A Comparison of Plasma Testosterone and Progesterone Levels in The Thredbo and Duckmaloi River Platypuses Over a Twelve Month Cycle.

1998 ◽  
Vol 20 (2) ◽  
pp. 305
Author(s):  
L. Hinds ◽  
D. Goldney
Keyword(s):  
Blood Sample ◽  
Breeding Season ◽  
Blood Cells ◽  
Peak Plasma ◽  
Plasma Testosterone ◽  
Plasma Progesterone ◽  
Breeding Potential ◽  
Testosterone Levels

A 1-2 ml blood sample was removed from the bill sinus of 208 captured platypuses from the Duckmaloi and Thredbo Rivers over the period January 1991-March 1993. Platypuses from the Duckmaloi were sampled monthly during 1992 and in February, August and December from the Thredbo River in the same year. The numbers and sex of platypuses sampled are recorded in the following Table. Samples were stored on ice and plasma separated from blood cells within 24 hours of sampling by centrifugation for I0 minutes and the supernatant stored at -20°C. The changes in plasma testosterone and progesterone for platypuses from both rivers were compared over a 12 month cycle. The levels of these two hormones were considerably less in the breeding season in the Thredbo River platypuses than in those from the Duckmaloi River. Peak plasma progesterone levels of the order of 90 ng/ml were measured in the Duckmaloi River females compared to levels of <5 ng/ml in Thredbo River females. Male plasma testosterone levels in animals from the Duckmaloi River peaked around 15 ng/ml, whereas Thredbo River males had levels of around 6 ng/mI. These data suggest that over the period of the two year study, platypus breeding potential in the Thredbo River was significantly impaired.

Seasonal variation in plasma testosterone and the testis in captive male dingoes, Canis familiaries dingo

1979 ◽  
Vol 27 (6) ◽  
pp. 939 ◽  
Author(s):  
PC Catling
Keyword(s):  
Seasonal Variation ◽  
Breeding Season ◽  
Plasma Testosterone ◽  
Testosterone Levels ◽  
Central Australia ◽  
Eastern Highlands

Eastern Highlands and Central Australian dingoes housed in Canberra do not have a testicular cycle. They are spermatogenically active and capable of mating with oestrous females and fathering young all year. They do exhibit a breeding season (April-June) but this is entirely governed by the female. During the breeding season testosterone levels rise; this is thought to be influenced by the presence of an oestrous female and copulation. There are indications that captive dingoes in Central Australia may have a testicular cycle. Colony dingoes showed little interest in and do not mate with an oestrous domestic female at times other than January-July. They also become almost aspermous outside the breeding season. In contrast, Central Australian dingoes housed in Canberra are spermatogenically active and capable of successful matings all year.

scholarly journals Testosterone Does not Increase in Response to Conspecific Challenges in the White-Bellied Antbird (Myrmeciza Longipes), A Resident Tropical Passerine

The Auk ◽  
2006 ◽  
Vol 123 (1) ◽  
pp. 61-66
Author(s):  
Bradley C. Fedy ◽  
Bridget J. M. Stutchbury
Keyword(s):  
Breeding Season ◽  
Temperate Zone ◽  
Plasma Testosterone ◽  
Tropical Species ◽  
Zone Model ◽  
Territorial Aggression ◽  
Social Instability ◽  
Testosterone Levels ◽  
Testosterone Secretion ◽  
Removal Experiments

Abstract Resident tropical passerines that exhibit year-round territorial aggression do not fit well into the temperate-zone model, because testosterone does not increase substantially during the breeding season. We studied patterns of testosterone secretion in the White-bellied Antbird (Myrmeciza longipes), a resident tropical species in Panama that maintains territories year-round and is capable of aggression throughout the year, regardless of its stage of reproduction. Levels of plasma testosterone were low (mean = 0.30 ng mL−1) throughout the breeding and nonbreeding seasons and did not differ between them. Testosterone also did not increase in response to simulated conspecific intrusions. When we used temporary removal experiments to induce natural, extended conflict between males, testosterone levels did not increase in response to the extended social instability that resulted. White-bellied Antbirds demonstrate an apparent uncoupling of testosterone and territorial aggression throughout the year. La Testosterona no Aumenta como Respuesta a Desafíos de Individuos Coespecíficos en Myrmeciza longipes, un Paserino Residente de la Zona Tropical

scholarly journals Ignoring the challenge? Male black redstarts ( Phoenicurus ochruros ) do not increase testosterone levels during territorial conflicts but they do so in response to gonadotropin-releasing hormone

2011 ◽  
Vol 278 (1722) ◽  
pp. 3233-3242 ◽  
Author(s):  
Beate Apfelbeck ◽  
Wolfgang Goymann
Keyword(s):  
Breeding Season ◽  
Gonadotropin Releasing Hormone ◽  
Plasma Testosterone ◽  
Releasing Hormone ◽  
Social Challenges ◽  
Testosterone Levels ◽  
Territorial Conflicts ◽  
Territory Defence ◽  
Simulated Territorial Intrusion ◽  
Territorial Intrusion

Competition elevates plasma testosterone in a wide variety of vertebrates, including humans. The ‘challenge hypothesis’ proposes that seasonal peaks in testosterone during breeding are caused by social challenges from other males. However, during experimentally induced male–male conflicts, testosterone increases only in a minority of songbird species tested so far. Why is this so? Comparative evidence suggests that species with a short breeding season may not elevate testosterone levels during territory defence. These species may even be limited in their physiological capability to increase testosterone levels, which can be tested by injecting birds with gonadotropin-releasing hormone (GnRH). We studied two populations of black redstarts that differ in breeding altitude, morphology and the length of their breeding season. Unexpectedly, males of neither population increased testosterone in response to a simulated territorial intrusion, but injections with GnRH resulted in a major elevation of testosterone. Thus, black redstarts would have been capable of mounting a testosterone response during the male–male challenge. Our data show, for the first time, that the absence of an androgen response to male–male challenges is not owing to physiological limitations to increase testosterone. Furthermore, in contrast to comparative evidence between species, populations of black redstarts with a long breeding season do not show the expected elevation in testosterone during male–male challenges.

Experimentally Elevated Plasma Testosterone Levels Do Not Influence Singing Behaviour of Male Blue Tits (Parus caeruleus) During the Early Breeding Season

Ethology ◽  
2006 ◽  
Vol 112 (10) ◽  
pp. 984-992 ◽  
Author(s):  
Hansjoerg P. Kunc ◽  
Katharina Foerster ◽  
Etiënne L. M. Vermeirssen ◽  
Bart Kempenaers
Keyword(s):  
Breeding Season ◽  
Plasma Testosterone ◽  
Parus Caeruleus ◽  
Elevated Plasma ◽  
Testosterone Levels ◽  
Blue Tits

PLASMA TESTOSTERONE LEVELS IN DONKEYS IN THE TROPICS

1977 ◽  
Vol 74 (1) ◽  
pp. 151-152 ◽  
Author(s):  
S. GOMBE ◽  
C. B. KATONGOLE
Keyword(s):  
Breeding Season ◽  
Adult Male ◽  
Laboratory Animals ◽  
Plasma Testosterone ◽  
Free Access ◽  
Testosterone Levels ◽  
Animal Physiology ◽  
Basal Plasma ◽  
The Tropics

Department of Animal Physiology, University of Nairobi, Chiromo, Nairobi, Kenya (Received 1 February 1977) The concentration of testosterone in the plasma of most male domestic and laboratory animals, for example bulls (Thibier, 1975), boars (Andresen, 1976) and rats (Mock, Kamel, Wright & Frankel, 1975) is usually in excess of 10 nmol/l. In seasonal breeders such as sheep, values as high as 90 nmol/l have been reported in the summer before the breeding season (Falvo, Buhl, Reimers, Foxcroft, Dunn & Dziuk, 1975). In contrast, Katongole (1971) found that in a temperate summer, plasma testosterone concentrations in Equidae, including the donkey, were 4·5 nmol/l or less. It was, therefore, of interest to investigate whether the basal plasma testosterone concentrations in donkeys would be higher and more stable in the tropics. Six potent adult male donkeys were kept in a large pen, fed rhode grass and given free access to salt and water. Blood

INFLUENCE OF METYRAPONE ON PLASMA CONCENTRATIONS OF TESTOSTERONE AND ANDROSTENEDIONE IN MAN

1971 ◽  
Vol 68 (3) ◽  
pp. 576-584 ◽  
Author(s):  
K. O. Nilsson ◽  
B. Hökfelt
Keyword(s):  
Body Weight ◽  
Male Patient ◽  
Gradual Increase ◽  
Plasma Concentrations ◽  
Plasma Testosterone ◽  
Testosterone Levels ◽  
Basal Plasma ◽  
Normal Males ◽  
A Minor ◽  
Secondary Hypogonadism

ABSTRACT Metyrapone was administered either orally, 750 mg every four h, in a total of six doses, or intravenously 30 mg per kg body weight as a four h infusion. In three males with normal endocrine functions, metyrapone given orally or intravenously induced a fall in plasma testosterone and an elevation of androstenedione within 2–8 h. When metyrapone was administered to a patient given dexamethasone to suppress endogenous ACTH production, the androstenedione levels did not alter whereas the testosterone levels showed a slight, transient decrease. In two normal females metyrapone administration was followed by a marked increase in plasma androstenedione whereas testosterone showed only a minor, gradual increase. In one male patient with Addison's disease the basal plasma testosterone was normal whereas the level of androstenedione was low. Following metyrapone intravenously, there was a slight suppression of plasma testosterone but no change in the androstenedione concentration. In one patient with primary hypogonadism, two with secondary hypogonadism and two with Klinefelter's syndrome the plasma testosterone was low under basal conditions and did not change following metyrapone. Basal plasma androstenedione was within the range for normal males and increased markedly following metyrapone in all the cases.

Effects of oestradiol benzoate (OeB) and human chorionic gonadotrophin (hCG) on the testes and accessory sex glands of the rat

1981 ◽  
Vol 96 (2) ◽  
pp. 273-280 ◽  
Author(s):  
Mridula Chowdhury ◽  
Robert Tcholakian ◽  
Emil Steinberger
Keyword(s):  
Treated Group ◽  
Inhibitory Effect ◽  
Male Rats ◽  
Plasma Testosterone ◽  
Control Group ◽  
Intact Male ◽  
Intact Control ◽  
Testosterone Levels ◽  
Oestradiol Benzoate ◽  
Direct Inhibitory Effect

Abstract. It has been suggested that treatment of intact male rats with oestradiol benzoate (OeB) causes an interference with testosterone (T) production by the testes by a direct inhibitory effect on steroidogenesis. To test this hypothesis, different doses (5, 10 or 25 IU) of hCG were administered concomitantly with 50 μg of OeB to adult intact or hypophysectomized male rats. The testicular and plasma testosterone, and serum hCG levels were determined. The sex accessory weights were recorded. In the intact OeB-treated group of animals, hCG stimulated both the secondary sex organs and plasma testosterone levels above the intact control group. However, in hypophysectomized animals, although plasma testosterone levels increased above that of intact controls, their secondary sex organ weights did not. Moreover, inspite of high circulating hCG levels, the testicular testosterone content and concentration remained suppressed in OeB-treated animals. The reason for such dichotomy of hCG action on OeB-treated animals is not clear at present.

A note on attainment of puberty of september-born early-maturing ewe lambs in relation to level of nutrition

1991 ◽  
Vol 53 (3) ◽  
pp. 407-409 ◽  
Author(s):  
F. Forcada ◽  
J. A. Abecia ◽  
L. Zarazaga
Keyword(s):  
Sexual Activity ◽  
Breeding Season ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Plasma Progesterone ◽  
Ewe Lambs ◽  
Early Maturing ◽  
Age At Puberty

The attainment of puberty in September-born early-maturing ewe lambs was studied at Zaragoza (latitude 41° 40' N). Thirty twin Salz females were allocated to two groups receiving two nutrition levels after 3 months of age: high (500 g/day lucerne hay and 500 g/day concentrate) (H) and low (500 g/ day lucerne hay) (L). Oestrus was detected daily by aproned rams. Corpora lutea were counted after oestrus and plasma progesterone levels monitored each week.In the first breeding season (January to February) the percentage of females showing sexual activity (silent emulation or oestrus and ovulation) was higher in the H compared with the L group (67 and 20%; P < 0/05). Nonpubertal oestrus before the main breeding season was detected in 67% of animals. In the main breeding season and for H and L groups respectively, percentage of females showing silent ovulation before puberty was 67 and 33% and mean age at puberty extended to 319 (s.e. 4-8) and 314 (s.e. 3·7) days. Ovulation rate at puberty was 1·73 (s.e. 0·13) and 1·33 (s.e. 0·15) respectively (P < 0·05).

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