The role of endocrine mechanisms in ventilator-associated lung injury in critically ill patients

The critically ill subjects are represented by a heterogeneous group of patients suffering from a life-threatening event of different origin, e.g. trauma, cardiopulmonary failure, surgery or sepsis. The majority of these patients are dependent on the artificial lung ventilation, which means a life-saving chance for them. However, the artificial lung ventilation may trigger ventilation-associated lung injury (VALI). The mechanical ventilation at higher volumes (volutrauma) and pressure (barotrauma) can cause histological changes in the lungs including impairments in the gap and adherens junctions and desmosomes. The injured lung epithelium may lead to an impairment of the surfactant production and function, and this may not only contribute to the pathophysiology of VALI but also to acute respiratory distress syndrome. Other components of VALI are atelectrauma and toxic effects of the oxygen. Collectively, all these effects may result in a lung inflammation associated with a subsequent profibrotic changes, endothelial dysfunction, and activation of the local and systemic endocrine responses such as the renin-angiotensin system (RAS). The present review is aimed to describe some of the pathophysiologic aspects of VALI providing a basis for novel therapeutic strategies in the critically ill patients.

Attenuated neuroendocrine response to hypoglycemic stress in patients with panic disorder

BACKGROUND/AIMS

There is a lack of information on the effects of metabolic stress exposure on hormone release in patients with panic disorder. The aim of this study was to test the hypothesis that neuroendocrine activation during hypoglycemic stress is altered in panic disorder patients compared to healthy subjects.

METHODS

Hormone responses to an intravenous bolus of insulin (0.1 IU/kg) were evaluated in both fully remitted, medication-free panic disorder patients and healthy controls (n = 9/group). Blood samples for determination of cortisol, growth hormone, prolactin, adrenaline and noradrenaline concentrations were obtained at rest and over a 90-min period after insulin injection.

RESULTS

In patients with panic disorder, basal prestress hormone levels were comparable to those in healthy subjects with the exception of plasma adrenaline, which was higher in panic disorder patients compared to controls. The degree of hypoglycemia induced by insulin administration was similar in patients and healthy subjects. Hypoglycemia-induced increases in growth hormone, prolactin and cortisol concentrations were significantly attenuated in panic disorder patients compared to healthy individuals. No differences between patients and controls were observed in adrenalin release induced by hypoglycemia.

CONCLUSIONS

The present data demonstrate that somatotropic, lactotropic and corticotropic activation during hypoglycemic stress is blunted in patients with panic disorder. It is suggested that in contrast to the effects of relatively mild stress conditions used in other studies published in the literature, intensive stressors inducing a broad spectrum of hormonal changes fail to provoke an adequate neuroendocrine response in patients with panic disorder.

TSH Response to 30 Min Stay in Sauna in the Morning and during Evening Hours

The response of plasma TSH to 30 min stay in sauna was compared in the morning and in the evening. Both in the morning and in the evening plasma TSH was significantly elevated after sauna, with more prolonged response in the evening. This difference resembles the different reactivity of TSH to exogenous TRH administration in various times of day.

Adrenal plasma steroid relations in glucocorticoid-naïve premenopausal rheumatoid arthritis patients during insulin-induced hypoglycemia test compared to matched normal control females

OBJECTIVE

Clinical and experimental data indicate the involvement of adrenal steroids in the complex of rheumatoid arthritis (RA) pathogenesis. A subtle adrenocortical hypocompetence has been suggested in a subset of glucocorticoid-naïve premenopausal females with RA.

METHODS

The interrelations among adrenal steroids: cortisol (CORT), 17alpha-hydroxyprogesterone (17-OHP), androstenedione (ASD), dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulphate (DHEAS) were evaluated in 15 glucocorticoid-naïve premenopausal females with RA and in 14 age- and body mass index- matched healthy females at basal and during insulin-induced hypoglycemia states. Spearman's correlations were used to analyze baseline plasma concentrations as well as areas under response curves of these steroids levels as assayed during the basal and/or insulin-induced hypoglycemia status.

RESULTS

Six among 15 RA patients, but none of 14 controls had combined "lower" quartile range of basal cortisol (< 431 nmol/l) and lower DHEAS (< 2.79 micromol/l) levels, i.e., concentrations within the lowest quartiles of the control group (p = 0.017). In all subjects combined, basal correlations were significantly positive between ASD and other steroids (CORT, 17OHP, DHEA, DHEAS). When patient and control groups were analyzed separately, the positive basal correlation between ASD and CORT was significant only in RA patients (p = 0.030). In contrast, a positive basal correlation between ASD and DHEA was significant only in controls (p = 0.004). When comparing the areas under response curves (AUCs), the correlation of ASD and CORT was significantly negative in RA (p = 0.009), but positive in controls (RA vs control difference in Spearman's correlations, p = 0.002). The correlation between AUCs of ASD and DHEA was strongly positive in controls (p = 0.006), but not in RA (RA vs. control difference p = 0.044).

CONCLUSIONS

The results suggest relative hypocompetence of adrenocortical function in premenopausal RA females. Different patterns of correlations of the adrenal steroids during basal vs. stimulatory testing suggested certain alterations in adrenal synthetic pathways or deficiencies in the dynamics of steroidogenesis in RA.

Increased prevalence and coincidence of antinuclear and antithyroid antibodies in the population exposed to high levels of polychlorinated pollutants cocktail

OBJECTIVES

Because of well known association between the exposure to persistent organochlorinated pollutants (POPs) and impaired immune system, it was attempted to check possible coincidence of nuclear and thyroperoxidase antibodies with the levels of major POPs.

METHODS

Antinuclear antibodies. (ANA) were estimated by indirect immunofluorescence test using Hep2- cells and thyroperoxidase antibodies (TPOab) by electrochemiluminiscent immunoassay in the cohort of 253 adults (82 males and 171 females) aged 21-75 years, among them 144 (46 males and 98 females) from the area polluted (POLL) by polychlorinated biphenyls (PCB) and 109 (36 males and 73 females) from the area of background pollutrion (BCGR). In the same cohort fifteen congeners of PCB and also total DDE (2,2'-bis(4-chlorophenyl)-1,1-dichloroethylene) and hexachlorobenzene (HCB) were estimated by high resolution gas chromatography/mass spectrometry.

RESULTS

Prevalence of ANA only was significantly higher in POLL than in BCGR in males (p < 0.001) and females (p < 0.001) and the same was true for the prevalence of TPOab in males (p < 0.05) and females (p < 0.01) from POLL. In addition, also the prevalence of coincident ANA+TPOab in males (p < 0.001) and females (p < 0.05) was significantly higher in POLL. In a total of 253 pooled males and females from both areas and stratified in terms of PCB level quintiles. The prevalence of ANA in the 4th and 5th quintile of each among three pollutants (PCB, DDE and HCB) was significantly higher (p < 0.01 or < 0.001) and showed the parallel increase with the level of all pollutants.

CONCLUSIONS

Significantly increased prevalence of ANA either only or in coincidence with TPOab was found related to increasing level of PCB, DDE and HCB.

Adrenomedullary response to hypoglycemia in first-degree relatives of patients with rheumatoid arthritis

Our recent studies showed blunted adrenomedullary responses to insulin-induced hypoglycemia in premenopausal females with rheumatoid arthritis (RA) and systemic sclerosis, suggesting dysregulation of the adrenomedullary hormonal system (AMHS). Since no relationship has been found between degree of AMHS dysfunction and clinical or inflammatory parameters in those patients, we hypothesize the presence of an inherited perturbation of the AMHS. To test this hypothesis, we evaluated adrenomedullary responses to insulin-induced hypoglycemia (0.1 IU/kg) in premenopausal female subjects: 17 glucocorticoid-naïve RA patients, 15 healthy first-degree family members (FDR), and 18 age- and body mass index-matched healthy controls. Our results demonstrate that when compared to controls, RA patients had lower baseline epinephrine levels (P= 0.01) and lower area under response curve (AUC) levels of norepinephrine (P < 0.001) and epinephrine (P < 0.003). In contrast, FDR had lower (P= 0.001) AUC levels of norepinephrine compared to controls and higher (P= 0.033) AUC levels of epinephrine compared to RA patients. There were no significant differences in epinephrine response between FDR and controls. Although we found lower norepinephrine responses to hypoglycemia in FDR of RA patients, adrenomedullary responses to hypoglycemia does not appear to be altered to the degree found in RA patients.

Adrenocortical response to low-dose ACTH test in female patients with rheumatoid arthritis

Alterations in adrenal steroid production have been suggested in females with rheumatoid arthritis (RA). The aim of the present study was to assess adrenocortical function in RA females. We examined 11 female RA patients (RA: age 30 +/- 2 years, BMI 21.0 +/- 0.7 kg/m(2)) and 10 matched healthy controls (C: age 31 +/- 1 years, BMI 21.6 +/- 0.6 kg/m(2)). Low-dose adrenocorticotropic hormone (ACTH) test (i.v. bolus of 1 microg synthetic ACTH) was performed at 10.00 h with blood sampling every 15 min for 90 min. Cortisol, 17-OH-progesterone (17OHP), androstenedione (ASD), and dehydroepiandrosterone (DHEA) were assayed in plasma. Baseline cortisol levels were higher in RA patients (RA: 385 +/- 38 versus C: 229 +/- 28 nmol/L, P= 0.007). In both study groups, ACTH administration increased all the four steroids measured (P < 0.001). Cortisol response to ACTH administration was diminished in RA patients when compared to controls (Delta(max): 284 +/- 24 in RA versus 424 +/- 31 nmol/L in C, P= 0.002). ACTH-induced maximal rise in plasma DHEA was significantly lower in RA patients when compared to controls (Delta(max): 2.59 +/- 0.68 in RA versus 5.57 +/- 1.25 ng/mL in C, P= 0.015). No significant between-groups differences were found in responses of ASD or 17OHP. The molar ratio of ASD:cortisol was significantly lower (P < 0.05) in RA patients at base line, but did not differ during ACTH test. After ACTH bolus, the cortisol:17OHP ratio decreased significantly in the RA group (P < 0.001), whereas there was no change in the control group. The present results show decreased secretion of cortisol and DHEA in RA patients in response to ACTH, suggesting a subtle HPA hypofunction at the adrenocortical level.

Growth hormone response to different consecutive stress stimuli in healthy men: is there any difference?

The contribution of growth hormone (GH), released during acute and repeated stressful situations, to the development of stress-related disorders is often neglected. We have hypothesized that the modulation of the GH response to sequential stress exposure in humans depends mainly on the nature of the stressor. To test this hypothesis, we compared GH responses to different stressful situations, namely aerobic exercise, hypoglycemia and hyperthermia, which were applied in two sequential sessions separated by 80-150 min. In addition, administration of the dopaminergic drug apomorphine was used as a pharmacological stimulus. GH responses to submaximal exercise (bicycle ergometer, increasing work loads of 1.5, 2.0 and 2.5 W/kg, total duration 20 min) and hyperthermia in a sauna (80 degrees C, 30 min) were prevented when preceded by the same stress stimulus. Hypoglycemia induced by insulin (0.1 IU/kg intravenously) resulted in a significant GH response also during the second of the two consecutive insulin tests, though the response was reduced. Administration of apomorphine (0.75 mg subcutaneously) or insulin prevented the increase in GH release in response to a sequential bolus of apomorphine, while hypoglycemia induced a significant elevation in GH levels even if applied after a previous treatment with apomorphine. In conclusion, the feedback inhibition of the GH response to a sequential stress stimulus depends on the stimulus used. Unlike in the case of exercise and hyperthermia, mechanisms involved in the stress response to hypoglycemia appear to overcome the usual feedback mechanisms and to re-induce the GH response when applied after another stimulus.

[Levels of hormones in plasma and in synovial fluid of knee joint of patients with rheumatoid arthritis]

BACKGROUND

Dysfunction of endocrine system is very likely one of the important risk factors involved in the pathogenesis of rheumatoid arthritis. The aim of the present study was to investigate the levels of selected hormones in plasma and in synovial fluid of knee joint of patients with rheumatoid arthritis or with osteoarthritis, which could affect the inflammatory processes.

METHODS AND RESULTS

Thirty nine patients with rheumatoid arthritis (22 females and 17 males) and 12 patients with osteoarthritis (6 females and 6 males) were investigated. Concentrations of the following hormones were determined in plasma and synovial fluids: cortisol, 17-beta-estradiol, progesterone, dehydroepiandrosterone, aldosterone, testosterone, prolactin, insulin and C-peptide by using radioimmunoassay kits. Increased levels of 17-beta-estradiol and insulin were found in patients with rheumatoid arthritis as compared to those with osteoarthritis. The plasma concentrations of other hormones under study were not significantly different in these groups of patients. Higher levels of 17-beta estradiol, progesterone and aldosterone were noted in inflammatory knee exudate of patients with rheumatoid arthritis. The levels of other hormones in exudates of patients with rheumatoid arthritis and those with osteoarthritis were not significantly different. The ratio of 17-beta estradiol / cortisol, 17-beta estradiol / testosterone and 17-beta estradiol / dehydroepiandrosterone showed increased proportions of estrogens over androgens or glucocorticoids in exudate from patients with rheumatoid arthritis.

CONCLUSIONS

These results demonstrated that steroid and peptide hormones are transferred to synovial fluid of knee. The presence of insulin, C-peptide and aldosterone was described for the first time in synovial fluid. In patients with rheumatoid arthritis a predomination of the levels of proinflammatory estrogens over androgens was found in knee exudate. Also the levels of aldosterone and progesterone were elevated in inflammation knee exudate. This suggests that these hormones present in synovial fluid may affect the local rheumatoid inflammatory processes.

Lower adrenocortical and adrenomedullary responses to hypoglycemia in premenopausal women with systemic sclerosis

OBJECTIVES

To evaluate function of the hypothalamic-pituitary-adrenal (HPA) axis, adrenomedullary hormonal system (AMHS), and sympathetic noradrenergic system (SNS) in premenopausal women with systemic sclerosis (SSc).

METHODS

Insulin-induced hypoglycemia (0.1 IU/kg) was performed in 17 longterm, glucocorticoid-naive SSc patients with low disease activity and in 18 healthy women matched for age and body mass index (BMI). Concentrations of glucose, adrenocorticotrophic hormone (ACTH), cortisol, androstenedione (ASD), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), 17a-hydroxyprogesterone (17OHP), epinephrine (EPI), norepinephrine (NE), interleukin 1ss (IL-1ss), IL-6, and tumor necrosis factor-a (TNF-a) were analyzed in plasma.

RESULTS

Basal plasma levels of cortisol, ASD, 17OHP, DHEAS, IL-1ss, IL-6, and TNF-a were not significantly different in SSc compared to controls. Patients had higher basal ACTH (6.76 +/- 1.0 pmol/l in SSc vs 4.14 +/- 0.45 pmol/l in controls; p < 0.05), lower basal DHEA (9.02 +/- 1.64 nmol/l in SSc vs 17.0 +/- 2.8 nmol/l in controls; p < 0.05), and lower basal NE (1.61 +/- 0.26 nmol/l in SSc vs 2.57 +/- 0.38 nmol/l in controls; p < 0.05). Patients had comparable responses of glucose and ACTH to hypoglycemia. General linear model for repeated measurements, with BMI and age as covariates, revealed that the responses of 17OHP (p < 0.05), ASD (p < 0.05), DHEA (p < 0.01), EPI (p < 0.001), and NE (p < 0.001) to hypoglycemia were lower in SSc compared to controls. Cortisol response to hypoglycemia tended to be lower in SSc patients (p = 0.06) compared to controls.

CONCLUSION

Our data indicate decreased adrenocortical and adrenomedullary functions in premenopausal women with SSc. Whether the observed changes in the neuroendocrine system are secondary to chronic disease deserves further investigation.

Insulin sensitivity indices: a proposal of cut-off points for simple identification of insulin-resistant subjects

Demanding measurement of insulin sensitivity using clamp methods does not simplify the identification of insulin resistant subjects in the general population. Other approaches such as fasting- or oral glucose tolerance test-derived insulin sensitivity indices were proposed and validated with the euglycemic clamp. Nevertheless, a lack of reference values for these indices prevents their wider use in epidemiological studies and clinical practice. The aim of our study was therefore to define the cut-off points of insulin resistance indices as well as the ranges of the most frequently obtained values for selected indices. A standard 75 g oral glucose tolerance test was carried out in 1156 subjects from a Caucasian rural population with no previous evidence of diabetes or other dysglycemias. Insulin resistance/sensitivity indices (HOMA-IR, HOMA-IR2, ISI Cederholm, and ISI Matsuda) were calculated. The 75th percentile value as the cut-off point to define IR corresponded with a HOMA-IR of 2.29, a HOMA-IR2 of 1.21, a 25th percentile for ISI Cederholm, and ISI Matsuda of 57 and 5.0, respectively. For the first time, the cut-off points for selected indices and their most frequently obtained values were established for groups of subjects as defined by glucose homeostasis and BMI. Thus, insulin-resistant subjects can be identified using this simple approach.

Comparison of hormone transfer to pleural and synovial exudates

OBJECTIVES

Local effects of hormones on immune and connective tissues could play some role in the development of local inflammation processes. The aim of this study was to investigate the levels of selected hormones in pleural exudates of patients with pleurisy and lung tumours, and compare these levels with hormone concentration in knee synovial fluid.

SUBJECTS AND METHODS

Eleven patients with pleural exudate (mean age 62+/-3) and l9 subjects with rheumatoid arthritis (of the same mean age) participated in the observations. Plasma, pleural exudates and synovial fluid levels of cortisol, prolactin, aldosterone, testosterone, 17-beta-estradiol, dehydroepiandrosterone, progesterone, insulin and C-peptide were determined by specific radioimmunoassay.

RESULTS

It was noted that all estimated hormones are transferred into pleural exudates and synovial fluid. Higher levels of dehydroepiandrosterone and C-peptide were observed in pleural exudates as compared to plasma. The concentrations of testosterone, prolactin and estradiol in males were lower in exudates as compared to plasma. Mean levels of cortisol, aldosterone, progesterone and insulin in plasma were similar to these found in pleural exudates. The comparison of hormone levels in pleural exudates and synovial fluid showed that the levels of cortisol, progesterone and dehydroepiandrosterone tended to be higher in the exudates as compared to synovial fluid. However, the levels of insulin, testosterone and estradiol in exudates were lower than these in inflammatory synovial fluid from patients with rheumatoid arthritis.

CONCLUSIONS

This study showed the presence of hormones in pleural exudates. The differences in hormone concentrations in pleural exudates and synovial fluid were observed suggesting a specificity of hormone transfer from plasma to these exudates.

Prolactin and Growth Hormone Responses to Hypoglycemia in Patients with Systemic Sclerosis and Psoriatic Arthritis

This study compared prolactin (PRL) and growth hormone (GH) responses to hypoglycemia in premenopausal females with systemic sclerosis (SSc) and psoriatic arthritis (PsA) with those in matched healthy controls. No differences were found in glucose and GH responses to hypoglycemia in both groups of patients compared to controls. SSc patients had lower PRL response (P < 0.05) to hypoglycemia compared to controls. PRL response tended to be lower also in PsA patients, however the difference did not reach level of statistical significance (P = 0.11). The present study showed decreased PRL response to hypoglycemia in premenopausal females with SSc.

Decreased pituitary response to insulin-induced hypoglycaemia in young lean male patients with essential hypertension

Essential hypertension is associated with changes in central catecholaminergic pathways which might also be reflected in the pituitary response to stress stimuli. The aim of this study was to determine whether the response of pituitary hormones, cortisol, plasma renin activity, aldosterone and catecholamines to insulin-induced hypoglycaemia is changed in hypertension. We studied 22 young lean male patients with newly diagnosed untreated essential hypertension and 19 healthy normotensive, age- and body mass index (BMI)-matched controls. All subjects underwent an insulin tolerance test (0.1 IU insulin/kg body weight intravenously) with blood sampling before and 15, 30, 45, 60 and 90 min after insulin administration. Increased baseline levels of norepinephrine (P<0.05), increased response of norepinephrine (P<0.001) and decreased response of growth hormone (P<0.001), prolactin (P<0.001), adrenocorticotropic hormone (P<0.05) and cortisol (P<0.001) were found in hypertensive patients when compared to normotensive controls. Increased norepinephrine levels and a decreased pituitary response to metabolic stress stimuli may represent another manifestation of chronically increased sympathetic tone in early hypertension.

Hormone concentrations in synovial fluid of patients with rheumatoid arthritis

OBJECTIVE

Alterations in local concentrations of hormones, affecting directly synovial cells, could be involved in the modulation of the rheumatic inflammatory processes. The aim of present study was to investigate the levels of selected hormones (steroids, peptide and thyroid hormones) in synovial fluid of knee joint of patients with rheumatoid arthritis (RA) and control individuals with non-rheumatic exudate (with osteoarthrosis, OA).

METHODS

Thirty-eight patients, 22 female and 16 males, with rheumatoid arthritis (RA) and 12 subjects with osteoarthrosis (OA, control group, 6 females and 6 males) participated in the study. Concentrations of cortisol (CS), 17-beta-estradiol (ES), dehydroepiandrosterone (DHEA), progesterone (PRG), aldosterone ALD), prolactin (PRL), insulin (INS), and C-peptide were determined by radioimmunoassay in synovial fluid. Insulin binding to isolated cell membrane of cells from synovial sediment was estimated by using radioiodine labeled insulin. In a group of patients (10 with RA and 4 with OS), the levels of free threeiodothyronine (FT3), TSH and growth hormone (GH) were also determined in synovial fluid.

RESULTS

Increased levels of ES in synovial fluid of RA patients were observed, and higher differences were noted in men. TE concentrations were moderately elevated in synovial fluid of RA patients, however the ratio of ES/TE was significantly higher in male RA compared to OA patients. Higher levels of PRG, ALD and growth hormone were noted in synovial fluid of RA patients. Besides the steroid hormones the presence of insulin and C-peptide was noted in synovial fluid and the correlation between the levels of these two peptides was highly significant. The concentrations of INS and C-peptide in synovial fluid of patients from RA and OA group were not significantly different, however, highly significant increase of insulin binding to isolated membrane of synovial cells was found. Concentrations of cortisol, dehydroepiandosterone, prolactin, TSH and FT3 in synovial fluid were not significantly different in RA and OA groups.

CONCLUSIONS

Besides the steroids also insulin, c-peptide, GH and FT3 were found in synovial fluid. The elevated ALD and GH levels in synovial fluid of RA patients and the presence of INS in synovial fluid with increase of INS binding to plasma membranes of cells from synovial fluid of RA patients suggest that besides the gonadal steroids also these hormones may affect the local inflammatory processes.

Low levels of dehydroepiandrosterone sulphate in plasma, and reduced sympathoadrenal response to hypoglycaemia in premenopausal women with rheumatoid arthritis

OBJECTIVES

To evaluate the function of the hypothalamic-pituitary-adrenal axis and sympathoadrenal system in premenopausal women with rheumatoid arthritis (RA).

METHODS

Insulin-induced hypoglycaemia (0.1 IU/kg) was produced in 15 glucocorticoid-naive patients with long term RA with low disease activity and in 14 healthy women matched for age and body mass index. Concentrations of glucose, adrenocorticotropic hormone (ACTH), cortisol, Delta4-androstenedione (ASD), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulphate (DHEAS), 17alpha-hydroxyprogesterone (17OHP), epinephrine (EPI), norepinephrine (NE), interleukin 6 (IL6), and tumour necrosis factor alpha (TNFalpha) were analysed in plasma.

RESULTS

Patients had comparable responses of glucose, cortisol, ACTH, ASD, and 17OHP to hypoglycaemia, without any signs of hypothalamic insufficiency. Patients had lower basal DHEAS than controls (3.03 (0.37) micromol/l v 5.1 (0.9) micromol/l, respectively; p<0.05); borderline lower basal DHEA levels (p = 0.067); while the response of DHEA to hypoglycaemia was comparable to that of controls. Patients with RA had lower EPI (p = 0.005) and NE (p<0.001) responses to hypoglycaemia. TNFalpha and IL6 were higher (p<0.05) in patients with RA (TNFalpha 8 (2.8) pg/ml in RA v 1.1 (0.5) pg/ml in controls and IL6 15.1 (6.7) pg/ml v 1.4 (0.7) pg/ml).

CONCLUSIONS

Lower basal DHEAS levels, without concomitant differences or changes in DHEA, ASD, 17OHP, and cortisol responses to hypoglycaemia in patients with RA, indicate an isolated decrease in adrenal androgen production. Significantly lower responses of EPI and NE to hypoglycaemia may suggest sympathoadrenal hyporeactivity in patients with RA.

Attenuated insulin response and normal insulin sensitivity in lean patients with ankylosing spondylitis

Chronic low-grade inflammation is associated with insulin resistance. The aim of this study was to determine insulin response to intravenous glucose load and insulin sensitivity in patients with ankylosing spondylitis (AS). Fourteen nonobese male patients with AS and 14 matched healthy controls underwent frequent-sampling intravenous glucose tolerance test (FSIVGTT). Insulin secretion and insulin sensitivity were calculated using the computer-minimal and homeostasis-model assessment 2 (HOMA2) models. Fasting glucose, insulin, cholesterol, high-density lipoprotein and low-density lipoprotein cholesterol, triglyceride levels, HOMA2, glucose effectiveness, insulin sensitivity and insulin response to FSIVGTT did not differ between patients and controls. Tumor necrosis factor-alpha and interleukin (IL)-6 concentrations tended to be higher in AS patients than in controls. Second-phase beta-cell responsiveness was 37% lower (p = 0.05) in AS patients than in controls. A negative correlation was found between the percentage of beta-cell secretion and IL-6 in all subjects (r = -0.54, p = 0.006). We found normal insulin sensitivity but attenuated glucose utilization in the second phase of FSIVGTT in AS patients. Our results indicate that elevated IL-6 levels may play a pathophysiological role in attenuating beta-cell responsiveness, which may explain the association between elevated IL-6 levels and increased risk for type 2 diabetes.

Peptide hormones and histamine in plasma and synovial fluid of patients with rheumatoid arthritis and osteoarthrosis

OBJECTIVES

Hormones other than adrenal and gonadal steroids may play also a significant role in the pathogenesis of rheumatoid arthritis. The aim of this study was to investigate the levels of selected peptide hormones and histamine in synovial fluid of knee joints and in plasma of patients with rheumatoid arthritis and with osteoarthrosis.

METHODS

The concentrations of insulin, C-peptide, prolactin, growth hormone, free triiodothyronine (FT3), thyrotropin (TSH), and histamine were determined in synovial fluid and plasma of 27 patients with rheumatoid arthritis (RA) and in 12 patients with osteoarthrosis (OA).

RESULTS

The presence of peptide hormones in synovial fluid was demonstrated. The levels of TSH and growth hormone were lower in synovial fluid than in plasma in both groups, while those of prolactin were comparable in synovial fluid and in plasma. The levels of C-peptide (p < 0.05), insulin and FT3 were higher in synovial fluid than in plasma of OA patients, but lower in synovial fluid of RA patients as compared to their levels in plasma. Significant positive correlations between the levels in plasma and synovial fluid were observed in prolactin (p < 0.001, r = 0.741) and TSH (p < 0.05, r = 0.88) only. After age adjustment, no significant differences in synovial fluid and in plasma levels of all hormones were found between OA and RA patients. The levels of histamine in plasma were similar in RA and OA patients, in synovial fluid of both groups histamine was found in almost undetectable amounts.

CONCLUSIONS

The selected peptide hormones, e.g. insulin, C-peptide, prolactin, growth hormone, FT3 and TSH, are present in synovial fluid of RA and OA patients, some of them in the concentrations comparable to these in plasma. The role of the locally present hormones in pathogenesis of RA has to be investigated in further studies and analyses.

Prolactin and growth hormone responses to hypoglycemia in patients with rheumatoid arthritis and ankylosing spondylitis

OBJECTIVE

Prolactin (PRL) and growth hormone (GH) are pituitary hormones with immunomodulating properties. Their upregulated secretion may play a role in the pathogenesis of chronic inflammatory diseases. We evaluated PRL and GH responses to secretion stimulus in patients with rheumatoid arthritis (RA) and ankylosing spondylitis (AS).

METHODS

Insulin hypoglycemia (0.1 IU/kg) was induced in 15 women with RA, 18 men with AS, and healthy controls matched for age, sex and body mass index. Plasma concentrations of glucose, PRL, GH, interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-a) were analyzed.

RESULTS

RA patients had significantly lower area under the curve (AUC) of PRL (p = 0.049) compared to RA controls. During hypoglycemia double or higher increase of plasma PRL occurred in 5 RA (33%) patients and in 8 RA controls (57%). Using the General Linear Model procedure, no significant differences in PRL or GH responses were observed in patients with RA and AS. TNF-a was higher in patients with RA compared to RA controls (p < 0.05). There was no significant difference in TNF-a concentrations between AS patients and AS controls. IL-6 was higher in RA patients compared to controls (p < 0.05) and in AS patients compared to controls (p < 0.01). Significant positive correlation was found between TNF-a levels and AUC of PRL in AS patients (r = 0.46, p = 0.047), but not in the 2 control groups or in RA patients.

CONCLUSION

Our results indicate no upregulated PRL or GH responses to stimulation in premenopausal women with RA or men with AS.

Gonadal and adrenal steroid hormones in plasma and synovial fluid of patients with rheumatoid arthritis

OBJECTIVES

Gonadal and adrenal steroids were shown to affect multiple immune processes including inflammatory response. These effects were documented, specifically, through an influence on local productions of cytokines and the functions of synovial cells at the site of inflammatory processes. The aim of this study was to investigate the levels of selected hormones in synovial fluid of knee joints of patients with rheumatoid arthritis (RA) and with osteoarthrosis (OS, control group).

METHODS

The concentrations of cortisol (CORT), 17-beta-estradiol (ES), dehydroepiandrosterone (DHEA), testosterone (TE), progesterone (PRG), and aldosterone (ALD) were determined in plasma and synovial fluid.

RESULTS

Significant positive correlations between the levels in plasma and synovial fluids were observed in hormones ES, PRG, TE, DHEA and ALD. In most hormones, the levels in synovial fluids were similar as in plasma; however, the content of ALD was higher in synovial fluid as compared to plasma. Higher levels of ES (in females), DHEA (in males), and ALD were observed in plasma and synovial fluids of RA patients as compared to OS patients. After adjustment to age, no significant RA vs. OS difference was noted in ES, TE, DHEA, PRG, and CORT in plasma and synovial fluid. Age-adjusted ALD concentration tended to be higher in synovial fluid of RA patients as compared to OS patients. The ratio of ES/TE concentrations in synovial fluid was significantly higher in male RA patients compared to OS group. Also the ES/CS and ES/DHEA ratios in synovial fluid were elevated in RA patients in comparison to controls.

CONCLUSIONS

These results demonstrated the prevalence of pro-inflammatory hormones in synovial fluid of RA patients, suggesting the possible role of these steroid hormones in inflammatory processes.

Repeated stress-induced stimulation of catecholamine response is not followed by altered immune cell redistribution

Stress response is considered an important factor in the modulation of immune function. Neuroendocrine hormones, including catecholamines, affect the process of immune cell redistribution, important for cell-mediated immunity. This longitudinal investigation was aimed at evaluating the effect of repeated stress-induced elevation of catecholamines on immune cell redistribution and expression of adhesive molecules. We assessed the responses of epinephrine (EPI), norepinephrine (NE), cortisol, changes in lymphocytes subpopulations, and percentages of CD11a+, CD11b+, and CD62L+ lymphocytes to a 20-min treadmill exercise of an intensity equal to 80% of the individual's Vo(2)max. The exercise was performed before and after 6 weeks of endurance training consisting of a 1-h run 4 times a week (ET) and after 5 days of bed rest (HDBR) in 10 healthy males. We did not observe any significant changes in the basal levels of EPI, NE, and cortisol in the plasma, nor in the immune parameters after ET and HDBR. The exercise test led to a significant (P <.001) elevation of EPI and NE levels after both ET and HDBR, a significant elevation (P <.01) of cortisol after HDBR, an increase in the absolute numbers of leukocytes, granulocytes, monocytes, CD3+, CD4+, CD8+, CD16+, CD19+ lymphocytes, percentage of CD11a+ and CD11b+ lymphocytes, and to a decrease of CD62L1 before, after ET, and after HDBR. We found comparable changes in all measured immune parameters after ET and HDBR. In conclusion, repeated stress-induced elevation of EPI and NE was not associated with an alteration in immune cell redistribution found in response to the single bout of exercise.

Effects of endurance training on endocrine response to physical exercise after 5 days of bed rest in healthy male subjects

The study was designed to evaluate how a bout of endurance training (ET) influences the endocrine response after head-down bed rest (HDBR). Eleven healthy males completed the study, which consisted of a 6-wk ET followed by 5 days of -6 degrees head-down HDBR. Treadmill exercise at 80% of pretraining maximal aerobic capacity (VO(2max)) was performed before and after ET as well as after HDBR. ET increased VO(2max) by 13%. The response of norepinephrine was attenuated after ET and exaggerated after HDBR (P < 0.001). The differences in epinephrine responses were not statistically significant. The responses of cortisol and plasma renin activity (PRA) were unchanged after ET and were enhanced after HDBR (P < 0.001). The response of growth hormone after HDBR was reduced (P < 0.05). Only the change in cortisol response was associated with the increment of VO(2max) after ET (r = 0.68, P < 0.01). Endurance training failed to completely prevent changes in endocrine responses seen after HDBR. Improvement of physical fitness was associated with an enhancement of the cortisol response to exercise following the period of bed rest.

Hypothalamic-pituitary-adrenal axis function in ankylosing spondylitis

OBJECTIVE

To assess basal function and responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis in patients with ankylosing spondylitis during dynamic testing.

METHODS

Insulin induced hypoglycaemia (IIH) (Actrapid HM 0.1 IU/kg, as intravenous bolus) was induced in 17 patients and 11 healthy controls matched for age, sex, and body mass index. Concentrations of glucose, adrenocorticotrophic hormone (ACTH), cortisol, insulin, dehydroepiandrosterone sulphate (DHEAS), 17alpha-hydroxyprogesterone, interleukin 6 (IL-6), and tumour necrosis factor alpha (TNFalpha) were determined in plasma.

RESULTS

Comparable basal cortisol levels were found in the two groups, with a trend to be lower in ankylosing spondylitis. In the ankylosing spondylitis group, there were higher concentrations of IL-6 (mean (SEM): 16.6 (2.8) pg/ml v 1.41 (0.66) pg/ml in controls; p<0.001) and TNFalpha (8.5 (1.74) pg/ml v 4.08 (0.42) pg/ml in controls; p<0.01). Glucose, insulin, ACTH, DHEAS, and 17alpha-hydroxyprogesterone did not differ significantly from control. The IIH test was carried out successfully in 11 of the 17 patients with ankylosing spondylitis, and the ACTH and cortisol responses were comparable with control. General linear modelling showed a different course of glycaemia (p = 0.041) in the ankylosing spondylitis patients who met the criteria for a successful IIH test compared with the controls.

CONCLUSIONS

The results suggest there is no difference in basal HPA axis activity and completely preserved responsiveness of the HPA axis in patients with ankylosing spondylitis. The interpretation of the different course of glycaemia during IIH in ankylosing spondylitis requires further investigation.

Effect of space flight and head-down bedrest on neuroendocrine response to metabolic stress in physically trained subjects

The aim of this study was to evaluate the association of plasma epinephrine (EPI) and norepinephrine (NE) responses to insulin induced hypoglycemia (ITT) 3 weeks before the space flight (SF), on the 5th day of SF, on the 2nd and 16th days after the landing in the first Slovak astronaut, and before and on the 5th day of prolonged subsequent head-down (-6 degrees) bed rest (BR) in 15 military aircraft pilots. Blood samples during the test were collected via cannula inserted into cubital vein, centrifuged in the special appliance Plasma-03, frozen in Kryogem-03, and at the end of the 8-day space flight transferred to Earth in special container for hormonal analysis. Insulin hypoglycemia was induced by i.v. administration of 0.1 IU/kg BW insulin (Actrapid HM) in bolus. Insulin administration led to a comparable hypoglycemia in pre-flight, in-flight conditions and before and after bed rest. ITT led to a pronounced increase in EPI levels and moderate increase in NE in pre-flight studies. However, an evidently reduced EPI response was found after insulin administration during SF and during BR. Thus, during the real microgravity in SF and simulated microgravity in BR, insulin-induced hypoglycemia activates the adrenomedullary system to less extent than at conditions of the Earth gravitation. Post-flight changes in EPI and NE levels did not significantly differ from those of pre-flight since SF was relatively short (8 days) and the readaptation to Earth gravitation was fast. It seems, that an increased blood flow in brain might be responsible for the reduced EPI response to insulin. Responses to ITT in physically fit subjects indicate the stimulus specificity of deconditioning effect of 5 days bed rest on stress response. Thus, the data indicate that catecholamine responses to ITT are reduced after exposure to real as well as simulated microgravity.

Effects of Space Flight and −6° Bed Rest on the Neuroendocrine Response to Metabolic Stress in Physically Fit Subjects

The aim of this study was to evaluate the association of plasma epinephrine (EPI) and norepinephrine (NE) responses to insulin-induced hypoglycemia (ITT) 3 weeks before the space flight (SF), on the fifth day of SF, on days 2 and 16 after landing in the first Slovak astronaut, and before and on the fifth day of prolonged bed rest (BR) in 15 military aircraft pilots, aged 33.5 +/- 1.4 years, body mass index (BMI) 26.5 +/- 0.7 kg/m(2), maximal oxygen uptake (VO(2max)) 55.2 +/- 2.4 mL/kg/min, who volunteered for the study. ITT was induced by i.v. administrations of 0.1 IU/kg body weight insulin (Actrapid HM) in a bolus. Insulin administration led to a comparable hypoglycemia in preflight, actual flight conditions, and before and after bed rest. ITT led to a pronounced increase in EPI levels and moderate increase in NE in preflight studies. However, an evidently reduced plasma elevation of EPI was found after insulin administration during SF and during BR. Thus, during the real microgravity in SF and simulated microgravity in BR, ITT activates the adrenomedullary system to less extent that at conditions of the Earth's gravitation. Post-flight changes in EPI and NE did not differ from those of preflight values, since SF was relatively short (8 days) and the readaptation to Earth's gravitation was fast. It seems that an increased blood flow in brain might be responsible for the reduced EPI response to insulin. Responses to ITT in physically fit subjects indicate the stimulus specificity of the deconditioning effect of 5 days of bed rest on the stress response.

Does Orthostatic Stress Influence the Neuroendocrine Response to Subsequent Hypoglycemia in Humans?

Neuroendocrine response to stress stimuli is influenced by previous stimuli of different nature. The aim of the study was to test whether antecedent orthostatic stress may affect the neuroendocrine response to subsequent hypoglycemia. A group of 12 (6 men, 6 women) nonobese, healthy volunteers aged 19 to 27 y (mean 24 +/- 0.8) participated in the study in two sessions: controlled insulin-induced hypoglycemia to 2.7 mmol/L for 15 min either with or without antecedent orthostatic stress (30 min of 60 degrees head-up tilt before insulin administration). Orthostatic stress caused a significant decrease in plasma volume (-9.6%; P < 0.001) and a significant increase in plasma renin activity, aldosterone, norepinephrine (P < 0.01), and adrenocorticotropic hormone (ACTH) concentrations (P < 0.05) in all subjects. Growth hormone response to hypoglycemia was diminished in women (P < 0.01). The epinephrine response to hypoglycemia was diminished in women in comparison to men (P < 0.001), but was unaffected by antecedent orthostatic stress. Hypoglycemia failed to induce the ACTH release after its elevation during orthostatic stress. ACTH response to moderate hypoglycemia without previous orthostatic stress was evident only in men in comparison to women (P < 0.05). We conclude that the epinephrine, growth hormone, and ACTH responses to hypoglycemia were diminished in women. Except ACTH, the neuroendocrine response to mild hypoglycemia was not affected by previous orthostatic stress in healthy subjects. In the case of ACTH, the first stress stimulus is consequential for the subsequent response of this hormone, probably due to short-loop negative feedback effects.

Effects of Real and Simulated Microgravity on Response of Sympathoadrenal System to Various Stress Stimuli

Changes in plasma levels of epinephrine (EPI) and norepinephrine (NE) were investigated in humans exposed to physical exercise (WL), to psychic stressor (mental arithmetic test, MAT), and to oral glucose administration (oGTT) before and during a stay in microgravity (real space flight, SF) or in simulated microgravity (head-down bed rest, HDBR). A permanent cannula inserted into the cubital vein and a special appliance, Plasma-03, were used for blood collection, plasma separation, and freezing of samples during SF. Plasma EPI, NE, dihydroxyphenylglycol (DHPG), and dihydroxyphenylalanine (DOPA) levels were measured by the high-pressure liquid chromatography (HPLC) method. Basal plasma EPI, NE, DHPG, and DOPA levels were found within the range of control values during SF. Preflight WL produced high increase in plasma NE and moderate elevation of plasma EPI, DHPG, and DOPA levels. Exaggerated exercise induced increases in plasma NE, DHPG, EPI, and DOPA levels were demonstrated in real microgravity. A return to preflight responses of sympathoadrenal system was seen after the landing. Plasma EPI, NE, and DHPG responses to MAT were relatively small, but increased during SF. During the oGTT the plasma EPI levels were slightly reduced in microgravity. Similarly as in SF, WL in HDBR was followed by significantly exaggerated responses of plasma catecholamines. These results show that both somatic and psychological stressors are able to induce an increased activation of sympathoadrenal system during SF or simulated microgravity in HDBR.

Effect of head-down bed rest on the neuroendocrine response to orthostatic stress in physically fit men

The role of neuroendocrine responsiveness in the development of orthostatic intolerance after bed rest was studied in physically fit subjects. Head-down bed-rest (HDBR, -6 degrees, 4 days) was performed in 15 men after 6 weeks of aerobic training. The standing test was performed before, after training and on day 4 of the HDBR. Orthostatic intolerance was observed in one subject before and after training. The blood pressure response after training was enhanced (mean BP increments 18+/-2 vs. 13+/- 2 mm Hg, p<0.05, means +/- S.E.M.), although noradrenaline response was diminished (1.38+/-0.18 vs. 2.76+/-0.25 mol.l(-1), p<0.01). Orthostatic intolerance after HDBR was observed in 10 subjects, the BP response was blunted, and noradrenaline as well as plasma renin activity (PRA) responses were augmented (NA 3.10+/-0.33 mol.l(-1), p<0.001; PRA 2.98+/-1.12 vs. 0.85+/-0.15 ng.ml(-1), p<0.05). Plasma noradrenaline, adrenaline and aldosterone responses in orthostatic intolerant subjects were similar to the tolerant group. We conclude that six weeks of training attenuated the sympathetic response to standing and had no effect on the orthostatic tolerance. In orthostatic intolerance the BP response induced by subsequent HDBR was absent despite an enhanced sympathetic response.

Pharmacological hyperprolactinemia attenuates hydrocortisone-induced expression of CD11b on human CD8+ cells in vivo

OBJECTIVE

To study the short-term influences of pharmacologic hyperprolactinemia on hydrocortisone (HC)-induced effects on selected immune parameters.

METHODS

A single dose of HC (40 mg per os) was administered to eleven healthy female volunteers 1 h after domperidone (10 mg per os) or placebo administration. Immune cell subsets and expression of adhesion molecules was assessed by flow cytometry at baseline and 4 and 6 h after HC administration. Intracellular staining of interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) production in CD4+ lymphocytes after phorbol myristate acetate and ionomycin stimulation was performed at the same time points.

RESULTS

HC administration was followed by a significant increase in cortisol levels, numbers of leukocytes and granulocytes and the percentage of CD16+, CD19+, CD11a+, CD11a+CD8+, CD11b+ and CD11b+CD8+ cells. The number of lymphocytes and monocytes and the percentage of CD3+, CD4+, CD4+/CD8+ ratio, CD62L+, CD54+ and CD54+CD16+ cells decreased, while the percentage of CD8+ cells was unaffected. Domperidone administration resulted in a significant increase in prolactin (PRL) concentrations. During hyperprolactinemia, the HC-induced increase in CD11b+CD8+ cells was significantly (p < 0.05) attenuated at 4 h. HC-induced changes in other immune parameters remained unaffected. No significant changes in the intracellular production of IL-4 and IFN-gamma in CD4+ lymphocytes were observed after a single dose of HC alone or during hyperprolactinemia.

CONCLUSIONS

This study shows an attenuated HC-induced increase in CD11b+CD8+ cells in the peripheral blood of healthy females during hyperprolactinemia. Our in vivo observations suggest that short-term interactions occur between PRL and glucocorticoids, affecting selected immune functions. Further studies are needed for confirmation of these results.

Body position and the neuroendocrine response to insulin-induced hypoglycemia in healthy subjects

Changes in body fluid distribution are known to influence neuroendocrine function. The aim of the present study was to test the hypothesis that changes in plasma volume affect the counterregulatory neuroendocrine response to hypoglycemia. The tests were performed in 12 subjects in two situations: 'head-up' (+60 degrees head-up tilt standing for 30 min and hypoglycemia in sitting position afterwards) and 'leg-up' (leg-up position for 30 min and hypoglycemia in leg-up position afterwards) in a random order. Insulin-induced hypoglycemia was adjusted to 2.7 mmol/l for 15 min by glucose infusion. Plasma volume was greater by 2.2% (p < 0.001) in leg-up and lower by 9.6% (p < 0.001) in head-up position compared to the basal value in sitting position. Head-up position was associated with increases in ACTH, aldosterone, norepinephrine levels and plasma renin activity (p < 0.01). Leg-up position resulted in decreases in plasma growth hormone and epinephrine concentrations (p < 0.05). Except epinephrine, the neuroendocrine response to hypoglycemia, if any, was mild. Hypoglycemia failed to activate ACTH release after head-up position. Body fluid redistribution did not modify hormonal changes during insulin hypoglycemia. In conclusion, we suggest that body position and accompanying plasma volume changes do not appear to affect neuroendocrine and counterregulatory responses to moderate, short duration hypoglycemia in healthy subjects.

[Use of the in vivo microdialysis technique in basic and clinical research]

Microdialysis is in vivo technique that permits monitoring of local concentrations of metabolites and drugs at specific sites in the body that makes it an attractive tool for the basic and clinical research. Microdialysis entered the experimental studies of the brain, and later also of the peripheral tissues such as adipose and muscle tissues, kidney, lung, eye, skin, and blood. There are several critical factors in the experimental implementations of microdialysis: the probe, the perfusion solution, tissue integrity, and the sensitivity of microdialysate analysis method. When the experimental conditions are optimised to give valid results, microdialysis can provide numerous data from the relatively small number of individual subjects. It can bring about detailed clinical information reflecting free metabolite and drug concentrations in studied tissues and/or in plasma. With the progress of analytical methods, applications and importance of the microdialysis technique in clinical and pharmacokinetic research and diagnostics will increase.

Cortisol elimination from plasma in premenopausal women with rheumatoid arthritis

OBJECTIVE

To test the hypothesis that cortisol elimination from plasma can contribute to relatively low cortisol in premenopausal women with rheumatoid arthritis (RA).

METHODS

Twelve premenopausal female patients with RA (39.8 (1.8) years) and nine healthy control women matched for age and body mass index (42 (3.3) years) were enrolled in the study. None of the patients had previously been receiving treatment with glucocorticoids. After dexamethasone suppression (2 mg by mouth) the evening before the study, 20 mg of hydrocortisone was given. Blood and saliva samples were drawn six hours after injection of hydrocortisone. Plasma and salivary cortisol were measured.

RESULTS

Dexamethasone administration suppressed plasma cortisol concentrations to an almost undetectable level in all subjects, except one with RA. In this subject, a raised concentration of plasma cortisol was verified by repeated analysis despite the fact that cortisol concentration in the saliva sample measured simultaneously was not raised. No significant difference in the disappearance curve of cortisol in plasma or in salivary cortisol levels was found between the patients with RA and the healthy controls.

CONCLUSIONS

The profile of disappearance of total cortisol from plasma, and salivary cortisol levels during the elimination phase after its intravenous administration, are unchanged in premenopausal women with RA. Alterations in cortisol clearance are not likely to have a role in cortisol availability in patients with RA.

Growth hormone and prolactin responses during partial and whole body warm-water immersions

AIM

To elucidate the role of core and skin thermoreceptors in the release of growth hormone (GH) and prolactin (PRL), a sequence of two experiments using whole-body (head-out) and partial (one forearm) hot water immersions was performed.

METHODS

Experiment 1: Nine healthy men were exposed to head-out and partial water immersions (25 min, 38-39 degrees C).

RESULTS

Head-out immersion increased the core temperature (38.0 +/- 0.1 vs. 36.7 +/- 0.1 degrees C, P < 0.001) and plasma concentration of the hormones (GH, 16.1 +/- 4.5 vs. 1.2 +/- 0.4 ng mL(-1), P < 0.01; PRL, 9.1 +/- 1.0 vs. 6.4 +/- 0.4 ng mL(-1), P < 0.05). During the partial immersion the core temperature was slightly elevated (36.8 +/- 0.1 vs. 36.6 +/- 0.1, P < 0.001), the concentration of GH increased (4.8 +/- 1.7 vs. 0.6 +/- 0.3, P < 0.05), while plasma PRL decreased (7.6 +/- 0.8, 6.0 +/- 0.6, 5.2 +/- 0.6, P < 0.01). Experiment 2: Seven volunteers immersed one forearm once in 39 degrees C and once in 38 degrees C water. The measurements were performed in 5-min intervals. The GH concentration increased gradually from the beginning of the immersions (min 10; 39 degrees C: 1.9 +/- 1.0 vs. 0.6 +/- 0.3 ng mL(-1), P < 0.01; 38 degrees C: 0.19 +/- 0.03 vs. 0.14 +/- 0.03, P < 0.05) and peaked after their completion (39 degrees C: +10 min, 3.7 +/- 2.0, P < 0.001; 38 degrees C: +15 min, 0.86 +/- 0.61, P < 0.01). The core temperature was unchanged until min 15 of the 39 degrees C bath. Thereafter, it increased about 0.15 degrees C above the baseline (P < 0.01). Immersion in 38 degrees C water did not induce core temperature changes.

CONCLUSIONS

Peripheral thermoreceptors are involved in GH release when the body is exposed to elevated environmental temperature while a substantial elevation of core temperature is a precondition of PRL release.

The response of endocrine system to stress loads during space flight in human subject

The responses of endocrine system to the exposure to stress-work load and hormonal changes during oral glucose tolerance tests were studied in the Slovak astronaut before (three weeks before flight), during (on the 4th and the 6th days of space flight), and after space flight (1-3 days and 15-17 days after space flight) on board of space station MIR. Blood samples during the tests were collected via cannula inserted into cubital vein, centrifuged in the special appliance Plasma-03, frozen in Kryogem-03, and at the end of the 8-day space flight transferred to Earth in special container for hormonal analysis. Preflight workload produced an increase of plasma norepinephrine and a moderate elevation of epinephrine levels. Plasma levels of insulin, growth hormone, prolactin and cortisol were not markedly changed immediately or 10 min after the end of work load. The higher increases of plasma growth hormone, prolactin and catecholamine levels were noted after workload during space flight as compared to preflight response. The higher plasma glucose and insulin levels were noted during the oral glucose tolerance test in space flight and also in the post flight period. Plasma epinephrine levels were slightly decreasing during glucose tolerance test; however, plasma norepinephrine levels were not changed. The similar patterns of catecholamine levels during glucose tolerance test were found when compared the preflight, in-flight and post flight values. These data demonstrate the changes of the dynamic responses of endocrine system to stress-work and metabolic loads during space flight in human subject.

Responses of sympathoadrenal and renin angiotensin systems to stress stimuli in humans during real and simulated microgravity

Changes of plasma hormone levels were investigated in human subjects after exposure to physical exercise (WL) and insulin induced hypoglycemia (ITT) during space flight or after head down bed rest (HDBR). Exaggerated responses of plasma epinephrine (EPI), norepinephrine (NE) and aldosterone (ALD) were observed after WL during space flight as compared to preflight response. Hypoglycemia during space flight induced attenuated responses of EPI, NE and augmented response of ALD. Exposure to WL during HDBR was followed by significantly exaggerated responses of plasma EPI, NE, ALD, PRA and cortisol. In HDBR the responses of plasma EPI, NE and cortisol were reduced and PRA response was exaggerated during ITT. These data indicate that hormonal responses to ITT and WL are similar at real and simulated microgravity.

Increased demand for steroid therapy in hyperprolactinemic patients with rheumatoid arthritis

The role of increased plasma prolactin (PRL) in rheumatoid arthritis (RA) is not fully explained. The aim of this study was to compare the clinical features and the treatment administered in RA patients with normal and elevated plasma PRL concentrations. Forty-nine patients with rheumatoid arthritis and 16 healthy subjects were included in this study In healthy controls, PRL concentrations were 7.6 micro/l (median), in 34 patients plasma PRL was less than 20 micro/l (9.9 micro/l) and in 15 patients it was elevated, with a median of 26.7 micro/l. No differences in clinical features were found compared with normal or increased plasma PRL. The introduction of corticoid therapy produced a significant difference. Steroid therapy was administered to 93% of the patients with hyperprolactinemia, compared with 59% of those with normal PRL concentrations. Daily prednisone doses higher than 5 mg were administered to 43% of the patients with elevated PRL, compared with 25% of patients with normal prolactin concentrations. In conclusion, the clinical feature of patients with rheumatoid arthritis did not differ in subjects with elevated PRL concentrations and in those with normal concentrations. The difference between these two groups was in the higher demand for steroid therapy in patients with hyperprolactinemia.

Somatotropic, lactotropic and adrenocortical responses to insulin-induced hypoglycemia in patients with rheumatoid arthritis

Neuroendocrine mechanisms have been suggested to play an important role in the onset and progression of rheumatoid arthritis (RA). The aim of this study was to evaluate hypothalamic-pituitary functions in RA patients by measurement of hormone responses to insulin-induced hypoglycemia. Insulin-hypoglycemia (Actrapid HM 0.1 IU/kg, i.v. as a bolus) was induced in 17 male patients and in 11 age-, gender-, and weight-matched healthy subjects. Concentrations of growth hormone (GH), prolactin (PRL) and cortisol were analyzed in plasma. PRL release after thyreoliberin stimulation (TRH, 200 g, i.v.) was determined in 21 patients with active forms of RA and in 12 control subjects to evaluate pituitary lactotropic response. In RA patients, basal concentrations of glucose, GH, PRL, and cortisol were in the normal range and they were comparable to those in the control group. Stress of hypoglycemia induced significant elevation of GH, PRL, and cortisol concentrations in all groups. Cortisol responses to hypoglycemia were comparable in patients and in control subjects. GH release during hypoglycemia was increased (p < 0.05) and PRL response was attenuated (p < 0.05) in RA patients versus control subjects. After TRH administration, PRL response was the same in patients as in healthy subjects. In conclusion, the present study revealed an altered hypothalamic-pituitary function in patients with RA, namely, an enhanced somatotropic and reduced lactotropic activation in response to insulin-induced hypoglycemia. Basal hormone levels and cortisol release during hypoglycemia were similar to those in healthy subjects.

Effect of simulated microgravity on endocrine response to insulin-induced hypoglycemia in physically fit men

Adaptation to microgravity is associated with alteration in some endocrine functions. In the present longitudinal study, the counterregulatory hormonal response to insulin-induced hypoglycemia (ITT, 0.1 IU/kg short acting insulin i. v.) was evaluated under simulated microgravity conditions in 15 physically fit subjects. ITT was performed at the beginning of the investigation, and again after completion of 6 weeks of endurance training and after a subsequent period of 4 days of head-down bed rest at a backward tilt of 6 degrees from the horizontal. Endurance training showed a significant increase in maximal aerobic capacity in previously well-trained subjects (increase by 12 %), as well as on attenuation of counterregulatory response of epinephrine to hypoglycemia. After 4 days of bed rest, basal concentrations of plasma norepinephrine was diminished (p < 0.002) and plasma renin activity was enhanced (p < 0.02). After bed rest, decreased responses of the two catecholamines (norepinephrine, p < 0.001; epinephrine, p < 0.001), growth hormone (p < 0.001), and cortisol (p < 0.05) were observed. Response of plasma renin activity after bed rest was increased (p < 0.01). This longitudinal study indicated that 4 days of bed rest in endurance-trained subjects induced increased response of PRA to hypoglycemia and attenuation of other counterregulatory neuroendocrine responses.

Endocrine activation in tachycardias

This article reviews the complex character of neuroendocrine response to paroxysmal tachycardia. While the endocrine influences in arrhythmogenesis are well perceived by the cardiologists, less attention has been paid to influence of tachycardia on neuroendocrine activation. However, this may significantly alter the clinical course of tachycardias and its responses to pharmacotherapeutic interventions. Main characteristics of hormones with direct relationship to cardiovascular system (ANP, AVP, catecholamines, angiotensin and others) are listed with description of regulation of their secretion and main biological effects, especially with regard to regulation of circulation. Changes in hemodynamics during tachycardia with accompanying changes in ANP, AVP renin-angiotensin-aldosterone system, sympatho-neural and sympatho-adrenal activation are reviewed. Further research and understanding require more complex approach and concentration on interrelationship of different regulatory hormones in tachycardia. (Fig. 2, Ref. 96.)

Effect of microgravity on plasma catecholamine responses to stressors during space flight

The effect of microgravity on the sympathicoadrenal system (SAS) activity in humans and animals has not yet been clarified. Our previous studies suggested that the SAS activity, evaluated by circulating and/or urinary catecholamine (CA) levels in astronauts during space flights, was found to be rather unchanged. However, CA levels were measured in astronauts only at rest conditions. The aim of the present study was to investigate effect of microgravity during space flight and post-flight readaptation on responsiveness of the SAS to somatic and psychic stressors evaluated by levels of catecholamines and their metabolite in the blood of the Slovak cosmonaut during his stay on board the space station Mir.

Plasma hormone levels in human subject during stress loads in microgravity and at readaptation to Earth's gravity

In great part of the investigations of endocrine system functions in astronauts during space flights the plasma levels of hormones and metabolites were determined only in resting conditions, usually from one blood sample collection. Such levels reflected the psychical and physical state and new hormonal homeostasis of organism at the time of blood collection, however, the functional capacity of neuroendocrine system to respond to various stress stimuli during space flight remained unknown. The aim of present investigations was to study dynamic changes of hormone levels during the stress and metabolic loads (insulin induced hypoglycemia, physical exercise and oral glucose tolerance test) at the exposure of human subject to microgravity on the space station MIR. The responses of sympatico-adrenomedullary system to these stress and workloads were presented by Kvetnansky et al.

Prolactin levels and autoantibodies in female patients with systemic lupus erythematosus

We investigated the relationships between prolactin (PRL) levels and antibody occurrence in systemic lupus erythematosus (SLE). No significant association between PRL levels and the majority of the autoantibodies studied (anti-U1 RNP, anti-rRNP, anti-Sm, anti-dsDNA, anti-DNP, auto-LCA, anti-EACA) could be confirmed (P > 0.05), anti-Ro/SSA antibodies being an exception. Our results showed significantly increased frequencies of these antibodies in the group of female SLE patients with normal PRL levels (< 20 micrograms/L): anti Ro/SSA in 53% (P < 0.025, chi 2 = 5.80, RR = 4.0) and anti-Ro/SSA + anti-Ro/La in 60% (P < 0.05, chi 2 = 4.05) compared with female SLE patients with hyperprolactinemia.

Effect of hyperthermic water bath on parameters of cellular immunity

Effects of hyperthermic water bath on selected immune parameters (lymphocyte subpopulations, natural killer (NK) cell counts and their activity) were studied in a group of 10 volunteers. Application of hyperthermic water bath (both topical and whole-body) was followed by a significant reduction of relative B lymphocyte counts. Whole-body hyperthermic water bath reduced relative total T lymphocyte counts, increased relative CD8+ T lymphocyte and NK cell counts and increased NK activity. Whole-body hyperthermic bath increased somatotropic hormone (STH) activity in eight out of 10 volunteers; higher relative counts of CD8+ lymphocytes and NK cells were observed compared with the group of volunteers not responding to hyperthermic water bath by STH secretion. In five volunteers STH was released in response to local hyperthermic water bath and the NK activity of lymphocytes also increased but their relative counts did not. The results suggest that these increases in CD8+ lymphocyte and NK cell counts are probably dependent on increased STH production.

Insulin, catecholamines, glucose and antioxidant enzymes in oxidative damage during different loads in healthy humans

Exercise, insulin-induced hypoglycemia and oral glucose loads (50 g and 100 g) were used to compare the production of malondialdehyde and the activity of antioxidant enzymes in healthy subjects. Twenty male volunteers participated in the study. Exercise consisted of three consecutive work loads on a bicycle ergometer of graded intensity (1.5, 2.0, and 2.5 W/kg, 6 min each). Hypoglycemia was induced by insulin (Actrapid MC Novo, 0.1 IU/kg, i.v.). Oral administration of 50 g and 100 g of glucose was given to elevate plasma glucose. The activity of superoxide dismutase (SOD) was determined in red blood cells, whereas glutathione peroxidase (GSH-Px) activity was measured in whole blood. The concentration of malondialdehyde (MDA) was determined by HPLC, catecholamines were assessed radioenzymatically and glucose was measured by the glucose-oxidase method. Exercise increased MDA concentrations, GSH-Px and SOD activities as well as plasma noradrenaline and adrenaline levels. Insulin hypoglycemia increased plasma adrenaline levels, but the concentrations of MDA and the activities of GSH-Px and SOD were decreased. Hyperglycemia increased plasma MDA concentrations, but the activities of GSH-Px and SOD were significantly higher after a larger dose of glucose only. Plasma catecholamines were unchanged. These results indicate that the transient increase of plasma catecholamine and insulin concentrations did not induce oxidative damage, while glucose already in the low dose was an important triggering factor for oxidative stress.

Role of body temperature in exercise-induced growth hormone and prolactin release in non-trained and physically fit subjects

OBJECTIVE

To study the role of physical fitness and hyperthermia in inducing growth hormone (GH) and prolactin (PRL) responses to exercise in physically fit and in non-trained healthy subjects.

METHODS

Ten wrestlers preparing for international competition (mean age 19), and nine untrained healthy males (mean age 21), volunteered in the study. They were exposed twice to the exercise consisting of 27 min swimming, freestyle, in water of 29 or 36 degrees C, with last 3 min increased to maximal effort. Measurement of blood pressure, heart rate, sublingual temperature and sampling of blood was performed before exercise, immediately after and after a 30-min period of rest.

RESULTS

Body temperature, heart rate, systolic blood pressure and plasma growth hormone (GH) were significantly elevated in both groups after swimming in water of either temperature (P < 0.01). The difference between GH responses to swimming in water of 29 degrees C vs 36 degrees C was significant only in non-trained subjects and was associated with the changes of body temperature. A rise in PRL concentration was found only in exercise in warmer water (P < 0.01). There were no statistical differences between athletes and controls in any response to swimming in water of the same temperature.

CONCLUSIONS

The augmented release of GH and PRL was the result of direct stimulation by increased body temperature.

Changes of serum TSH level during oral glucose tolerance test: comparison of morning and evening test with plain circadian TSH rhythm

OBJECTIVE

To compare the changes of TSH level in serum during oral glucose tolerance test (OGTT) with those resulting from a plain circadian rhythm and, in addition, to compare such changes between the morning and evening hours.

METHODS

Oral glucose tolerance tests were performed in groups of 8-20 adults after the oral administration of glucose (75 g in 400 ml tap water) at 8.00, 10.00 and 20.00 h. Blood samples for the estimation of TSH (supersensitive IRMA method) were taken in 30 min intervals for following 3 hours. In the same groups of subjects the blood samples were obtained between 8.00 and 13.00 h or between 20.00 and 23.00 h one week later for the assessment of plain circadian rhythm of TSH levels.

RESULTS

The level of TSH in a group subjected to OGTT at 8.00 h was significantly decreased (P<0.05) between 8.30 and 10.30 h, i.e. 30-150 min after glucose administration which was parallel to the circadian decrease found in the same subjects. However, this was followed by an increase of TSH up to the original level reached at 11.00 h which was contrasting to a circadian decrease. Similar pattern was found also when OGTT was started at 10.00 h. In a group subjected to the evening OGTT at 20.00 h similar decrease of TSH level was found at 21.00 h which was contrasting to the circadian increase. However, this was followed by a remarkable increase of TSH level between 21.00 and 23.00 h which was parallel to the circadian trend, but much more abrupt than that found without the previous administration of glucose.

CONCLUSIONS

In both the morning and evening OGTT a decrease of TSH level was found between 30 and 90 min after glucose administration which was followed by an increase between 90 and 180 min after that. The decrease during the morning test was parallel to the circadian trend, while the increase was opposite to that. However, an inverse figure was found in the evening test, the decrease of TSH being opposite and following increase being parallel to the circadian trend.