Increased Plasma Testosterone Research Articles

Birth weight, growth indices, and seminal parameters in male offspring are resilient features to maternal pre-conceptional dietary manipulation in sheep

Gestational diet manipulation can lead to inadequate fetal nutrient supply resulting in low birth weight, limited postnatal growth, and consequently, reduced reproductive performance in the progeny. However, effects of short-term maternal pre-conceptional dietary manipulation on postnatal growth and reproductive parameters of male offspring in large animals remains unexplored. To determine these consequences, female crossbred (Polypay x Dorset) sheep were allocated to three groups (n = 33/group) of dietary manipulation for 21 days prior to mating under the following conditions: (1) control at 100 % of maintenance energy requirements (40 Kcal of metabolizable energy/kg body weight [BW]), (2) undernutrition (UN) at 50 % of Control intake, and (3) overnutrition (ON) at 200 % of maintenance energy. Singleton ram lambs (UN:9; C:12; ON:6) were monitored from birth until 8 months of age, including birth weight, weekly weights, weight gain, body mass index (BMI), and circulating testosterone. After weaning, monthly scrotal circumference and subcutaneous fat depth were measured. Semen morphology and motility were evaluated at 7 and 8 months of age. Birth weight, weight gain, and BMI at birth and weaning were not significantly different among nutritional treatments. None of the pre-conceptional diets affected body weight change from weaning until 36 weeks of age, BMI, fat depth, or scrotal circumference across the experiment. A sustained rise in plasma testosterone concentrations was detected when ram lambs were, on average, 82 days old and 37 kg. Both testosterone concentrations and scrotal circumference were positively correlated to body weight regardless of treatment group. In addition, seminal parameters did not differ among treatments, but a transient increase in plasma testosterone at 18 weeks of age was observed in ON ram lambs compared to control rams. In conclusion, birth weight, growth indices, and seminal parameters in singleton rams are resilient features in the progeny upon maternal pre-conceptional dietary manipulation in sheep.

Sexually inexperienced bucks, photostimulated or not, showed increased plasma testosterone and sexual behaviors with nulliparous and multiparous goats outside of breeding season

The objectives of this study were to determine whether sexually inexperienced photostimulated and nonphotostimulated males had increased plasma testosterone levels and sexual behaviors during their first contact with nulliparous (N) and multiparous (M) females and whether these males could induce sexual responses in females outside of breeding season. Six photostimulated (PH) males were artificially subjected to long days (16 h/light/day/2.5 months), and six nonphotostimulated (NO) males were exposed to the natural photoperiod. Three PH males were exposed to N females (n = 30), and three PH males were exposed to M females (n = 30). Three NO males were exposed to N females (n = 30), and three were exposed to M females (n = 30). In spring (March-April), the males and females remained together for 15 days. The PH males had increased plasma testosterone levels compared to baseline levels during first contact with the N (10.8 ± 2.6 ng/mL) and M females (9.3 ± 1.9 ng/mL) (P < 0.001). Similarly, the NO males had increased plasma testosterone levels during their first contact with N (11.4 ± 1.1 ng/mL) and M females (11.0 ± 0.6 ng/mL) (P < 0.001). Nudging, anogenital sniffing, and mounting attempts varied between the PH and NO males (P < 0.001), whereas mounting with intromission did not differ (P > 0.05). Estrous behavior and ovulation did not differ between N and M females in contact with PH males or between M females in contact with NO males (P > 0.05), whereas the N females in contact with NO males had the lowest response (P < 0.05). We conclude that sexually inexperienced photostimulated and nonphotostimulated males exhibit increased plasma testosterone levels; exhibit sexual behaviors during their first contact with nulliparous and multiparous females; and can stimulate sexual activity in females outside of breeding season.

Urtica Dioica Leaf Extract Attenuates Oxidative Stress Induced by Environment Pollutant Benzo[a] Pyrene in Mouse Testicular Tissues

Background: Epidemiological studies have shown that elevated levels of air pollutants are associated with various adverse health effects, including infertility. Objective: We aimed to assess the protective effects of aqueous Urtica dioica leaf extract against benzo[a]pyrene -induced oxidative damage in mouse testis. Methods: Mice exposed to benzo[a]pyrene were treated with or without aqueous Urtica dioica extract for five weeks, and changes in body and testes weights, messenger RNA levels and activities of antioxidant enzymes, plasma testosterone levels, sperm characteristics, and testicular tissue histology were determined. Results: Exposure to benzo[a]pyrene remarkably reduced testis and body weights, the expression and activity of antioxidant enzymes, increased lipid peroxidation, decreased plasma testosterone levels and sperm count and motility, affected sperm morphology and viability, and damaged the seminiferous tubules. Treatment with aqueous Urtica dioica leaf extract attenuated benzo[a]pyrene -induced oxidative stress in the testicular tissue by increasing the expression of antioxidant genes. Further, Urtica dioica leaf extract reduced lipid peroxidation, increased antioxidative enzyme activity, enhanced sperm characteristics, increased plasma testosterone levels, and improved the morphology of the seminiferous tubules. Conclusion: Aqueous Urtica dioica leaf extract protects testicular tissue from benzo[a]pyrene -induced oxidative damage and could potentially reverse benzo[a]pyrene -induced infertility.

Evaluation of Genistein as a Mitochondrial Modulator and Its Effects on Sperm Quality.

Phytoestrogens, such as isoflavones, are bioactive compounds found in plants with defense and protection functions. In the human body, they simulate the behavior of the hormone estradiol and can modulate the function of the male hypothalamic-pituitary-gonadal axis. This study aims to describe the effects of genistein on sperm quality of Wistar rats (male/adult) after a short oral administration protocol (50 mg/day, for 5 days), focusing on mitochondrial function. No signs of toxicity were observed in the animals during the period. The testicular mass of rats from the genistein-treated group was lower than that from the control group. Isoflavone increased the number of viable Leydig and Sertoli cells, spermatogonia, and primary spermatocytes in the treated group. The rounded spermatid count was similar to the control group, and a decrease in elongated spermatids was observed in the treated group. Genistein treatment increased plasma testosterone levels in the treated group. To the best of our knowledge, this is the first report of an in vivo short protocol demonstrating that genistein administration stimulates the overall oxygen consumption in rat seminal samples. Therefore, genistein induced a pro-spermatogenesis effect, enhanced plasma testosterone levels, and increased oxygen consumption, improving sperm mitochondrial efficiency. Similar protocols can be explored in animal and human infertility issues.

Effects of Exogenous Human Chorionic Gonadotropin Administration on Plasma Testosterone and Semen Production in the Veiled Chameleon (Chamaeleo calyptratus)

Gamete collection, gamete preservation, hormone analysis, and artificial insemination have become integral parts of in situ and ex situ conservation programs for threatened and endangered species, and while these methods have been used to assist conservation in many different vertebrate groups, limited work has been done in reptiles. For example, semen collection in lizards has only recently been described and determined to be safe. The purpose of this study was to determine effective doses of human chorionic gonadotropin (hCG) for increasing plasma testosterone concentrations in the veiled chameleon (Chamaeleo calyptratus), as well as to determine whether the rise in testosterone impacts semen collection. A cross-over design was used. Chameleons were given injections of 100 IU, 200 IU, and 300 IU of hCG/animal and serial plasma testosterone measurements were collected over 24 hours. 100 IU/animal was determined to increase plasma testosterone concentrations similar to 200 IU, and 300 IU/animal. Following this, we determined weekly injections of hCG (100 IU/animal) would maintain elevated testosterone concentrations over 30 days. Additionally, we determined that elevated testosterone secondary to repeated injections of hCG decreased testicular size as determined by ultrasound. Repeated hCG injections and long-term elevation of plasma testosterone concentrations did not increase the likelihood to collect a semen sample with electroejaculation or improve ejaculate quality. Further research is needed to exogenously stimulate spermatogenesis and increase ejaculate quality to perform timed semen collections in male reptile species.

Effects of dietary supplementation of multi-strain probiotics on semen quality, seminal plasma compositions, and fertilization ability of rainbow trout (Oncorhynchus mykiss) broodstock spermatozoa

The present experiment aims to study the effects of dietary multi-strain probiotics on semen quality, seminal plasma compositions, and fertilization ability of male rainbow trout. For this purpose, a total of 48 broodstocks with an average initial weight of 1366.1±33.8g were divided into 4 groups and 3 replicates. Fish were fed with diets containing 0 (control), 1×109 (P1), 2×109 (P2), and 4×109 (P3) CFU probiotic kg-1 diet for 12 weeks. Results showed that dietary supplementation of probiotics significantly increased plasma testosterone level, motility time of spermatozoa, sperm density, and spermatocrit value in P2 and P3 treatments and Na+ level in P2 treatment compared to the control group (P<0.05). The activities of aspartate aminotransferase and lactate dehydrogenase had significantly decreased in the P2 treatment compared to the control group (P<0.05). No considerable variations were observed between control fish and treatment groups (P>0.05) in semen biochemical parameters, percentage of motile spermatozoa, osmolality, and pH of seminal plasma. Based on the results, the highest fertilization rate (97.2±0.9%) and eyed egg survival (95.7±1.6%) were observed in the P2 treatment, and those values showed remarkable differences with the control group (P<0.05). The results indicated that multi-strain probiotics have potential efficacy on semen quality and fertilization ability of rainbow trout broodstock spermatozoa.

Testing the extreme male hypothesis in the valproate mouse model; sex-specific effects on plasma testosterone levels and tyrosine hydroxylase expression in the anteroventral periventricular nucleus, but not on parental behavior.

Autism is a neurodevelopmental disorder with a strong male bias in prevalence and severity. The extreme male hypothesis proposed that autism is a manifestation of extreme male traits as evidenced by increased masculine behaviors, hypermasculinization of some brain regions, and alterations in androgen metabolism. In the present study, the extreme male hypothesis was tested in the valproate (VPA) mouse model. Females of the C57BL/6JOlaHsd mouse strain were treated with 500 mg/kg VPA on gestational day 12. Offspring of both sexes were tested at 3 to 4 months of age in the elevated plus maze (EPM), open field, sociability tests, and for parental behavior. After sacrifice at 5 to 6 months of age, plasma testosterone was measured in males, while the brains of both sexes were examined for tyrosine hydroxylase (TH) expression in the anteroventral periventricular nucleus (AVPV). VPA treatment significantly increased plasma testosterone levels and decreased AVPV TH expression in males, whereas the expression of TH in females remained at the same level. In parental behavior test none of the pup-oriented behavior was affected by VPA treatment in both sexes, the exception was nest quality which was lower after VPA exposure in males, but not in females. Our results suggest a hypermasculinizing effect of VPA that occurred specifically in males but not in females, and this effect could be related to changes in androgen physiology. Nevertheless, a generalized interpretation of the extreme male hypothesis on brain and behavior should be avoided due to the complex effects of VPA.

Elevated Maternal Testosterone Levels Alter PFOA Elimination and Tissue Distribution in Pregnant Rats.

Perfluorooctanoic acid (PFOA) is an enduring synthetic chemical that harms human health. Recent studies indicate heightened bioaccumulation of PFOA, particularly in pregnant women experiencing preeclampsia. Since plasma testosterone levels are elevated in pregnant women with preeclampsia, we hypothesized that hyperandrogenic conditions during pregnancy may hinder PFOA elimination and contribute to their higher body burden. Pregnant Sprague-Dawley rats were s/c injected with vehicle or testosterone propionate from gestational day (GD) 15 to 20 to increase plasma testosterone levels by 2-fold, similar to levels in preeclampsia. On GD 16, [14C]-PFOA (9.4 pmol/kg) was given intravenously, and subsequently, 14C radioactivity was measured in maternal blood, urine, feces, and tissues. PFOA was primarily eliminated through urine; however, less PFOA was excreted in urine of pregnant rats with elevated testosterone levels than controls. Fecal excretion of PFOA was minimal and did not significantly differ between groups. The total elimination of PFOA (urine plus feces) was significantly reduced by 12% in pregnant rats with elevated testosterone levels. In controls, PFOA distribution was highest in placenta, followed by the kidneys, liver, brain, heart, lungs, and spleen. Pregnant rats with elevated testosterone levels displayed 12% higher concentrations of PFOA in these tissues than controls. Furthermore, the renal expression of Oat2 and Oat3 was significantly decreased, while Oatp1 and Oat-k expression was significantly increased in pregnant rats with elevated testosterone levels than controls. In conclusion, elevated maternal testosterone levels decrease urinary elimination of PFOA, possibly through altered expression of renal transporters leading to increased tissue concentrations of PFOA in pregnant rats.

Intramuscular administration of l-arginine boosts testicular hemodynamics, plasma concentrations of testosterone and nitric oxide in heat-stressed rams

The current study aimed to assess, for the first time, the effects of intramuscular injection of l-arginine (L-arg) on testicular hemodynamics, echogenicity, and plasma concentrations of testosterone, total antioxidant capacity, and nitric oxide (NO) in Ossimi rams. Twelve sexually matured heat-stressed rams were randomly assigned to one of two groups: the L-arg group (n = 6) received 5 mg/kg L-arg dissolved in 2 ml normal saline 0.9%, or the control group (n = 6) received merely 2 ml of normal saline 0.9%. Blood sampling, B-mode ultrasound assessment of the testicular parenchyma, and pulsed-wave Doppler ultrasound of the testicular artery for both right and left testis were performed immediately before 0 min and 1, 4, 24, 48, 72, and 168 h after L-arg or saline administration. In the L-arg group, resistive index (RI) and pulsatility index (PI) means were significantly lower compared to the control group at 4–168 h post-treatment. Plasma testosterone concentrations were higher (P < 0.05) at 4 h and onward in the L-arg treated compared to the control rams, the same for NO levels however its increase (P < 0.05) was observed as soon as 1 h post-treatment. In L-arg treated rams, NO concentrations were positively correlated to plasma testosterone concentrations (r = 0.7, p < .01), but negatively correlated to both RI and PI (r = −0.8 and −0.6, respectively, p < .01). In conclusion, l-arginine administration enhanced testicular blood flow and increased plasma testosterone and nitric oxide concentrations in heat-stressed rams.

Exposure of rams in sexual rest to sexually activated males in spring increases plasma LH and testosterone concentrations

Eight stimulating rams, and twelve stimulated rams, were used to determine whether a similar endocrine response to the introduction of sexually active males in spring in a flock of ewes is observed in a flock of rams. The stimulating rams (n = 4) were induced into a sexually active state by exposure to 2 months of long days (16 h light/d) (15 December-15 February). At the end of the long-day period, rams were returned to the natural photoperiod. Control-stimulating rams (n = 4) were kept under the natural photoperiod. On April 20, stimulated rams were divided into 2 groups, and joined with activated (ACT; n = 6) or control stimulating rams (C; n = 6). On the day of ram introduction, stimulated rams were blood sampled for 8 h at 20-min intervals, from 4 h before to 4 h after ram introduction, and next day from 24 to 28 h after ram introduction, and analyzed for plasma LH concentrations, and 10, 20 and 30 days after ram introduction to measure plasma testosterone levels. Mean (±SEM) plasma LH concentrations (ng/ml) of stimulated rams were similar during the 4 h before stimulating-ram introduction (ACT: 0.59 ± 0.03; C: 0.53 ± 0.04; P > 0.05). The introduction of the photoperiod-treated stimulating rams increased LH concentrations of stimulated rams during the 4 h after their introduction (1.14 ± 0.37) compared with the C group (0.51 ± 0.03; P < 0.05), especially during the first hour (ACT: 0.93 ± 0.16; C: 0.49 ± 0.03; P < 0.05), and during the blood sampling period 24–28 h after ram introduction (0.75 ± 0.07 vs. 0.58 ± 0.04; P < 0.05). Before the introduction of stimulating rams, the LH pulse frequencies and amplitudes did not differ between groups; however, LH pulsatility was higher at 4 h (0.58 ± 0.11 pulses/h; P < 0.05), and had trend to be higher 24 h (0.50 ± 0.06) (P = 0.10) after the introduction of the photoperiod-treated stimulating rams compared with the control-stimulating rams (0.29 ± 0.08 and 0.29 ± 0.10, respectively). As for LH pulses, there was an effect of group (P < 0.05) on LH amplitude, which presented a trend to be higher in ACT rams 4 h after ram introduction (1.68 ± 0.30; P < 0.10) and higher 24 h (1.07 ± 0.08; P < 0.05) after ram introduction, compared with LH amplitudes of C rams (0.71 ± 0.06 and 0.82 ± 0.07, respectively). Plasma testosterone concentrations of rams exposed to photoperiod-treated activated rams were higher than those of rams exposed to control-stimulating rams, at 4 h, 20 and 30 days after ram introduction (P < 0.05). In conclusion, sexually active rams in spring are able to stimulate LH and testosterone secretion of other rams in sexual rest, a phenomenon we called “ram-to-ram effect".

Exogenous testosterone administration decreases rates of ovarian follicle growth in domestic chickens

Avian egg yolks provide critical nutrients and energy reserves for a growing embryo. Once a follicle is selected into the ovulatory hierarchy, rings of yolk precursors are deposited daily until the yolk is large enough to ovulate. The composition of hen egg yolk and the mechanisms responsible for deposition in the ovarian follicle are well-studied. However, the factors that affect the rate of yolk deposition, and the number of days it takes for follicles to grow to the optimal size for ovulation, are less well-known. Social interactions appear to impact the rate of yolk deposition in many avian species and testosterone is a key hormone involved in regulating those interactions. Therefore, we hypothesized that testosterone would influence the rate of follicle growth. We tested the influences of exogenous testosterone treatment by rubbing either testosterone propionate cream (1.25 %) or a control cream to hen combs daily for 7 days to increase plasma testosterone concentrations. We then collected eggs and measured egg and yolk weight, yolk diameters, and stained and counted the number of concentric rings in each yolk. Testosterone-treated hens laid fewer eggs and grew their yolks more slowly than control hens. Testosterone also caused an increase in yolk weight but not yolk diameter. These results indicate that testosterone may play a role in the rate of yolk deposition in birds.

17α-estradiol does not adversely affect sperm parameters or fertility in male mice: implications for reproduction-longevity trade-offs.

17α-estradiol (17α-E2) is referred to as a nonfeminizing estrogen that was recently found to extend healthspan and lifespan in male, but not female, mice. Despite an abundance of data indicating that 17α-E2 attenuates several hallmarks of aging in male rodents, very little is known with regard to its effects on feminization and fertility. In these studies, we evaluated the effects of 17α-E2 on several markers of male reproductive health in two independent cohorts of mice. In alignment with our previous reports, chronic 17α-E2 treatment prevented gains in body mass, but did not adversely affect testes mass or seminiferous tubule morphology. We subsequently determined that chronic 17α-E2 treatment also did not alter plasma 17β-estradiol or estrone concentrations, while mildly increasing plasma testosterone levels. We also determined that chronic 17α-E2 treatment did not alter plasma follicle-stimulating hormone or luteinizing hormone concentrations, which suggests 17α-E2 treatment does not alter gonadotropin-releasing hormone neuronal function. Sperm quantity, morphology, membrane integrity, and various motility measures were also unaffected by chronic 17α-E2 treatment in our studies. Lastly, two different approaches were used to evaluate male fertility in these studies. We found that chronic 17α-E2 treatment did not diminish the ability of male mice to impregnate female mice, or to generate successfully implanted embryos in the uterus. We conclude that chronic treatment with 17α-E2 at the dose most commonly employed in aging research does not adversely affect reproductive fitness in male mice, which suggests 17α-E2 does not extend lifespan or curtail disease parameters through tradeoff effects with reproduction.

Photoperiodic control of singing behavior and reproductive physiology in male Fife fancy canaries

Temperate-zone birds display marked seasonal changes in reproductive behaviors and the underlying hormonal and neural mechanisms. These changes were extensively studied in canaries (Serinus canaria) but differ between strains. Fife fancy male canaries change their reproductive physiology in response to variations in day length but it remains unclear whether they become photorefractory (PR) when exposed to long days and what the consequences are for gonadal activity, singing behavior and the associated neural plasticity. Photosensitive (PS) male birds that had become reproductively competent (high song output, large testes) after being maintained on short days (SD, 8 L:16D) for 6 months were divided into two groups: control birds remained on SD (SD-PS group) and experimental birds were switched to long days (16 L:8D) and progressively developed photorefractoriness (LD-PR group). During the following 12 weeks, singing behavior (quantitatively analyzed for 3 × 2 hours every week) and gonadal size (repeatedly measured by CT X-ray scans) remained similar in both groups but there was an increase in plasma testosterone and trill numbers in the LD-PR group. Day length was then decreased back to 8 L:16D for LD-PR birds, which immediately induced a cessation of song, a decrease in plasma testosterone concentration, in the volume of song control nuclei (HVC, RA and Area X), in HVC neurogenesis and in aromatase expression in the medial preoptic area. These data demonstrate that Fife fancy canaries readily respond to changes in photoperiod and display a pattern of photorefractoriness following exposure to long days that is associated with marked changes in brain and behavior.

Effect of Chronic Moderate Caloric Restriction on the Reproductive Function in Aged Male Wistar Rats

Caloric restriction (CR) has been shown to be an effective nutritional intervention for increasing longevity in some animal species. The objective of this study was to evaluate CR’s effects on metabolic and reproductive parameters in 12-month-old male Wistar rats. The rats were distributed in three groups: control, CR at 15%, and CR at 35% for 6 (up to 18 months of age) and 12 months (up to 24 months of age). At the end of CR treatment, we evaluated reproductive (male sexual behavior (MSB), sperm quality) and biochemical parameters (plasma glucose, glucose-regulating hormone, and sex steroid levels), and quantified annexin V in the seminiferous epithelium. Results showed that MSB and sperm quality were improved after 6 months of CR associated with increases in plasma testosterone and decrease annexin V in the seminiferous epithelium of the testicles compared to their control group. The metabolic profile of the CR rats also improved compared to controls. However, these effects of CR on reproductive parameters were not maintained after 12 months of CR. Findings suggest that beginning CR at the age of maturity reestablishes the behavioral sexual response and reproductive function in older animals after 6 months of CR and improves endocrine functioning during aging.

Kiss1-dependent and independent release of luteinizing hormone and testosterone in perinatal male rats.

Prenatal and postnatal biphasic increases in plasma testosterone levels derived from perinatal testes are considered critical for defeminizing/masculinizing the brain mechanism that regulates sexual behavior in male rats. Hypothalamic kisspeptin neurons are indispensable for stimulating GnRH and downstream gonadotropin, as well as the consequent testicular testosterone production/release in adult male rats. However, it is unclear whether kisspeptin is responsible for the increase in plasma testosterone levels in perinatal male rats. The present study aimed to investigate the role of Kiss1/kisspeptin in generating perinatal plasma LH and the consequent testosterone increase in male rats by comparing the plasma testosterone and LH profiles of wild-type (Kiss1+/+) and Kiss1 knockout (Kiss1-/-) male rats. A biphasic pattern of plasma testosterone levels, with peaks in the prenatal and postnatal periods, was found in both Kiss1+/+ and Kiss1-/- male rats. Postnatal plasma testosterone and LH levels were significantly lower in Kiss1-/- male rats than in Kiss1+/+ male rats, whereas the levels in the prenatal embryonic period were comparable between the genotypes. Exogenous kisspeptin challenge significantly increased plasma testosterone and LH levels and the number of c-Fos-immunoreactive GnRH neurons in neonatal Kiss1-/- and Kiss1+/+ male rats. Kiss1 and Gpr54 (kisspeptin receptor gene) were found in the testes of neonatal rats, but kisspeptin treatment failed to stimulate testosterone release in the cultured testes of both genotypes. These findings suggest that postnatal, but not prenatal, testosterone increase in male rats is mainly induced by central kisspeptin-dependent stimulation of GnRH and consequent LH release.

Cysteine-Cysteine Motif Chemokine Receptor 5 Expression in Letrozole-Induced Polycystic Ovary Syndrome Mice.

Polycystic ovary syndrome (PCOS), which affects 5–10% of women of reproductive age, is associated with reproductive and metabolic disorders, such as chronic anovulation, infertility, insulin resistance, and type 2 diabetes. However, the mechanism of PCOS is still unknown. Therefore, this study used a letrozole-exposed mouse model in which mice were orally fed letrozole for 20 weeks to investigate the effects of letrozole on the severity of reproductive and metabolic consequences and the expression of cysteine–cysteine motif chemokine receptor 5 (CCR5) in letrozole-induced PCOS mice. The letrozole-treated mice showed a disrupted estrous cycle and were arrested in the diestrus phase. Letrozole treatment also increased plasma testosterone levels, decreased estradiol levels, and caused multicystic follicle formation. Furthermore, histological analysis of the perigonadal white adipose tissue (pgWAT) showed no significant difference in the size and number of adipocytes between the letrozole-treated mice and the control group. Further, the letrozole-treated mice demonstrated glucose intolerance and insulin resistance during oral glucose and insulin tolerance testing. Additionally, the expression of CCR5 and cysteine-cysteine motif ligand 5 (CCL5) were significantly higher in the pgWAT of the letrozole-treated mice compared with the control group. CCR5 and CCL5 were also significantly correlated with the homeostasis model assessment of insulin resistance (HOMA-IR). Finally, the mechanisms of insulin resistance in PCOS may be caused by an increase in serine phosphorylation and a decrease in Akt phosphorylation.

Chronic Dietary Exposure of Roosters to a Glyphosate-Based Herbicide Increases Seminal Plasma Glyphosate and AMPA Concentrations, Alters Sperm Parameters, and Induces Metabolic Disorders in the Progeny.

The effects of chronic dietary Roundup (RU) exposure on rooster sperm parameters, fertility, and offspring are unknown. We investigated the effects of chronic RU dietary exposure (46.8 mg kg−1 day−1 glyphosate) for 5 weeks in 32-week-old roosters (n = 5 RU-exposed and n = 5 control (CT)). Although the concentrations of glyphosate and its main metabolite AMPA (aminomethylphosphonic acid) increased in blood plasma and seminal fluid during exposure, no significant differences in testis weight and sperm concentrations were observed between RU and CT roosters. However, sperm motility was significantly reduced, associated with decreased calcium and ATP concentrations in RU spermatozoa. Plasma testosterone and oestradiol concentrations increased in RU roosters. These negative effects ceased 14 days after RU removal from the diet. Epigenetic analysis showed a global DNA hypomethylation in RU roosters. After artificial insemination of hens (n = 40) with sperm from CT or RU roosters, eggs were collected and artificially incubated. Embryo viability did not differ, but chicks from RU roosters (n = 118) had a higher food consumption, body weight and subcutaneous adipose tissue content. Chronic dietary RU exposure in roosters reduces sperm motility and increases plasma testosterone levels, growth performance, and fattening in offspring.

Measuring the Effects of a Single Dose of Human Chorionic Gonadotropin (hCG) on Plasma Testosterone Concentrations in Leopard Geckos (Eublepharis macularius)

Current estimates suggest that one-fifth of all reptiles are currently threatened with extinction because of anthropogenic activity, and that if nothing is done to mitigate these impacts, massive extinctions will occur over the coming decades. Assisted reproductive technologies (ART) can be used to develop ex vivo conservation programs to ensure species survival until environmental deficiencies can be corrected. Geckos represent one of the most diverse groups of reptiles on earth and need protection; however, to date, no ART have been developed for these animals. Exogenous human chorionic gonadotropin (hCG) is routinely used to alter reproductive hormones of vertebrates and are integrated in ART. The purpose of this study was to determine if a single dose of hCG could increase plasma testosterone concentrations in the leopard gecko (Eublepharis macularius) within 24 h of administration. The study was performed in September, which is considered the nonbreeding season for this species in the northern hemisphere. Twelve captive-bred, adult, male leopard geckos were randomly divided into three treatment groups and administered an intramuscular injection of hCG (50 or 100 IU) or saline. Whole blood was collected prior to injection (baseline) and 12 and 24 h after injection. Plasma testosterone concentrations were measured using an enzyme immunoassay kit. There was no significant difference (P = 0.195) in testosterone concentrations between treatment groups. Because there was no difference, an observed testosterone range (61.0 ± 42.5, 5.5–149.0) for September was calculated. These results suggest that captive leopard geckos may be in a recrudescence phase in September in the northern hemisphere.

Melatonin improves testicular haemodynamics, echotexture and testosterone production in Ossimi rams during the breeding season.

The objective was to determine effects of a single parenteral dose of melatonin on testicular blood flow indices, testicular echogenicity and plasma testosterone concentrations in rams during the physiological breeding season. We hypothesized that melatonin enhances testicular blood flow, echogenicity and plasma testosterone concentrations during the breeding season in rams. During the breeding season, 12 sexually mature Ossimi rams were randomly allocated to either a melatonin group (n=8) that received 18mg of melatonin in 1ml of corn oil (injected SC) or a control group (n=4) that received 1ml corn oil only. Blood collection and ultrasonographic assessment of the testes and supratesticular arteries were conducted immediately before treatment (W0) and once weekly for 6weeks after melatonin injection (W1-W6). Mean plasma testosterone concentrations were greater (p<.05; at least 1ng/ml) in the melatonin-treated group compared to the control group from W4 to W6 after treatment. A decrease (p<.05) in both resistive index (RI) and pulsatility index (PI) began 1week after melatonin injection (W1) and persisted until the end of the experiment, with mean RI and PI values in the melatonin group lower (p<.05) than those in the control group on W3 and W4. Furthermore, plasma testosterone concentrations in melatonin-treated rams were inversely correlated to both RI and PI (r=-.7 and -.6, respectively, p<.01). Testicular echogenicity decreased (p<.05) 1week after melatonin injection (W1) and remained lower (p<.05) in the melatonin-treated group compared to the control group until the end of the study (W6). In conclusion, melatonin administration significantly altered testicular blood flow and echogenicity and increased plasma testosterone concentrations in Ossimi rams during the breeding season.

Wildfire affects expression of male sexual plumage through suppressed testosterone circulation in a tropical songbird

Natural disturbances like drought and wildfires are expected to increase in prevalence, so understanding how organisms are affected is a key goal for conservationists and biologists alike. While many studies have illustrated long‐term effects of perturbations on survival and reproduction, little is known of short‐term effects to physiology and sexual signal expression. Ornamental traits have been proposed as reliable indicators of environmental health, yet studies are lacking in the context of natural disturbances. Here we present short‐term (7–65 days) responses of male red‐backed fairywrens Malurus melanocephalus to wildfire near the onset of the typical breeding season. Young males of this species are characterized by plastic expression of sexual plumage phenotypes depending on circulating testosterone and body condition. Using two populations with fairywren captures before and after separate wildfires we illustrate that wildfire suppressed molt into ornamented plumage. Neither baseline plasma corticosterone or furcular fat stores were affected by fire. However, fire seemed to interfere with the termporal increase in plasma testosterone during the pre‐breeding season, leading to a lower proportion of males molting into ornamented plumage. Collectively, these findings suggest that wildfires inhibit or greatly delay acquisition of ornamentation in males through enduring suppression of testosterone circulation.