Effect of intraventricular injection of 5,6-dihydroxytryptamine on spermatogenesis and plasma testosterone levels in the rat

1985 ◽  
Vol 106 (3) ◽  
pp. 395-NP ◽  
Author(s):  
T. K. Das ◽  
R. Mazumder ◽  
N. M. Biswas
Keyword(s):  
Quantitative Evaluation ◽  
Wistar Rats ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Seminiferous Epithelium ◽  
Intraventricular Injection ◽  
Plasma Testosterone ◽  
Testosterone Levels ◽  
Testicular Steroidogenesis

ABSTRACT Quantitative evaluation of spermatogenesis at stage VII of the cycle of the seminiferous epithelium and radioimmunoassay of plasma testosterone were performed in adult Wistar rats after intraventricular injection of 5,6-dihydroxytryptamine (5,6-DHT). The rats were killed 2, 10 and 21 days after injection. Brain 5-hydroxytryptamine (5-HT) and plasma testosterone levels were found to be significantly lower in all rats treated with 5,6-DHT. A significant reduction in step 7 spermatid count was also observed after 10 and 21 days. Supplementation with human chorionic gonadotrophin for 21 days in rats injected with 5,6-DHT partially prevented the step 7 spermatid degeneration and increased testosterone levels without producing any effect on brain concentrations of 5-HT. These results suggest that changes in testicular steroidogenesis and spermatogenesis are secondary to pituitary gonadotrophin release which, in turn, is under the influence of brain 5-HT neurones. J. Endocr. (1985) 106, 395–400

SHORT-TERM EFFECTS OF COPULATION, HUMAN CHORIONIC GONADOTROPHIN INJECTION AND NON-TACTILE ASSOCIATION WITH A FEMALE ON TESTOSTERONE LEVELS IN THE MALE RAT

1974 ◽  
Vol 60 (3) ◽  
pp. 429-439 ◽  
Author(s):  
K. PURVIS ◽  
N. B. HAYNES
Keyword(s):  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Physical Contact ◽  
Male Rats ◽  
Male Rat ◽  
Plasma Testosterone ◽  
Short Term ◽  
Testosterone Levels ◽  
Peripheral Plasma ◽  
First Contact

SUMMARY Peripheral plasma testosterone levels in the male rat were increased above control levels 5 min after the first intromission with an oestrous female, or 8–10 min after first contact with the female. The levels remained raised for at least 30 min if copulation was allowed to continue. Intravenous injection of human chorionic gonadotrophin resulted in an increased peripheral concentration of plasma testosterone after 10–15 min and an increase of testosterone content of the testis 5–10 min after injection, indicating that the rat testis has a potential to respond rapidly to gonadotrophin. The results suggested that if the testosterone surge during copulation was gonadotrophin-dependent, it was initiated before the first intromission. Indeed, plasma testosterone levels were raised in male rats 5 min after being placed in the proximity of oestrous females but not allowed physical contact.

EFFECT OF GLUCOCORTICOIDS ON PLASMA TESTOSTERONE IN MEN

1978 ◽  
Vol 89 (1) ◽  
pp. 126-131 ◽  
Author(s):  
G. Schaison ◽  
F. Durand ◽  
I. Mowszowicz
Keyword(s):  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Plasma Testosterone ◽  
Acth Stimulation ◽  
Testosterone Levels ◽  
Before And After ◽  
The Mean ◽  
Normal Men ◽  
Lh Secretion ◽  
Dexamethasone Suppression

ABSTRACT ACTH decreases plasma testosterone levels in men. The aim of this study was to assess the part played by the glucocorticoids in this effect, and the mechanism of their action. Plasma androstenedione, testosterone, cortisol and LH were measured in 8 normal men, before and after the following tests: ACTH stimulation (2 mg im), metyrapone administration (500 mg/every 4 h/6 times) and dexamethasone suppression (8 mg/day/3 days). In addition, androstenedione and testosterone were evaluated under human chorionic gonadotrophin (5000 IU HCG/day/3 days) before and after dexamethasone suppression (8 mg/day/6 days). In all patients, ACTH decreased plasma testosterone from 5.87 ± 1.59 (sd) ng/ml to 3.06 ± 0.8 (sd) ng/ml (P < 0.001). In contrast, after metyrapone, the mean plasma testosterone was increased to 6.98 ± 1.75 (sd) ng/ml. This increase, though not statistically significant, was observed in all patients but one. Both tests resulted in a significant increase of plasma androstenedione (P < 0.01 and P < 0.001, respectively). Dexamethasone suppressed both testosterone and androstenedione levels. None of the three tests had a significant effect on the LH concentration. HCG injection increased the mean plasma testosterone to 11.46 ± 2.80 ng/ml. Dexamethasone significantly depressed (P < 0.01) the testosterone response to HCG. These data are consistent with the following conclusions: 1) The decrease of plasma testosterone levels, observed in men after ACTH administration, is not observed after metyrapone induced ACTH increase. This confirms that it is related to cortisol levels rather than to ACTH itself. 2) Glucocorticoids act directly on testicular biosynthesis since they do not induce any change in LH secretion and since dexamethasone reduces testosterone response to HCG.

scholarly journals Testosterone Response of Cryptorchid and Hypophysectomized Rats to Human Chorionic Gonadotrophin (hCG) Stimulation

1985 ◽  
Vol 38 (4) ◽  
pp. 445 ◽  
Author(s):  
Y M Hodgson ◽  
DM de Kretser
Keyword(s):  
Single Injection ◽  
Serum Testosterone ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Testosterone Levels ◽  
Hypophysectomized Rats ◽  
Secondary Rise

The testosterone responses to a single injection of HCG (100 i.u.) in hypophysectomized (hypox.), cryptorchid or sham-operated rats were followed over a 5-day period. In sham-operated rats, hCG induced a biphasic rise in serum testosterone, peaks being observed at 2 and 72 h. Reduced testis weights, elevated FSH and LH levels and reduced serum testosterone levels were found after 4 weeks of cryptorchidism, but hCG stimulation resulted in a normal 2 h peak in serum testosterone. However, the secondary rise at 72 h in cryptorchid rats was significantly lower than sham-operated rats.

THE EFFECT OF INTRAVENOUSLY ADMINISTERED HUMAN CHORIONIC GONADOTROPHIN ON PLASMA LEVELS OF TESTOSTERONE AND 5α-DIHYDROTESTOSTERONE IN NORMAL MALE SUBJECTS

1973 ◽  
Vol 72 (3) ◽  
pp. 615-624 ◽  
Author(s):  
W. Maurer ◽  
U. Volkwein ◽  
J. Tamm
Keyword(s):  
Plasma Levels ◽  
Initial Phase ◽  
Plasma Concentrations ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Plasma Testosterone ◽  
Normal Male ◽  
Peripheral Conversion ◽  
Male Subjects

ABSTRACT HCG was infused intravenously into normal male subjects. The doses administered were 500, 100 and 50 IU, respectively. During the initial phase of the infusions the plasma testosterone (T) levels decreased. Thirty minutes after starting the infusion of 500 and 100 IU HCG, respectively, the plasma testosterone increased. Significantly elevated values were observed 60 to 180 minutes after the cessation of HCG administration. The dihydrotestosterone (DHT) concentrations in the plasma showed a varying pattern. On the average this steroid also exhibited an increase in plasma following the HCG administration. From the results no conclusions can be drawn as to the extent to which the plasma concentrations of DHT have been influenced by a secretion from the testes or by a peripheral conversion of T into DHT.

THE HEMICASTRATED RAT: DEFINITION OF A MODEL FOR THE STUDY OF THE REGULATION OF TESTICULAR STEROIDOGENESIS

1982 ◽  
Vol 92 (2) ◽  
pp. 213-223 ◽  
Author(s):  
A. I. FRANKEL ◽  
W. W. WRIGHT
Keyword(s):  
Group Analysis ◽  
Age Groups ◽  
Basic Mechanism ◽  
Compensatory Hypertrophy ◽  
Significant Rise ◽  
Plasma Testosterone ◽  
Testosterone Levels ◽  
Testicular Steroidogenesis ◽  
Definition Of ◽  
Single Testis

A comprehensive study has been made of the hemicastrated rat from 2 to 12 months of age in order to define what might represent an ideal model in which to study testicular regulation. Although there was no compensatory hypertrophy in the remaining testis of the mature hemicastrated rat, levels of plasma testosterone fell significantly within 4 h after surgery in all age groups older than 3 months, and were restored to normal levels almost immediately, usually within 8 h. There were no significant changes in LH and prolactin, and the significant rise in FSH was sufficiently delayed (2 days or more) to suggest that none of these three hormones was implicated in any obvious way in the compensatory restoration of plasma testosterone levels. Although a single testis was capable of maintaining normal plasma testosterone concentrations, its response to human chorionic gonadotrophin at 24 h after hemicastration was significantly less than that of intact animals, suggesting that the single testis was functioning at near-maximal capacity. The hormonal responses to repetitive blood sampling and to sham-surgery simulated the response to hemicastration remarkably. However, these responses were never statistically significant in within-group analysis, and therefore did not obscure the significant fall of plasma testosterone levels in response to hemicastration. The basic mechanism by which plasma testosterone is restored in the hemicastrated rat is still unknown, but the options have been narrowed.

SELECTIVE RELEASE OF FOLLICLE-STIMULATING HORMONE DURING THE PERIOD OF OVULATION INDUCED BY HUMAN CHORIONIC GONADOTROPHIN IN DIOESTROUS RATS

1977 ◽  
Vol 75 (1) ◽  
pp. 179-180 ◽  
Author(s):  
SHUJI SASAMOTO ◽  
SHIGEO HARADA ◽  
KAZUYOSHI TAYA
Keyword(s):  
Luteinizing Hormone ◽  
Wistar Rats ◽  
Follicle Stimulating Hormone ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Present Communication ◽  
Follicular Maturation ◽  
Female Wistar Rats ◽  
Premature Ovulation ◽  
Stimulating Hormone

Laboratory of Veterinary Physiology, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183, Japan (Received 2 May 1977) When an amount of human chorionic gonadotrophin (HCG) sufficient to cause ovulation is given to 4-day cyclic rats on the day of dioestrus, premature ovulation is induced the next morning (Eto & Imamichi, 1955). The pattern of release of follicle-stimulating hormone (FSH) responsible for the initiation of follicular maturation of the next set of follicles (Schwartz, 1969; Welschen & Dullaart, 1976) after HCG-induced ovulation has not been previously evaluated. The present communication is concerned with this problem and indicates that a large amount of FSH is released within 12 h of administration of HCG, with only a small concomitant rise in the concentration of luteinizing hormone (LH). Adult female Wistar rats were maintained under a 14 h light : 10 h darkness schedule (lights on 05.00 h), and those showing three or

VIRILIZING ADRENOCORTICAL ADENOMA RESPONSIVE TO GONADOTROPHIN

1975 ◽  
Vol 78 (1) ◽  
pp. 77-85 ◽  
Author(s):  
M. Blichert-Toft ◽  
H. Vejlsted ◽  
H. Kehlet ◽  
R. Albrechtsen
Keyword(s):  
Young Female ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Adrenocortical Function ◽  
Plasma Testosterone ◽  
Adrenocortical Adenoma ◽  
Androgen Excess ◽  
Pronounced Increase ◽  
Steroid Excretion ◽  
Trophic Hormones

ABSTRACT A virilizing adrenocortical adenoma was demonstrated in a young female. Urinary 17-ketosteroid excretion and subfractions, plasma testosterone level and urinary 17-ketogenic steroid excretion were markedly increased. Dehydroepiandrosterone was the main constituent of the androgen excess. Otherwise the adrenocortical function was found to be normal as evaluated from measurements of cortisol, corticosterone and their metabolites under basal conditions and during dynamic tests. The androgen excess showed an unexpected response to trophic hormones. Human chorionic gonadotrophin stimulation resulted in a pronounced increase in androgen production, whereas no gonadotrophin-dependency could be demonstrated by means of the oestrogen suppression test. Similarly, no corticotrophin-dependency could be demonstrated by corticotrophin stimulation and suppression tests. Removal of the tumour resulted in normalization of the androgen production and no abnormal response upon human chorionic gonadotrophin administration could now be found. The inappropriate response of tumours to trophic hormones is discussed. It is concluded that the reliability of stimulation and suppression tests in determining the site of excessive androgen production should be accepted with reservation.

PLASMA CONCENTRATION OF TESTOSTERONE IN YOUNG BULLS IN RELATION TO AGE, RATE OF WEIGHT GAIN AND STIMULATION WITH HUMAN CHORIONIC GONADOTROPHIN

1980 ◽  
Vol 86 (3) ◽  
pp. 465-469 ◽  
Author(s):  
ANNE SUNDBY ◽  
WEIERT VELLE
Keyword(s):  
Weight Gain ◽  
Correlation Coefficients ◽  
Multiple Correlation Coefficient ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Daily Weight Gain ◽  
Plasma Testosterone ◽  
Testosterone Concentration ◽  
Subsequent Decrease ◽  
The Difference

In 86 bulls ranging in age between 3 and 11 months, the maximal plasma testosterone concentration (n = 7) well as the mean concentration (n = 7, same samples) were found to increase with age to peak values at 7–8 months with a subsequent decrease. The multiple correlation coefficient for monthly gain as a function of testosterone concentration and age was 0·85 (P <0·001), for monthly gain as a function of age 0·84 (P <0·001) and for monthly gain as a function of testosteroneconcentration 0·44 (P <0·001). The deviation in levels of measured plasma testosterone from the curve expressed by multiple regression analyses of testosterone concentration as a function of age was correlated with the average daily weight gain during the testing period of 9 months and found to be not significant (r = 0·21). The difference between concentrations of plasma testosterone after stimulation with human chorionic gonadotrophin (HCG) and the spontaneous maximal concentration of this hormone was not significant. High correlation coefficients were found between maximal (r = 0·8) and mean (r = 0·6) concentrations of plasma testosterone before and after an injection of HCG (P <0·001).

A QUANTITATIVE STUDY ON FEEDBACK CONTROL OF LH BY TESTOSTERONE IN YOUNG ADULT AND OLD MALE RATS

1978 ◽  
Vol 89 (4) ◽  
pp. 789-795 ◽  
Author(s):  
Karl M. Pirke ◽  
Michael Geiss ◽  
Rainer Sintermann
Keyword(s):  
Young Adult ◽  
Feedback Control ◽  
Quantitative Study ◽  
Wistar Rats ◽  
Male Rats ◽  
Plasma Testosterone ◽  
Testosterone Levels ◽  
Male Wistar Rats ◽  
Old Rats ◽  
Lh Secretion

ABSTRACT The hypothalamic-pituitary gonadal axis was studied in young adult (3 month old) and old (24 to 27 month old) male Wistar rats. Plasma testosterone decreased significantly in old animals (x̄: 262 ng/100 ml (n = 35); versus x̄: 110 ng/100 ml (n = 30)). The fall in LH was less pronounced but still significant (54.5 ng LH-RP-1/ml in young versus 39.5 ng/ml in old rats). Groups of 6 to 8 animals of both ages were castrated and implanted with silastic capsules continuously releasing testosterone. The length of the capsules was directly proportional to the plasma testosterone levels achieved (range between 63 and 350 ng/100 ml). After one week young castrated rats not substituted with testosterone showed LH values three times higher (x̄: 351 ng/ml) than old rats treated in the same way (x̄ = 126 ng/ml). LH values in the animals substituted with testosterone indicate that the sensitivity of the negative testosterone-LH feedback is greatly increased in old rats. Testosterone can be depressed to 60 ng/100 ml before an increase in LH occurs. In young rats no increase in LH was observed when testosterone values were higher than 170 ng/100 ml. In the range between 170 and 100 ng/100 ml about half of the young animals reacted with increased LH secretion, while an increase was observed in all young animals when testosterone dropped below 100 ng/100 ml.

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