Plasma Total Testosterone Concentrations Research Articles

Initial Characterization of Male Southern Stingray (Hypanus americanus) Reproductive Parameters and Preliminary Investigation of Sperm Cryopreservation.

Simple SummaryUnderstanding the reproductive biology of a species is critical for the development of biobanks and assisted reproductive techniques to aid in the genetic management of isolated populations. Male southern stingray (Hypanus americanus) reproductive examinations were opportunistically conducted in March and June. Semen and plasma were collected to characterize ejaculate parameters and to investigate the effect of plasma total testosterone on semen quality. Semen was used for preliminary sperm cryopreservation studies. Changes in semen quality were observed with changes in plasma testosterone concentrations and body conditions. Southern stingray spermatozoa were highly sensitive to cooling rates with slower rates, producing a higher post-thaw survival.This study investigated the reproductive biology and sperm cryopreservation of ex situ southern stingrays (Hypanus americanus) by semen collection and characterization and the development and validation of an enzyme-linked immunoassay for plasma total testosterone. Semen was collected in March and June using a manual massage technique, and the ejaculates were assessed for volume, pH, osmolarity, motility, status (0–5 scale: 0 = no forward progression, 5 = rapid linear progression) and total sperm count. Semen was extended in Hank’s elasmobranch ringer solution containing 10% DMSO, 10% glycerol or 5% glycerol with 5% N-methylformamide and cryopreserved using a conventional freezing method (~−50 °C/min) or a modified slow freezing method (~−3 °C/min). Body condition was scored from 1–5 and was noted to be low in March (1.93 ± 0.07) due to feeding practices and increased by June (2.93 ± 0.05) after dietary corrections were made. A concomitant increase (p < 0.05) in plasma total testosterone concentration and sperm motility was noted between March (8.0 ± 7.2 ng/mL, 5.71 ± 2.77%) and June (97.3 ± 11.3 ng/mL, 51.4 ± 14.3%). Samples cryopreserved using a modified slow freeze method (~−3 °C/min) had higher post-thaw motility and plasma membrane integrity than conventionally cryopreserved samples. Data indicate that southern stingray sperm morphometrics adheres to those of other elasmobranch species and that a slow cooling rate may be an avenue of research to improve southern stingray sperm survival during cryopreservation.

Plasma total testosterone and risk of incident atrial fibrillation: The Atherosclerosis Risk in Communities (ARIC) study

ObjectiveWhether endogenous testosterone concentrations are associated with atrial fibrillation (AF) development is not well established. We assessed the association between plasma total testosterone concentrations and incident AF in a population-based longitudinal study. Study designUsing data from the prospective Atherosclerosis Risk in Communities (ARIC) study, we identified incident AF among 9282 participants who had plasma total testosterone measured by liquid chromatography tandem mass spectrometry at Visit 4 (1996–1998). Main outcome measuresAF cases were identified by electrocardiograms performed during study visits, hospital records/discharge codes, and death certificates through 2013. We estimated hazard ratios (HRs) and 95% confidence intervals (95% CIs) for incident AF across quartiles of plasma total testosterone, stratified by sex, with multivariable Cox models. ResultsThe mean age of the participant sample at ARIC Visit 4 was 63 years (range 52–75); 54.5% were women. Mean (SD) plasma total testosterone levels were 537 ng/dL (213) for men and 27.6 ng/dL (34.7) for women. Over a mean of 13.7 years of follow-up, 1664 incident cases of AF were identified. Comparing those in the highest quartile of plasma total testosterone concentration to those in the lowest quartile and after adjustment for potential confounding variables, there was a positive association between plasma total testosterone and incident AF in men (HR 1.33, 95% CI 1.07, 1.66), but no such association in women (HR 0.99, 95% CI 0.80, 1.22).Conclusion A higher plasma total testosterone concentration was associated with a modestly greater incidence rate of AF in men.

Pharmacokinetic Study of Compound K in Japanese Subjects After Ingestion of Panax ginseng Fermented by Lactobacillus paracasei A221 Reveals Significant Increase of Absorption into Blood.

Compound K (CK) is a metabolite of a saponin in Panax ginseng, formed from ginsenoside, a triterpenoid glycoside, by human intestinal bacteria. Lactobacillus paracasei A221 isolated from fermented food can hydrolyze (deglycosylate) the main ginsenoside, ginsenoside Rb1, and generate CK. However, the pharmacokinetics of L. paracasei A221 fermented ginseng (FG) and nonfermented ginseng (NFG) have not been investigated so far. The aim of this study was to investigate the pharmacokinetics of CK after oral administration of single doses of FG and NFG in healthy Japanese adults. An open-label, randomized, single-dose, two-period, crossover study was conducted in 12 Japanese healthy volunteers (five men and seven women, aged 40-60 years). All subjects were equally allocated into two groups and administered tablets containing FG or NFG. Until 24 h after the administration, blood samples were sequentially collected, plasma concentrations of CK were measured, and the pharmacokinetic parameters were calculated. We also expected restoration of decreased testosterone level as one of the beneficial effects of FG and measured plasma total testosterone concentrations in male volunteers. The means of Tmax, Cmax, and area under the concentration-time curve (AUC) were significantly different between the two groups. In the FG group, AUC0-12h (ng h/mL) and AUC0-24h (ng h/mL) were, respectively, 58.3- and 17.5-fold higher than those in the NFG group. Moreover, mean testosterone concentration in the FG group significantly increased 24 h after administration. These results showed that the main ginsenoside metabolite of ginseng, CK, produced by L. paracasei A221 has potential utility in health maintenance in healthy middle-aged and old Japanese adults.

Hypothalamic Gliosis by MRI and Visceral Fat Mass Negatively Correlate with Plasma Testosterone Concentrations in Healthy Men.

Objective:To determine whether a relationship was evident between gliosis in the mediobasal hypothalamus (MBH) and plasma testosterone concentrations in menMethods:41 adult men (ages 18–50 years) from 23 twin pairs underwent fasting morning blood draw and brain MRI. T2 relaxation time was used to quantify gliosis in the MBH and control areas in the putamen and amygdala. Plasma concentrations of testosterone and 17β-estradiol were measured by LC-MS/MS. Body composition including visceral adiposity was measured by dual X-ray absorptiometry.Results:A negative association was found between MBH T2 relaxation time and plasma concentrations of both free and total testosterone (r = −0.29, P<0.05 and r = −0.37, P<0.01, respectively). Visceral adiposity exhibited a negative correlation with plasma total testosterone concentration (r = −0.45, P=0.001) but a positive correlation with MBH T2 relaxation time (r = 0.24, P=0.03). The negative correlation between plasma total testosterone and MBH T2 relaxation time remained significant after adjustment for visceral adiposity, age, BMI, and insulin resistance.Conclusions:In healthy men across a range of BMIs, MBH gliosis was associated with higher visceral adiposity but lower endogenous testosterone. These findings suggest that MBH gliosis could provide novel mechanistic insights into gonadal dysfunction in men with obesity.

Androgen Responses to Sprint Exercise in Young Men

The purpose of this study was to investigate the effects of a 6-month sprint training program on plasma androgens and catecholamine (CA) concentrations in response to a 6 s sprint in adolescent boys [training group (TG), n=6; control group (CG), n=6]. A 6 s-sprint test was performed on a cycle ergometer before and after training (Pre-T and Post-T, respectively). Plasma total testosterone (TT), bioavailable testosterone (BT), and CA concentrations were measured at rest, after a warm-up, immediately after a 6 s-sprint, and during the recovery (i. e. 5 and 20 min). After training period, plasma TT concentrations increased significantly at the end of the sprint and during the recovery in the TG. No effects for sampling times and period were observed in BT levels. Plasma TT concentrations after 5 min of recovery were positively correlated with the corresponding values of plasma lactate (La) concentrations and with post-6 s-sprint plasma adrenaline (A) concentrations (r=0.52; p<0.01 and r=0.61; p<0.01, respectively). These results suggest that sprint training increases plasma TT concentrations in response to sprint exercise in adolescent boys. Plasma A and plasma La concentrations increases in response to sprint exercise could be involved in this elevation of plasma TT concentrations.

Relationship of Prostate -Specific Antigen to Age and Testosterone in Men With Type 2 Diabetes Mellitus

To determine whether prostate-specific antigen (PSA) concentrations in type 2 diabetic men with hypogonadotrophic hypogonadism are lower than those in eugonadal men with type 2 diabetes and whether PSA concentrations are related to plasma testosterone concentrations. In this cross-sectional study, we measured serum total testosterone, sex hormone-binding globulin, free testosterone, PSA, hematocrit, and hemoglobin A1c in consecutive type 2 diabetic men who presented to 2 endocrinology referral centers between January 2006 and January 2007. We collected other clinical and demographic data including age, height, weight, and ethnicity. Of 400 eligible patients, 280 men met inclusion criteria. Plasma PSA concentrations were lower in type 2 diabetic men with low free testosterone concentrations than in those with normal free testosterone concentrations (0.89 +/- 0.07 ng/mL vs 1.10 +/- 0.08 ng/mL, [corrected] P = .011). PSA concentrations were positively related to age (r = 0.34, P<.001), total testosterone (r = 0.29, P<.001), free testosterone (r = 0.17, P = .02), and sex hormone-binding globulin (r = 0.22, P<.001) and negatively related to body mass index (r = -0.28, P<.001). In stepwise backward regression analysis, PSA concentration was predicted by age (P<.001) and free testosterone (P<.001), but not by body mass index or sex hormone-binding globulin. Plasma PSA concentrations are lower in type 2 diabetic men with hypogonadism than in eugonadal men with type 2 diabetes, and plasma PSA is related to age, plasma total testosterone concentrations, and free testosterone concentrations in patients with type 2 diabetes.

Sex Steroid Hormones and the Androgen Receptor Gene CAG Repeat and Subsequent Risk of Prostate Cancer in the Prostate-Specific Antigen Era

Objective: Sex steroid hormones are thought to contribute to the growth, differentiation, and progression of prostate cancer. We investigated plasma levels of sex steroid hormones and length of the androgen receptor gene CAG repeat in relation to incident prostate cancer diagnosed in the prostate-specific antigen (PSA) era. Methods: Using a nested case-control design, we included 460 prostate cancer cases diagnosed after providing a blood specimen in 1993 but before February 1998 among men in the Health Professionals Follow-up Study. Controls were 460 age-matched men without prostate cancer who had a screening PSA test after the date of providing a blood specimen. We measured plasma concentrations of total testosterone, free testosterone, dihydrotestosterone, androstanediol glucuronide, estradiol, and sex hormone binding globulin (SHBG) and determined the length of the androgen receptor gene CAG repeat. Conditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) of prostate cancer. Results: Mean concentrations of the sex steroids adjusted for SHBG, and mean CAG repeat length did not differ significantly between the prostate cancer cases and controls. No significant associations with total prostate cancer were detected for plasma total testosterone concentration (comparing highest versus lowest quartiles: OR, 0.78; 95% CI, 0.48-1.28; P trend = 0.73) or the other sex hormones after adjusting for SHBG. However, plasma total testosterone concentration was positively associated with low-grade disease (Gleason sum < 7: OR, 1.91; 95% CI, 0.89-4.07; P trend = 0.02) and inversely associated with high-grade disease (Gleason sum ≥ 7: OR, 0.26; 95% CI, 0.10-0.66; P trend = 0.01). Similar patterns for grade were observed for free testosterone. Short CAG repeat length was not associated with total prostate cancer (≤ 19 versus ≥ 24: OR, 0.84; 95% CI, 0.57-1.23; P trend = 0.22) or grade of disease. No clear associations with regionally invasive or metastatic (≥ T3b, N1, or M1) were found for any of the hormones or the CAG repeat, although the number of these cases was small. Conclusions: The overall lack of association of prostate cancer diagnosed in the PSA era with sex steroid hormones and the androgen receptor gene CAG repeat length is consistent with the hypothesis that these factors do not substantially contribute to the development of early prostate cancer in the PSA era. The influence of plasma total and free testosterone concentrations on prostate cancer grade merits further evaluation.

Sex Steroid Hormones and the Androgen Receptor Gene CAG Repeat and Subsequent Risk of Prostate Cancer in the Prostate-Specific Antigen Era

Sex steroid hormones are thought to contribute to the growth, differentiation, and progression of prostate cancer. We investigated plasma levels of sex steroid hormones and length of the androgen receptor gene CAG repeat in relation to incident prostate cancer diagnosed in the prostate-specific antigen (PSA) era. Using a nested case-control design, we included 460 prostate cancer cases diagnosed after providing a blood specimen in 1993 but before February 1998 among men in the Health Professionals Follow-up Study. Controls were 460 age-matched men without prostate cancer who had a screening PSA test after the date of providing a blood specimen. We measured plasma concentrations of total testosterone, free testosterone, dihydrotestosterone, androstanediol glucuronide, estradiol, and sex hormone binding globulin (SHBG) and determined the length of the androgen receptor gene CAG repeat. Conditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) of prostate cancer. Mean concentrations of the sex steroids adjusted for SHBG, and mean CAG repeat length did not differ significantly between the prostate cancer cases and controls. No significant associations with total prostate cancer were detected for plasma total testosterone concentration (comparing highest versus lowest quartiles: OR, 0.78; 95% CI, 0.48-1.28; P(trend) = 0.73) or the other sex hormones after adjusting for SHBG. However, plasma total testosterone concentration was positively associated with low-grade disease (Gleason sum < 7: OR, 1.91; 95% CI, 0.89-4.07; P(trend) = 0.02) and inversely associated with high-grade disease (Gleason sum > or = 7: OR, 0.26; 95% CI, 0.10-0.66; P(trend) = 0.01). Similar patterns for grade were observed for free testosterone. Short CAG repeat length was not associated with total prostate cancer (< or = 19 versus > or = 24: OR, 0.84; 95% CI, 0.57-1.23; P(trend) = 0.22) or grade of disease. No clear associations with regionally invasive or metastatic (> or = T3b, N1, or M1) were found for any of the hormones or the CAG repeat, although the number of these cases was small. The overall lack of association of prostate cancer diagnosed in the PSA era with sex steroid hormones and the androgen receptor gene CAG repeat length is consistent with the hypothesis that these factors do not substantially contribute to the development of early prostate cancer in the PSA era. The influence of plasma total and free testosterone concentrations on prostate cancer grade merits further evaluation.

Endogenous plasma testosterone levels and commission errors in women: A preliminary report

A correlation between elevated testosterone and aggressive behavior has been demonstrated in animals and to a lesser degree in humans, primarily in the context of dominance. Some aggression, namely non-premeditated aggression, is characterized by impaired impulse control. Real-world aggressive histories and self-reported impulsivity have correlated with commission errors (failures to withhold responses to nontarget stimuli) in versions of the continuous performance test (CPT). To begin exploring whether testosterone may play a role in aggression due more to a direct relationship with impaired impulse control, we related plasma total testosterone concentrations of 27 psychiatrically healthy women to commission errors in two variants of the CPT — with and without interstimulus distracters. Controlling for age and IQ, testosterone did not relate to rates of correct detections in either task, but correlated positively with commission errors in the distracter CPT variant. In light of the fact previous studies find commission errors on the CPT are associated with impulsivity, the results of this study support a positive relationship between testosterone and impulsivity.

Low testosterone levels in diabetic men and animals: a possible role in testicular impotence

Poorly controlled NOD spontaneously diabetic mice were proven to have significantly less plasma and testicular testosterone than well-controlled diabetic mice (489 ± 15 ng/dl and 3.89 ± 0.79 μg/100 g tissue, vs. 176 ± 24 and 9.00 ± 1.24, respectively), and these in turn had significantly less than NOD non-diabetic control mice. These data were consistent with our previous observation of a decrease in total plasma and testicular testosterone levels in streptozotocin diabetic rats. A greater difference between total plasma testosterone levels and free testosterone levels was found in streptozotocin diabetic rats (17 ± 4 ng/dl vs. 91 ± 7 ng/dl) than in control rats (660 ± 141 vs. 352 ± 77). Fat droplets, depicting blocked testosterone synthesis, were found in the testicular Leydig cells of streptozotocin diabetic rats and disappeared with insulin treatment. No difference was found among plasma total testosterone concentrations in people in different stages of diabetes, as had been previously reported. However, human diabetic males, free of complications but poorly controlled, had less free testosterone than those without complications but well controlled (18.0 ± 2.0 pg/ml vs. 22.8 ± 1.3), who in turn had significantly less than age-matched controls (25.3 ± 1.1 pg/ml). These data suggest gonadal dysfunction in diabetes mellitus.

Relationship of high density lipoprotein cholesterol with total and free testosterone and sex hormone binding globulin

A cross-sectional study was performed to see if the previously described association between high density lipoprotein (HDL) cholesterol and plasma total testosterone concentration reflected a relationship with free testosterone or with sex hormone binding globulin (SHBG). In 295 employed middle-aged men, measurements were made of total testosterone and SHBG in serum and of testosterone in saliva, and also of plasma total and HDL cholesterol, plasma triglycerides and other factors which might influence HDL cholesterol levels such as body mass index, alcohol and smoking habits and thyroid hormone levels. In a multiple regression analysis using the GLIM package programme total testosterone concentrations had a persistent positive association with HDL cholesterol (t = 3.5, P less than 0.001) - this association was independent of SHBG (which had a negative association with HDL: t = -1.8, P less than 0.07. The association of HDL cholesterol with testosterone was independent of and stronger than the association of HDL cholesterol with body mass index, alcohol intake and cigarette smoking. Salivary testosterone (a measure of the circulating free hormone) also had a positive independent association with HDL cholesterol. The relationship between HDL cholesterol and testosterone thus appears to reflect an association with circulating hormone levels rather than with the hormone binding globulin.

Age Variation of the 24-Hour Mean Plasma Concentrations of Androgens, Estrogens, and Gonadotropins in Normal Adult Men*

The 24-h mean plasma concentrations of androgens (dihydrotestosterone and total and free testosterone), estrogens (estrone and estradiol), and gonadotropins (LH and FSH) were measured in 35 healthy men, aged 21-85 yr, who were rigorously screened to exclude factors known or suspected to alter endocrine function. The plasma total testosterone concentration showed a slow continuous decline with age, decreasing about 35% between 21 and 85 yr of age; the free testosterone level was closely correlated with that of total testosterone over the entire observed concentration range. The concentrations of dihydrotestosterone, estrone, estradiol, and LH were age invariant. The concentration of FSH showed a continuous linear increase with age; the level at age 85 was about 2.5 times the level at age 21. The following conclusions were drawn. 1) Testosterone secretion appears to decline slowly and continuously throughout adult life in men. 2) Measurement of the plasma free testosterone level adds no independent information in healthy men, since its level is closely correlated with that of total testosterone at all concentrations. 3) The continuous rise with age in FSH concentration while LH is age invariant cannot be explained by changes in testosterone or estrogen production, but might be due to a decline of inhibin production with age.

Hypophyso-gonadal function in humans during the first year of life. 1. Evidence for testicular activity in early infancy.

Total and unbound testosterone and Delta(4)-androstenedione have been determined in 104 cord blood samples. The same sexual steroids and pituitary gonadotropins have been measured in 46 normal male infants aged 27-348 days and 34 normal female infants aged 19-332 days. In cord blood of female neonates mean total and unbound testosterone was 29.6+/-7.5 and 0.89+/-0.4 ng/100 ml, respectively (mean+/-1 SD); Delta(4)-androstenedione was 93+/-38 ng/100 ml. In male neonates mean plasma total and unbound testosterone was 38.9+/-10.8 and 1.12+/-0.4 ng/100 ml; Delta(4)-androstenedione was 85+/-27 ng/100 ml. In female infants testosterone concentrations remained constant during the 1st yr of life with a mean concentration of 7+/-3 ng/100 ml. Mean unbound testosterone and Delta(4)-androstenedione concentrations were 0.05+/-0.03 and 16.7+/-8.3 ng/100 ml, respectively. Mean plasma levels of follicle-stimulating hormone and luteinizing hormone were 8.7+/-3.3 and 12.9+/-7.7 mU/ml. In male infants mean plasma total testosterone concentration increased to 208+/-68 ng/100 ml from birth to 1-3 mo of age, decreasing thereafter to 95+/-53 ng/100 ml at 3-5 mo, 23.2+/-18 ng/100 ml at 5-7 mo, and reached prepubertal levels (6.6+/-4.6 ng/100 ml) at 7-12 mo. Mean unbound testosterone concentration plateaued from birth to 1-3 mo of age (1.3+/-0.2 ng/100 ml) decreasing to prepubertal values very rapidly. Mean Delta(4)-androstenedione concentration, although progressively decreasing during the 1st yr of life to 11.7+/-4.5 ng/100 ml, was higher than in the female at 1-3 mo of life (34+/-11 ng/100 ml). Mean plasma level of follicle-stimulating hormone was 6.7+/-2.9 mU/ml, and that of luteinizing hormone was 19.7+/-13.5 mU/ml, significantly higher than in the female. There was no correlation between gonadotropin and age or testosterone. The present data demonstrate that the testes are active during the first natal period. It is tempting to correlate this phenomenon to a progressive maturation of the hypothalamo-pituitary-gonadal axis. It is possible that the surge in testosterone occurring the first 3 mo could play a role in the future life pattern of the male human being.