Interrelationship between pituitary-testicular axis activity and raised environmental temperature in the rat

1983 ◽  
Vol 97 (2) ◽  
pp. 193-200 ◽  
Author(s):  
Z. Chap ◽  
E. Bedrak
Keyword(s):  
Heat Exposure ◽  
Serum Testosterone ◽  
Serum Levels ◽  
Serum Prolactin ◽  
Testosterone Concentration ◽  
Serum Lh ◽  
Gonadotrophin Releasing Hormone ◽  
The Relationship ◽  
Environmental Temperatures

The relationship between the testes and the adenohypophysis in rats exposed to heat was assessed by (1) the determination of adenohypophysial concentrations of FSH, LH and prolactin as well as serum levels of prolactin and testosterone in rats maintained at 35 °C for various periods of time and (2) the elucidation of the responsiveness to stimulation with gonadotrophin releasing hormone (GnRH) or human chorionic gonadotrophin (hCG) of the rat acclimatized for 40 days to a temperature of 35 °C. The results demonstrated that while heat exposure caused a transient change in the concentration of FSH and LH in the adenohypophysis, the level of prolactin increased by twofold within 24 h and remained significantly higher than in control animals. A concurrent significant decrease in the concentrations of prolactin and testosterone in the serum of rats exposed to heat was also observed. Challenging the rat with exogenous GnRH resulted in a significant increase in serum LH and FSH concentrations in control rats and rats exposed to heat, but the magnitude of the rise in LH was greater in the latter group. However, this phenomenon was not accompanied by a rise in serum testosterone concentration in the rat exposed to heat. Challenging the animals with hCG provoked an increase in serum testosterone, but the magnitude of the rise was greater by far in the control rats. It is concluded that exposure of the intact rat to increased environmental temperatures is accompanied by accumulation of prolactin in the lactotrophs, reduced serum prolactin concentration, decreased capacity of the testes to synthesize testosterone and consequently reduced serum testosterone concentration. These phenomena are independent of the capacity of the adenohypophysis to synthesize LH.

ANNUAL RHYTHMS OF LUTEINIZING HORMONE, FOLLICLE-STIMULATING HORMONE, PROLACTIN AND TESTOSTERONE IN THE SERUM OF MALE RHESUS MONKEYS

1979 ◽  
Vol 83 (2) ◽  
pp. 131-139 ◽  
Author(s):  
W. BECK ◽  
W. WUTTKE
Keyword(s):  
Rhesus Monkeys ◽  
Serum Testosterone ◽  
Serum Levels ◽  
Serum Prolactin ◽  
First Year ◽  
Thyrotrophin Releasing Hormone ◽  
Testosterone Levels ◽  
Serum Lh ◽  
June July ◽  
Male Rhesus

Six male rhesus monkeys were kept under rigidly controlled conditions for 1–2 years. During August of the first year a thyrotrophin releasing hormone (TRH) test was performed on each of the monkeys by giving 10 μg TRH as a bolus injection. Significantly increased serum prolactin levels occurred 15 min after the injection. After a training period of 2 months, during which blood samples were collected every other day by puncture of the saphenous vein, blood was collected three times a week for 14 months. Serum levels of prolactin, LH, FSH and testosterone were measured by radioimmunoassay. Mean serum prolactin levels increased significantly during June, July and August in all six animals. Peak levels were observed in August and September and then levels declined gradually to reach a minimum in April and May. Mean serum testosterone levels closely paralleled the annual pattern of prolactin. Mean serum LH levels significantly decreased during the time when mean serum prolactin and testosterone levels were increasing and they increased again at the time of decreasing mean prolactin levels, i.e. mean serum LH and prolactin were negatively correlated. In individual monkeys, however, a rigid negative correlation between serum prolactin and LH could not be demonstrated. Mean serum FSH levels did not change significantly.

ENDOCRINE STUDIES AND SUCCESSFUL TREATMENT IN A PATIENT WITH TRUE HERMAPHRODITISM

1979 ◽  
Vol 91 (1) ◽  
pp. 184-192
Author(s):  
Evangelina Valdés ◽  
Carlos Fernández del Castillo ◽  
Raul Gutiérrez ◽  
Fernando Larrea ◽  
Martha Medina ◽  
...  
Keyword(s):  
Chromosome Complement ◽  
Reproductive Function ◽  
External Genitalia ◽  
Serum Testosterone ◽  
Serum Levels ◽  
Normal Children ◽  
Serum Lh ◽  
Genital Ambiguity ◽  
And Gender ◽  
Lh Rh

ABSTRACT A 12-year old, 46 XX true hermaphrodite born with genital ambiguity was studied and successfully treated. The serum LH and FSH profile resembled that of a pubertal normal individual, and LH-RH administration induced a normal LH response. Baseline testosterone serum levels were within the range for normal children. Exogenous HCG stimulation induced a significant serum testosterone increase up to values similar to those observed in normal post-pubertal males. Surgical examination disclosed the presence of bilateral ovotestis, normal Mullerian derivatives, epididymis, and vas deferens. A complete ovotestis with testicular predominance and the testicular portion of the contralateral ovotestis as well as the Wolffian derivatives, were removed. A further HCG stimulation 3 months after surgery, failed to induce serum testosterone increase. Spontaneous menarche was observed 6 months after surgery and ovulation was well documented. At present the patient has several characteristics of female sex including those of chromosome complement, gonad, internal and external genitalia, hormone levels and gender identity, thus demonstrating that treatment was successful and that reproductive function could be obtained. The finding of spontaneous ovulation following removal of the testicular portion suggests normal cyclic gonadotrophic release implying a difference between animal models and man in regard to hypothalamic virilization.

EFFECTS OF MATING AND INJECTION OF LUTEINIZING HORMONE RELEASING HORMONE ON SERUM LUTEINIZING HORMONE AND TESTOSTERONE CONCENTRATIONS IN RABBITS

1978 ◽  
Vol 76 (3) ◽  
pp. 417-425 ◽  
Author(s):  
C. A. BLAKE ◽  
PATRICIA K. BLAKE ◽  
NANCY K. THORNEYCROFT ◽  
I. H. THORNEYCROFT
Keyword(s):  
Luteinizing Hormone ◽  
Serum Testosterone ◽  
Serum Levels ◽  
Transient Increase ◽  
Marked Rise ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Serum Lh ◽  
Before And After ◽  
Lh Rh

The effects of coitus and injection of luteinizing hormone releasing hormone (LH-RH) on serum concentrations of LH, testosterone and dihydrotestosterone (17β-hydroxy-5α-androstan-3-one; DHT) were tested in male rabbits. Before experimentation, male and female rabbits were housed in individual cages in the same room. Male rabbits were then bled by cardiac puncture before and after placement with female rabbits or intravenous injection of LH-RH. Serum LH, testosterone and DHT were measured by radioimmunoassay. Sexual excitement (sniffing, chasing and mounting), with or without intromission, caused a marked rise in serum testosterone and DHT concentrations in only some of the bucks. These increases were accompanied or preceded by a small, transient increase in serum LH. In the rest of the bucks, sexual excitement with or without intromission had either no effect on serum levels of all three hormones, or only serum testosterone and DHT decreased during the collection period. Similar responses were measured in bucks which were housed in a room without does for 2–4 weeks before experimentation. Injection of 10, 30 or 100 ng or 50 μg LH-RH caused serum LH, testosterone and DHT to rise in all bucks tested, but the magnitude of the rises in serum testosterone and DHT were not related to the magnitude of the LH rise. In both mated and LH-RH-injected bucks, the rises in serum testosterone and DHT were greatest in animals with low initial testosterone and DHT values. Under the conditions of this study, the data suggest that: (1) serum testosterone and DHT rise in only some male rabbits after sexual excitement (with or without intromission), (2) the rises in serum testosterone and DHT are dependent on a small transient increase in serum LH and (3) sexual excitement is less likely to cause release of LH-RH in bucks with raised serum testosterone and DHT concentrations.

PITUITARY-GONADAL FUNCTION IN MALE PATIENTS WITH MYOTONIC DYSTROPHY - SERUM LUTEINIZING HORMONE, FOLLICLE STIMULATING HORMONE AND TESTOSTERONE LEVELS AND HISTOLOGICAL DAMAGE OF THE TESTIS

1977 ◽  
Vol 84 (2) ◽  
pp. 382-389 ◽  
Author(s):  
Ryoyu Takeda ◽  
Misao Ueda
Keyword(s):  
Myotonic Dystrophy ◽  
Serum Testosterone ◽  
Serum Levels ◽  
Seminiferous Tubules ◽  
Reciprocal Relation ◽  
Logarithmic Scale ◽  
Serum Luteinizing Hormone ◽  
Serum Lh ◽  
Male Patients ◽  
Lh Rh

ABSTRACT Variations in serum levels of LH and FSH after administration of synthetic LH-RH, and basal levels of serum testosterone were studied in 9 male patients with myotonic dystrophy. The degree of testicular damage, as determined histologically on biopsy specimens, was also studied. Results were as follows: 1) it was observed that both the basal and stimulated (maximal) levels of serum LH and FSH were significantly higher than levels found in 9 sex- and age-matched normal controls. 2) The basal level of serum testosterone was consistently lower in the patient group. One patient, however, showed a low normal level, which represented a statistically significant reciprocal relation to both LH and FSH levels as expressed on a logarithmic scale. 3) There was a significant trend which indicated that the higher the serum LH, FSH levels, or the lower the basal levels of serum testosterone, the more extensive was the damage to the seminiferous tubules. From these findings it was concluded that hypogonadism in patients with myotonic dystrophy, is characterized by the development of lesions in the seminiferous tubules.

ENHANCED TESTOSTERONE IN FEMALE PATIENTS WITH ANOREXIA NERVOSA: ITS NORMALIZATION AFTER WEIGHT GAIN

1979 ◽  
Vol 90 (2) ◽  
pp. 328-335 ◽  
Author(s):  
B. Baranowska ◽  
S. Zgliczyński
Keyword(s):  
Body Weight ◽  
Anorexia Nervosa ◽  
Weight Gain ◽  
Serum Testosterone ◽  
Gonadal Hormones ◽  
High Serum ◽  
Control Group ◽  
Testosterone Concentration ◽  
Female Patients ◽  
Serum Lh

ABSTRACT In order to elucidate the mechanism of disturbances of gonadal hormones secretion in anorexia nervosa 14 female patients were investigated. A control group also consisted of 14 women of the same age. The serum LH, progesterone, oestrogens: oestrone + oestradiol (Oe1 + Oe2), oestriol (Oe3) and testosterone were determined by radioimmunological methods. In patients with anorexia nervosa the serum testosterone and Oe3 concentrations were dramatically elevated, whereas LH, progesterone and Oe1 + Oe2 were decreased as compared with the control group. Considerable weight gain induced by cyproheptadine treatment caused a normalization of the serum testosterone and Oe3 concentrations in all the patients. A negative correlation between the testosterone level and the deficit in body weight was observed. The mechanism causing the dramatically high serum testosterone concentration in the female patients with anorexia nervosa is discussed.

THE SEQUENCE OF HORMONAL CHANGES DURING PROSTAGLANDIN INDUCED LUTEOLYSIS OF THE SUPERLUTEINIZED RAT OVARY

1978 ◽  
Vol 87 (3) ◽  
pp. 617-624 ◽  
Author(s):  
P. A. Torjesen ◽  
R. Dahlin ◽  
E. Haug ◽  
A. Aakvaag
Keyword(s):  
Binding Sites ◽  
Limit Of Detection ◽  
Serum Levels ◽  
Female Rats ◽  
Serum Prolactin ◽  
Hormonal Changes ◽  
Subsequent Increase ◽  
Serum Progesterone ◽  
Serum Lh ◽  
Prostaglandin F

ABSTRACT Immature female rats were pre-treated with pregnant mare's serum gonadotrophin (PMSG) and human chorionic gonadotrophin (HCG) to achieve superluteinization. Eight days after the HCG administration luteolysis was induced by sc injection of 5 μg of the prostaglandin F2α (PGF2α) analogue cloprostenol (Estrumate®). The serum levels of progesterone, 20α-dihydroprogesterone (20α-DHP), prolactin (PRL) and luteinizing hormone (LH) as well as the number of ovarian LH binding sites were measured during the first 23 h after cloprostenol injection. The serum levels of progesterone decreased from 500 to 200 ng/ml within 25 min after cloprostenol administration. A further decrease to 20 ng/ml occurred during the next 4 h, and serum progesterone remained low for the rest of the period. An increase in serum prolactin (PRL) to values between 28 and 44 ng/ml was observed after 3 h and the values remained elevated for the next 7 h. Although the serum levels of progesterone declined immediately, the serum 20α-dihydroprogesterone (20α-DHP) levels remained at 60 to 140 ng/ml for the first 5 h and then gradually increased to values corresponding to the initial progesterone levels 14 to 23 h after treatment. The number of ovarian LH binding sites was between 1.2 and 1.4 × 10−12 mol/mg protein during the first 9 h after prostaglandin (PG) injection, and then decrreased to 0.8 and 0.5 × 10−12 mol/mg protein at 14 and 23 h, respectively. The serum LH levels remained below the limit of detection for the assay (10 ng/ml) throughout the observation period. PGF2α injection induced the same basic changes in the serum levels of progesterone and 20α-DHP as cloprostenol treatment. Thus, the first effect of PG treatment measured was an immediate decline in the serum levels of progesterone, and this decline probably initiated the subsequent increase in pituitay PRL and ovarian 20α-DHP secretion. Therefore, the decrease in the number of ovarian LH binding sites appeared to be a consequence rather than a mediator of luteolytic effects of the prostaglandins.

ACTIVATION OF ANTERIOR PITUITARY. THYROID AND ADRENAL GLAND IN RATS AFTER DISTURBANCE STRESS

1977 ◽  
Vol 86 (3) ◽  
pp. 489-497 ◽  
Author(s):  
K.-D. Döhler ◽  
K. Gärtner ◽  
A. von zur Mühlen ◽  
U. Döhler
Keyword(s):  
Emotional Stress ◽  
Experimental Period ◽  
Serum Levels ◽  
Normal Serum ◽  
Male Rats ◽  
Serum Prolactin ◽  
Blood Collection ◽  
Pituitary Hormone ◽  
Serum Lh ◽  
Pituitary Thyroid Axis

ABSTRACT Groups of adult male rats were decapitated without anaesthesia 30 seconds or 5, 10, 15 and 60 min after disturbance stress (investigators entering the animal room and moving the cages). The serum concentrations of LH, FSH, TSH, prolactin, triiodothyronine (T3) and thyroxine (T4) were measured by radioimmunoassay and corticosterone by a fluorometric method. With regard to the hormone levels measured in serum obtained within 30 seconds after induction of disturbance stress to resemble most closely the actual unstressed levels of endogenous hormones in circulation, serum corticosterone levels increased within 5 min. indicating that the procedure was stressful to the animals. In addition the serum prolactin and TSH levels were significantly elevated within 5 min, T3 within 60 min. Whereas corticosterone reached peak levels after 15 min. the serum levels of prolactin, TSH and T3 were still rising after 60 min. The FSH levels remained rather stable during the first 10 min. but started to rise during the following 5 min. At 60 min FSH levels were back to normal. Serum LH and T4 showed only minor fluctuations during the experimental period. These results indicate, that not only is the pituitary-adrenal axis stimulated by emotional stress, but also the pituitary-thyroid axis. It also seems, that emotional stress leads to a general activation of pituitary hormone release. Hence, proper care should be taken with regard to animal keeping, handling and the method of blood collection when dealing with rats as experimental animals.

CIRCADIAN FLUCTUATIONS OF SERUM HORMONE LEVELS IN PREPUBERTAL MALE AND FEMALE RATS

1976 ◽  
Vol 83 (2) ◽  
pp. 269-279 ◽  
Author(s):  
K. D. Döhler ◽  
W. Wuttke
Keyword(s):  
Age Groups ◽  
Serum Testosterone ◽  
Female Rats ◽  
Serum Prolactin ◽  
Male And Female ◽  
Hormone Levels ◽  
Male And Female Rats ◽  
Serum Lh ◽  
Serum Hormone ◽  
Old Females

ABSTRACT Diurnal variations in serum hormone levels during 2 different stages of prepubertal development were investigated in male and female rats. Groups of 13 to 18 and 25 to 30 day old male and female rats were decapitated at 4-hour by intervals during a period of 24 h. Their blood was collected and hormones were measured by radio-immunoassay. FSH levels were constantly high in 13 to 18, but low in 25 to 30 day old females. FSH was low in younger males, and significantly higher but without diurnal fluctuations in the older males. Serum LH was low in approximately 40% of the 13 to 18 day old females, while 40% had moderately high levels, and the remaining females extremely high levels of the hormone. Most of the extremely high LH peaks were found at 15.00 h and some at 03.00 h. Older females and males of both age groups had constantly low serum LH levels. Serum oestradiol was high in males and females during days 13 to 18, but it was lower in the 25 to 30 day old animals. In the young females prolactin was slightly elevated between 15.00 h and 19.00 h, while in the males the serum prolactin fluctuations were not significant. Serum testosterone was low in females at all times. The 13 to 18 day old males had higher testosterone levels than the 25 to 30 day old males. Both groups showed slight, but insignificant fluctuations in serum testosterone. These results confirm result published previously and furthermore they demonstrate the existence of circasemedian or circadian rhythms for both the gonadotrophins and gonadal steroids. These results, also suggest that the maturation of the positive feedback action of oestradiol on gonadotrophin release in female rats occurs between day 10 and 20.

Hyperprolactinaemia attenuates the gonadotrophin releasing hormone receptor response to gonadectomy in rats

1982 ◽  
Vol 95 (2) ◽  
pp. 267-274 ◽  
Author(s):  
R. N. Clayton ◽  
L. C. Bailey
Keyword(s):  
Female Rats ◽  
Male Rats ◽  
Serum Prolactin ◽  
Intact Male ◽  
Adult Rats ◽  
Releasing Hormone ◽  
Receptor Response ◽  
Serum Lh ◽  
Gonadotrophin Releasing Hormone ◽  
Qualitative Index

Measurement of pituitary gonadotrophin releasing hormone (Gn-RH) receptor content provides a qualitative index of prior exposure of the pituitary gland to endogenous Gn-RH. The effect of moderate hyperprolactinaemia (serum prolactin = 95–250 μg/l), achieved with three pituitary grafts beneath the renal capsule, on the pituitary Gn-RH receptor content and serum LH responses to gonadectomy of adult rats has been studied. In males the presence of hyperprolactinaemia for 7 days completely prevented the increase in Gn-RH receptor content 3 days after castration and inhibited the serum LH rise by 45%. By 6 days after castration, Gn-RH receptors had increased in the hyperprolactinaemic castrated animals but values were 33% lower than in sham-grafted controls, while the serum LH increase was attenuated by 30%. Pituitary LH content was also lower in grafted castrated animals 6 days after castration. Hyperprolactinaemia for 3 weeks had no effect on Gn-RH receptors or pituitary LH content of intact male rats, although basal serum LH was decreased by 50%. Hyperprolactinaemia also attenuated the increases in Gn-RH receptors, serum LH and pituitary LH which occurred 6 days after ovariectomy in female rats. In all experiments the pituitary content of prolactin was reduced by 80–90% in animals bearing pituitary grafts. These results suggest that hyperprolactinaemia restricts the Gn-RH receptor response to gonadectomy by decreasing endogenous hypothalamic Gn-RH secretion.

The contribution of corticosterone and testosterone to the suppression of serum LH in hyperprolactinaemic adult male rats with pituitary transplants

1987 ◽  
Vol 113 (1) ◽  
pp. 111-116 ◽  
Author(s):  
R. F. A. Weber ◽  
M. P. Ooms ◽  
J. T. M. Vreeburg
Keyword(s):  
Adult Male ◽  
Serum Testosterone ◽  
Serum Levels ◽  
Male Rats ◽  
Male Rat ◽  
Serum Concentrations ◽  
Testosterone Secretion ◽  
Accessory Sex Glands ◽  
Serum Lh ◽  
Stimulation Of

ABSTRACT The effects of hyperprolactinaemia on serum levels of LH were investigated in adult male rats of the R × U strain. Hyperprolactinaemia was induced by three pituitary grafts under the kidney capsule, transplanted on day 0 of each experiment. Special attention was paid to the contribution of prolactin-stimulated testes, adrenals and corticosterone. In experiment 1, hyperprolactinaemia significantly reduced the serum concentrations of LH in intact rats. In spite of a significant increase in the serum levels of corticosterone, serum testosterone was not significantly affected by hyperprolactinaemia. The weights of both the adrenals and accessory sex glands were significantly increased at autopsy. In experiment 2, treatment with 10 mg corticosterone s.c. daily from day 14 to day 28 after pituitary grafting significantly reduced serum levels of both LH and testosterone. The suppression of testosterone in the hyperprolactinaemic corticosterone-treated animals was significantly less than in the corticosterone-treated control animals. The weights of the accessory sex glands were significantly increased in the hyperprolactinaemic animals. In experiment 3, rats were adrenalectomized and half of them were substituted with corticosterone. Serum testosterone levels significantly increased in both hyperprolactinaemic adrenalectomized rats and in adrenalectomized corticosterone-treated animals without any significant effect on serum LH. Again the weights of the accessory sex glands were significantly increased in the hyperprolactinaemic animals. In experiment 4, rats were adrenalectomized, gonadectomized and corticosterone treated on day 0 and then implanted with a 2, 1·5 or 1 cm silicone elastomer capsule containing testosterone. On day 28 after pituitary grafting, LH levels were significantly suppressed in animals with a 2 or 1·5 cm testosterone implant. The weights of the accessory sex glands were not increased in the hyperprolactinaemic animals. These results show that in the male rat the inhibitory effects of hyperprolactinaemia on serum LH levels may be due to (1) increased sensitivity of the hypothalamic-pituitary axis to the negative feedback action of testosterone by prolactin and by the prolactin-stimulated corticosterone secretion and (2) stimulation of testicular testosterone secretion by prolactin, which can also explain the increased weights of the accessory sex glands. Even in the presence of high serum concentrations of corticosterone, stimulation of testicular testosterone secretion by prolactin was observed. J. Endocr. (1987) 113,111–116

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