Are there any differences between stress hormone levels in non-stress conditions and in potentional stress overload (heart catheterisation) in sows?

In order to study a possible effect of mini-invasive heart intervention on a response of hypothalamo-pituitary-adrenal stress axis, we analyzed four stress markers (cortisol, cortisone, DHEA and DHEAS) in 25 sows using minimally invasive heart catheterisation as the stress factor. The marker levels were assessed in four periods of the experiment, (1) the baseline level on the day before intervention, (2) after the introduction of anesthesia, (3) after conducting tissue stimulation or ablation, and (4) after the end of the catheterisation. For statistical analyses we used the non-parametric Friedman test for four dependent samples (including all four stages of the operation) or three dependent samples (influence of operation only, baseline level was excluded). Statistically significant differences in both Friedman tests were found for cortisol and for cortisone. Significant differences for DHEA as well as for DHEAS were found for all tested stages but not for the effect of operation itself. We have concluded that cortisol levels are blunted by the influence of anesthesia after its administration, and therefore decrease back to the baseline at the end of the operation. The other markers (cortisone, DHEA and DHEAS) acted as balanced systems against the injurious stress effect.

Reduced levels of circulating 7alpha-hydroxy-dehydroepiandrosterone in treated adolescent obese patients.

Elevated levels of glucocorticoids lead to the development of obesity and metabolic syndrome. Local glucocorticoid levels are regulated through the enzyme 11beta-hydroxysteroid dehydrogenase 1 (11beta-HSD 1), an enzyme that regenerates active cortisol from inert cortisone. Increased expression of 11beta-HSD 1 in adipose tissue promotes higher body mass index (BMI), insulin resistance, hypertension, and dyslipidemia. Human 11beta-HSD 1 is also responsible for inter-conversion of 7-hydroxylate metabolites of dehydroepiandrosterone (7-OH-DHEA) to their 7-oxo-form. To better understanding the mechanism of the action, we focused on 7-OH- and 7-oxo-DHEA, and their circulating levels during the reductive treatment in adolescent obese patients. We determined plasma levels of 7alpha-OH-DHEA, 7beta-OH-DHEA, and 7-oxo-DHEA in 55 adolescent patients aged 13.04-15.67 years, BMI greater than 90th percentile. Samples were collected before and after one month of reductive therapy. Circulating levels of 7alpha-OH-DHEA decreased during the reductive therapy from 1.727 (1.614; 1.854, transformed mean with 95 % confidence interval) to 1.530 nmol/l (1.435; 1.637, p<0.05) in girls and from 1.704 (1.583; 1.842) to 1.540 nmol/l (1.435; 1.659, p<0.05) in boys. With regard to the level of 7-oxo-DHEA, a significant reduction from 1.132 (1.044; 1.231) to 0.918 nmol/l (0.844; 1.000, p<0.05) was found after the treatment, but only in boys. No significant difference in 7beta-OH-DHEA levels was observed. In conclusions, diminished levels of 7alpha-OH-DHEA indicate its possible effect on activity of 11beta-HSD 1. Further studies are necessary to clarify whether competitive substrates for 11beta-HSD 1 such as 7alpha-OH-DHEA could inhibit production of glucocorticoids and may be involved in metabolic processes leading to reduction of obesity.

Chronic cigarette smoking alters circulating sex hormones and neuroactive steroids in premenopausal women.

Chronic smoking alters the circulating levels of sex hormones and possibly also the neuroactive steroids. However, the data available is limited. Therefore, a broad spectrum of free and conjugated steroids and related substances was quantified by GC-MS and RIA in premenopausal smokers and in age-matched (38.9+/-7.3 years of age) non-smokers in the follicular (FP) and luteal phases (LP) of menstrual cycle (10 non-smokers and 10 smokers, in the FP, and 10 non-smokers and 8 smokers in the LP). Smokers in both phases of the menstrual cycle showed higher levels of conjugated 17-hydroxypregnenolone, 5alpha-dihydroprogesterone, conjugated isopregnanolone, conjugated 5alpha-pregnane-3beta,20alpha-diol, conjugated androstenediol, androstenedione, testosterone, free testosterone, conjugated 5alpha-androstane-3alpha/beta,17beta-diols, and higher free testosterone index. In the FP, the smokers exhibited higher levels of conjugated pregnenolone, progesterone, conjugated pregnanolone, lutropin, and a higher lutropin/follitropin ratio, but lower levels of cortisol, allopregnanolone, and pregnanolone. In the LP, the smokers exhibited higher levels of free and conjugated 20alpha-dihydropregnenolone, free and conjugated dehydroepiandrosterone, free androstenediol, 5alpha-dihydrotestosterone, free and conjugated androsterone, free and conjugated epiandrosterone, free and conjugated etiocholanolone, 7alpha/beta-hydroxy-dehydroepiandrosterone isomers, and follitropin but lower levels of estradiol and sex hormone binding globulin (SHBG) and lower values of the lutropin/follitropin ratio. In conclusion, chronic cigarette smoking augments serum androgens and their 5alpha/beta-reduced metabolites (including GABAergic substances) but suppresses the levels of estradiol in the LP and SHBG and may induce hyperandrogenism in female smokers. The female smokers had pronouncedly increased serum progestogens but paradoxically suppressed levels of their GABA-ergic metabolites. Further investigation is needed concerning these effects.

Might cardiac catheterization influence diurnal rhythm of the steroid stress hormones secretion?

Glucocorticoids (GCs) are steroid hormones produced by the adrenal cortex in reaction to stress stimuli. GCs production is not stable over a 24-hour period; the plasma concentration peaks in the morning (approximately upon awakening) and then the plasma levels decrease, reaching the nadir in the evening. In our experiments, the levels of cortisol, cortisone, DHEA and DHEAS were tested in young female pigs (n=23) during heart catheterization at two different day times (in the morning and in the afternoon). The non-parametric Mann-Whitney test for statistical analysis was used. We found only minimal statistical differences in studied markers between the morning and afternoon group (p>0.05). The absence of circadian variation in GCs levels could originate either at an early age of our experimental pigs, or in stressful conditions on the experiment day, or most likely the day before (e.g. social isolation, fasting, transport, and catheterization), respectively. We can conclude there is no difference in the stress load between morning and afternoon experiments, and therefore we can assume the stress load is not a limiting factor for the timing when catheterization should be preferably performed.

Is there circadian variation in cortisol levels in young sows in heart catheterization?

Cortisol is the main glucocorticoid (GC) hormone in pigs associated with stress response. It is well known that GCs levels are not stable during the day; their concentration is a circadian variable with the peak in the morning and the nadir in the night (in diurnal animals). Circadian variation is present during postnatal ontogeny. The onset of the circadian fluctuation occurs in pigs at the age of 3 to 20 weeks (according to the literature). The aim of our pilot study was to determine if young sows (used in cardiosurgical experiments) already developed the circadian variation. Twelve-week-old sows were used in the heart catheterization experiment. Cortisol was measured during four different stages of the experiment at two different times of the day (the operation was performed in the morning or afternoon). To determine circadian variation the Mann-Whitney test was used; to determine changes in cortisol levels within the experiment the Friedman test was performed. We didn't find any circadian variation (p>0.05) or statistical significant variation in the Friedman test (p>0.05). We assumed that our pigs are too young to have circadian rhythm present. Our findings are in accordance with many authors.

Immunoprotective steroids and SHBG in non-treated hypothyroidism and their relationship to autoimmune thyroid disorders.

Immunomodulatory steroids, dehydroepiandrosterone and its 7-hydroxylated metabolites and sex hormone-binding globulin (SHBG) were determined in sera of 88 women aged 18-75 years. The group consisted of 34 healthy women, 37 women with subclinical and 17 women with manifest hypothyroidism. In all subjects the laboratory parameters of thyroid function (thyrotropin, free thyroxine and triiodothyronine) and thyroid autoantibodies to thyroid peroxidase and thyroglobulin were determined. The aim was to find out 1) whether the above steroids and SHBG levels differ in individual groups according to thyroid status, 2) whether correlations exist among investigated steroids and thyroid laboratory parameters, and 3) whether the respective steroid and SHBG levels differ according to the presence of principal thyroid autoantibodies. With the exception of 7beta-hydroxy-dehydroepindrosterone levels, which were decreased in patients with manifest hypothyroidism (p<0.05), no significant differences in steroid and SHBG levels among groups according to diagnosis were found. On the other hand, significantly decreased levels of all the immunomodulatory steroids studied were found in subjects with positive titres of thyroid autoantibodies. This finding was supported by a tight negative correlation among the above steroids and thyroid autoantibodies. In addition, these steroids correlated negatively with thyrotropin and positively with free thyroid hormones. The results point to a negative relationship between the above mentioned immunoprotective steroids and the extent of the autoimmune process in hypothyroidism.

A novel radioimmunoassay of 7-oxo-DHEA and its physiological levels.

A novel radioimmunoassay (RIA) of unconjugated 7-oxo-dehydroepiandrosterone (7-oxo-DHEA) in human serum was developed for the first time. This steroid is an intermediate in the biosynthesis of immunomodulatory 7-hydroxylated DHEA metabolites, and has been shown to possess thermogenic properties. The method employs polyclonal rabbit antiserum to (19E)-3beta-hydroxy-7,17,19-trione-19-O-(carboxymethyloxime):BSA conjugate and a homologous radioiodinated derivative with tyrosine methyl ester. The cross reactivity of the antiserum with structurally closest 7-hydroxyepimers of DHEA was lower than 1.7%, with DHEA 0.4%, with all other related steroid less than 0.4%. The method includes ether extraction of serum (0.5 ml), followed by RIA. Its detection limit was 0.06 pmol (18 pg)/tube, the average intra- and inter-assay coefficients of variation were 4.1% and 8.3%, respectively. Mean recovery of serum spiked with 7-oxo-DHEA varied between 78.8% and 112%. Its levels in three serum pools were compared with a low-resolution gas chromatography-mass spectrometry method with satisfactory results. The method has been used for determination of 7-oxo-DHEA in serum samples of 215 subjects (91 males and 124 females) without overt endocrine disorders, aged 5-71 years. The over-all mean+/-S.D. was 0.280+/-0.227, the median 0.239 nmol/l. No significant sex differences were recorded. The only group which differed significantly from all other ones were males below 10 years, significantly lower values than in other age groups were found also in the first two age groups of females.