Changes In Plasma Testosterone Concentrations Research Articles

Initial Characterization of Male Southern Stingray (Hypanus americanus) Reproductive Parameters and Preliminary Investigation of Sperm Cryopreservation.

Simple SummaryUnderstanding the reproductive biology of a species is critical for the development of biobanks and assisted reproductive techniques to aid in the genetic management of isolated populations. Male southern stingray (Hypanus americanus) reproductive examinations were opportunistically conducted in March and June. Semen and plasma were collected to characterize ejaculate parameters and to investigate the effect of plasma total testosterone on semen quality. Semen was used for preliminary sperm cryopreservation studies. Changes in semen quality were observed with changes in plasma testosterone concentrations and body conditions. Southern stingray spermatozoa were highly sensitive to cooling rates with slower rates, producing a higher post-thaw survival.This study investigated the reproductive biology and sperm cryopreservation of ex situ southern stingrays (Hypanus americanus) by semen collection and characterization and the development and validation of an enzyme-linked immunoassay for plasma total testosterone. Semen was collected in March and June using a manual massage technique, and the ejaculates were assessed for volume, pH, osmolarity, motility, status (0–5 scale: 0 = no forward progression, 5 = rapid linear progression) and total sperm count. Semen was extended in Hank’s elasmobranch ringer solution containing 10% DMSO, 10% glycerol or 5% glycerol with 5% N-methylformamide and cryopreserved using a conventional freezing method (~−50 °C/min) or a modified slow freezing method (~−3 °C/min). Body condition was scored from 1–5 and was noted to be low in March (1.93 ± 0.07) due to feeding practices and increased by June (2.93 ± 0.05) after dietary corrections were made. A concomitant increase (p < 0.05) in plasma total testosterone concentration and sperm motility was noted between March (8.0 ± 7.2 ng/mL, 5.71 ± 2.77%) and June (97.3 ± 11.3 ng/mL, 51.4 ± 14.3%). Samples cryopreserved using a modified slow freeze method (~−3 °C/min) had higher post-thaw motility and plasma membrane integrity than conventionally cryopreserved samples. Data indicate that southern stingray sperm morphometrics adheres to those of other elasmobranch species and that a slow cooling rate may be an avenue of research to improve southern stingray sperm survival during cryopreservation.

Gonadotropin-induced testosterone response in peripubertal male alligators

Based on the response to three different gonadotropin challenges, we evaluated seasonal production of testosterone in a group of captive-raised four-year-old male alligators that varied in size. To stimulate gonadal steroidogenesis, we injected each alligator with ovine FSH (150 ng/ml plasma). Plasma testosterone concentrations were measured in repeated blood samples taken between 0 and 72 h after FSH injection. To determine if there was seasonal variation in response, we repeated the experiment on the same alligators three times during the breeding season (March, May, and July, 2000). All alligators responded to exogenous FSH by exhibiting increased plasma concentrations of testosterone ( p<0.0001 for all months). However, the degree of the response depended on body size. Thus, larger alligators produced more testosterone and were more affected by changes in season compared to smaller alligators. We have previously observed that juvenile male alligators display seasonal changes in plasma testosterone concentrations that mimic the cycle observed in adult males. Our present data suggest that seasonal changes in plasma testosterone appear to be associated not only with changes in gonadotropin release but in gonadal responsiveness as well. We propose, given these observations, that alligators experience an extended period of puberty, during which the gonads synthesize gradually increasing steroid hormone concentrations. These peripubertal animals are not juveniles but sub-adults capable of responding to the seasonal signals associated with reproductive timing in adults.

Age-related changes in plasma testosterone concentrations and genital organs content of bulk and trace elements in the male dromedary camel

There is a paucity of information regarding the influence of plasma testosterone concentrations and inorganic cations secreted in the different seminal fractions on the spermatozoon activity throughout the reproductive life of the one-humped camels. To demonstrate these relationships, the genital organs of 12 prepubertal (<3 years), 9 peripubertal (3–<5 years), 16 mature (5–<15 years) and 15 aged (≥15 years) camels were collected from the Buraidah slaughter house (Al-Qassim Province, Saudi Arabia) during two consecutive breeding seasons (November–April) over 2 years. Plasma testosterone concentrations (mean±S.E.) did not exceed 1.4 ng/ml in prepubertal animals with a 3–4 fold increase in peripubertal (3.2±0.4 ng/ml) and mature (4.8±0.6 ng/ml) camels followed by about 50% decrease (2.6±0.3 ng/ml) in aged ones. These hormonal changes were correlated significantly with concentrations of certain elements in the testes (highest Na, Ca and Cu contents), epididymides (highest P and Fe contents), prostrate (highest Zn content), and bulbo-urethral glands (highest K and Mg contents). The significance of some interrelationships among the different cations and their biological effects on sperm production and metabolic activity were discussed.

Growth-related changes in testicular mass and plasma testosterone concentrations in long-finned pilot whales, Globicephala melas.

Blood samples and testes were collected from long-finned pilot whales (Globicephala melas) off the Faroe Islands at irregular intervals over a period of 3 years (July 1986-December 1989). Changes in testis mass (n = 674) and plasma testosterone concentrations (n = 214), measured by radioimmunoassay, were examined with respect to age, bodylength and bodymass of the animals. Corresponding to a rapid testicular growth (from 0.25 kg up to 1.9 kg), puberty occurred in male pilot whales of 4.6-5.7 m in bodylength, 1.2-1.9 tonnes in bodymass and 11-22 years of age. Changes in plasma testosterone concentrations confirmed this result, with very low values (< 2 ng ml-1) in immature animals (testis mass < 0.2 kg), followed by a sharp increase (from 2 to 29 ng ml-1) during the pubertal period, and the maintenance of high concentrations with large variability (> 1.5 ng ml-1 to 14 ng ml-1) in mature males. Testosterone concentrations were significantly correlated with testis mass (P < 0.001), but not with bodylength or age, and very large individual variations were observed in mature males. The average age, length and mass at the attainment of sexual maturity were estimated at 16.99 +/- 0.30 years, 5.162 +/- 0.013 m and 1.403 +/- 0.005 tonnes, respectively.

Seasonal changes in plasma testosterone concentrations in response to administration of hCG in a desert rodent, the sand rat (Psammomys obesus)

In adult male sand rats inhabiting the Béni-Abbès area (Algeria), testicular endocrine activity increased in early summer (June-July), was highest in autumn-winter and decreased throughout spring. Testosterone secretion by the testis of the sand rat was stimulated (by 10-60-fold) throughout the year by exogenously administered hCG (25 i.u.). However, the response exhibited annual changes mainly characterized by a marked increase in early summer (June-July); the response to hCG was depressed in autumn and became minimal in winter and in early spring. The results strongly suggest that the summer onset of testicular endocrine activity is, at least in part, due to an increase in the testis sensitivity to LH.

Seasonal changes in plasma testosterone concentrations and Leydig cell and accessory gland activity in the Cape horseshoe bat (Rhinolophus capensis).

Male Cape horseshoe bats were studied in the Cape Province of South Africa (33 degrees 17'S, 26 degrees 25'E) between January 1983 and June 1985. The reproductive cycle is characterized by reactivation of the seminiferous tubules in early summer (October) after a 4-month (June to September) period of winter inactivity. Spermiogenesis occurred between January and April, and spermatozoa were released to the epididymides in April and May. Spermiogenesis was associated with Leydig cell activity and increasing plasma testosterone concentrations. At this time components of the reproductive accessory glands became secretorily active or showed increasing secretory activity. During winter Leydig cells were secretorily inactive and plasma testosterone concentrations dropped, but components of the accessory complex remained active. There was a second period of Leydig cell secretory activity and increasing and peak plasma testosterone values in late winter/early summer which may be associated with copulation or the initiation of a new cycle of spermatogenesis.

Seasonal changes in the testes and accessory reproductive organs and seasonal and circadian changes in plasma testosterone concentrations in the male grey squirrel ( Sciurus carolinensis)

A 27-month study of cycles of regression and recrudescence of testis function in adult, grey squirrels in a natural environment in southern England has shown concomitant variation in mean testes weights, mean plasma testosterone concentrations, and mean weights of accessory sex organs, this variation being closely associated with months of the year. Testis regression occurred in the period June to August, the exact timing differing among individuals. In 1979–1980 the testes of all squirrels then remained regressed for 7 months, whereas in the autumn of 1980 testes were regressed in most squirrels for 4 months. There was also evidence of testis regression in some individuals in March 1979 and March 1981. Males born and housed in a small woodland enclosure in 1979–1980 and well fed with grain did not experience the long period of regressed testes. Plasma testosterone concentrations measured hourly over 24 hr in squirrels with large, active testes varied from 0.4 to 20 nmol/ 1, both within and between individuals, the higher concentrations being observed between midday and midnight. The range in the age of males at puberty, based on fusion of the epiphyses of the wrist, was 1.0 to 1.25 year. Juvenile males housed in a woodland enclosure together with adult males and females remained prepubertal up to 2 years of age.

Effect of castration and testosterone administration on seminal vesicles and prostates of rats.

ArticleEffect of Castration and Testosterone Administration on Seminal Vesicles and Prostates of RatsGuilford G. Rudolph, and Willard R. StarnesGuilford G. RudolphFrom the Radioisotope Unit, Thayer Veterans Administration Hospital and Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, and Willard R. StarnesFrom the Radioisotope Unit, Thayer Veterans Administration Hospital and Department of Biochemistry, Vanderbilt University, Nashville, TennesseePublished Online:30 Nov 1954https://doi.org/10.1152/ajplegacy.1954.179.3.415MoreSectionsPDF (668 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByAge-related changes in plasma testosterone concentrations and genital organs content of bulk and trace elements in the male dromedary camelAnimal Reproduction Science, Vol. 62, No. 4Bulk and trace elements in the accessory glands of buffalo bullsBritish Veterinary Journal, Vol. 148, No. 6Active Principle of Swine Prostate Extract: II. Effect of a Peptide Isolated from Swine Prostate Extract on Rat ProstateJapanese Journal of Pharmacology, Vol. 56, No. 4Characterization of prostaglandin E2 20-hydroxylase of sheep vesicular glandsBiochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism, Vol. 879, No. 2Recognition Processes and Behavior, with Special Reference to Effects of Testosterone on PersistenceActinomycin: Inhibition of testosterone-stimulated glycogen synthesis in the rat prostate and seminal vesiclesLife Sciences, Vol. 7, No. 10 More from this issue > Volume 179Issue 3November 1954Pages 415-418 Copyright & PermissionsCopyright © 1954 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1954.179.3.415PubMed13228601History Received 25 June 1954 Published online 30 November 1954 Published in print 30 November 1954 Metrics