Both zinc deficiency and supplementation affect plasma melatonin levels in rats

At physiological levels, zinc and various hormones affect each other reciprocally. Reduction in zinc levels in pinealectomized rats suggests the relation between zinc and melatonin. The effect of both zinc deficiency and supplementation on plasma melatonin levels in rats were investigated in this study. The study was done in Sel?uk University, Experimental Medicine Research and Application Center. Twenty-four adult male Sprague Dawley rats were divided into 3 groups. Eight rats were fed with zinc-deficient diet. Zinc supplementation was administered intaperitoneally to 8 rats. The remaining 8 rats were used as controls. All rats sacrificed 3 weeks later. Plasma melatonin and zinc levels were determined. The plasma zinc levels of the zinc-supplemented group were higher than those of the other groups as expected (P<0.01). Similarly, the melatonin levels in the zinc-supplemented group were higher than those in the other groups. A significant decrease was observed in melatonin levels of the zinc-deficient group compared to the control and zinc-supplemented group (P<0.01). The results of this study suggest that zinc deficiency decreases the melatonin levels and zinc supplementation may increase the plasma melatonin levels in rats.     

Serum leptin concentration and its effect on puberty in Naqu Tibetan adolescents

This study aimed to clarify the regularity of leptin in Naqu Tibetan adolescents. This study investigated the concentration of fasting serum leptin and clarified its relationship between BMI and other indices. Healthy Naqu Tibetan adolescents aged 12-18 were investigated randomly in the study. They were divided into seven groups (each year as one group, 12 boys and 12 girls in each group); serum concentrations of leptin, estradiol, testosterone (T), follicle stimulating hormone (FSH) and luteinizing hormone (LH) were analyzed. The height and body weight of the 168 healthy Naqu Tibetan adolescents were also assessed. The leptin level in boys decreased with age but increased in girls; in boys and girls they both differed between groups (p<0.05). In boys, the leptin level was inversely correlated with body mass index (BMI), FSH, and T (p<0.05), while in girls, it was positively related to BMI, FSH, LH, and E2 (p<0.01).These findings suggested that during puberty the serum leptin concentration increased with age in girls while it decreased in boys; in the same age group, the leptin level in girls was significantly higher than in boys. Leptin may have some relationship with puberty in Tibetan adolescents.     

Effect of zinc supplementation on the distribution of various elements in the serum of diabetic rats subjected to an acute swimming exercise

The present study aims to examine the effect of supplementation of zinc on the distribution of various elements in the sera of diabetic rats subjected to an acute swimming exercise. A total of 80 Sprague–Dawley-type adult male rats were equally allocated to one of eight groups: Group 1, general; Group 2, zinc-supplemented; Group 3, zinc-supplemented diabetic; Group 4, swimming control; Group 5, zinc-supplemented swimming; Group 6, zinc-supplemented diabetic swimming; Group 7, diabetic swimming; and Group 8, diabetes. The rats were injected with 40 mg/kg/day subcutaneous streptozotocin (STZ) twice, with a 24-h interval between two injections. Zinc was supplemented at a dose of 6 mg/kg/day (ip) for 4 weeks. Blood samples were collected at the end of the 4-week study, and serum levels of lead, cobalt, molybdenum, chrome, sulfur, magnesium, manganese, sodium, potassium, phosphorus, copper, iron, calcium, zinc, and selenium (mg/L) were determined with atomic emission. The lowest molybdenum, chrome, copper, iron, potassium, magnesium, sodium, phosphorus, lead, selenium, and zinc values were obtained in Group 7 and 8. These same parameters were higher in the swimming exercise group (Group 4), relative to all other groups. The values in zinc-supplemented groups were found lower than the values in Group 4, but higher than those in Group 6 and 7. The results obtained from the study demonstrate that acute swimming exercise and diabetes affect the distribution of various elements in the serum, while zinc supplementation can prevent the negative conditions associated with both exercise and diabetes.     

Effects of zinc deficiency and supplementation on malondialdehyde and glutathione levels in blood and tissues of rats performing swimming exercise

The aim of the study was to investigate the effects of zinc deficiency and supplementation on lipid peroxidation and glutathione levels in blood and in some tissues of rats performing swimming exercise. Forty adult male Sprague-Dawley rats were divided into four groups: group 1, zinc-deficient consisted of swimming rats; group 2 consisted of zinc-supplemented swimming rats; groups 3 and 4 were the swimming and nonswimming controls, respectively. The levels of malondialdehyde and glutathione were measured after 4 wk of zinc-deficient or zinc-supplemented diet and 30 min of swimming exercise daily. The erythrocyte glutathione levels of groups 2 and 4 were significantly higher than those of groups 1 and 3 (p<0.01). The plasma malondialdehyde level of group 1 was significantly higher than all other groups. The glutathione levels in liver, kidney, striated muscle, and testes of group 2 were higher than in the other groups (p<0.01) and higher in kidney and striated muscle of group 3 than in groups 1 and 4 (p<0.01). The tissue malondialdehyde levels of striated muscle, liver, kidney, and testes of group 1 were significantly higher than for all other groups (p<0.01). Our findings suggest that both swimming exercise and zinc deficiency result in an increase of lipid peroxidation in tissues and that zinc supplementation prevents these alterations by the activation of the antioxidant system.     

Age, insulin, SHBG and sex steroids exert secondary influence on plasma leptin level in women

AIM: As the link between body fat and leptin is well known, the aim of the study was to seek for secondary regulators of plasma leptin level. PATIENTS: 86 women (mean: age 47.0+/-14.3 years; estradiol 50.0+/-60.6 ng/l; FSH 52.4+/-42.9 IU/l; BMI 26.9+/-5.9) divided into three groups according to their BMI. Group A: 39 normal weight women (mean: age 44.4+/-16.0 years; estradiol 69.6+/-79.8 ng/l; FSH 50.4+/-47.7 IU/l; BMI 22.9+/-1.3). Group B: 27 overweighted women (mean: age 55.0+/-6.4 years; estradiol 25.1+/-17.2 ng/l; FSH 75.6+/-26.3 IU/l; BMI 27.7+/-1.6). Group C: 21 obese women with mean: age 48.7+/-12.2 years; estradiol 36.9+/-44.0 ng/l; FSH 42.3+/-36.6 IU/l and BMI 34.6+/-4.9. METHODS: Standard clinical evaluation and hormone evaluation (LH, FSH, prolactin, estradiol, leptin, insulin-like growth factor-I (IGF-I), human growth hormone (hGH), insulin-like growth factor binding protein-3 (IGFBP-3), insulin, dihydroepiandrosterone sulphate (DHEAS), sex hormone binding globin (SHBG) and testosterone were done in basic condition which levels of were measured by RIA kits. Statistical analysis. Shapiro-Wilk test, Mann-Whitney-Wilcoxon u test, Spearman rank correlation coefficient and stepwise multiple regression: p values of 0.05 or less were considered as significant. RESULTS: Taking all women into account (n=86) the plasma leptin level correlated directly with age (r=0.32; p<0.02), body mass (r=0.60; p<0.001), BMI (r=0.71; p<0.001) as well as inversely with estradiol (r=-0.21; p<0.05), IGF-I (r=-0.24; p<0.05), SHBG (r=-0.34; p<0.01) and DHEAS (r=-0.30; p<0.01). However only in the group B leptin/age relation remained (r=0.40; p<0.05) after the division according to BMI. In the group B the leptin /DHEAS (r=-0.40; p<0.05) and leptin/PRL (r=0.51; p<0.05) links were also present. In the group C the leptin/SHGB relation (r=-0.56; p<0.02) only remained and an association between insulin and leptin was found (r=0.48; p<0.05). The body mass and BMI relation to age were again present only in all 86 women (r=0.30; p<0.002: r=0.36; p<0.001 resp.). Having split the women into groups, these links either disappeared or became inverse (rC=-0.39; p<0.05). Taking into consideration age/leptin relation in all women, the division according to the menopausal status revealed the direct relation in premenopausal women (n=29; r=0.43; p<0.02) and a reverse one in postmenopausal women (n=38; r=-0.32; p<0.05). The plasma leptin level was the highest (p<0.001) in group C (23.2+/-10.4 microg/l) and the lowest was found in the group A (8.9+/-4.1 microg/l). That corresponded with the differences in mean body mass index and mean body mass. The stepwise multiple regression revealed that body mass index accounted for 31% (p<0.001) and plasma SHBG level accounted for 17.7% (p<0.02) of plasma leptin variance in all women. In the group A body mass and age together accounted for 61% (p<0.01) and estradiol alone accounted for 44% (p<0.02) of plasma leptin variance. In the group B insulin alone accounted for 39% (p<0.05) and together with testosterone accounted for 46% (p<0.05) of plasma leptin variance. Finally in obese women none of the evaluated parameters significantly accounted for leptin variance. CONCLUSION: The results presented in this paper confirmed the strong influence of body fat mass on serum leptin concentration. However insulin, SHBG, sex steroids as well as age may also exert secondary influence on plasma leptin level in certain groups of women.     

Effect of Zinc Supplementation on Antioxidant Activity in Young Wrestlers

This study aims to examine the effect of zinc supplementation on free-radical formation and antioxidant system in individuals who are actively engaged in wrestling as a sport. The study registered a total of 40 male subjects, of whom 20 were wrestlers and 20 were sedentary individuals. The subjects were equally allocated to four groups: group 1, zinc-supplemented sportsmen group; group 2, sportsmen group without supplementation; group 3, zinc-supplemented sedentary group; group 4, sedentary group without supplementation. Blood samples were collected from all subjects twice, once at the beginning of the study and once again at the end of 8-week procedures. The blood samples collected were analyzed to determine the levels of malondialdehyde (MDA), serum glutathione (GSH), serum glutathione peroxidase (GPx) activity, serum superoxide dismutase (SOD) activity (ELISA colorimetric method) and zinc (colorimetric method). No difference was found between MDA levels of the study groups in the beginning of the study. The highest MDA value at the end of the study was obtained in group 4 (p < 0.01). MDA levels in group 2 were established to be significantly higher than those in groups 1 and 3 (p < 0.01). GSH level, GPx, and SOD activities and zinc level measured in the beginning of the study were not different between groups. Measurements performed at the end of the study showed that groups 1 and 3 (zinc-supplemented groups) had the highest GSH level, GPx, and SOD activities and zinc level (p < 0.01). These parameters were not different in the groups without supplementation (groups 2 and 4). Results obtained at the end of the study indicate that zinc supplementation prevents production of free radicals by activating the antioxidant system. In conclusion, physiologic doses of zinc supplementation to athletes may beneficially contribute to their health and performance.     

Effect of zinc deficiency and supplementation on lipid peroxidation of renal tissue in ovariectomized rats

The aim of this study was to investigate how zinc deficiency and supplementation affects lipid peroxidation in the renal tissue in ovariectomized rats. Four study groups were formed with 10 Spraque-Dawley rats each. Two of the groups served as normal and ovariectomized controls; the other two were ovariectomized rats that were zinc deficient and zinc supplemented, respectively. The zinc-deficient ovariectomized rats showed greater renal and plasma lipid peroxidation, as indicated by higher malondialdehyde levels than all other groups (p<0.05). These values were higher in the ovariectomized controls than those of the normal controls and of the ovariectomized, zinc-supplemented groups (p<0.05), which, in, turn, showed no significant differences of their respective renal and plasma malondialdehyde values. The renal and erythrocyte glutathione levels in the zinc-supplemented rats were higher than those in all other groups (p<0.05). The zinc-deficient group had the lowest renal and erythrocyte glutathione levels (p<0.05). The renal tissue zinc levels in the ovariectomized rats were higher than those in the zinc-deficient animals, but lower than in the normal controls and zincsupplemented rats (p<0.05). The zinc-supplemented animals had the highest renal tissue zinc levels (p<0.05). The results of this study suggest that zinc deficiency increases renal tissue damage in ovariectomized rats and that zinc supplementation can be used to prevent this condition.     

The influence of estradiole and tibolone administration on leptin levels in women with surgically induced menopause

Background: Several studies suggest that changes in estrogens and androgens during menopause play a role in the regulation of leptin production. Some authors present hypothesis that sex hormone replacement therapy can modulate leptin levels but up to date evidence shows that the influence of endogenous estrogens, androgens levels and sex hormone therapy on leptin concentration remains uncertain. Aim: To evaluate the influence of surgically induced menopause on serum leptin levels and the influence of different types of hormonal therapy on serum leptin concentrations. Methods: 58 women with surgically induced menopause were divided into three groups. Women who did not receive any hormonal substitution (group 1), women who received Estradiol l mg per day (group 2) and women who received Tibolone 2,5 mg per day (group3). The levels of leptin, estradiol, testosterone, testosterone, dehydroepiandrosterone sulfate, FSH, LH and progesterone were measured in all subjects on the 5th day and after 3 months following the surgical procedure. Results: Mean serum leptin concentrations did not differ statistically in any of the studied groups in the begining and in the end of the study. There was no correlations between serum leptin and estradiol, LH, FSH, progesterone, testosterone, free testosterone and DHEAS concentrations in any of groups before and after treatment. Conclusion: Changes in sex hormone concentrations caused by ovariectomy do not influence serum leptin concentrations. Also the short term administration of low dose estrogen therapy or tibolone in postmenopausal subjects does not change serum leptin levels.     

Pinealectomy and melatonin administration in rats: their effects on plasma leptin levels and relationship with zinc

The aim of this study was to examine effects of pinealectomy and melatonin administration plasma leptin levels and its relationship with zinc in rats. The study was conducted on 40 adult male Sprague-Dawley rats. They were divided into four groups each containing 10 animals. Group 1 served as control. Group 2 was pinealectomized group. Animals in Group 3 were pinealectomized and injected with melatonin (3 mg/kg/day, ip). Group 4 received melatonin alone (3 mg/kg/day, ip). At the end of the experiments, all animals were decapitated and trunk blood collected. Plasma leptin and zinc levels were determined by radioimmunoassay and Atomic Absorption Spectrophotometer methods, respectively. Although mean weights of the animals at the beginning were not significantly different among the groups, the mean weight of the pinealectomized group was found to be significantly lower than all other groups at the end of a six-month period (p < 0.01). Plasma leptin and zinc levels were the highest in melatonin-administered group (group 4; p < 0.01). The lowest plasma leptin and zinc levels were obtained in the pinealectomized group (group 2; p < 0.01). Changes in these two parameters were not statistically significant in groups 1 and 3. Our findings indicate that pinealectomy results in a decrease in leptin and zinc levels in rats, and that melatonin administration to pinealectomized rats prevents the decrease in the these parameters. In addition, long-term administration of melatonin to rats leads to an increase in both leptin and zinc concentrations.     

Possible involvement of inhibin in altered follicle-stimulating hormone (FSH) secretion during dissociated luteinizing hormone (LH) and FSH release: unilateral castration and experimental cryptorchidism

Male rats were either unilaterally or bilaterally castrated, or were rendered cryptorchid when they were either 15 or 45 days old. Subsequently, blood was sampled over the next several weeks and plasma luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (T), and immunoreactive inhibin-alpha (irI alpha) levels were measured by specific radioimmunoassays (RIAs). At the end of the experiment, gonadal expression of inhibin-alpha, inhibin-beta A, and inhibin-beta B subunits was measured by S1 nuclease analysis and in situ hybridization. In both age groups, bilateral castration (BC) produced the expected marked (p less than or equal to 0.01) increases in plasma LH and FSH levels, and concomitant decreases in T and irI alpha secretion within 1 - 2 days after surgery. In 15-day-old animals, unilateral castration (UC) significantly increased FSH and decreased circulating levels of irI alpha, but did not measurably alter LH or androgen production. At 7 days after surgery, the level of inhibin mRNA in the remaining testis was unchanged. In 45-day-old animals, UC caused a measurable increase in FSH, with little or no changes in the circulating levels of irI alpha. Plasma T levels were lowered (p less than or equal to 0.05) by UC; however, there were no statistical changes in LH levels in these UC rats. Finally, T administration markedly reversed UC-induced increase in FSH secretion in both age groups. Androgen therapy also interfered with inhibin release in 45-day-old, but not in 15-day-old rats. In rats 15 days old at the time of surgery, cryptorchidism produced a small but measurable increase (p less than or equal to 0.05) in LH release at Week 6 only, which was accompanied by a significant (p less than or equal to 0.01) decline in T secretion. Plasma FSH levels were elevated at all times in cryptorchid rats, and at 2, 4, and 6 wk, these levels were not statistically distinguishable (p greater than 0.05) from those of castrated animals. In this group of rats, cryptorchidism caused a transient increase (p less than or equal to 0.05) in irI alpha values 1 wk after surgery, but no changes at later times. Finally, measurement of testicular inhibin-alpha subunit messenger RNA (mRNA) levels showed an approximately 2-fold increase compared to total RNA levels in the testis. However, because of the significant decrease in total RNA levels per testis caused by cryptorchidism, the absolute change in inhibin-alpha subunit mRNA levels per testis corresponded to an approximately 3-fold decrease.(ABSTRACT TRUNCATED AT 400 WORDS)     

Content of Minerals and Fatty Acids and Their Correlation with Phytochemical Compounds and Antioxidant Activity of Leguminous Seeds

This study was carried out to determine the effect of zinc on oxidative DNA damage in rats with experimental acute and chronic kidney deficiency. Six groups of five Wistar-Albino rats each were assigned as controls (C), acute kidney deficiency (AKD), zinc-supplemented (+Zn), acute kidney deficiency, zinc-supplemented (AKD + Zn), chronic kidney deficiency (CKD) and zinc-supplemented chronic kidney deficiency (CKD + Zn). The levels of 8-Oxo-2′-deoxyguanosine (8-OHdG) were determined, being the lowest in the CKD group (p < 0.05), higher in the C group than those of rats with CKD but lower than that of all the other groups (p < 0.05). There were no significant differences between the controls and the CKD + Zn group, or between the AKD and the +Zn groups. Among all groups, the highest 8-OHdG level was found in the AKD + Zn group (p < 0.05). DNA damage was greater in acute renal failure than in rats with chronic renal failure. The DNA damage in the zinc group was significantly higher than in the controls.     

Effects of zinc deficiency and pinealectomy on cellular immunity in rats infected with Toxoplasma gondii

The effects of zinc and/or melatonin deficiencies on cellular immunity were investigated in rats infected with Toxoplasma gondii. A total of 50 adult male Sprague-Dawley rats were divided into 5 groups of 10 rats each. In group I, the rats were infected with T. gondii and fed a zinc-deficient diet; in group II, the rats were infected and their pineal gland was surgically removed. Group III included rats that were infected, pinealectomized, and fed a zinc-deficient diet. Group IV consisted of T. gondii-infested rats that received no treatment of any kind, and group V were normal controls. After 3 wk of treatment, all rats were sacrificed and the percentages of CD3, CD4, and CD8 lymphocytes, zinc, and melatonin levels in plasma and the percentage of lymphocyte in blood smears were analyzed. The CD3 ratios of groups I–III were significantly lower than those of groups IV and V (p<0.01). The CD4 lymphocytes were significantly higher in group IV than that in all other groups (p<0.05). In group IV, the CD8 lymphocytes were higher than in groups I–III (p<0.01) and those in group V were higher than for groups I and III (p<0.01). Lymphocyte incidence in group IV was higher than in the other four groups (p<0.01). The plasma zinc and plasma melatonin levels in groups I–III were significantly lower than those in the controls (p<0.01, both cases). These results suggest that zinc and/or melatonin deficiency have a negative influence on cellular immunity in rats with toxoplasmosis.     

Comparison of plasma leptin and zinc levels in elite athletes and sedentary people

In consideration of leptin effects such as reducing food intake and increasing energy consumption, many researchers have sought to examine the relation between leptin and exercise. The presence of reports arguing that zinc, can be a mediator in leptin production indicates a possible relation between zinc and leptin. The present study aims to determine plasma leptin levels in elite weightlifters and examine their relation with zinc. The study enrolled 30 healthy volunteers in the 18-27 age range. The subjects were allocated to groups in equal numbers: Group 1, Control Group: the group included subjects who did not exercise regularly. Group 2, Elite Weightlifter Group: the group included elite weight lifters who were selected to the national team in their weight classes, who exercised regularly and whose values were measured during rest in the training period. Levels of plasma leptin and zinc were determined in the blood samples collected from the subjects included in the study. Comparison of serum leptin and zinc values between groups showed that leptin and zinc levels in the control group were significantly higher than those in the weightlifters and that leptin levels decreased significantly in parallel with the low zinc levels. It can be concluded that physical activity brings about changes in leptin secretion, which in turn, can be significantly related with zinc (p < 0.01).     

Interrelationships of porcine X and Y chromosomes with pituitary gonadotropins and testicular size

Endocrine and testicular responses to unilateral castration on 1, 10, 56, or 112 days of age were characterized in 132 Chinese Meishan (MS) x White composite (WC) crossbred boars in which testicular size associates with a quantitative trait locus (QTL) on X chromosome. At 220 days of age, testicles of boars unilaterally castrated on Day 1 or 10 weighed more and had greater total daily sperm production (DSP) than one testicle of bilaterally intact boars (P < 0.05); compensation did not double these two responses. Boars with MS alleles at the X chromosome QTL had smaller testicles, darker colored parenchyma, and lower total DSP than boars with WC alleles (P < 0.05). The MS alleles engendered greater (P < 0.05) plasma FSH and LH during puberty than WC alleles. Plasma FSH increased (P < 0.05) within 48 h of unilateral castration on Days 1, 10, and 56. Subsequent increases occurred earlier during puberty (P < 0.05) after unilateral castration at younger ages than after unilateral castration at older ages. Pubertal increases in plasma FSH and LH were greater (P < 0.05) in boars with MS alleles than in those with WC alleles for the X chromosome QTL. Breed of Y chromosome had no effect on testicular traits, FSH, testosterone, or estrone. For LH, boars with an MS Y chromosome had greater (P < 0.01) plasma LH across all ages than boars with a WC Y chromosome. We conclude that a gene or groups of genes that reside on the porcine X chromosome regulate testicular development and pubertal gonadotropin concentrations.     

Gonadal function in male mountain bikers

Some studies reported testicular disorders associated with biking in mountain cyclists, which include injuries, erectile dysfunction, and higher scrotal temperatures. But none of these studies evaluated gonadal function. Therefore, the aim of this study was to evaluate gonadal function in male mountain bikers. Twenty-two male professional mountain bikers and 30 healthy noncyclist controls were included in the study. The mean age and body mass index were similar in both groups. Fasting blood samples for the measurement of the levels of total testosterone (TT), sex-hormone binding globulin (SHBG), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were obtained from all study participants before any physical activity. In addition, because insulin sensitivity and leptin modulate gonadal function, the concentrations of insulin, glucose, and leptin were also measured in the same samples. Calculated free testosterone (cFT) and bioavailable testosterone (bioT) were calculated from SHBG and TT. Basal hormonal levels including insulin, leptin, LH, FSH, SHBG, TT, glucose, and homeostasis model assessment scores were similar between the groups. However, bioT and cFT levels were significantly lower (p ≤ 0.05) in the mountain bikers than those in the controls. Despite the lower mean testosterone levels in the study group, the levels of LH and FSH were similar to controls. Insulin and leptin do not contribute to lower testosterone levels. In conclusion, male mountain bikers have lower testosterone concentrations compared to controls. This alteration cannot solely be explained by testicular dysfunction. The etiology of lower testosterone levels in cyclists appears to be complex and requires further research. The influence of such a decline on the athlete's performance, quality of life, and muscle strength is not known as yet.     

Effects of unilateral castration on serum luteinizing hormone, follicle stimulating hormone, and testosterone concentrations in one-, two-, and three-year-old stallions

The endocrine control of compensatory hypertrophy was investigated in 12 Morgan stallions, four each at one, two and three years of age. Half were assigned to be unilaterally castrated (UC) in January and half to remain intact (IN). Nine blood samples were taken from each stallion at half-hour intervals 30, 90, and 150 d after unilateral castration for radioimmunoassay of serum concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), and testosterone. Mean serum LH concentration was greater (P<0.06) in UC than IN stallions; however, the difference was greatest at 30 d and least at 150 d. Serum LH was greater (P<0.01) in two- and three-year-olds than in one-year-olds. The mean log(10) for serum FSH concentration was greater (P<0.06) in UC than IN stallions. Mean serum testosterone concentrations were similar in UC and IN stallions for all sample days, suggesting that the single testes of the UC stallions produced as much testosterone as the two testes of the IN stallions. Two- and three-year-old stallions had greater (P<0.01) serum testosterone than one-year-old stallions. Unilateral castration of stallions was associated with a significant increase in serum LH and FSH concentrations and, perhaps, higher intratesticular testosterone, which may explain, in part, the compensatory hypertrophy noted in the remaining testis.     

Serum concentration of nine hormones in aging male population and association with potency and libido problems

Aim was to determine if a serum levels of free testosterone and selected eight hormones are in correlation with potency and libido problems in aging male. Male population older then 45 years of two Slavonian villages was called for voluntary examination. Every patient filled a questionnaire concerning medical history, operations and potency and libido problems. Based on answers we formed six groups of patients, but only three were analyzed further. Population with potency and libido problems is on average older. In group of patients with normal potency and libido (PNLN group) average levels of free testosterone are 46.01 pmol/L, LH 4.62 IU/L and FSH 6.20 IU/L. In group of patients with mild-damaged potency and normal libido (PMLN group) average levels of free testosterone are 44.61 pmol/L, LH 6.19 IU/L and FSH 8.18 IU/L. In PALA group of patients with absent potency and libido (PALA group) average levels of free testosterone are 41,89 pmol/L, LH 8.07 IU/L and FSH 11.27 IU/L. Significant higher levels of FSH and LH were found compared with the control group (for FSH p<0.001 and p < 0.003, and for LH p <0.003 and p < 0.021). No significant difference in serum levels of free or binned testosterone were found between three groups. Even if average serum levels of free testosterone is found lower in patients with libido and potency problems, this difference is not significant and testosterone deficiency itself can not explain potency and libido problems in aging male.     

The effects of stanozolol and boldenone undecylenate on plasma testosterone and gonadotropins and on testis histology in pony stallions

Fifty 2- to 16- yr old pony stallions were randomly assigned to one of five treatments: Group 1, controls (no treatment); Group 2, 0.55 mg/kg stanozolol weekly for 13 treatments; Group 3, 1.1 mg/kg stanozolol every 3 wk for 5 treatments; Group 4, 1.1 mg/kg boldenone undecylenate every 3 wk for 5 treatments; and Group 5, 0.55 boldenone undecylenate weekly for 13 treatments. Mean plasma testosterone levels for Groups 2, 4, and 5 were elevated over controls (P < 0.01) at 2, 8, and 9 wk, respectively. Testosterone levels for ponies in Group 3 did not differ from controls (P > 0.05). There were no differences in mean plasma luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels among groups (P > 0.05). Daily spermatid production per gram of testicular parenchyma (DSP/gm) in Group 5 was lower than in controls (P < 0.05), whereas DSP/gm was not different among groups 1 to 4 (P > 0.05). There were no differences among groups (P > 0.05) in the percentage of Stage 8 tubules or relative number of Leydig cells. The mean diameter of Leydig cells was less for Group 5 than for controls (P < 0.05), but was not different for Groups 1 to 3 (P > 0.05).     

Effects of testosterone metabolites on serum gonadotropin concentrations in immature male rats.

The ability of testosterone, androsterone, 5alpha-androstane-3alpha,17beta-diol, and 5alpha-androstane-3beta,17beta-diol to prevent the castration-induced rise in serum gonadotropin levels was investigated in immature male rats. Rats castrated at 30 days of age were treated once per day by subcutaneous injection of 12.5-100 mug of the steroid per 100 g body weight per day for 3 days, beginning on the day of castration. The animals were sacrificed 24 h after the last injection. Testosterone propionate, androsterone propionate, and 5alpha-androstane-3alpha,17beta-diol dipropionate were also tested at the approximate molar equivalent of 100 mug of the free alcohol form per 100 g body weight per day. Testosterone propionate and 5alpha-androstane-3alpha,17beta-diol were the only compounds tested that prevented the castration induced rise in luteinizing hormone (LH) concentrations. Testosterone propionate also inhibited the rise in follicle stimulating hormone (FSH) concentrations whereas 5alpha-androstane-3alpha,17beta-diol inhibited the rise in FSH in one but not in another experiment. These were the only compounds tested that affected serum FSH concentrations. The lower doses of testosterone tested significantly increased serum LH, but not FSH concentrations compared to castrate control animals. The highest dose tested partially inhibited the rise in serum LH concentrations. Both androsterone and androsterone propionate maintained ventral prostate weights. Although neither compound prevented the castration induced rise in serum LH, two groups receiving androsterone had serum LH concentrations significantly lower than the castrate control group. 5alpha-Androstane-3beta,17beta-diol and 5alpha-androstane-3alpha,17beta-diol dipropionate failed to maintain ventral prostate weights or prevent the rise in serum gonadotropin levels. These results indicate that 5alpha-androstane-3alpha,17beta-diol is capable of preventing the castration induced rise in serum LH concentrations in the immature male rat and thus may participate in the regulation of LH secretion in these animals.     

Immunoactive inhibin as a marker of Sertoli cell function following cytotoxic damage to the human testis

Sertoli and Leydig cell functions were evaluated in men with testicular damage due either to cytotoxic chemotherapy (CCT) or radiotherapy (XRT). Serum immunoactive inhibin, follicle-stimulating hormone (FSH), luteinizing hormone (LH) and testosterone concentrations were measured in 15 men (19-50 years) who had received 6-10 courses of combination CCT (mustine, vinblastine, procarbazine and prednisolone) for Hodgkin's disease 1-8 years earlier and 18 men (21-49 years) who had undergone unilateral orchidectomy for testicular seminoma followed by XRT (30 Gy) to the remaining testis, 1-4 years earlier. Normal men (n = 16, 19-36 years) acted as controls. Median inhibin (422 U/l) and testosterone (16.0 nmol/l) levels in the CCT-treated group were not significantly different from controls, whereas median FSH (14.5 IU/l) and LH (10.0 IU/l) levels were higher (p less than 0.0001 and p less than 0.001) than normal (2.9 and 5.5 IU/l). The median inhibin/FSH (I/FSH) ratio in the patients was lower (p less than 0.0001) than in the controls (33.8 vs. 187.0) as was the testosterone/LH (T/LH) ratio (1.7 vs. 3.8, p less than 0.001). In the XRT-treated group, both median inhibin (194.5 U/l) and testosterone (12.7 nmol/l) levels were lower (p less than 0.0001 and p less than 0.01) than normal (532.8 U/l and 20.0 nmol/l) in the presence of greatly elevated FSH (26.0 IU/l) and LH (14.5 IU/l) levels. In conclusion, CCT-induced testicular damage is associated with subtle Sertoli and Leydig cell dysfunction demonstrated by the reduced I/FSH and T/LH ratios; however, compensatory mechanisms maintain normal testosterone and inhibin levels.(ABSTRACT TRUNCATED AT 250 WORDS)