Minimizing the effects of multicollinearity in the polynomial regression of age relationships and sex differences in serum levels of pregnenolone sulfate in healthy subjects.

BACKGROUND: Pregnenolone sulfate (PregS) is known as a steroid conjugate positively modulating N-methyl-D-aspartate receptors on neuronal membranes. These receptors are responsible for permeability of calcium channels and activation of neuronal function. Neuroactivating effect of PregS is also exerted via non-competitive negative modulation of GABA(A) receptors regulating the chloride influx. Recently, a penetrability of blood-brain barrier for PregS was found in rat, but some experiments in agreement with this finding were reported even earlier. It is known that circulating levels of PregS in human are relatively high depending primarily on age and adrenal activity. METHODS: Concerning the neuromodulating effect of PregS, we recently evaluated age relationships of PregS in both sexes using polynomial regression models known to bring about the problems of multicollinearity, i.e., strong correlations among independent variables. Several criteria for the selection of suitable bias are demonstrated. Biased estimators based on the generalized principal component regression (GPCR) method avoiding multicollinearity problems are described. RESULTS: Significant differences were found between men and women in the course of the age dependence of PregS. In women, a significant maximum was found around the 30th year followed by a rapid decline, while the maximum in men was achieved almost 10 years earlier and changes were minor up to the 60th year. The investigation of gender differences and age dependencies in PregS could be of interest given its well-known neurostimulating effect, relatively high serum concentration, and the probable partial permeability of the blood-brain barrier for the steroid conjugate. CONCLUSIONS: GPCR in combination with the MEP (mean quadric error of prediction) criterion is extremely useful and appealing for constructing biased models. It can also be used for achieving such estimates with regard to keeping the model course corresponding to the data trend, especially in polynomial type regression models.

Circulating levels of pregnanolone isomers during the third trimester of human pregnancy.

This study addresses the question of whether changes in the biosynthesis and metabolism of neuroactive pregnanolone isomers (PIs) might participate in the timing of parturition in humans. The time profiles of unconjugated allopregnanolone (3alpha-hydroxy-5alpha-pregnan-20-one, P3alpha5alpha), pregnanolone (3alpha-hydroxy-5beta-pregnan-20-one, P3alpha5beta), isopregnanolone (3beta-hydroxy-5alpha-pregnan-20-one, P3beta5alpha) and epipregnanolone (3beta-hydroxy-5beta-pregnan-20-one, P3beta5beta), pregnenolone, their polar conjugates, progesterone, 5alpha-dihydroprogesterone (P5alpha), and 5beta-dihydroprogesterone (P5beta) were monitored in the plasma of 30 healthy women during the third trimester of pregnancy, at 1-week intervals from the 30th week of gestation using GC-MS. Changes in the steroid levels were evaluated by two-way ANOVA with gestational age and subject as independent factors. The mean concentrations of free PIs ranged from 2 to 50 nmol/L, while the mean levels of their polar conjugates were 40-100 x higher. The ratio of 5alpha-PIs to progesterone significantly but inconspicuously culminated in the 35th week. The decelerating biosynthesis of free 5beta-PIs from the 31st week and their escalating sulfation was found from the 30th week. The changes were particularly evident in the second most abundant PI pregnanolone that may, like the allopregnanolone, sustain the pregnancy via attenuation of hypothalamic GABA(A)-receptors and prevent uterine contractility via binding to nuclear pregnane X receptor.

Serum profiles of free and conjugated neuroactive pregnanolone isomers in nonpregnant women of fertile age.

BACKGROUND: Pregnanolone isomers (PI) with a hydroxy group in the 3alpha-position are neuroinhibitors operating via positive modulation of GABA(A) receptors. The 3beta-PI and sulfates of PI and pregnenolone exert the opposite effect. In addition to the brain's in situ synthesis, some circulating steroids can penetrate the blood-brain barrier. METHODS: To assess the physiological impact of peripheral endogenous neuroactive pregnanolone isomers and their polar conjugates in women, serum allopregnanolone (P3alpha5alpha), isopregnanolone (P3beta5alpha), pregnanolone (P3alpha5beta), epipregnanolone (P3beta5beta), pregnenolone, estradiol (including their polar conjugates), and additional steroids were measured in 16 women in the follicular and luteal phases of the menstrual cycle using gas chromatography/mass spectrometry and RIA for the analysis. Linear models and Spearman's correlations were used for data evaluation. RESULTS AND DISCUSSION: The levels of conjugated PI were from one to almost three orders of magnitude higher in comparison with the free steroids. The results indicate that a substantial proportion of the progesterone is metabolized in the sequence progesterone-->5beta-dihydroprogesterone-->P3alpha5beta-->conjugated P3alpha5beta. The sulfation of PI and particularly of P3alpha5beta moderates the levels of free PI and restrains estradiol biosynthesis via progesterone degradation. PI including the conjugates reflected changing progesterone formation during the menstrual cycle. In the follicular phase, the positive correlation with conjugated pregnenolone, the independence of progesterone, and the negative age relationships of PI indicate their adrenal origin. The dependence on progesterone and the independence of conjugated pregnenolone suggest a gonadal source of PI in the luteal phase. The neuroactivating PI prevailed over neuroinhibiting PI.

Syntheses of 19-[O-(carboxymethyl)oxime] haptens of epipregnanolone and pregnanolone.

O-(Carboxymethyl)oximes 1 and 2 derived from two epimeric 5beta-pregnanolones (3beta-hydroxy-5beta-pregnan-20-one and 3alpha-hydroxy-5beta-pregnan-20-one) in position 19 were prepared. Two synthetic routes were employed, both using protection of the 20-keto group after reduction into the (20R)-alcohol in the form of acetate. In the first route, (20R)-19-hydroxy-5beta-pregnan-3beta,20-diyl diacetate (3) was transformed into the corresponding 19-[O-(carboxymethyl)oxime] methyl ester 6, then deacetylated by acid and partially silylated with tert-butyldimethylsilyl chloride. The desired 3-O-silylated derivative 8 was separated, oxidized to the 20-ketone and protecting groups were sequentially removed to give the first title hapten 1. The second route started from (20R)-19-hydroxy-3-oxopregn-4-en-20-yl acetate (11), which was hydrogenated in the presence of base to the 5beta-pregnan-3-one derivative 12, protected in position 19 with tert-butyldimethylsilyl group and reduced with borohydride. The prevailing 3alpha-alcohol 15 was separated, protected in position 3 with a methoxymethyl group, deprotected in position 19 and transformed into the 19-[O-(carboxymethyl)oxime] 19. After deacetylation, esterification with diazomethane and oxidation in position 20, the pregnanolone skeleton was regenerated. Final deprotection steps gave the second title hapten 2. Both haptens, i.e., (19E)-3beta- and -3alpha-hydroxy-20-oxo-5beta-pregnan-19-al 19-[O-(carboxymethyl)oxime], were designed for the development of immunoassays of the corresponding parent neuroactive steroids.

Reinstatement of serum pregnanolone isomers and progesterone during alcohol detoxification therapy in premenopausal women.

BACKGROUND: Alcohol abuse is associated with menstrual irregularities related to the inhibition of progesterone secretion involved in regulation of the menstrual cycle. Reduced progesterone metabolites, including pregnanolone isomers (PIs), are efficient neuromodulators. The authors attempted to evaluate whether levels of PIs reflect impairment in progesterone biosynthesis in premenopausal women treated for alcohol addiction and whether alcohol detoxification therapy contributes to the restoration of their reproductive functions and psychosomatic stability by influencing steroid biosynthesis. METHODS: Serum allopregnanolone (3alpha-hydroxy-5alpha-pregnan-20-one; P3alpha5alpha), pregnanolone (P3alpha5beta), isopregnanolone (P3beta5alpha), epipregnanolone (P3beta5beta), progesterone, pregnanolone sulfate (PregS), pregnanolone, and estradiol were measured in 20 women during therapy (at start, three days, 14 days, one month, and four months) by gas chromatography-mass spectrometry or radioimmunoassay. The results were evaluated by a linear mixed model for longitudinal data, with stage of the treatment and subject as categorical factors, phase of the menstrual cycle as a time-varying covariate, and age of the subject as a covariate and by regression in individual stages of the menstrual cycle. RESULTS: During detoxification treatment, progesterone increased in the luteal phase. P3alpha5alpha, P3beta5alpha, and P3beta5beta rose in both phases of the menstrual cycle. DISCUSSION: Given the similar mechanism in the effects of alcohol and steroids in activating gamma-aminobutyric acid A receptors, the restoration of progesterone and PIs during therapy could be explained by an adaptation to increasing requests for gamma-aminobutyric acid A-receptor activating substances owing to the cessation of alcohol intake or by the regeneration of progesterone formation. In conclusion, the reinstatement of progesterone, P3alpha5alpha, and P3beta5beta serum levels demonstrates the favorable effect of detoxification therapy on both reproductive functions and the psychosomatic stability of premenopausal women treated for alcohol addiction.

Altered profiles of serum neuroactive steroids in premenopausal women treated for alcohol addiction.

Long-term alcohol consumption results in menstrual irregularities due to the inhibition of progesterone secretion. Some progesterone metabolites, including three pregnanolone isomers (PI), abate, while pregnenolone sulfate (PregS) and dehydroepiandrosterone sulfate (DHEAS) increase, alcohol tolerance. The rationale of this study was to evaluate how the neuroactive steroids reflect the impaired progesterone formation in premenopausal women treated for alcohol addiction, and whether detoxification therapy could restore female reproductive functions and psychosomatic stability by reinstatement of the steroid biosynthesis. Accordingly, serum allopregnanolone (3alpha-hydroxy-5alpha-pregnan-20-one (P3alpha5alpha)), pregnanolone (P3alpha5beta), isopregnanolone (P3beta5alpha) and epipregnanolone (P3beta5beta), progesterone, PregS, pregnenolone, 17alpha-hydroxy-pregnenolone (Preg17), 17alpha-hydroxy-progesterone (Prog17), DHEA, DHEAS, cortisol and estradiol were measured in 20 women during the therapy (start, 3 days, 14 days, 1 month, 4 months), and in 17 controls, using GC-MS or RIA and evaluated by age-adjusted ANCOVA with status and phase of the menstrual cycle (PMC) as factors, and status-PMC interaction. The patients exhibited depressed progesterone, Prog17, PI, and estradiol, a decreased progesterone/pregnenolone ratio, a decreased ratio of neuroinhibiting P3alpha5alpha to neuroactivating PregS, and an elevated PregS and PregS/pregnenolone ratio. The treatment mostly restored the indices. The reduction of neuroinhibiting pregnanolone isomers in the patients is primarily associated with the impairment in ovarian steroid biosynthesis. Nevertheless, changes in enzyme activities connected with the formation of PI and the influence of altered physiological requirements on the balance between endogenous neuroinhibiting and neuroactivating steroids are also likely. The reinstatement of serum estradiol, progesterone, and PI during the therapy demonstrates its favorable effect on both reproductive functions and the psychosomatic stability of the patients.

The identification and simultaneous quantification of 7-hydroxylated metabolites of pregnenolone, dehydroepiandrosterone, 3beta,17beta-androstenediol, and testosterone in human serum using gas chromatography-mass spectrometry.

7-Hydroxy-metabolites of dehydroepiandrosterone (DHEA) and 3beta,17beta-androstenediol (AD) possess immunomodulatory and neuroprotective properties; therefore, the measurement of these steroids in patients with autoimmune diseases or disturbances in the CNS may be of interest. A gas chromatography-mass spectrometry (GC-MS) method for the determination of 7-hydroxy-metabolites of pregnenolone, DHEA, AD, and testosterone including the parent steroids was applied to serum samples from 12 adult men (27-66 years), 13 male adolescents (13-20 years), 5 boys (6-10 years), 15 women in the follicular phase of the menstrual cycle (22-45 years), 17 women in the luteal phase (22-45 years), and 4 girls (6-10 years). The steroids were age and sex dependent, but independent of the menstrual cycle. The ratio of the 7alpha-hydroxy-metabolites to their parent steroids were age dependent, exhibiting an increasing trend (p < 0.0001, ANOVA) from pregnenolone (5%) to AD (20%). The ratio of 7beta- to 7alpha-metabolites ranged from 0.6 to 1. These results are consistent with models suggesting 7alpha-hydroxylation of the parent steroid, conversion to a 7-oxo-steroid and finally to the 7beta-hydroxylated-metabolite. Partial correlations suggested that 7-hydroxylation might reduce the concentration of circulating androgens. Despite the three times lower concentration of AD-metabolites, their antiglucocorticoid, immunomodulatory, and neuroprotective effects may be comparable to that of DHEA based on their reported greater biological activity.

Neuroactive pregnanolone isomers during pregnancy.

The pregnanolone isomers (PI) allopregnanolone (3alpha-hydroxy-5alpha-pregnan-20-one), pregnanolone (3alpha-hydroxy-5beta-pregnan-20-one), isopregnanolone (3beta-hydroxy-5alpha-pregnan-20-one), epipregnanolone (3beta-hydroxy-5beta-pregnan-20-one), progesterone, and estradiol were measured in 138 pregnant women. The sampling was carried out from the first through the 10th month of pregnancy. Gas chromatography-mass spectrometry analysis and RIA were used for the measurement of steroid levels. The ratios of individual PI were similar to those found previously around parturition: about 25:10:7:1 for allopregnanolone, pregnanolone, isopregnanolone, and epipregnanolone, respectively. All the PI showed a significant increase during pregnancy, which was more pronounced in the 3alpha-steroids. The results indicated changing ratios between 3alpha- and 3beta-PI and between 5alpha- and 5beta-PI throughout pregnancy. The constant allopregnanolone/isopregnanolone ratio found through pregnancy weakened the hypothesis of the role of isopregnanolone in the onset of parturition. The ratio of estradiol (stimulating uterine activity) to 5alpha-PI and epipregnanolone exhibited significant changes during pregnancy in favor of estradiol up to the sixth or seventh month, in contrast to the constant estradiol/pregnanolone ratio. A pregnancy-stabilizing role of pregnanolone, counterbalancing the stimulating effect of estradiol on the onset of parturition, was suggested.

Plasma levels of 7-hydroxylated dehydroepiandrosterone (DHEA) metabolites and selected amino-thiols as discriminatory tools of Alzheimer's disease and vascular dementia.

OBJECTIVE: The early differential diagnosis of Alzheimer's disease (AD) remains still problematic. We developed a laboratory test enabling us to distinguish patients with AD from those with vascular dementia (VD) and healthy subjects. METHODS: The AD group consisted of 22 women and 18 men. The VD group consisted of 16 women and 8 men. Age-matched controls consisted of 12 women and 9 men. Plasma pregnenolone sulfate (PregS), dehydroepiandrosterone (DHEA) and its sulfate (DHEAS) were determined by radioimmunoassay. 17-Hydroxypregnenolone (17Preg) and 7-hydroxylated metabolites of DHEA (7alphaDHEA, 7betaDHEA) were determined by radioimmunoassay after separation by high performance liquid chromatography (HPLC). Homocysteine (Hcy), cysteine (Cys), cysteinylglycine (Cysgly) and glutathione (GSH) were measured by HPLC. RESULTS: The ANOVA results of significant between-group differences were as follows: The PregS and the 17-Preg and DHEAS levels were independent from the diagnosis. The 7alphaDHEA levels significantly depended on the sex (p < 0.05) and diagnosis (p < 0.01). Amino-thiols were influenced by the diagnosis (p < 0.01, p = 0.0541, p < 0.01 and p = 0.0536 for Cys, Hcy, Cysgly and GSH, respectively). Using a stepwise backward regression analysis, the following parameters were obtained: X = 11.5 + 4.03 x sex +1.09 x Hcy + 0.190 x PregS - 4.76 x DHEAS + 3.00 x DHEA - 34.3 x 77alphaDHEA - 0.885 x Cysgly from which P-value as a discriminator was calculated according to the formula: P = 1/(1 + e(-x)). Then, for P > 0.5, a subject was considered as AD-positive (with 89% correct prediction). DISCUSSION: The opportunity of early differential diagnosis of AD should help physicians to use suitable treatment for retardation of pathological processes.

Sex- and age-related changes in epitestosterone in relation to pregnenolone sulfate and testosterone in normal subjects.

Epitestosterone has been demonstrated to act at various levels as a weak antiandrogen. So far, its serum levels have been followed up only in males. Epitestosterone and its major circulating precursor pregnenolone sulfate and T were measured in serum from 211 healthy women and 386 men to find out whether serum concentrations of epitestosterone are sufficient to exert its antiandrogenic actions. In women, epitestosterone exhibited a maximum around 20 yr of age, followed by a continuous decline up to menopause and by a further increase in the postmenopause. In men, maximum epitestosterone levels were detected at around 35 yr of age, followed by a continuous decrease. Pregnenolone sulfate levels in women reached their maximum at about age 32 yr and then declined continuously, and in males the maximum was reached about 5 yr earlier and then remained nearly constant. Epitestosterone correlated with pregnenolone sulfate only in males. In both sexes a sharp decrease of the epitestosterone/T ratio around puberty occurred. In conclusion, concentrations of epitestosterone and pregnenolone sulfate are age dependent and, at least in prepubertal boys and girls, epitestosterone reaches or even exceeds the concentrations of T, thus supporting its role as an endogenous antiandrogen. The dissimilarities in the course of epitestosterone levels through the lifespan of men and women and its relation to pregnenolone sulfate concentrations raise the question of the contribution of the adrenals and gonads to the production of both steroids and even to the uniformity of the mechanism of epitestosterone formation.