Metabolic effects of testosterone during prolonged physical exercise and fasting

Summary Previous studies have shown a decrease in plasma testosterone during prolonged physical exercise and 72 h fasting in rats.To determine whether this hormonal change has an influence upon energy metabolism, two experiments were carried out, in which the plasma levels of testosterone were elevated during prolonged physical exercise and fasting in male wistar rats.The effects of acute and chronic increases in the levels of circulating testosterone were studied, on the one hand after human chorionic gonadotropin (H.C.G.) injection, and on the other by prolonged testosterone perfusion with an osmotic minipump. Blood and tissue sampling were performed to evaluate blood glucose, alanine, and lactate, and tissue glycogen. The results in fed and rest control rats showed no changes in blood parameters under the effect of hypertestosteronemia but there was an increase in muscle glycogen after testosterone perfusion.In 72 h fasted rats both types of hypertestosteronemia were associated with a decrease in blood alanine and lactate ranging from 25% to 35%. Only testosterone perfusion was associated with higher concentrations of muscle glycogen.After 7 h of treadmill running, testosterone perfusion and H.C.G. injection induced a 35% decrease in blood alanine and a slight decrease in blood glucose, with no change in other parameters.Whereas an elevation in the level of testosterone can induce muscle glycogen compensation in the fed resting state, it cannot counteract the exhaustion of muscle glycogen during running.     

Plasma renin activity and serum aldosterone during prolonged physical strain

Summary Plasma renin activity (PRA), serum aldosterone and the serum and urinary levels of sodium and potassium have been investigated in 24 young men participating in a 5-day military training course with heavy continuous physical exercise, energy and sleep deprivation. The subjects were divided into three groups. Group 1 did not get any extra sleep or food, group 2 were compensated for the energy deficiency, and group 3 slept 3 h each night. The basic diet given to all the subjects was about 5,000 kJ and 2 g NaCl·24 h^–1·cadet^–1. The high calorie diet contained approximately 25,000–35,000 kJ and 20 g of NaCl·24 h^–1·cadet^–1.The study showed that serum aldosterone and PRA were extremely activated during such prolonged physical strain combined with lack of food and salt, whereas sleep deprivation did not seem to have any large influence. Only small variations were found in the serum levels of sodium and potassium and the urinary level of potassium during the course, whereas a decrease was seen in urinary sodium concentration. The fairly good correlations between the decrease in urinary sodium levels and the increase in PRA (r=0.7) and further between PRA and serum aldosterone (r=0.8) during the course indicate that there is a causal connection between the decrease in urinary sodium excretion and the increase in PRA and serum aldosterone. An increased response was seen during a short term exercise test in groups 1 and 3, whereas no such increase was seen in the subjects of group 2, probably because the higher salt intake abolishes the renin-aldosterone response to exercise. In spite of high catecholamine levels during the course, the serum potassium response to physical exercise was unchanged. The circulating catecholamines did not seem to have any significance for renin secretion and sodium reabsorption during the course. Further, there was no sign of exhaustion in Na/K homeostasis during the experiment.     

Urinary excretion of electrolytes during prolonged physical activity in normal man

Summary Nine normal young male students were studied during 2 days of relative rest, during 2 days of physical training and again during the succeeding 2 days of relative rest.Twenty-four hour urine collections showed that sodium and potassium excretion were lower during the exercise days, while urinary aldosterone excretion was increased. No differences in the 24-h urinary excretion of creatinine, calcium, and magnesium were found between the resting and exercise days.Hemoglobin concentration, hematocrit and red cell counts were decreased at 14 h and 42 h after exercise; these findings together with the increased serum bilirubin concentration could result from hemolysis.Plasma renin activity, angiotensin II and aldosterone concentration were increased 14 h after exercise but returned to baseline 42 h after exercise.Our data shows that one should take into account previous exercise when interpreting results of certain of these tests.     

Decreased serum levels of oestradiol,testosterone and prolactin during prolonged physical strain and sleep deprivation,and the influence of a high calory diet

Summary The changes in oestradiol, testosterone and prolactin, and the effects of a high calory diet, were investigated in eleven young male cadets participating in a 5 days' ranger training course involving heavy and continuous physical activities with less than 1500 kcal·day^–1 and almost without sleep.Prolactin decreased continuously during the first 24 h to 25% of precourse values. Testosterone decreased during the day time and reached below 25% of precourse values after 48 h. Oestradiol did not change during the first 48 h but then decreased to about 50% of precourse values. In conclusion, oestradiol, testosterone and prolactin are strongly reduced during prolonged strain. These changes were not reversed by a high calory diet.     

Effects of prolonged physical exercise and fasting upon plasma testosterone level in rats

Summary Prolonged physical exercise and fasting in male rats were studied to determine the effect of these two treatments on plasma testosterone level. Blood and tissue samples were drawn after 1 h, 3 h, 5 h, and 7 h treadmill running, and after 24 h, 48 h, and 72 h of fasting. Both treatments resulted in a significant fall in plasma testosterone, plasma luteinizing hormone (LH), plasma Insulin (IRI) and in liver and muscle glycogen stores. In the course of these two treatments the injection of a supra maximal dose of Human Chorionic Gonadotropin (HCG) produced a rise in plasma testosterone similar to that in control rats. This indicates that the decrease of plasma LH may be responsible for the decrease in plasma testosterone, which is time-related with the decrease in glycogen stores. The possible metabolic role of the decrease in plasma testosterone is discussed.     

Oxidation of exogenous carbohydrate during prolonged exercise: the effects of the carbohydrate type and its concentration

Summary We studied rates of exogenous carbohydrate (CHO) oxidation during 90 min of cycling exercise in trained cyclists exercising at 70% of maximal oxygen consumption (VO_2max) when they ingested glucose, sucrose, or glucose polymer solutions at concentrations of 7.5%, 10% or 15%. Drinks were labelled with [U-¹⁴C]glucose or sucrose and were ingested at a rate of 100 ml · 10 min^–1. Rates of oxidation of the ingested CHO were calculated from the specific radio-activity of the labelled CHO, expired¹⁴CO₂ and carbon dioxide output (VCO₂). Total CHO oxidation, determined from oxygen consumption andVCO₂ was not influenced by CHO type or concentration. Gastric emptying (P=0.01) and the rate of exogenous CHO oxidation (P=0.028) was greatest for the glucose polymer solutions, and least for glucose. Although gastric emptying (P=0.006) decreased with increasing CHO concentration, CHO delivery to the intestine and exogenous CHO oxidation increased linearly with increasing CHO concentration. The percentage of the CHO delivered to the intestine that was oxidized ranged from 30.0% for 7.5% CHO to 38.1% for 15% CHO. Our results indicated that the rate of gastric emptying for CHO was not controlled to provide a constant rate of energy delivery as is commonly believed and that factors subsequent to gastric emptying limit the rate of exogenous CHO oxidation from the ingested solution.     

Interaction of apolipoproteins A-I and E in the regulation of DNA,RNA, and protein biosynthesis in cultured rat hepatocytes

Experiments on hepatocyte culture showed that apolipoprotein A-I—tetrahydrocortisol complex increases the rate of DNA, RNA, and protein biosynthesis measured by radioactive label incorporation. Apolipoprotein E acted as competitor of the apolipoprotein A-I—tetrahydrocortisol complex and abolished biological activity of the latter. We hypothesize that this mechanism of regulation plays an important role in processes of intracellular regeneration and proliferation. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 144, No. 12, pp. 629–631, December, 2007     

Modifications of serum glycoproteins the days following a prolonged physical exercise and the influence of physical training

Summary Eight male subjects (mean age 24.1±2.6 years) performed at intervals of 2 weeks successively a 3 h and two 2 h runs of different running speed. The days following the running there were moderate elevations of C-reactive protein, haptoglobin, alpha-1-acid glycoprotein, coeruloplasmin, transferrin, alpha-1-antitrypsin and plasminogen. There were small or no changes of albumin, alpha-2-macroglobulin and hemopexin. The elevations of the acute phase reactants were examined in three male subjects following a 2 h run before and after an endurance training period of 9 weeks. This demonstrated a decreased acute phase response after training as illustrated by the changes of C-reactive protein, haptoglobin and alpha-1-acid glycoprotein in spite of higher posttraining running speeds. Well-trained athletes have elevated levels of the serum protease inhibitors alpha-1-antitrypsin, alpha-2-macroglobulin and C₁-inhibitor. These antiproteolytic glycoproteins might limit exercise-induced inflammatory reactions.This research was supported by the Bundesinstitut für Sportwissenschaften (Köln-Lövenich)     

The effect of a high calory diet on hormonal changes in young men during prolonged physical strain and sleep deprivation

Summary Major changes occur in the serum level of several hormones during 5 days of heavy and continuous physical activities, with less than a total of 2 h of sleep. The present investigation was designed to evaluate the importance of caloric deficiency, energy requirement being about 8,000–10,000 kcal/24 h. A comparison between well fed subjects and those with food deprivation revealed significantly higher levels of (T₃) triiodothyronin, insulin and thyroid stimulating hormone (TSH) in the well-fed subjects, who also had lower levels of growth hormone (hGH) and cortisol, whereas no difference was found between the two groups for thyroxin (T₄). Increased levels were found for T₃ and T₄ in both groups during the first day of activity, with a concomitant decrease in TSH and a subsequent decrease of T₄ during the next 2 days. T₃ decreased only in the low-calory group whereas increased levels were found in the iso-calory group throughout the course. The resting levels of insulin decreased during the course in the low-calory group whereas it increased in the iso-calory group. High levels were maintained throughout the course for hGH. Cortisol showed high levels just before the start of the course and then decreased from day 2 to day 4. No difference was found between the morning and evening levels for cortisol, indicating disappearance of the circadian rhythm. The present investigation has shown that energy deficiency during prolonged physical strain is responsible for the decreased serum levels of T₃ and insulin and may contribute to the decrease in TSH and the increase in hGH and cortisol.     

Beta-blocker induced changes in the cholesterol: High-density lipoprotein cholesterol ratio and risk of coronary heart disease

Summary The lowering of blood pressure with beta-blocking drugs has had a low impact on coronary heart disease (CHD) mortality and the question has been raised whether adverse changes in plasma lipoproteins offset the benefits of blood pressure reduction. Comparison of plasma lipoprotein concentrations in hypertensive patients treated with commonly used beta-blockers with lipoprotein concentrations in patients with coronary heart disease shows that these drugs cause clinically important shifts in the cholesterol ratio [total cholesterol (TC): high-density lipoprotein cholesterol (HDLC)] and reductions in the atheroprotective lipoprotein HDLC. The magnitude of these changes is sufficient to increase the risk of heart attack two- to four-fold depending on the initial cholesterol ratio and the duration of treatment. Only beta-blockers with marked intrinsic sympathomimetic agonist activity (pindolol) or combined alpha-beta-blocking properties (Labetalol) appear free of adverse effects on plasma lipoproteins and triglycerides. Chronic treatment with other betablockers should be accompanied by cholesterol and HDLC measurements at the beginning of therapy. Plasma lipoprotein measurements at 3–6 month intervals seem mandatory in patients with cholesterol values greater than 6 mmol/l (230 mg/dl) and (TC):HDLC ratios above 5 at the start of treatment. The risk of a coronary event must be regarded as unacceptable when the cholesterol ratio exceeds a critical value of about 6. Further controlled studies are needed to evaluate the effects of beta-blockers in hypertension when administered for periods of up to a year or more. More information is required on the behaviour of lipoprotein subspecies and apoproteins. Since the changes in lipoproteins reported in studies referred to in this review may have been submaximal the risks and the benefits from beta-blocker therapy must be carefully considered.     

The effects of dietary manipulation upon the respiratory exchange ratio as a predictor of maximum oxygen uptake during fixed term maximal incremental exercise in man

Summary This study examined the effects of dietary manipulation upon the respiratory exchange ratio ( ) as a predictor of maximum oxygen uptake ( ). Seven healthy males performed fixed term maximal incremental treadmill exercise after an overnight fast on three separate occasions. The first test took place after the subjects had consumed their normal mixed diet (45±5% carbohydrate (CHO)) for a period of three days. This test protocol was then repeated after three days of a low CHO diet (3±2% CHO), and again after three days of a high CHO diet (61±5% CHO). Respiratory gases were continuously monitored during each test using an online system. No significant changes in mean exercise oxygen uptake ( ), or maximum functional heart rate (FHR_max) were found between tests. Mean exercise carbon dioxide output ( ) and R were significantly lower than normal after the low CHO diet (bothp<0.001) and significantly higher than normal after the high CHO diet (bothp<0.05). Moreover, compared with the normal CHO diet, the R-time relationship during exercise was at all times significantly (p<0.001) shifted to the right after the low CHO diet, and shifted to the left, being significantly so (p<0.05) over the final 5 min of exercise, after the high CHO diet. As a result, predictions of based on the R-time relationship were similar to recorded after the normal CHO dietary condition (-1.5±1.9%), but higher after the low CHO diet (+14.8±3.9%,p<0.001) and lower after the high CHO diet (–7.0±4.5%,p<0.01). These results indicate that dietary manipulation can significantly affect respiratory gas exchanges during fixed term maximal incremental exercise, and by doing so can significantly influence predictions of based on R.     

Progesterone serum levels during the follicular phase of the menstrual cycle originate from the crosstalk between the ovaries and the adrenal cortex

BACKGROUND: The preovulatory rise of progesterone is important for ovulation, but both its regulation and its origin are controversial. Three experiments were performed to determine whether follicular phase progesterone arises from the ovary, the adrenal cortex or both. METHODS: The first study was performed in patients scheduled for assisted reproduction, who received a long-acting GnRH agonist either during intake of an oral contraceptive or during the luteal phase of an otherwise untreated menstrual cycle. The second study was also performed during down-regulation with a GnRH agonist: some patients with elevated progesterone levels received dexamethasone (DXM). Others with similarly elevated basal progesterone levels and those with low progesterone levels were not treated with DXM and served as controls. Finally, adrenocorticotrophic hormone (ACTH) tests were performed in normocyclic volunteers both during early and late follicular phase and during intake of a contraceptive pill. RESULTS: During the suppression of endogenous gonadotrophin secretion progesterone levels rose after the administration of ACTH, but not of GnRH. DXM did not prevent the preovulatory rise of the serum progesterone concentration. The ACTH-stimulated concentration of progesterone and of 17alpha-hydroxyprogesterone were significantly reduced during intake of ethinyl estradiol. CONCLUSIONS: Progesterone arises in the adrenal cortex during most of the follicular phase, whereby its function is modulated by an unknown ovarian factor, which is suppressed by ethinyl estradiol. The source of progesterone shifts towards the ovaries prior to ovulation.     

Behaviour of saliva cortisol [C], testosterone [T] and the T/C ratio during a rugby match and during the post-competition recovery days

Competition is a more demanding situation than other strenuous exercise of equivalent duration; it results in stronger physiological changes. The object of this study was to get information on the duration of the recovery period by measuring changes of saliva cortisol [C], testosterone [T] and their ratio T/C in a group of international rugby players (n=20) during the week following a rugby match (6 days). Using non-invasive saliva assays, we were able to take samples during the day of competition and the post-competitive days. Hormone levels were assayed with a routine in-house radioimmunoassay (RIA) method. Throughout the competition, C levels increased sharply (about 2.5-fold compared resting values) and returned to basal values within 4 h. Conversely, the T level decreased slightly. During the recovery period, C levels were lower and T levels were higher than basal values, resulting in a very high T/C ratio until the 5th day. This high post-competitive T/C ratio phase is probably required to restore the break-down of homeostasis induced by the very hard mental and physical strain associated with a rugby match. Thus, a period of 1 week recovery appears to be the minimal duration between two competitions.     

High interindividual variability in the CD4/CD8 T cell ratio and natalizumab concentration levels in the cerebrospinal fluid of patients with multiple sclerosis

Strongly decreased leucocyte counts and a reduced CD4/CD8 T cell ratio in the cerebrospinal fluid (CSF) of natalizumab (NZB)‐treated multiple sclerosis (MS) patients may have implications on central nervous (CNS) immune surveillance. With regard to NZB‐associated progressive multi‐focal leucoencephalopathy, we aimed at delineating a relationship between free NZB, cell‐bound NZB, adhesion molecule (AM) expression and the treatment‐associated shift in the CSF T cell ratio. Peripheral blood (PB) and CSF T cells from 15 NZB‐treated MS patients, and CSF T cells from 10 patients with non‐inflammatory neurological diseases and five newly diagnosed MS patients were studied. Intercellular adhesion molecule‐1 (ICAM‐1), leucocyte function antigen‐1 (LFA‐1), very late activation antigen‐4 (VLA‐4), NZB saturation levels, and T cell ratios were analysed by flow cytometry. NZB concentrations were measured by enzyme‐linked immunosorbent assay (ELISA). Lower NZB saturation levels (P < 0·02) and a higher surface expression of ICAM‐1 and LFA‐1 (P < 0·001) were observed on CSF CD8 T cells. CSF T cell ratios (0·3–2·1) and NZB concentrations (0·01–0·42 µg/ml) showed a pronounced interindividual variance. A correlation between free NZB, cell‐bound NZB or AM expression levels and the CSF T cell ratio was not found. Extremely low NZB concentrations and a normalized CSF T cell ratio were observed in one case. The differential NZB saturation and AM expression of CSF CD8 T cells may contribute to their relative enrichment in the CSF. The reduced CSF T cell ratio appeared sensitive to steady‐state NZB levels, as normalization occurred quickly. The latter may be important concerning a fast reconstitution of CNS immune surveillance.     

Modifying effect of the AR gene trinucleotide repeats and SNPs in the AHR and AHRR genes on the association between persistent organohalogen pollutant exposure and human sperm Y:X ratio

Persistent organohalogen pollutants (POPs) have been suggested to be involved in changing the proportion of ejaculated Y-bearing sperm. The androgen receptor (AR), aryl hydrocarbon receptor (AHR) and aryl hydrocarbon receptor repressor (AHRR) may modulate the effect of POPs with regard to previously observed sperm Y:X ratio changes. The objective of this study was to investigate whether sperm Y:X ratio changes in subjects exposed to 2,2'4,4'5,5'-hexachlorobiphenyl (CB-153) and dichlorodiphenyl dichloroethene (p,p'-DDE) were modified by polymorphisms in the AR, AHR and AHRR genes. Semen for analysis of Y- and X-bearing sperm by two-colour fluorescence in situ hybridization and blood for leukocyte DNA genotyping and analysis of CB-153 and p,p'-DDE concentrations were obtained from 195 Swedish fishermen. The polymorphic CAG and GGN repeats in the AR and the R554K and P185A single-nucleotide polymorphisms in the AHR and AHRR genes, respectively, were determined by direct sequencing and allele-specific PCR. The effect of p,p'-DDE was modified by CAG or GGN repeat category in relation to the proportion of Y-bearing sperm (P = 0.005 and 0.02 for CAG and GGN, respectively). Moreover, p,p'-DDE, but not CB-153, levels were associated with Y-sperm proportion in men with CAG < 22 (P < 0.001), but not in those carrying CAG > or = 22 (P = 0.73). This association was even more pronounced in subjects carrying a short CAG repeat in combination with an AHRR G-allele. The association in regard to p,p'-DDE was found for GGN = 23 but not for the GGN < 23 or GGN > 23 subgroups (P = 0.01, 0.44 and 0.99, respectively). In conclusion The endocrine-disrupting action of POPs, in relation to the observed changes in sperm Y:X ratio, may be modulated by the genes involved in sex steroid and dioxin-mediated pathways.     

The impact of joint angle and movement velocity on sex differences in the functional hamstring/quadriceps ratio

Background

Females are two to eight times more likely to suffer a non-contact injury compared with males thus the purpose of this study was to explore the influence of joint angle and movement velocity on sex differences in the functional hamstring to quadriceps ratio (H/Q_FUNC).

超声与血清t-PSA和f-PSA／t—PSA比值对前列腺癌诊断的价值

目的探讨血清总前列腺特异性抗原（t-PSA）、游离前列腺抗原／总前列腺抗原（f-PSA／t-PSA）比值与超声联检对前列腺癌（PCa）的诊断价值。方法将38例经手术和病理证实的PCa患者与45例前列腺增生（BPH）患者和40名正常人的t-PSA、f-PSA／t-PSA比值检测结果进行对比。并和超声联检结果进行分析。结果PCa患者血清t-PSA含量显著高于其它两组,差异有统计学意义（P〈0．01）。t-PSA和f-PSA／t-PSA比值作为单一指标应用于诊断PCa时,灵敏度分别为47．37％、73．68％,准确性分别为51．8l％、71．08％,与超声影像学三者联检,诊断PCa的灵敏度为94．73％,特异性为95．56％,准确性为95．18％。三者联检均高于其单检的敏感性,差异有统计学意义（P〈0．01）。结论t-PSA、t-PSA／foPSA是诊断PCa的较好指标。血清t-PSA、t-PSA／f—PSA比值和影像学联检可大大提高对PCa的诊断率,对PCa患者早期诊断、早期治疗和监控有重要作用。