Blood Plasma Testosterone Concentrations Research Articles

Expression of Aquaglyceroporins in Spermatozoa from Wild Ruminants Is Influenced by Photoperiod and Thyroxine Concentrations

This work identified the presence of AQPs in frozen-thawed sperm of wild ruminants and assessed the influence of the interaction between photoperiod and thyroxine on AQP expression, and on testosterone secretion. Thyroxine and melatonin were administered to ibexes. In a second experiment, performed in mouflons, circulating thyroxine was reduced via treatment with propylthiouracil (PTU), and an artificial long day (LD) photoperiod established. In the ibexes, the melatonin treatment increased the blood plasma testosterone concentration, reduced the cryoresistance ratio (CR) for sperm viability and the presence of an intact acrosome, and increased the percentage of sperm with AQP7 in the acrosome and of AQP3 and AQP10 in the midpiece. In the mouflons, neither the PTU treatment, the LD, nor the combination of both affected the CR of any sperm variable. The percentage of sperm with AQP3 increased in the post-acrosome region but decreased in the tail in the LD+PTU group. The percentage of sperm with AQP10 in the principal piece and endpiece was lower in the PTU+LD group than in the control and LD groups. The influence of photoperiod/melatonin on AQP expression might be indirectly exerted through changes in the testosterone concentration, and thus ultimately affect sperm cryoresistance.

Influence of circulating testosterone concentration on sperm cryoresistance: The ibex as an experimental model

Recent studies have noted that the circulating testosterone concentration may affect the ability of spermatozoa to survive cryopreservation. However, few attempts to confirm such a relationship have been made. Wild ruminant species have very marked seasonal changes in their reproductive function and strong annual changes in their plasma testosterone concentration. The present work examines the influence of induced changes in testosterone secretion on sperm variables following conventional slow freezing and ultra-rapid freezing, using the Iberian ibex as an experimental model. In a first experiment, testosterone levels were reduced in the middle of the rutting season (December) using the antiandrogen cyproterone acetate (CA). In a second experiment, testosterone levels were increased at the end of the rutting season (January) via the use of the androgen testosterone propionate (TP). During December, the testosterone concentration was found to be higher in the blood and seminal plasma of untreated males than in those of CA-treated males (p<0.001 and p<0.05, respectively). Compared with controls, the TP-treated animals had higher blood plasma testosterone concentrations but lower seminal plasma testosterone concentrations during January (p<0.01 and p<0.001, respectively). The seminal vesicles of the TP-treated males were larger than those of untreated males (p<0.05). When CA was administered, sperm viability improved compared with controls (p<0.05), irrespective of the freezing protocol followed. For the ultra-rapid freezing procedure, the cryoresistance ratio for motility decreased when TP was administered (p<0.05). The values for fresh sperm morphometric variables decreased during the 50days after the end of CA treatment (p<0.001) and increased over the same time after the end of TP treatment (p<0.001). The circulating testosterone concentration appears to influence sperm cryoresistance. This may explain the seasonal changes seen in sperm freezability in some species, independent of fresh sperm quality.

Soybean isoflavone affects in rabbits: Effects on metabolism, antioxidant capacity, hormonal balance and reproductive performance

Though soybean isoflavones (SBI) have pharmaceutical properties, the compounds also have endocrine disrupting activities that may adversely affect fertility of mammals. The effects of SBI on metabolism, antioxidant capacity, hormonal balance and reproductive performance of male rabbits were investigated. Adult male rabbits (n = 21) fed an isoflavone-free diet were orally treated with 0 (control; CON), 5 (small; LSBI) or 20 (large; HSBI) mg of SBI/kg body weight/day for 12 weeks. Both SBI doses resulted in lesser blood plasma total protein concentrations, while there were no effects on glucose and cholesterol concentrations compared to CON. The HSBI-treated males had the greatest (P < 0.05) blood plasma total antioxidant capacity and least malondialdehyde. Treatment with both SBI doses induced a 43% increase in triiodothyronine concentrations (P < 0.05) and 82% in reaction times (P < 0.001), while decreased sperm concentrations (P = 0.01) and blood plasma testosterone concentrations (P = 0.017) 26% and 19%, respectively. The total functional sperm fraction was less (P < 0.05) in the HSBI group; however, there was no effect of the LSBI treatment as compared to values for the CON group. The kindling rates of females mated to HSBI-treated males tended to be less (P = 0.081) than those of does mated with LSBI or CON males. In conclusion, only the HSBI treatment improved antioxidant status; whereas, treatment with both LSBI and HSBI doses induced a hormonal imbalance which led to an impaired testis function indicating the sensitivity of the adult male reproductive system to SBI actions.

Physiological Response, Semen Quality and Blood Metabolites of Friesian Bulls Treated with Zinc-Selenomethionine under Hot Summer Conditions in Egypt

The present study aimed to evaluate the impact of administration of zincmethionine and selnomethionine to Friesian bulls during hot summer conditions in Egypt on physiological thermoregulatory response, sexual desire, some physical and chemical semen characteristics and blood metabolites. Twenty sexually mature Friesian bulls were divided into five similar groups (4 bulls/ each). Bulls in the 1st group were unsupplemented and served as a control, while those in the 2nd,3rd,4th and 5th groups were orally supplemented with zincmethionine (Z-Met) at a levels of 2 and 4 mg/kg of BW/day and selenomethionine (Se-Met) at a levels of 0.3 and 0.6 mg/kg of BW/day, respectively, for two months as preliminary period and other three months as a main collection period. Rectal and skin temperatures, pulse rate (PR) and respiration rate (RR) were measured once each week through the experimental period. During the main collection period, semen was collected twice weekly and evaluated for semen-ejaculate volume (SEV), percentage of progressive sperm motility (PSM), live sperm (LS) and sperm abnormalities (SAB), sperm-cell concentration (SCC/ml) and total-sperm output (TSO/ejaculate). Blood samples were collected pre-treatment and monthly during the main collection period to determine concentration of total proteins (TP), albumin (AL) and globulin (GL); thyroxin (T4), triiodothyronine (T3), cortisol and testosterone hormones and zinc (Zn) and selenium (Se) levels in blood plasma. Also, activity of ALT, AST, ALP, ACP, SOD and GSH enzymes, as well as concentration of fructose, zinc and selenium were estimated in seminal plasma.The obtained results revealed that reaction time (RT) was shorter (P<0.05) and blood plasma testosterone concentration was higher (P<0.05) in all treated groups than the control group, begin the shortest (P<0.05) and highest (P<0.05) values of RT and testosterone concentration were recorded for bulls treated with Z-Met, especially in G3 group. Physical semen characteristics (SEV, PSM, LS, SCC/ml, TSO/ejaculate and SAB) were improved (P<0.05) in all treated groups as compared with the control one, being the best (P<0.05) values for bulls treated with Z-Met, especially in G3 group. Also, bulls treated with Z-Met in G3 group showed the lowest (P<0.05) activity of ALT, AST, ALP and ACP enzymes, highest (P<0.05) activity of SOD and GSH enzymes, and fructose, Zn and Se concentrations in seminal plasma as compare to other treated groups and control one. Bulls treated with Z-Met and Se-Met showed increased (P<0.05) levels of AL, T4, T3, Zn and Se, while GL and cortisol levels decreased (P<0.05) in blood plasma as compared to control one. In conclusion, orally administration of zincmethionine and selenomethionine to Friesian bulls had a valuable impact on sexual desire, semen quality and blood metabolites. Therefore, it can be recommended to treating the Frisian bulls with zincmethionine at a level of 4 mg/kg of BW/day during two preliminary months and three main semen collection months for improving the sexual desire, semen quality and blood metabolites under hot summer conditions in Egypt.

Effect of vitamin E or propolis supplementation on semen quality, oxidative status and hemato-biochemical changes of rabbit bucks during hot season

This study was designed to determine the effects of supplementation of vitamin E or propolis to bucks’ diets on semen quality, oxidative status and hemato-biochemical changes during summer season. Thirty adult male New Zealand white rabbits were randomly allocated into three equal groups, 10 bucks each. Bucks received a maintenance diet supplemented by vitamin E (150mg/kg diet, E-group) or propolis (150mg/kg diet, P-group) or not supplemented (control, C-group) for ten consecutive weeks. Semen and blood samples were collected to analyze semen quality traits and hemato-biochemical parameters, respectively. Ambient temperature and relative humidity were recorded daily and used to estimate the temperature humidity index (THI). Results indicated that bucks in the E- and P-groups had better libido (lower reaction time, P<0.05) and higher sperm concentration and viability than the control group (P<0.01). These enhancements were parallel to an increase in blood plasma testosterone concentrations in the vitamin E and propolis-treated groups (P<0.01). Additionally, concentrations of seminal plasma total protein and initial fructose were significantly increased in the semen of both treated-groups. For blood components, either vitamin E or propolis supplementation enhanced hematopoiesis including the number of red blood cells, hematocrite value and hemoglobin concentration (P<0.01). Also, concentrations of blood plasma glucose and high density lipoprotein (HDL) were increased, while those of blood plasma cholesterol and triglycerides were decreased (P<0.01) in both treated-groups. Supplementation with vitamin E or propolis enhanced (P<0.01) oxidative status of the blood plasma, whereas propolis-treated bucks had the highest value of total antioxidant capacity followed by vitamin E treated-bucks. Also, malondialdehyde activity was lower (P<0.05) in the propolis-treated bucks compared with the control, while bucks of the E-group were intermediate. In summary, inclusion of vitamin E or propolis in male rabbits' diets during the hot season could be used effectively to mitigate negative impacts of elevated temperature on semen quality, oxidative status and hemato-biochemical features.

Seasonal changes of scrotal circumference, blood plasma testosterone concentration and semen characteristics in Racka rams

Seasonal changes of scrotal circumference, blood plasma testosterone concentration and semen characteristics were studied over a period of 12months in rams of the Hungarian Black Racka breed. Significant differences between seasonal averages of the parameters measured were established in multiple cases. As regards changes in scrotal circumference, the highest average value obtained in September (31.92cm) exceeded the lowest value measured in January (22.08cm) by 44.7%. It has been found that the season significantly affects the testicular dimensions (r=0.87, P<0.01). Significant correlations were found between scrotal circumference and day length (r=0.43, P<0.05) as well as between scrotal circumference and monthly average temperature (r=0.73, P<0.01). The lowest blood plasma testosterone (T) level (2.31±0.14ng/ml) was measured in winter and the highest in autumn (17.81±0.7ng/ml). Significant differences between the seasonal values were observed on multiple occasions. The GnRH-provoked maximal testosterone level (Tincr) was found in autumn, in the breeding season (54.02±3.78ng/ml). A significant correlation was found between T and Tincr on the one hand and scrotal circumference on the other (r=0.62, P<0.01 and r=0.69, P<0.01, respectively). Ejaculate volume tended to increase from spring (0.52±0.03ml) to autumn (0.88±0.03ml). The lowest sperm concentration (4.92±0.13×109/ml) was measured in winter and the highest in summer (6.56±0.21×109/ml) (P<0.001). Total sperm count per ejaculate was the lowest in spring (3.15±0.23×109/ml) and the highest in autumn (5.22±0.45×109/ml) (P<0.001). Sperm motility was at a low level in February (4.42±0.20) and subsequently showed the highest values in the summer months, with similar monthly averages in June–August (5.00±0.00, P<0.001). The percentage of abnormal spermatozoa was the highest in winter (18.48±3.23%) and the lowest in autumn (7.95±1.58%) (P<0.001), and it was significantly higher in February than in other months of the year (22.17±1.61%, P<0.001–P<0.02). The lowest number of deformed spermatozoa was observed in October (6.15±0.72%).

Effect of age, pubertal stage and season on testosterone concentration in male dromedary camel

The present study was conducted in the Laboratory of Animal Physiology and Biotechnology, Department of Animal Production, Faculty of Agriculture, Mansoura University, Egypt. The present investigation aimed at studying effects of ages, pubertal stages and seasons of the year on testosterone concentrations in blood plasma and tissue homogenate of the testes. The testes used in the current study were collected from a total of 104 one-humped male camels ( Camelus dromedarius). Samples were taken from pre (1–3.5 years) and post (3.5–13 years) pubertal camels. Testes were studied for a two consecutive seasons. The freshly prepared homogenate of the testicular tissue and blood plasma were used for determining the concentrations of testosterone in plasma and testicular extract. The concentrations of testosterone in blood plasma and testicular tissue were significantly increased during the breeding season compared with that of non-breeding season; the concentration of testosterone was higher in testicular tissue than in blood plasma. Testosterone concentrations in plasma and testicular tissue were increased in breeding than in non-breeding season. In addition, the testosterone concentrations were closely related with seasonal changes, stage of puberty and advancing age.

Changes of Fructose Concentrations in Seminal Plasma and Glucose and Testosterone Concentrations in Blood Plasma in Rams Over the Course of a Year

The present study was performed to examine seasonal changes in the fructose concentrations of seminal plasma and glucose and testosterone concentrations of blood plasma over the course of a year (from November 2004 to November 2005) using 5 Suffolk rams. Osmolality of the seminal plasma was also measured. The fructose concentrations in the seminal plasma increased as the breeding season approached, with the maximum in October (179.8 mg/dl) and the minimum in May (6.9 mg/dl), although there were no significant differences during the year. Osmolality of the seminal plasma in February (304 mOsm) was significantly (P<0.05) lower than in January (325 mOsm), July (327 mOsm), and August (325 mOsm). It was also significantly (P<0.05) lower in November (308 mOsm) than in January and August. The blood plasma glucose concentration in October (79.3 mg/dl) was significantly (P<0.05) higher than in January and February (43.2 and 43.7 mg/dl, respectively). The blood plasma testosterone (T) concentrations were significantly (P<0.05) higher in September (8.5 ng/ml) and October (10.2 ng/ml) than in other months. The fructose concentrations in the seminal plasma appeared to be related to the glucose and T concentrations in the blood plasma. These results show that fructose concentrations in the seminal plasma and blood plasma glucose and T concentrations tended to increase during the breeding season, with the highest concentrations in October.

Attributes of broiler breeder males characterized by low and high sperm mobility

The attributes of broiler breeder males characterized by sperm mobility phenotype were studied in replicate experiments. Low and high phenotypes were observed in the first experiment over a 10-wk interval. Average straight line velocity differed between phenotypes (P < or = 0.05) as evidenced by computer-assisted sperm motion analysis. The second experiment compared low and high phenotypes from the same broiler breeder strain over a 29-wk interval. Body weight and fertility were measured in this experiment. Body weight data approximated parallel lines. The low phenotype averaged 227 g more than the high phenotype over the course of the experiment. Individual males were used as semen donors at 50, 54, 58, 62, and 65 wk of age. Eggs were collected for 2 wk after a single insemination at each age. Mean overall fertility (+/− SEM) was 44 +/− 4 and 69 +/− 2% for low and high sperm mobility phenotypes, respectively (P < or = 0.0001). As determined by transmission electron microscopy, the percentage of sperm with aberrant mitochondria was greater for the low sperm mobility phenotype (P < or = 0.0001). Neither blood plasma testosterone concentration nor testis weight differed between phenotypes. Sperm mobility is a biologically significant predictor of broiler breeder semen quality. The relationship between sperm mobility phenotype and body weight warrants further investigation.

Simulated Drought Affects Male Reproductive Function in Deer Mice (Peromyscus maniculatus bairdii)

Reproduction stops during the breeding season of many rodent populations, including Peromyscus maniculatus. The proposition that water availability mediates the midseason breeding hiatus in male deer mice was evaluated in the present study. Paired testicular and epididymal weights (absolute and relative to body mass) were reduced after 10 wk of restricted water consumption. Spermatogenesis was also impaired by limited water intake. Blood plasma testosterone concentrations were reduced, but plasma luteinizing hormone (LH) titers were unaffected by water restriction. Finally, the number of offspring sired was reduced in mice with restricted access to water. Carcass water content did not significantly differ between animals with restricted (25% of ad lib.) or unrestricted access to water; however, body mass was reduced about 15% after chronic water intake restriction. Although reproductive function (i.e., reproductive organ mass, plasma testosterone titers, and sperm counts) was significantly depressed in water-restricted mice, the reproductive systems of about 25% of the animals were relatively unaffected by water restriction. In order to study the physiological factors associated with individual reproductive responses to water restriction, animals were rank ordered according to their epididymal sperm numbers; individuals in the top (Q₁) and bottom (Q₄) quartiles of epididymal sperm counts were further compared. Water-restricted Q₁ deer mice did not significantly differ on any parameter from mice with ad lib. access to water. No water-restricted Q₄ deer mice possessed any epididymal sperm. Deer mice in Q₄ significantly reduced paired testicular and epididymal masses as compared with animals in the top quartile. It was important that Q₄ deer mice reduced their body mass by 34%. Plasma LH titers were significantly depressed in Q₄ animals as compared with Q₁ mice or mice with ad lib. water. Body fat content was also reduced only in the Q₄ deer mice. Taken together, these findings suggest that water availability may act as an extrinsic cue to suppress fertility in deer mice independently of temperature and day length and somewhat independently from food because despite an absolute reduction in food consumption with the onset of water restriction, food intake corrected for body mass did not differ. Animals that stopped reproductive function (Q₄ mice) lost substantial body fat and total mass. Water-restricted males that maintained body fat levels also maintained reproductive function. Differential hydrolysis of adipose tissue in response to decreased testosterone titers may account for the phenotypic variation in reproductive responsiveness to water restriction. These results are discussed in terms of their ecological and evolutionary implications.

Metabolism of High Concentrations of Dietary Zearalenone by Young Male Turkey Poults

Six male turkey poults (3 weeks of age) were fed a starter ration artificially contaminated with 800 mg zearalenone/kg for a 2-week period to examine zearalenone metabolism and residues in various tissues, excreta, and blood plasma. Zearalenone had no effect on either feed consumption or body weight gain. All the birds fed zearalenone frequently showed strutting behavior, displayed an increased size and coloration of caruncles and dewlaps, and had swollen vent tissue. None of these signs were seen among six control birds fed uncontaminated starter feed. Hormone analysis, however, revealed that the testosterone concentrations in blood plasma were the same in both controls and treated birds.Analysis after 14 days of feeding showed that most of the dietary zearalenone had been metabolized into α-zearalenol. Levels of zearalenone and α-zearalenol were: blood plasma 66 ± 27 and 194 ± 80 ng/ml, excreta 182 ± 33 and 644 ± 86 μg/g, lung 56 ± 45 and 202 ± 161 ng/g, heart 57 ± 40 and 238 ± 121 ng/g, kidney 122 ± 25 and 477 ± 53 ng/g, and liver 276 ± 54 and 2715 ± 590 ng/g, respectively. Only traces of β-zearalenol could be detected in plasma, excreta, and the various tissues. The percentage α-zearalenol of total zearalenone plus α-zearalenol rose significantly in both blood plasma and excreta during the experimental period. Almost all zearalenone and α-zearalenol was found conjugated in blood plasma, and the conjugates consisted of both glucuronides and sulfate conjugates. Approximately 65% of all zearalenone and α-zearalenol in excreta was found to be conjugated.

Induction of early rutting in male red deer (Cervus elaphus) by melatonin and its dependence on LHRH.

Eight red deer stags, 2 control, 3 control-immunized (i.e. a low titre of LHRH antibodies after active immunization 2 years earlier) and 3 superior cervical ganglionectomized, were given a s.c. implant of melatonin in May at the nadir of the sexual cycle; 5 other stags remained untreated. All the melatonin-treated animals shed the velvet-like skin from the antlers in June or July at least 1 month before the untreated controls, and had an early increase in blood plasma testosterone concentrations. The treated stags were also precocious in the development of rutting behaviour, although this inductive effect was blocked dramatically in the control-immunized stags after a booster immunization against LHRH; these animals failed to show any further reproductive development and cast their antlers. It is concluded that continuous exposure to melatonin in early summer will induce premature seasonal testicular development, an effect dependent on the secretion of LHRH, and similar to that produced by exposure to short daylengths.

Relationship of carnitine and acylcarnitines in ejaculated sperm to blood plasma testosterone of dairy bulls.

Blood plasma testosterone concentrations were significantly negatively correlated (r = -0.91, P<0.05) with blood plasma carnitine concentrations among dairy bulls of varying fertility levels. Blood plasma testosterone was positively correlated with spermatozoa total carnitine (r = 0.32), spermatozoa acylcarnitines (r = 0.35), and sperm motility (r = 0.49), whereas blood plasma carnitine concentration was negatively correlated with spermatozoa acylcarnitines (r = -0.48), spermatozOa total carnitine (r = -0.36), and sperm motility (r = -0.39). Furthermore, the concentrations of total carnitine (r = 0.67), free carnitine (r = 0.75), and acylcarnitines (r = 0.60) of spermatozoa were positively correlated with sperm motility ratings. Bulls exhibiting the highest fertility levels also had the higher concentration of blood plasma testosterone and lower concentration of blood plasma carnitine. Although several correlation coefficients are not statistically significant, they compare favorably with published values and support the biological importance of these blood plasma constituents as they are related to spermatozoa carnitines and their function in maintaining sperm motility and thus fertility.

Correlation Between Fluctuations of Testosterone Levels in Systemic Circulation and Sexual Behavior in Intact Female Japanese Monkeys in the Laboratory Condition

Heterosexual interactions of pairs of Japanese monkeys were studied in connection with fluctuations of testosterone concentrations in blood plasma of females, using seven intact adult females and two males. Blood was collected from the females daily or with a few days interruption. Testosterone, estradiol-17b, and progesterone in blood plasma were determined by radioimmunoassay. The behavioral records were obtained through heterosexual pairing tests of 30 minutes duration. Testosterone levels in blood plasma considerably fluctuated in each female from day to day, and statistically significant change could not be detected during the normal menstrual cycle. Male approach to females increased simultaneously with the increment of plasma testosterone level in three out of seven females. In seven normal menstrual cycles both copulation with ejaculation in the early follicular phase of the menstrual cycle and male approach in the late follicular phase of the cycle were observed in significantly higher frequencies on days of high level of testosterone, as compared with them on days of low level of testosterone in respective phase. These results suggest that testosterone enhances some types of sexual behavior of the male partner, at least, in the existence of estradiol-17s in the late follicular phase of the menstrual cycle.

Determination of seven unconjugated steroids in the blood and seminal plasma of the fertile male rabbit.

Seven unconjugated steroids were measured in the blood and seminal plasmas of fertile male rabbits by radioimmunoassay. The blood plasma testosterone concentration was 4--5 times that of the seminal plasma. Dehydroepiandrosterone, estrone and 17beta-estradiol were found in measurable amounts in the blood plasma; however, these steroid levels were slightly lower in seminal plasma. Androstenedione and 5alpha-dihydrotestosterone were present in equal quantities in both the seminal and blood plasmas. By contrast, seminal plasma pregnenolone level was about twice that of the blood plasma. The determination of seminal plasma steroids may lend itself as a complementary assessment to blood steroid determinations for the evaluation of the normal function of various reproductive organs.