Effects of cadmium chloride administration on the testicular growth and plasma testosterone secretion of Chios ram-lambs

The aims of the present study were to examine the variability of testosterone secretion in the Virginia Opossum over a 24 h period and to develop a testosterone stimulation test that would provide an index of the prevailing testosterone biosynthetic capacity of the testes; the latter was used to clinically evaluate the efficacy of a gonadotrophin-releasing hormone agonist contraceptive. Sexually-mature captive opossums (n = 12) located in Africam Safari (Mexico) sampled every 12 h over 24 h consistently showed basal (<0.21 ng mL–1) blood testosterone concentrations. Intra-muscular injection of buserelin (2 μg mL–1) and human chorionic gonadotrophin (hCG; 1000 IU) resulted in an increase (P < 0.05) of plasma testosterone concentrations with maximal concentrations (3.9 ng mL–1 and 5.8 ng mL–1 respectively) occurring 120 min after injection. Plasma testosterone declined relatively rapidly to basal concentrations after 240 min with hCG but remained elevated after the same period of time with buserelin. Male opossums treated with (n = 6) and without (n = 6) a controlled-release deslorelin implant (Suprelorin; 4.7 mg deslorelin) were evaluated over a 10-week period for changes in testosterone secretion (hCG stimulation test) and sperm production (spermatorrhea). At the end of this period, the animals were hemi-castrated and their relative testicular quantitative histology compared. Testosterone concentration decreased over the course of the study in both treated and control animals (P < 0.0001) but there was no apparent effect of deslorelin on testosterone secretion, testicular histology (relative proportions of testicular cell types and seminiferous tubule diameter), or sperm production (presence of sperm in the cauda epididymis or urine)

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Testicular growth and hormonal parameters in the male Snell dwarf mouse

Acta Endocrinologica ◽

10.1530/acta.0.1150399 ◽

1987 ◽

Vol 115 (3) ◽

pp. 399-405 ◽

Cited By ~ 8

Author(s):

M. T. Hochereau-de Reviers ◽

M. M. de Reviers ◽

C. Monet-Kuntz ◽

C. Perreau ◽

I. Fontaine ◽

...

Keyword(s):

Sertoli Cells ◽

Normal Values ◽

Accessory Gland ◽

Plasma Testosterone ◽

Cell Multiplication ◽

Daily Production ◽

Testicular Growth ◽

Adult Mice ◽

Snell Dwarf ◽

Dwarf Mice

Abstract. Dwarf mice show delayed testicular growth and their adult testis weights are half the normal value. The aims of the present work were firstly, to compare the developmental profiles of plasma gonadotropins and of testicular cell multiplication and differentiation in dwarf vs normal mice and secondly, to determine the effect of hMG supplementation on dwarf mice. In the dwarf mice no pubertal rise in plasma FSH was observed, and the adult values remained very low when compared with those of normal mice; plasma LH decreased after 40 days of age and remained equal to half the normal values. In adults, testicular testosterone content was greatly increased in dwarf mice compared with normal mice, whereas plasma testosterone and accessory gland weights were reduced. At 24 days of age, the total numbers per testis of Leydig and Sertoli cells were reduced in dwarf vs normal mice, whereas in adult mice their differentiation, but not their total numbers, was reduced. This resulted in lower daily production of leptotene primary spermatocytes and of round spermatids in dwarf than in normal mice. hMG supplementation promoted Leydig and Sertoli cell multiplication, but did not produce full differentiation, resulting in increased daily production of round spermatids. In conclusion, in adult dwarf mice a deficiency in plasma gonadotropins prevents full differentiation of Leydig and Sertoli cells without affecting the number of these cells.

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Studies of zinc nutrition in sheep. I. The relation of zinc to growth, testicular development, and spermatogenesis in young rams

Australian Journal of Agricultural Research ◽

10.1071/ar9690889 ◽

1969 ◽

Vol 20 (5) ◽

pp. 889 ◽

Cited By ~ 67

Author(s):

EJ Underwood ◽

M Somers

Keyword(s):

Zinc Deficiency ◽

Size Structure ◽

Clinical Signs ◽

Feed Consumption ◽

Testicular Development ◽

Sperm Production ◽

Poor Growth ◽

Testicular Growth ◽

Ram Lambs ◽

And Function

Ram lambs fed on a diet containing 2.4 p.p.m. zinc made poor growth, developed clinical signs of severe zinc deficiency, showed impaired testicular growth, and showed a complete cessation of spermatogenesis within a period of 20–24 weeks. Lambs fed on the same diet supplemented with zinc sulphate to provide total zinc levels of 17.4 and 32.4 p.p.m. had a higher feed intake, made significantly greater liveweight gains, and showed no signs of zinc deficiency. Testicular growth and sperm production were markedly improved by both the zinc supplements. No differences in liveweight gains or feed consumption between the two supplemented groups were observed but testicular growth and sperm production were highly significantly greater in the lambs receiving the larger zinc supplement. It was concluded that a dietary zinc intake of 17.4 p.p.m. is adequate for growth of ram lambs but is inadequate for normal testicular development and function. Lambs in which consumption of the diet containing 32.4 p.p.m. zinc was restricted to that of the zinc-deficient group showed no significant improvement in liveweight gains, but testicular development and sperm production were significantly greater than in the zinc-deficient lambs. Complete remission of all signs of zinc deficiency and full recovery of testicular size, structure, and function were achieved in a zinc repletion period lasting 20 weeks.

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Breed differences in testicular growth and gonadotropin secretion in prepubertal ram lambs

Theriogenology ◽

10.1016/0093-691x(83)90116-4 ◽

1983 ◽

Vol 19 (5) ◽

pp. 749-758 ◽

Cited By ~ 6

Author(s):

J.R. Lucas ◽

D.R. Notter ◽

F.S. McClaugherty ◽

G.W. Anderson ◽

F.C. Gwazdauskas

Keyword(s):

Gonadotropin Secretion ◽

Testicular Growth ◽

Breed Differences ◽

Ram Lambs

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An ocular capacity to promote photoperiodic testicular growth in the quail

Journal of Endocrinology ◽

10.1677/joe.0.0960085 ◽

1983 ◽

Vol 96 (1) ◽

pp. 85-90 ◽

Cited By ~ 6

Author(s):

J. D. Baylé ◽

J. Oliver ◽

B. Sicard

Keyword(s):

Optic Nerve ◽

Anterior Chamber ◽

Plasma Testosterone ◽

Testosterone Levels ◽

Immature Male ◽

Testicular Growth ◽

Ocular Implants

Disk-shaped, 0·6 × 0·2 mm pellets of radioluminous material were inserted in the anterior chamber of the eyes of sexually immature male quail on short daylengths. Two weeks later testicular weights and plasma testosterone levels were significantly increased compared with controls. The effectiveness of the ocular implants varied according to the spectrum of emission of the radioluminous material. Sectioning of the optic nerve suppressed all gonadal response to retinal photostimulation.

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A study of sexual development in ram lambs

Animal Science ◽

10.1017/s0003356100002671 ◽

1986 ◽

Vol 43 (3) ◽

pp. 459-468 ◽

Cited By ~ 10

Author(s):

F. M. S. Al-Nakib ◽

G. A. Lodge ◽

J. B. Owen

Keyword(s):

Body Weight ◽

Testosterone Level ◽

Sexual Development ◽

Sexual Maturity ◽

Semen Quality ◽

Plasma Testosterone ◽

Artificial Rearing ◽

Sexual Characteristics ◽

Ram Lambs ◽

Mating Performance

ABSTRACTTwo experiments were designed to study the effect of rearing method, female company, and repeated libido and semen tests on the pattern of sexual development of ram lambs. Four artificial rearing treatments (AR) were compared with natural rearing (NR) in one experiment and four artificial compared with three natural rearing treatments in a second experiment. Lambs on AR treatments in both experiments, as well as naturally reared lambs in the second experiment, were reared with or without females either before and/or after weaning. Half the lambs in the second experiment were libido and semen tested, and their mean plasma testosterone level was also measured, while the rest were only tested at the end of the experiment. The effect of method of rearing and female company on body growth, testes diameter, libido and semen quality were also investigated.A close relationship was found between body weight and sexual characteristics (for example, testis diameter, semen traits, libido, testosterone level and age at the onset of sexual maturity). NR resulted in faster growth than AR but was not appreciably different from early weaned-naturally reared treatments. It was also observed that mating performance improved steadily with advancement in age and increase in body weight. The onset of sexual maturity was attained at a minimum of 23 kg body weight and a minimum of 198 days of age. However, the heavier the lamb when sexually mature, the better its mating performance.Previous libido tests of ram lambs improved their subsequent mating performance, but had no effect on semen quality. However, libido tests did not improve the performance of those ram lambs which did not exhibit initial libido.It is suggested that early weaning at 2 months of age could be a suitable system for ram lambs weaned off their mothers for breeding purposes. These lambs should be reared as an all-male group but libido tested at monthly intervals commencing at 3 months of age. The criteria for selecting these lambs at an earlier age should be body weight and testis diameter.

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

The Auk ◽

10.1093/auk/123.1.61 ◽

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

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THE TEMPORAL RELATIONSHIP BETWEEN THE SECRETION OF LUTEINIZING HORMONE AND TESTOSTERONE IN MAN

Journal of Endocrinology ◽

10.1677/joe.0.0640017 ◽

1975 ◽

Vol 64 (1) ◽

pp. 17-26 ◽

Cited By ~ 41

Author(s):

P. H. ROWE ◽

P. A. RACEY ◽

G. A. LINCOLN ◽

M. ELLWOOD ◽

J. LEHANE ◽

...

Keyword(s):

Blood Flow ◽

Data Analysis ◽

Luteinizing Hormone ◽

Temporal Relationship ◽

New Method ◽

Plasma Testosterone ◽

Human Testis ◽

Testosterone Secretion ◽

Testicular Blood Flow ◽

Lh Releasing Hormone

SUMMARY It has been suggested recently that testosterone secretion by the human testis may be controlled by factors other than luteinizing hormone (LH). In order to re-examine this hypothesis, plasma LH and testosterone concentrations were determined throughout the day in eight studies. A new method of data analysis revealed that the levels of the two hormones were closely related, but that the testicular response to LH was sluggish. These results explain some inconsistencies in the literature. It was demonstrated that average values for LH varied throughout the day, with a morning maximum and an evening minimum. It was also shown that injections of LH releasing hormone in man resulted in an increase in plasma testosterone above control levels. These results are consistent with the concept that LH controls the major changes in testosterone secretion in men. They do not exclude, however, the possible existence of other factors which might affect the peripheral concentration of testosterone, such as changes in testicular blood flow.

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PLASMA TESTOSTERONE LEVELS IN INTACT AND HEMICASTRATED GROWING COCKERELS

Journal of Endocrinology ◽

10.1677/joe.0.0810169 ◽

1979 ◽

Vol 81 (2) ◽

pp. 169-174 ◽

Cited By ~ 16

Author(s):

F. J. M. DRIOT ◽

M. DE REVIERS ◽

J. WILLIAMS

Keyword(s):

Plasma Testosterone ◽

Early Age ◽

Blood Samples ◽

Testosterone Levels ◽

Testosterone Secretion ◽

Testicular Hypertrophy

Changes in the levels of testosterone in plasma were measured by radioimmunoassay in blood samples taken at frequent intervals between 2 and 26 weeks of age from entire cockerels and cockerels hemicastrated before 2 weeks of age. In both groups the pattern of testosterone secretion could be divided into three clearly defined phases. In young birds, the levels of testosterone in plasma were low (0·3 ng/ml) but in the prepubertal period, at 11 weeks of age, they started to rise and continued to rise until 22 weeks of age when adult levels, which fluctuated between 2·5 and 3·5 ng/ml, were reached. In the immediate period after hemicastration, the concentration of testosterone decreased temporarily. From 11 weeks of age the levels of testosterone in the hemicastrated birds were approximately 75% of those in intact birds. These results are discussed in relation to the compensatory testicular hypertrophy which occurs in growing cockerels hemicastrated at an early age.

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