Salivary testosterone concentration and testicular volume in male infants

In order to investigate the changes in testicular volumes (TV) and salivary testosterone concentrations (ST) in normal male infants aged from birth to one year, TV in 158 and ST in 61 infants were measured cross-sectionally during this period. ST of normal male adolescents in Tanner's public hair stage from P2 to P5 (n = 20) were also measured as the control. To clarify the relationship between remarkable height increase and testosterone (T) during early male infancy, longitudinal follow-up of 10 male infants (4 from birth to 4 months, 6 from birth to 7 months) were also carried out by simultaneous measurement of ST and crown-heel length. Maximum TV (ml) was observed at 1-4 months (1.7 +/- 0.6) (mean +/- SD) and was significantly higher than the values at birth (0.5 +/- 0.1, P less than 0.01) and at 6-12 months of age (1.4 +/- 0.4, P less than 0.01). Maximum St (ng/dl) was also observed at 1-4 months, with the mean value being 3.4 +/- 1.5, which was significantly higher than 1.9 +/- 0.8 at 6-12 months (P less than 0.01). The ST at four month was not significantly different from that at Tanner's pubic hair stage P2. The longitudinal study showed that the rise in ST was concomitant with the maximum increase in crown-heel length at 1-4 months. The fluctuations in ST and height increase were also apparently synchronous during the first year.     

Salivary testosterone determination in studies of child health and development

Measurement of hormones in children's saliva has excited interest because of numerous potential applications in developmental studies. Although assays of children's saliva for some hormones (e.g., cortisol) are widely available and used, the availability and use of assays of children's saliva testosterone is restricted. By adapting a commercially available serum testosterone kit, our laboratory has developed a reliable, efficient, and highly sensitive procedure for measuring testosterone in children's saliva that does not require separation or extraction. The minimum detection limit was 0.8 pg/mL. Intraassay coefficients of variation (CV) were between 3.66 and 6. 78% at concentrations 9.25 to 86.41 pg/mL, and interassay CVs were between 5.70 and 6.61% at concentrations of 7.3 to 118.51 pg/mL. The standard curve was highly reproducible (M slope = -0.70 and Mr = 0. 99). Method accuracy, determined by spike recovery, and linearity, determined by serial dilution, were 99.20 and 92.80%, respectively. Values from matched serum and saliva samples showed strong linear relationships. The assay captured near 99.09% of the range of individual differences in boys' (N = 90) and girls' (N = 85), ages 8-12, am and pm salivary testosterone levels. This assay can be easily applied to the investigation of testosterone-behavior relations in the context of studies on child health and development. It may help many child development researchers improve or expand their research activities.     

Salivary testosterone concentrations in prepubertal and pubertal males: comparison with total and free plasma testosterone

Salivary testosterone (T) levels in male children and adolescents were measured and compared with plasma T. Salivary concentrations correlated well with plasma total T (r = 0.72) and even better with free plasma T (r = 0.89) in subjects with plasma T levels of pubertal or adult levels (greater than 1.0 nmol/l). In subjects with prepubertal or low plasma T (less than 1.0 nmol/l), there was neither a correlation with plasma total, nor with free T. In hCG tests (responder and nonresponder), salivary T reflected plasma levels faithfully. The results suggest that salivary T, which is suitable for repeated sampling, is a good marker of T secretion in pubertal males.     

Salivary levels of immunoglobulin and dental caries in children

IgG, IgA, IgM and lysozyme levels were determined in whole unstimulated saliva from ten children aged seven-nine years. IgA levels were significantly higher (p less than 0.05) in caries-susceptible subjects when compared with the caries-free ones. High levels of IgG seemed to correlate with a high DMF score. No correlation was found between lysozyme levels and DMF score.     

Amniotic fluid testosterone and testosterone glucuronide levels in the determination of foetal sex

Unconjugated testosterone levels were assayed in 351 amniotic fluid samples obtained at 15-19 weeks gestation. The median values for unconjugated testosterone in the 166 female foetuses and 185 male foetuses were 137 and 712 pmol/l respectively. Sixteen amniotic fluid samples from male foetuses had unconjugated testosterone levels lower than the highest female unconjugated testosterone value (361 pmol/l). Testosterone glucuronide was measured in amniotic fluid from 48 female and 55 male foetuses. There was a significant sex difference in the median values of testosterone glucuronide between female (median 160 pmol/l, range 64-465 pmol/l) and male (median 817 pmol/l, range 68-3707 pmol/l) amniotic fluid specimens (P less than 0.001). Of the sixteen male foetuses with amniotic fluid unconjugated testosterone levels in the female range, 12 had amniotic fluid testosterone glucuronide levels within the male testosterone glucuronide range of values. Hence used in conjunction with unconjugated testosterone, testosterone glucuronide increased the predictive accuracy of foetal sexing from 95.4 to 98.9%. Testosterone sulphate was measured in 24 female and 25 male amniotic fluid samples. There was no Testosterone sulphate was measured in 24 female and 25 male amniotic fluid samples. There was no significant difference between female (median 2591 pmol/l) and male (median 2964 pmol/l) testosterone sulphate levels.     

Salivary testosterone does not predict mental rotation performance in men or women

Multiple studies report relationships between circulating androgens and performance on sexually differentiated spatial cognitive tasks in human adults, yet other studies find no such relationships. Relatively small sample sizes are a likely source of some of these discrepancies. The present study thus tests for activational effects of testosterone (T) using a within-participants design by examining relationships between diurnal fluctuations in salivary T and performance on a male-biased spatial cognitive task (Mental Rotation Task) in the largest sample yet collected: 160 women and 177 men. T concentrations were unrelated to within-sex variation in mental rotation performance in both sexes. Further, between-session learning-related changes in performance were unrelated to T levels, and circadian changes in T were unrelated to changes in spatial performance in either sex. These results suggest that circulating T does not contribute substantially to sex differences in spatial ability in young men and women. By elimination, the contribution of androgens to sex differences in human performance on these tasks may be limited to earlier, organizational periods.     

Dermatoglyphic asymmetry and testosterone levels in normal males

Dermatoglyphic prints and salivary samples were taken on a sample of 39 adult males. A statistical relationship between dermatoglyphic asymmetry and adult testosterone levels as measured in saliva was examined for seven dermatoglyphic variables by means of correlation, regression, and analysis of covariance, controlling for age and stature when necessary. The first two types of analyses indicated a significant effect of testosterone level upon the asymmetry of three dermatoglyphic variables: a-b ridge count, palmar pattern intensity, and the combined pattern intensity of palm and digits. Analysis of covariance, which examined the effect of testosterone level as a categorical variable, while holding age or stature constant, demonstrated the asymmetry of five variables to be significantly affected by testosterone level: radial digital count, digital pattern intensity, palmar pattern intensity, total digital ridge count, and the combined palmar and digital intensity. Although there is as yet only associational evidence linking levels of prenatal and secondary testosterone, the results of the present study lend support to the hypothesis that prenatal testosterone levels may have a significant effect on the development of dermatoglyphics. © 1993 Wiley-Liss, Inc.     

Salivary testosterone and cortisol responses in professional rugby players after four resistance exercise protocols

The acute response of free salivary testosterone (T) and cortisol (C) concentrations to four resistance exercise (RE) protocols in 23 elite men rugby players was investigated. We hypothesized that hormonal responses would differ among individuals after four distinct RE protocols: four sets of 10 repetitions (reps) at 70% of 1 repetition maximum (1RM) with 2 minutes' rest between sets (4 x 10-70%); three sets of five reps at 85% 1RM with 3 minutes' rest (3 x 5-85%); five sets of 15 reps at 55% 1RM with 1 minute's rest (5 x 15-55%); and three sets of five reps at 40% 1RM with 3 minutes' rest (3 x 5-40%). Each athlete completed each of the four RE protocols in a random order on separate days. T and C concentrations were measured before exercise (PRE), immediately after exercise (POST), and 30 minutes post exercise (30 POST). Each protocol consisted of four exercises: bench press, leg press, seated row, and squats. Pooled T data did not change as a result of RE, whereas C declined significantly. Individual athletes differed in their T response to each of the protocols, a difference that was masked when examining the pooled group data. When individual data were retrospectively tabulated according to the protocol in which each athlete showed the highest T response, a significant protocol-dependent T increase for all individuals was revealed. Therefore, RE induced significant individual, protocol-dependent hormonal changes lasting up to 30 minutes after exercise. These individual responses may have important ramifications for modulating adaptation to RE and could explain the variability often observed in studies of hormonal response to RE.     

Plasma testosterone levels and ovarian testosterone content in adult mice treated with diethylstilbestrol neonatally

Neonatal female NMRI mice (n = 16) were treated with 5 micrograms diethylstilbestrol (DES) per day, for the first 5 days after birth and killed postpubertally. Control females (n = 52) were injected with vehicle only and killed in different stages of the estrous cycle. The plasma testosterone level was significantly lower in DES females than in control females in any of the estrous phases. Ovariectomy (n = 5), adrenalectomy (n = 5) or a combination of both ablations (n = 3) did not affect the plasma testosterone in DES treated females while it was significantly reduced in control females (ovariectomy n = 5; adrenalectomy n = 9); most effective was the combination ovariectomy-adrenalectomy (n = 7). Ovarian homogenates from DES treated females (n = 10) had a significantly lower testosterone content than homogenates from control females in any phase of the estrous cycle (6-10 females per phase), which held true on both a per ovary basis and when related to ovarian weight. After a 2 h incubation in vitro, the testosterone levels had increased significantly in DES homogenates (n = 6) and to a lower extent in homogenates from control females in estrus (n = 9). No similar effect was found in homogenates from diestrus (n = 10) or proestrus (n = 9) females. The results are discussed in relation to the special ovarian morphology of adult but neonatally DES treated females and also with respect to endocrine control mechanisms.     

Acute suppression of endogenous testosterone levels by exogenous testosterone in normal men

The effect of exogenous testosterone on endogenous plasma testosterone was studied in normal men. Intramuscularly administered testosterone-19,19,19-d3 rapidly appeared in the systemic circulation in large amounts. Endogenous plasma testosterone was suppressed to near-castrate levels. The suppressed level began to rise between 6 and 10 h, and reached a preinjection level at 24 h after the injection. Plasma LH decreased with a concomitant decrease in endogenous testosterone and began to rise as soon as plasma total testosterone returned to physiological levels.     

Serum testosterone levels in young normal horses

Serum testosterone levels were measured in normal young male horses (29 to 34 weeks old). No differences were found between gelded and intact males. The values for all the horses were low. On the basis of their testosterone levels, all the horses were prepubertal.     

Eumelanin levels in rufous feathers explain plasma testosterone levels and survival in swallows

Pigment‐based plumage coloration and its physiological properties have attracted many researchers to explain the evolution of such ornamental traits. These studies, however, assume the functional importance of the predominant pigment while ignoring that of other minor pigments, and few studies have focused on the composition of these pigments. Using the pheomelanin‐based plumage in two swallow species, we studied the allocation of two pigments (the predominant pigment, pheomelanin, and the minor pigment, eumelanin) in relation to physiological properties and viability in populations under a natural and sexual selection. This is indispensable for studying the evolution of pheomelanin‐based plumage coloration. Pheomelanin and eumelanin share the same pathway only during their initial stages of development, which can be a key to unravel the functional importance of pigment allocation and thus of plumage coloration. Using the barn swallow, Hirundo rustica, a migratory species, we found that plasma testosterone levels increased with increasing the proportion of eumelanin pigments compared with pheomelanin pigments, but not with the amount of pheomelanin pigments, during the mating period. In the Pacific swallow Hirundo tahitica, a nonmigratory congener, we found that, during severe winter weathers, survivors had a proportionally smaller amount of eumelanin pigments compared with pheomelanin pigments than that in nonsurvivors, but no detectable difference was found in the pheomelanin pigmentation itself. These results indicated that a minor pigment, eumelanin, matters at least in some physiological measures and viability. Because the major pigment, pheomelanin, has its own physiological properties, a combination of major and minor pigments provides multiple information to the signal receivers, potentially enhancing the signaling function of pheomelanic coloration and its diversification across habitats.     

Relative digit lengths and testosterone levels in Guinea baboons

A growing body of literature suggests that the ratio of the lengths of the second to fourth digits (2D:4D) on human hands is sexually dimorphic and associated with prenatal exposure to gonadal hormones, circulating serum testosterone, and a number of psychological and behavioral measures. Little research has investigated digit ratios in nonhuman species. In the present study, we investigated sex differences in digit ratios and their possible association with serum testosterone in a captive group of Guinea baboons (Papio papio). Contrary to the sex difference typically reported in humans, male baboons exhibited a substantially larger 2D:4D than did female baboons. Consistent with the human data, however, lower 2D:4D was associated with higher serum testosterone among the males. The present findings suggest that the relationship between digit ratios and male gonadal hormones may be phylogenetically well-conserved, although they also suggest possible species differences in the causal relationships between developmental mechanisms and sex-differentiated digit length patterns.     

Salivary testosterone measurements among women: relative magnitude of circadian and menstrual cycles.

Measures of testosterone among women are potentially useful in behavioral research, but information is needed on how much error is introduced by variability across the menstrual cycle. Morning and evening salivary testosterone concentrations were measured at weekly intervals across one menstrual cycle in each of 22 women, using the luteinizing hormone surge to mark midcycle. Menstrual cycles were statistically significant but smaller than daily cycles or individual differences. Menstrual cycle effects can be ignored in most research relating psychological and behavioral variables to individual differences in testosterone.