SEASONAL VARIATION IN CIRCULATING GONADOTROPIN AND TESTOSTERONE LEVELS AND IN TESTIS SIZE OF YEARLING RAMS DURING AND SUBSEQUENT TO IMMUNONEUTRALIZATION OF ESTRADIOL OR TAMOXIFEN TREATMENT IN THE NONBREEDING SEASON

1987 ◽  
Vol 67 (2) ◽  
pp. 391-404 ◽  
Author(s):  
LEE M. SANFORD
Keyword(s):  
Endocrine Function ◽  
Tamoxifen Treatment ◽  
Feedback Signal ◽  
Testis Size ◽  
Testosterone Levels ◽  
Nonbreeding Season ◽  
Lh Pulsatility ◽  
17Β Estradiol ◽  
Hypothalamic Pituitary Axis ◽  
Baseline Levels

Seasonal variations in endocrine function and testis size with manipulation of the estrogen negative-feedback signal were assessed for yearling rams. Groups of three rams were passively immunized against estradiol-17β (estradiol) or injected with the antiestrogen tamoxifen (30 mg d−1) for 8 wk (July and August). In comparison with a group of four control rams, seasonal changes in many reproductive parameters were different for treated rams (group × period, P < 0.01). Immunized rams had higher mean LH levels at weeks 2 and 8, and higher baseline levels of LH and more frequent releases at week 8. Mean testosterone levels were increased between weeks 4 and 8 to values that were twice those of the breeding season as a consequence of higher baseline levels and larger episodic secretions. This was not associated with enhanced testicular regrowth, although regression in early winter occurred at a faster rate. Estradiol immunoneutralization was also associated with elevated levels of FSH. Tamoxifen had an inhibitory estrogen-like action on the hypothalamic-pituitary axis. Treatment suppressed LH pulsatility consistently and lowered testosterone to near undetectable values during the first 4 wk; this was associated with progressive decreases in testis size which were reversed with cessation of treatment. During the last month of tamoxifen treatment, the magnitude of the LH and FSH responses to exogenous GnRH was reduced. Key words: Estrogen immunization, tamoxifen, testosterone, gonadotropins, testis, ram

Prenatal intervention by P271 reduces LH pulsatility and testosterone levels in PCOS condition

2017 ◽  
Author(s):  
Sareh Zeydabadinejad ◽  
Fahimeh Ramezani Tehrani ◽  
Azita Zadeh-Vakili ◽  
Mahsa Noroozzadeh
Keyword(s):  
Testosterone Levels ◽  
Lh Pulsatility ◽  
Prenatal Intervention

Reproductive hormone secretion and spermatogenic function in thyroidectomized rams receiving graded doses of exogenous thyroxine

1986 ◽  
Vol 111 (2) ◽  
pp. 245-253 ◽  
Author(s):  
Y. Chandrasekhar ◽  
M. J. D'Occhio ◽  
B. P. Setchell
Keyword(s):  
Hormone Secretion ◽  
Reproductive Function ◽  
Pulse Frequency ◽  
Endocrine Function ◽  
Sex Hormone Binding Globulin ◽  
Testosterone Levels ◽  
Reproductive Endocrine ◽  
Lh Release ◽  
Lh Releasing Hormone ◽  
The Relationship

ABSTRACT This study aimed to obtain a better understanding of the relationship between circulating thyroxine (T4) concentrations and reproductive endocrine function in the ram. Mature Merino rams were thyroidectomized and supplemented with 0, 30, 100 and 300% of normal T4 for 10 weeks. Thyroidectomy had no apparent effect on spermatogenic function but interfered with sperm maturation, the latter being returned to normal by 30% T4 replacement. Circulating testosterone levels were reduced by thyroidectomy and restored to control levels by 30% T4; when T4 levels were supranormal (300%), circulating testosterone levels were again reduced. The lowered circulating testosterone levels in thyroidectomized rams occurred as a result of suppressed testosterone secretion from the testis, observed under basal conditions and also following LH-releasing hormone (LHRH) and human chorionic gonadotrophin injection. In thyroidectomized rams, sex hormone binding globulin (SHBG) levels were depressed without changes in testosterone clearance rate (TCR), while in rams with supranormal T4 levels, TCR was increased without changes in SHBG levels. Subnormal levels of T4 also restored to normal the reduced LH pulse frequency in thyroidectomized rams. Reduced LH pulse frequency, together with diminished LH release following LHRH injection in thyroidectomized rams, suggested effects of T4 at the hypothalamo-pituitary axis. The present study demonstrates that complete lack of thyroid hormones suppresses normal reproductive endocrine function in the ram, but that this can be restored to normal by 30% T4 replacement. The results support the theory that T4 plays a permissive rather than a regulatory role in reproductive function in males. J. Endocr. (1986) 111, 245–253

Relationship between male hormonal status, Bezold–Jarisch reflex function, and ACE activity (cardiac and plasmatic)

2016 ◽  
Vol 94 (2) ◽  
pp. 231-236
Author(s):  
Otávio Arruda Heringer ◽  
Karla Oliveira dos Santos Cassaro ◽  
Nara Carolina Mateus Rabello Barbosa ◽  
Girlandia Alexandre Brasil ◽  
Andrews Marques do Nascimento ◽  
...  
Keyword(s):  
Negative Relationship ◽  
Morphometric Parameters ◽  
Male Rat ◽  
Hormonal Status ◽  
Hemodynamic Parameters ◽  
Converting Enzyme ◽  
Testosterone Levels ◽  
Cardiovascular Hemodynamics ◽  
17Β Estradiol ◽  
Ace Activity

The negative relationship between androgens and the Bezold–Jarisch reflex (BJR) has been demonstrated, but no studies evaluated the physiological influence of testosterone on this reflex. We evaluated the influence of male rat castration on the BJR, cardiac morphometric parameters, and the plasmatic and the cardiac angiotensin converting enzyme (ACE) activity. After castration (CAS), the rats were divided into 24 and 72 h (CAS24H, CAS72H), and 7 and 21 days (CAS7D, CAS21D) groups. The BJR was studied by administering increasing doses of phenylbiguanide (PBG; 1.5–24 μg/kg) at different times after castration. Castration results in the following: (i) reduction in testosterone levels (SHAM: 238.7 ± 15.1; CAS24H: 9.0 ± 0.5; CAS72H: 6.7 ± 0.4; CAS7D: 5.2 ± 0.2; and CAS21D: 2.2 ± 0.3 ng/dL; p < 0.05); (ii) no changes in 17β-estradiol; (iii) a reduced BJR sensitivity (PBG 6 μg/kg; SHAM: 77 ± 7; CAS24H: 63 ± 10; CAS72H: 55 ± 6; CAS7D: 54 ± 4; and CAS21D: 35 ± 2%; p < 0.01); (iv) a decrease in cardiac (SHAM: 107 ± 6; CAS24H: 92 ± 2; CAS72H: 82 ± 3; CAS7D: 54 ± 3; and CAS21D: 43 ± 4%; p < 0.05) and plasmatic (SHAM: 135 ± 8; CAS24H: 102 ± 5; CAS72H: 99 ± 3; CAS7D: 89 ± 4; and CAS21D: 56 ± 6%; p < 0.05) ACE activity. No changes were observed in cardiac morphometry and hemodynamic parameters. Therefore, castration leads to decrease in testosterone levels as early as 24 h, reduction in ACE activity and loss of BJR sensitivity 7 days after castration. The loss of BJR sensitivity was not related to cardiac morphometric changes and cardiovascular hemodynamics.

scholarly journals Acute Effects of Glucagon on Reproductive Hormone Secretion in Healthy Men

2020 ◽  
Vol 105 (6) ◽  
pp. 1899-1905
Author(s):  
Chioma Izzi-Engbeaya ◽  
Sophie Jones ◽  
Yoshibye Crustna ◽  
Pratibha C Machenahalli ◽  
Deborah Papadopoulou ◽  
...  
Keyword(s):  
Hormone Secretion ◽  
Reproductive Hormones ◽  
Metabolic Effects ◽  
Acute Administration ◽  
Reproductive Hormone ◽  
Glucagon Receptor ◽  
Healthy Men ◽  
Testosterone Levels ◽  
Reproductive Axis ◽  
Lh Pulsatility

Abstract Context Glucagon increases energy expenditure; consequently, glucagon receptor agonists are in development for the treatment of obesity. Obesity negatively affects the reproductive axis, and hypogonadism itself can exacerbate weight gain. Therefore, knowledge of the effects of glucagon receptor agonism on reproductive hormones is important for developing therapeutics for obesity; but reports in the literature about the effects of glucagon receptor agonism on the reproductive axis are conflicting. Objective The objective of this work is to investigate the effect of glucagon administration on reproductive hormone secretion in healthy young men. Design A single-blinded, randomized, placebo-controlled crossover study was conducted. Setting The setting of this study was the Clinical Research Facility, Imperial College Healthcare NHS Trust. Participants Eighteen healthy eugonadal men (mean ± SEM: age 25.1 ± 1.0 years; body mass index 22.5 ± 0.4 kg/m2; testosterone 21.2 ± 1.2 nmol/L) participated in this study. Intervention An 8-hour intravenous infusion of 2 pmol/kg/min glucagon or rate-matched vehicle infusion was administered. Main Outcome Measures Luteinizing hormone (LH) pulsatility; LH, follicle-stimulating hormone (FSH), and testosterone levels were measured. Results Although glucagon administration induced metabolic effects (insulin area under the curve: vehicle 1065 ± 292 min.µU/mL vs glucagon 2098 ± 358 min.µU/mL, P &lt; .001), it did not affect LH pulsatility (number of LH pulses/500 min: vehicle 4.7 ± 0.4, glucagon 4.2 ± 0.4, P = .22). Additionally, there were no significant differences in circulating LH, FSH, or testosterone levels during glucagon administration compared with vehicle administration. Conclusions Acute administration of a metabolically active dose of glucagon does not alter reproductive hormone secretion in healthy men. These data are important for the continued development of glucagon-based treatments for obesity.

scholarly journals Estrogen receptor antagonism uncovers gender-dimorphic suppression of whole body fat oxidation in humans: differential effects of tamoxifen on the GH and gonadal axes

2015 ◽  
Vol 173 (4) ◽  
pp. 479-487 ◽  
Author(s):  
Vita Birzniece ◽  
Ken K Y Ho
Keyword(s):  
Estrogen Receptor ◽  
Fat Metabolism ◽  
Fat Oxidation ◽  
Serum Levels ◽  
Sex Hormone Binding Globulin ◽  
Tamoxifen Treatment ◽  
Whole Body ◽  
Open Label ◽  
Testosterone Levels ◽  
Gh Secretion

ContextTamoxifen, a selective estrogen receptor modulator, suppresses GH secretion in women but not in men. It increases testosterone levels in men. As GH and testosterone stimulate fat metabolism, the metabolic consequences of tamoxifen may be greater in women than in men.ObjectiveTo determine whether tamoxifen suppresses fat oxidation (Fox) to a greater degree in women than in men.DesignAn open-label study of ten healthy postmenopausal women and ten healthy men receiving 2-week treatment with tamoxifen (20 mg/day).Endpoint measuresGH response to arginine stimulation, serum levels of IGF1, testosterone and LH (men only), sex hormone binding globulin (SHBG) and whole body basal and postprandial Fox.ResultsIn women, tamoxifen significantly reduced the mean GH response to arginine stimulation (Δ −87%,P<0.05) and circulating IGF1 levels (Δ −23.5±5.4%,P<0.01). Tamoxifen reduced postprandial Fox in women (Δ −34.6±10.3%;P<0.05). In men, tamoxifen did not affect the GH response to arginine stimulation but significantly reduced mean IGF1 levels (Δ −24.8±6.1%,P<0.01). Tamoxifen increased mean testosterone levels (Δ 52±14.2%;P<0.01). Fox was not significantly affected by tamoxifen in men.ConclusionTamoxifen attenuated the GH response to stimulation and reduced postprandial Fox in women but not in men. We conclude that at a therapeutic dose, the suppressive effect of tamoxifen on fat metabolism is gender-dependent. Higher testosterone levels may mitigate the suppression of GH secretion and Fox during tamoxifen treatment in men.

110 EFFECT OF MELATONIN TREATMENT ON LIBIDO AND ENDOCRINE FUNCTION OF DROMEDARY CAMEL BULLS OUT OF THE BREEDING SEASON

2017 ◽  
Vol 29 (1) ◽  
pp. 163 ◽  
Author(s):  
A. Swelum ◽  
I. Saadeldin ◽  
H. Ba-Awadh ◽  
A. Alowaimer
Keyword(s):  
Breeding Season ◽  
Reproductive Performance ◽  
Repeated Measures ◽  
Endocrine Function ◽  
Gland Secretion ◽  
Control Group ◽  
Dromedary Camel ◽  
Testosterone Levels ◽  
Significant Difference ◽  
Length Changes

The reproductive performance of camels is poor and has remained a major obstacle to the growth of dromedary populations. The limited breeding season is one of the most important causes of the poor reproductive performance. In seasonal animals, melatonin is the chemical messenger that allows the perception of daylight length changes. Commercial melatonin products have been developed for the manipulation of seasonal breeding in animals. The present study aimed to evaluate the influence of melatonin implantation on libido, serum melatonin, and testosterone concentrations in dromedary camels during the non-breeding season (June and July). Ten camel bulls were used in the 35-day-long trial; 5 of them were implanted with 30 Melovine® implant (Ceva, Libourne, France) subcutaneously on Day 0, whereas the other 5 camel bulls remained untreated as a control. Libido was evaluated weekly in response to oestrous-induced female camels treated with oestrogen (1 mL Oestrocon; oestradiol benzoate 5 mg mL−1) 2 days before assessment of libido. Libido was scored as follows: 0 = not interested: the male did not show any libido; 1 = low interested: the male went near the female and showed low frequency of sniffing and flehmen; 2 = interested: the male went near the female, it showed sniffing, flehmen, grinding of teeth/whistling, yawning; 3 = high interested: the male went near the female and was very agitated, it showed sniffing, flehmen, grinding of teeth/whistling, yawning, urination, and tail raising. It stood with open legs, and poll gland secretion and neck rubbing were observed; 4 = excited, like 3, but the male showed blatering and dulaa extrusion, was very excited, stood with open legs, high poll gland secretion and neck rubbing were observed. Blood samples were collected weekly. Serum melatonin and testosterone concentrations were evaluated using commercial ELISA kits. Comparisons among groups were evaluated using repeated-measures ANOVA, using SAS software (SAS Institute Inc., Cary, NC, USA). A difference was considered significant at the P < 0.05 level. The results revealed that at Day 0, all camel bulls in 2 groups had no libido and there was no significant difference in the melatonin or testosterone levels in the 2 groups. The libido increased gradually in the melatonin group and reached the maximum (3–5) at week 4 and week 5. The control group had low libido (0–1) along the trial. Statistically, the libido was significantly higher in the melatonin group than control group. Additionally, testosterone levels were significantly higher in melatonin group than control group, especially in the fourth week of the present trial (565.07 ± 33.04 pg mL−1 and 458.49 ± 25.36 pg mL−1, respectively). In conclusion, melatonin implantation in the non-breeding season significantly improved the libido and the reproductive performance of dromedary camel bulls. Therefore, it may be possible to improve the reproductive efficiency of camels by extending the breeding season through treatment with melatonin during the non-breeding season.

scholarly journals Rapid and Widespread Effects of 17β-Estradiol on Intracellular Signaling in the Male Songbird Brain: A Seasonal Comparison

Endocrinology ◽  
2012 ◽  
Vol 153 (3) ◽  
pp. 1364-1376 ◽  
Author(s):  
Sarah A. Heimovics ◽  
Nora H. Prior ◽  
Chris J. Maddison ◽  
Kiran K. Soma
Keyword(s):  
Breeding Season ◽  
Intracellular Signaling ◽  
Ventromedial Hypothalamus ◽  
Brain Regions ◽  
Camp Response Element Binding ◽  
Nonbreeding Season ◽  
Multiple Regions ◽  
17Β Estradiol ◽  
Caudomedial Nidopallium ◽  
Central Gray

Across vertebrate species, 17β-estradiol (E2) acts on the brain via both genomic and nongenomic mechanisms to influence neuronal physiology and behavior. Nongenomic E2 signaling is typically initiated by membrane-associated estrogen receptors that modulate intracellular signaling cascades, including rapid phosphorylation of ERK. Phosphorylated ERK (pERK) can, in turn, rapidly phosphorylate tyrosine hydroxylase (TH) and cAMP response element-binding protein (CREB). Recent data suggest that the rapid effects of E2 on mouse aggressive behavior are more prominent during short photoperiods (winter) and that acute aromatase inhibition reduces songbird aggression in winter only. To date, seasonal plasticity in the rapid effects of E2 on intracellular signaling has not been investigated. Here, we compared the effects of acute (15 min) E2 treatment on pERK, pTH, and pCREB immunoreactivity in male song sparrows (Melospiza melodia) pretreated with the aromatase inhibitor fadrozole during the breeding and nonbreeding seasons. We examined immunoreactivity in 14 brain regions including portions of the song control system, social behavior network, and the hippocampus (Hp). In both seasons, E2 significantly decreased pERK in nucleus taeniae of the amygdala, pTH in ventromedial hypothalamus, and pCREB in mesencephalic central gray, robust nucleus of the arcopallium, and caudomedial nidopallium. However, several effects were critically dependent upon season. E2 decreased pERK in caudomedial nidopallium in the breeding season only and decreased pCREB in the medial preoptic nucleus in the nonbreeding season only. Remarkably, E2 decreased pERK in Hp in the breeding season but increased pERK in Hp in the nonbreeding season. Together, these data demonstrate that E2 has rapid effects on intracellular signaling in multiple regions of the male brain and also demonstrate that rapid effects of E2 can be profoundly different across the seasons.

THE EFFECTS OF CLOMIPHENE ON ENDOCRINE FUNCTION IN MALE PATIENTS WITH ADRENOCORTICAL INSUFFICIENCY AND FOLLOWING CASTRATION

1968 ◽  
Vol 58 (1) ◽  
pp. 38-48 ◽  
Author(s):  
R. A. Harkness ◽  
E. T. Bell ◽  
J. A. Loraine ◽  
A. A. A. Ismail ◽  
W. I. Morse
Keyword(s):  
Follicle Stimulating Hormone ◽  
Endocrine Function ◽  
Adrenocortical Insufficiency ◽  
Marked Rise ◽  
Testosterone Levels ◽  
Main Effect ◽  
Male Patients ◽  
Stimulating Hormone

ABSTRACT The effect of clomiphene administration on steroid and gonadotrophin output has been studied in three male patients with adrenocortical insufficiency and in three castrate men. In the patients with adrenocortical insufficiency the main effect of clomiphene was to produce a marked increase in the output of urinary testosterone and of its metabolites, androsterone and aetiocholanolone. It is concluded that this effect results from testicular stimulation. In the castrate males clomiphene caused a less marked rise in the excretion of dehydroepiandrosterone (DHA), androsterone and aetiocholanolone, presumably indicating adrenocortical stimulation. Testosterone levels may have fallen slightly during the administration of the compound. Little or no effect on the output of »total gonadotrophic activity« or of follicle-stimulating hormone (FSH) was produced by clomiphene.

Interaction of 17β-estradiol and ketoconazole on endocrine function in goldfish (Carassius auratus)

2013 ◽  
Vol 132-133 ◽  
pp. 19-25 ◽  
Author(s):  
Zhenhua Yan ◽  
Guanghua Lu ◽  
Donghai Wu ◽  
Qiuxia Ye ◽  
Zhengxin Xie
Keyword(s):  
Carassius Auratus ◽  
Endocrine Function ◽  
Goldfish Carassius Auratus ◽  
17Β Estradiol

Aptamer–17β‐estradiol–antibody sandwich ELISA for determination of gynecological endocrine function

2020 ◽  
Author(s):  
Yue Huang ◽  
Li Zhang ◽  
Zhenzuo Li ◽  
Subash C. B. Gopinath ◽  
Yeng Chen ◽  
...  
Keyword(s):  
Sandwich Elisa ◽  
Endocrine Function ◽  
17Β Estradiol
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