Testosterone metabolism by human axillary bacteria

Abstract

The involvement of the skin microflora in the formation of human underarm odour (UAO) is unequivocal. It has been clearly demonstrated that there is an association between the axillary skin population of aerobic coryneform bacteria and UAO intensity [ 11. Additionally, the sweat secreted by axillary apocrine glands only develops the characteristic UAO after degradation by skin coryneform bacteria or some staphylococci [ 21. Recently, it has been shown that human axillary secretions contain highly odorous 16-androstene steroids such as 5 a-androst-16-en-3-one (androstenone) and 5a-androst-16-en-3a-ol (3a-androstenol), which possess odours reminiscent of UAO. Although androstenone is probably a product of microbial action in the axilla [3], its origin remains uncertain. What is certain is that many axillary aerobic coryneform bacteria possess the ability to metabolize testosterone [4,5].In this communication, we have used a UAO model system in vitro to screen axillary bacterial isolates for production of UAO, and have related this to their ability to transform testosterone.Preliminary experiments showed that some skin bacteria, principally aerobic coryneforms, produced typical UAO when incubated with extracts of the axillary vault skin. Axillary extracts were collected by scrubbing the axillary vault with 5 ml of diethyl ether contained in a 2 cm diameter Teflon cylinder. The extracts were filtered through a 0.22 p m porosity cellulose acetate filter, and then 1 ml aliquots were pipetted into 15 ml glass bottles, and dried with a stream of filtered nitrogen. Axillary bacteria were collected from 34 male subjects, using the cup-scrub technique of Williamson & Kligman [6], and plated on to media to select aerobic coryneforms, Micrococcaceae and propionibacteria. Representative strains were grown for 48 h in appropriate liquid media, and then centrifuged and resuspended in 0.1 Mphosphate buffer, pH 6.0, to yield an absorbance of 1.0 at a wavelength of 500 nm. One millilitre of suspension was added to each bottle of axillary extract, and incubated for 6 h at 37"C, after which any odour was determined organoleptically by two expert odour assessors.STo whom correspondence should be addressed. Abbreviations used: UAO. underarm odour; DHT, dihydrotestosterone; PFBO, pentatluorobenzyl oxime; TBDMS, t-butyldimethylsilyl.In the metabolic studies, representative strains of UAOproducing (UAO + ve) and UAO-non-producing (UAOve) axillary bacteria (0.1 ml overnight culture) were incubated for 2 weeks in 4 ml of tryptone soya broth containing 0.1% (w/v) Tween 80 and 0.1% (w/v) yeast extract, to which had been added [4-"C]testosterone ( 1 pCi) and unlabelled testosterone (0.5 mg) in 0.1 ml of ethanol. Extraction was performed with ethyl acetate (3 x 3 ml) and the pooled extracts were purified by passing them through a Florisil Sep-Pak cartridge (Waters Associates). After rotary evaporation to dryness, the residues were dissolved in dichloromethane (0.1 ml) and one-half was subjected to t.1.c. in benzene-acetone (4: 1, v/v), with sta...

Cross-Sex Hormonal Treatment and Body Uneasiness in Individuals with Gender Dysphoria

“…These findings could be the results of hormone-induced body mass redistribution [41]. Also, we found more satisfaction with body scent in the CHT group, a finding in line with the literature showing that androgen-related changes in physiological mechanisms result in a less masculine scent, which MtF individuals appear to appreciate [45][46][47].…”

Digit ratio (2D:4D) predicts facial, but not voice or body odour, attractiveness in men

“…Indeed, voice quality significantly changes with therapeutic administration of testosterone (e.g. [55]) or more subtly with normal daily variations of testosterone concentration [14], and some major compounds of axillary odours are by-products of androgen substances [29].…”

“…As for faces [15], voice frequency and thus attractiveness are related to the level of salivary testosterone [14]. Similarly, androgen level is likely to influence body odour since steroid compounds of axillary odour such as androstadienone are present more in males [28] and are products of testosterone transformation by underarm bacteria [29,30].…”

Androstadienone’s influence on the perception of facial and vocal attractiveness is not sex specific

“…In the first hypothesis (sex-specific effects), androstadienone would act as a signal of mate quality (see Thornhill and Gangestad, 1999; for a link between body odor and mate quality). Being a by-product of testosterone (Rennie et al, 1989), androstadienone could constitute a testosterone-dependent sexual trait: these traits, such as deep voices or masculine facial features, signal biological quality to a prospective mate (Folstad and Karter, 1992) and increase attractiveness (Collins, 2000;Perrett et al, 1998). Consequently, men should be more attractive to women in the presence of androstadienone, and this effect should be enhanced during the fertile phase of the perceiver's menstrual cycle (in accordance with the increased preference for masculine faces, voices and bodies around ovulation: Gangestad and Thornhill, 2008).…”