The extent to which testosterone in women acts by conversion to oestradiol or by increase of free oestradiol is not yet clear. Eds ER Kandel, JH Schwartz & TM Jessell. , Perry PJ, MacIndoe J, Holman T & Ellingrod V. Psychosexual effects of three doses of testosterone cycling in normal men. Bancroft J, Sherwin B, Alexander GM, Davidson DW & Walker A 1991 Contraceptives, androgens, and the sexuality of young women.
. According to Kaplan, this man is having difficulty with the ____ phase of sexual response. Kupfermann I 1991 Hypothalamus and limbic system: peptidergic neurons, homeostasis, and emotional behavior. Wise 1996, Robinson & Berridge 2000). b. belongs to a class of medications known as antiandrogens. All of the following are sexual changes that can occur in females as they age EXCEPT: b. lack of uterine contractions at orgasm.
More than 90% of testosterone in the male is produced by the testes. Totawa: Humana Press. Age changes and sex differences in serum dehydroepiandrosterone sulfate concentrations throughout adulthood.
Androstenedione has a substantial capacity for conversion to both oestradiol and testosterone; dehydroepiandrosterone (DHEA) has a very limited capacity for conversion to testosterone. Still many Americans lag behind in their proficiency with the technology.
Boomer .
b. may experience erections that are not as firm as when he was younger. Of more relevance, five of the breast feeders reported reduced sexual interest, and their testosterone and androstenedione levels were consistently and significantly lower than the breast feeders who reported no reduction in sexual interest. Yohimbine on its own produced no observable effect, whereas naloxone produced partial erection in three of the six men studied. These results suggest that, at least in those women in whom testosterone has an effect on their sexuality, cyclical variation in testosterone levels should be manifested by cyclical patterns of sexual interest and/or responsiveness.
In The Physiology of Reproduction, edn 2, pp 3105. . Controlled studies of the treatment with testosterone of women presenting with sexual problems have been few. Bagatell CJ, Heiman JR, Matsumoto AM, Rivier JE & Bremner WJ 1994b Metabolic and behavioral effects of high-dose, exogenous testosterone in healthy men. Such studies consistently show a reduction in the level of sexual interest during testosterone withdrawal, usually evident within 3 to 4 weeks, consistent with testosterone being necessary for normal levels of sexual interest (and arousability). Do testosterone levels correlate with measures of sexual interest or activity as women get older? 1998, 2003a, Exton et al. The role of testosterone in the emerging sexual arousability of the peri-pubertal male is not well understood. With the antagonist, however, one can expect to interfere with the normal physiological process. c. All males experience sexual response in the same way. When hormone replacement therapy is administered to hypogonadal men, ____.
The conceptual nervous system, based on functional responses or behaviours, rather than structure or specific mediating mechanisms, was first presented by Hebb (1955).
OT has also been proposed as a key factor in affliative behaviour (Insel 1992).
Journal of Clinical Endocrinology and Metabolism 75 15031507. A third study also warrants attention. J Bancroft. Scandinavian Journal of Psychology 44B 241250. (1989) found no difference in testosterone levels between women presenting with low sexual interest and controls; Riley & Riley (2000) found a marginally lower free androgen index (FAI) in women complaining of life-long absence of sexual drive than in controls.
In. Serono International Symposium on Biology of Menopause. There is consistent evidence of the importance of oestradiol for normal vaginal lubrication.
Journal of Steroid Biochemistry and Molecular Biology 55 197209.
Brain processing of visual sexual stimuli in treated and untreated hypogonadal patients.
I have proposed the following theory, the desensitization hypothesis, to account for this (Bancroft 2002b, 2003). Journal of Urology 158 17641767. In this paper, sexual interest is conceptualized as an aspect of sexual arousal, when all four components may be involved to some extent, but where at least sexual information processing (e.g. Nathorst-Boos J, von Schoultz B & Carlstrom K 1993 Elective ovarian removal and estrogen replacement therapy effects on sexual life, psychological wellbeing and androgen status. This suggested an age-related decline in testosterone-dependent central arousability (i.e. Alder E, Cook A, Davidson D, West C & Bancroft J 1986 Hormones, mood and sexuality in lactating women. This may in part reflect methodological limitations of brain imaging; some relevant areas of the brain, especially the hypothalamus, are more difficult to image in this way.
-endorphin may facilitate appetitive behaviour by acting on the ventral tegmental area to activate the mesolimbic dopaminergic system.
Most controlled studies of testosterone replacement in hypogonadal men have used a period of withdrawal as a baseline, followed by the administration of testosterone and placebo, using a double-blind cross-over design (for review see Bancroft 2003). Bole-Feysot C, Goffin V, Edery M, Binart N & Kelly PA 1998 Prolactin (PRL) and its receptor: actions, signal transduction pathways and phenotypes observed in PRL receptor knockout mice. Eds CB Travis & JW White. Riley A & Riley E 2000 Controlled studies on women presenting with sexual drive disorder: I. Endocrine status.
b. Physiological reactions become more pronounced. Which of the following is the BEST example of vasocongestion? , Mitchell JB, Lal S, Olivier A, Quirion R & Meaney MJ. Eds.
Sherwin BB, Gelfand MM & Brender W 1985 Androgen enhances sexual motivation in females: a prospective, crossover study of sex steroid administration in the surgical menopause. Their findings were broadly similar to those of Michael et al.(1989).
Given this pattern, if testosterone is important for sexual arousability in women, we should expect to find related temporal patterns of arousability through the cycle. Other explanations for these adverse sexual effects need to be considered (e.g. (1987) reported some increase in PRL while watching erotic videos; Carani et al. In Central Regulation of Autonomic Functions, pp 367386. Testosterone manipulation in eugonadal men has produced results consistent with the earlier hypogonadal studies. Twenty-four-hour mean plasma testosterone concentration declines with age in normal premenopausal women.
The research of Masters and Johnson suggests that physiologically speaking, there is/are: Which of the following statements concerning the Grafenberg spot is TRUE? Journal of Urology 157 849854. , pp 959973. Bancroft J 2002a Sexual arousal.
A pituitary hormone secreted copiously following orgasm in both sexes is known as: Which of the following is NOT a physiosexual change that occurs in the excitement phase of the aging female? The evidence is more consistent for the male than for the female. Bancroft J, Loftus J & Long JS 2003 Distress about sex: a national survey of women in heterosexual relationships.
The greater variability in the sensitivity to androgens in women could result from a greater genetic variability in women, on the grounds that in women behavioural responsiveness to gonadal steroids is less crucial to reproduction than is the case with men. Metabolic and behavioral effects of high-dose, exogenous testosterone in healthy men. Which of the following would MOST likely enhance his sexual desire? Lancet 1 (8367)1618.
Carney A, Bancroft J & Mathews A 1978 Combination of hormonal and psychological treatment for female sexual unresponsiveness: a comparative study.