DEVELOPMENT OF STRESS-INDUCED PITUITARY PROLACTIN AND TSH RELEASE IN MALE RATS

1977 ◽  
Vol 85 (4) ◽  
pp. 729-735 ◽  
Author(s):  
M. Fenske ◽  
W. Wuttke
Keyword(s):  
Elevated Serum ◽  
Stress Factors ◽  
Male Rats ◽  
Serum Prolactin ◽  
Prolactin Release ◽  
Basal Serum ◽  
Normal Environment ◽  
Pituitary Prolactin ◽  
Serum Tsh ◽  
Tsh Levels

ABSTRACT Blood was collected from male rats of various ages under control conditions and after introduction of two stress factors. All animals were sacrificed between 15.00 and 16.00 h. Serum prolactin levels in immature male rats were found to be very low between birth and day 15 after birth. Neither exposure to a new environment, for example removal from the animal rooms for the duration of 10 min, nor exposure to concentrated ether vapour resulted in increased serum prolactin levels. Between day 20 and 35 basal serum prolactin levels were increased, they then fell at adult values. During this period of increasing serum prolactin levels pituitary prolactin release became stress-susceptable; i. e. elevated serum prolactin levels were observed after introduction of stress factors as in adult male rats. Serum TSH levels were found to be high between birth and day 10. Low TSH levels measured between day 15 and 40 and adult values were detected after day 40. Neither ether nor removal of the animals from their normal environment changed serum TSH levels at any age tested. These results indicate that the hypothalamo-pituitary in immature rats reacts in a similar way as that in adult animals from day 16–20 onwards. Serum TSH levels in these animals, however, are reduced, indicating that an increase in serum TSH is not necessary for normal processes of maturation.

Prolactin release, oestrogens and proliferation of prolactin-secreting cells in the anterior pituitary gland of adult male rats

1986 ◽  
Vol 108 (3) ◽  
pp. 399-403 ◽  
Author(s):  
R. L. Pérez ◽  
G. A. Machiavelli ◽  
M. I. Romano ◽  
J. A. Burdman
Keyword(s):  
Cell Proliferation ◽  
Pituitary Gland ◽  
Adult Male ◽  
Anterior Pituitary ◽  
Pituitary Hormones ◽  
Anterior Pituitary Gland ◽  
Male Rats ◽  
Serum Prolactin ◽  
Prolactin Release ◽  
Experimental Conditions

ABSTRACT Relationships among the release of prolactin, the effect of oestrogens and the proliferation of prolactin-secreting cells were studied under several experimental conditions. Administration of sulpiride or oestradiol released prolactin and stimulated cell proliferation in the anterior pituitary gland of adult male rats. Clomiphene completely abolished the rise in cell proliferation, but did not interfere with the sulpiride-induced release of prolactin. Treatment with oestradiol plus sulpiride significantly increased serum prolactin concentrations and the mitotic index compared with the sum of the stimulation produced by both drugs separately. Bromocriptine abolished the stimulatory effect of oestradiol on the serum prolactin concentration and on cell proliferation. In oestradiol- and/or sulpiride-treated rats, 80% of the cells in mitoses were lactotrophs. The remaining 20% did not stain with antisera against any of the pituitary hormones. The number of prolactin-secreting cells in the anterior pituitary gland significantly increased after the administration of oestradiol or sulpiride. The results demonstrate that treatment with sulpiride and/or oestradiol increases the proliferation and the number of lactotrophs in the anterior pituitary gland of the rat. J. Endocr. (1986) 108, 399–403

Syndrome of'inappropriate secretion of thyroid-stimulating hormone' by partial target organ resistance to thyroid hormones

1981 ◽  
Vol 97 (3) ◽  
pp. 361-368 ◽  
Author(s):  
J. Salmerón De Diego ◽  
C. Alonso Rodriguez ◽  
A. Salazar Orlando ◽  
P. Sanchez Garcia Cervigon ◽  
E. Caviola Mutazzi ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
Elevated Serum ◽  
Pituitary Tumour ◽  
Thyroid Stimulating Hormone ◽  
Target Organ ◽  
Resistance To Thyroid Hormones ◽  
Serum Thyroid Hormone ◽  
Serum Tsh ◽  
Tsh Levels ◽  
Stimulating Hormone

Abstract. A 74 year old woman was found to have elevated serum thyroid-stimulating hormone (TSH) levels and elevated serum thyroid hormone levels, with clinical euthyroidism. There was no evidence of a pituitary tumour. TSH levels increased substantially during methimazole therapy. Administration of dexamethasone was followed by a prompt fall in serum TSH levels. Triiodothyronine (T3) was administered over a period of 20 days in doses from 25 μg to as much as 100 μg daily causing a rise in serum T3 above 700 ng/100 ml, a decline of T4 and a blunting of the response to thyrotrophinreleasing hormone (TRH), with normal metabolic responses (pulse rate, photomotogram, cholesterol). These results suggest that the patient's disorder is due to partial target organ resistance to thyroid hormones.

PROLACTIN STIMULATION TEST WITH PERPHENAZINE: AN EVALUATION OF PLASMA PROLACTIN LEVELS AND PITUITARY SECRETORY ACTIVITY IN THE RAT

1976 ◽  
Vol 68 (3) ◽  
pp. 355-368 ◽  
Author(s):  
A. A. VAN DER GUGTEN ◽  
P. C. SAHULEKA ◽  
G. H. VAN GALEN ◽  
H. G. KWA
Keyword(s):  
Adult Male ◽  
Secretory Activity ◽  
Female Rats ◽  
Male Rats ◽  
Plasma Prolactin ◽  
Prolactin Release ◽  
Oestrogen Treatment ◽  
Endocrine Status ◽  
Pituitary Prolactin ◽  
Single Plasma

SUMMARY Many investigations of the regulation of prolactin synthesis and release are based on single plasma prolactin determinations. The purpose of the present experiment was to ascertain whether groups of rats (i.e. young or adult, male or female animals, being either intact, gonadectomized or gonadectomized and treated with oestrone), differing in age and/or endocrine status, will react to a single dose of perphenazine by an acute release of pituitary prolactin in proportion to their initial plasma prolactin levels. No consistent relation existed between the classification of the twelve groups of rats into three categories of basal plasma prolactin levels (i.e. < 20, 25–50, > 125 ng/ml) and their response to perphenazine. Even though all groups showed a highly significant increase of plasma prolactin levels the magnitude of the maximum prolactin response at 30 min varied greatly within the groups of one category and thus was not related to the initial prolactin levels. The effect of 14 days of oestrone treatment in increasing plasma prolactin levels in gonadectomized animals was greatest in young and adult male rats, less in young females and not significant in adult females. The results obtained after perphenazine treatment in the latter group made it clear that the effect of oestrogen treatment on prolactin release can be completely blocked by increasing synthesis and/or release of the prolactin-release inhibiting factor (PIF). Since perphenazine induces decrease of pituitary prolactin and a concomitant increase of plasma prolactin levels through lowered PIF-action, the positive effect of oestrogens on prolactin release (as observed in gonadectomized male and young female rats) apparently is caused by a different mode of action. The implications of these findings for the regulation of prolactin release, as affected by the endocrine status of the rat, is discussed. Moreover, comparison of prolactin lost from the pituitary and gained in the circulation of the experimental animals, with amounts of prolactin that were observed to disappear from plasma during the experiment, provided suggestive evidence that the capacity to synthesize and/or eliminate prolactin, after a sudden provoked release of the hormone, differed among the groups. The rates of synthesis by the pituitary, of release from the pituitary into the circulation as well as of elimination of the hormone from the circulation (equally involved in determining actual plasma levels) are thought, therefore, to be far more important for the elucidation of prolactin regulation than single plasma prolactin determinations.

INFLUENCE OF TESTOSTERONE ON THE SECRETION OF THYROTROPHIN IN THE RAT

1965 ◽  
Vol 50 (1) ◽  
pp. 155-160 ◽  
Author(s):  
G. P. van Rees ◽  
E. L. Noach ◽  
J. A. M. J. van Dieten
Keyword(s):  
Thyroid Hormone ◽  
Testosterone Propionate ◽  
Male Rats ◽  
Thyroxine Treatment ◽  
High Doses ◽  
Serum Tsh ◽  
Tsh Levels

ABSTRACT Castration of male rats decreases both pituitary and serum TSH-levels. Administration of testosterone propionate increases serum TSH-levels in castrated males, but its effect on pituitary TSH-content appears to be complex: whereas treatment with physiological amounts of testosterone prevents the decrease induced by castration, administration of high doses of testosterone results in low pituitary TSH-contents not unlike those seen in untreated castrated rats. Testosterone administered to thyroxine-maintained thyroidectomized rats had the same effects as mentioned above, but if thyroxine treatment was omitted, no effect of testosterone on pituitary and serum TSH-levels could be observed. It is thought that testosterone interferes with the effect of thyroid hormone on the secretion of TSH.

The effects of dopaminergic blockade on serum TSH and prolactin levels in thyrotoxicosis

1984 ◽  
Vol 106 (3) ◽  
pp. 330-335 ◽  
Author(s):  
S. Swart ◽  
B. P. O'Malley ◽  
J. Vora ◽  
D. B. Barnett ◽  
F. D. Rosenthal
Keyword(s):  
Significant Decline ◽  
Serum Prolactin ◽  
Control Group ◽  
Dopamine Antagonist ◽  
Serum Samples ◽  
Before And After ◽  
Dopaminergic Tone ◽  
Long Acting ◽  
Serum Tsh ◽  
Tsh Levels

Abstract. In the first part of this study, we have demonstrated that, in 7 patients with untreated thyrotoxicosis, a 7 day regime of the long acting dopamine antagonist metoclopramide (10 mg orally 8 hourly) produces more adequate dopaminergic blockade at pituitary level than a single oral 10 mg dose of the compound as assessed by serum prolactin responses. Subsequently, we have employed this protracted oral metoclopramide regime to evaluate the contribution of dopaminergic tone to the abnormal TSH and prolactin responsiveness of thyrotoxicosis. Serum TSH and prolactin responses to iv TRH (200 μg) were measured in 10 untreated thyrotoxic patients before and after a 7 day period of metoclopramide 10 mg orally 8 hourly. Ten euthyroid individuals were studied in similar fashion, their serum samples being analysed for prolactin levels alone, thus providing a control group for prolactin responsiveness to TRH, before and after metoclopramide. In the thyrotoxic patients basal TSH levels did not change as a consequence of metoclopramide therapy and the TSH response to TRH remained flat. Basal prolactin levels were similar in thyrotoxic and euthyroid individuals and the increase in prolactin, seen in both groups after metoclopramide, was smaller in the thyrotoxic group than in the euthyroid group. Prolactin responsiveness to TRH was significantly impaired in the thyrotoxic subjects as compared to euthyroid subjects. After metoclopramide there was a significant decline in prolactin responsiveness in the euthyroid group, and a similar, though insignificant, trend in the thyrotoxic patients. We conclude that in thyrotoxicosis dopaminergic tone plays no major part in the suppression of TSH levels, nor in the impaired prolactin responsiveness to TRH.

EFFECT OF PROLONGED ORAL ADMINISTRATION OF TRH ON PLASMA LEVELS OF THYROTROPHIN AND PROLACTIN IN NORMAL INDIVIDUALS AND IN PATIENTS WITH PRIMARY HYPOTHYROIDISM

1977 ◽  
Vol 85 (4) ◽  
pp. 744-752 ◽  
Author(s):  
Harald M. M. Frey ◽  
Egil Haug
Keyword(s):  
Elevated Serum ◽  
Primary Hypothyroidism ◽  
Trh Test ◽  
Normal Individuals ◽  
Term Administration ◽  
Maximal Rise ◽  
Trh Receptor ◽  
Serum Tsh ◽  
Tsh Levels

ABSTRACT Forty mg TRH/day was given orally for 3 weeks to 10 euthyroid women and 10 women with primary hypothyroidism on low replacement doses of thyroxine. Once weekly oral TRH was replaced by an iv TRH-test (0.4 mg) with measurement of serum concentration of TSH, prolactin (PRL), thyroxine (T4), triiodothyronine (T3) and cholesterol. In the normal group, mean serum T4 concentration increased after one week and remained elevated. Serum TSH concentration showed a slight tendency to decline. Maximal rise in TSH concentration after iv TRH (ΔTSH) fell from a mean of 4.0 ng/ml to 1.4 ng/ml within one week and stayed low. T3, cholesterol, PRL and ΔPRL were normal and unchanged throughout. In the hypothyroid group T4, T3, cholesterol, PRL and ΔPRL were not influenced by the TRH administration. In 2 patients (with the highest serum T4 concentrations) serum TSH concentration was normal and resistant to iv TRH. Of the 8 patients with elevated TSH, basal level and ΔTSH did not change in 2 (with subnormal T4 levels and the highest TSH levels). In the other 6 (with intermediate T4 levels) basal TSH fell from a mean of 10.1 ng/ml to 4.2 ng/ml, and ΔTSH from 10.0 ng/ml to 3.3 ng/ml after three weeks. It is concluded that in addition to feed-back effect of thyroid hormones, the pituitary response to long-term administration of TRH is determined by other factors. Among these may be reduced pituitary TRH receptor capacity and the activity of the TSH producing cells.

DIFFERENTIAL SENSITIVITY OF PROLACTIN RELEASE TO DOPAMINE AND THYROTROPHIN-RELEASING HORMONE IN INTACT AND PITUITARY STALK-SECTIONED RHESUS MONKEYS

1980 ◽  
Vol 84 (3) ◽  
pp. 479-487 ◽  
Author(s):  
R. L. NORMAN ◽  
S. K. QUADRI ◽  
H. G. SPIES
Keyword(s):  
Rhesus Monkeys ◽  
Differential Sensitivity ◽  
Pituitary Stalk ◽  
Serum Prolactin ◽  
Prolactin Release ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Basal Serum ◽  
Hypothalamic Influence ◽  
Higher Doses

The effects of dopamine and thyrotrophin-releasing hormone (TRH) on prolactin release was studied in 14 intact and six pituitary stalk-sectioned (SS) female rhesus monkeys (Macaca mulatta). Baseline prolactin values were ninefold higher in SS animals (149 ± 16 ng/ml) than in intact animals (16 ± 1 ng/ml). Prolactin release after intravenous administration of TRH in doses of 0,125,250, 500 and 1000 ng revealed that SS monkeys were more sensitive to the prolactin-releasing activity of this tripeptide than were intact animals. A significant (P < 0·05) increment in serum prolactin was observed in SS animals after injection of 125 ng TRH whereas 250 ng was required to raise prolactin levels in the circulation of intact animals significantly (P <0·05). Furthermore, at each comparable dose level of TRH, the increment in serum prolactin was distinctly greater in SS animals than in intact monkeys. Infusion of dopamine at the rate of 10 μg/kg body weight per min significantly (P <0·05) lowered prolactin levels within 60 min in intact animals and no further decline was observed with 20 or 40 μg dopamine. Serum prolactin concentrations were not affected by saline infusion or by 5 μg dopamine. Infusion of dopamine at the rate of 10 μg/kg body wt per min also resulted in significant (P <0·01) suppression of serum prolactin in SS animals. This prolactin decrease was apparent within 40 min. Prolactin release after 500 ng TRH was less in these dopamine-treated SS monkeys than after an infusion of saline. Higher doses of dopamine (20 and 40 μg) did not cause a further decrease in basal serum prolactin concentrations, but these two dopamine treatments blocked the increase in prolactin elicited by 500 ng TRH. The results suggest that the removal of hypothalamic influence, possibly related to the effects of dopamine, renders the pituitary gland more sensitive to the prolactin-releasing action of TRH.

DNA SYNTHESIS AND DEPLETION OF PROLACTIN IN THE PITUITARY GLAND OF THE MALE RAT

1978 ◽  
Vol 77 (1) ◽  
pp. 129-136 ◽  
Author(s):  
H. M. LLOYD ◽  
J. M. JACOBI ◽  
J. D. MEARES
Keyword(s):  
Growth Hormone ◽  
Dna Synthesis ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Prolactin Secretion ◽  
Male Rats ◽  
Male Rat ◽  
Serum Prolactin ◽  
Inhibitory Effects ◽  
Pituitary Prolactin

Haloperidol, bromocriptine and diethylstilboestrol dipropionate were given in various régimes to male rats to determine their effects on pituitary DNA synthesis, prolactin secretion and growth hormone secretion. Haloperidol increased serum prolactin but did not stimulate pituitary DNA synthesis or reduce pituitary prolactin concentrations. Haloperidol potentiated the effects of oestrogen on serum prolactin and on pituitary DNA synthesis; pituitary prolactin concentrations were greatly reduced, and growth hormone secretion was slightly inhibited. The inhibitory effects of bromocriptine in oestrogen-stimulated rats were demonstrated by smaller pituitary weights and decreased DNA synthesis; serum prolactin levels were lowered and pituitary prolactin concentrations were increased. Haloperidol, given to rats treated with oestrogen and bromocriptine, reversed the inhibitory effects of bromocriptine on DNA synthesis and serum prolactin; pituitary prolactin concentrations fell to well below normal. The results suggest that the haloperidol potentiation of oestrogeninduced pituitary DNA synthesis may depend upon stimulation of prolactin secretion together with reduction of intracellular prolactin levels.

scholarly journals Time-dependent effects of starvation on pituitary, hypothalamic and serum prolactin levels in rats: Comparison to the galanin expression pattern

2016 ◽  
Vol 68 (1) ◽  
pp. 117-123
Author(s):  
Predrag Vujovic ◽  
Iva Lakic ◽  
Nebojsa Jasnic ◽  
Tanja Jevdjovic ◽  
Sinisa Ðurasevic ◽  
...  
Keyword(s):  
Energy Homeostasis ◽  
Metabolic Response ◽  
Expression Patterns ◽  
Male Rats ◽  
Serum Prolactin ◽  
Dark Phase ◽  
Ad Libitum ◽  
Pituitary Prolactin ◽  
Circulating Levels ◽  
Hypothalamic Level

Given that both prolactin and galanin take part in the regulation of energy homeostasis and that galanin is localized within lactotrophs, this study was aimed at comparing the pituitary expression patterns of prolactin and galanin during different phases of metabolic response to starvation in adult Wistar male rats. Food was removed at the onset of the dark phase (6:00 pm) and the animals were deprived for 6, 12, 24 and 48 h. Each of the starved groups (n=6) was killed simultaneously with a group of ad libitum-fed rats (n=6), and the intrapituitary levels of prolactin and galanin were examined. Galanin expression in the hypothalamus and the circulating levels of prolactin were also assessed. Starvation induced a rise in the intrapituitary prolactin level (p<0.001), whereas the opposite trend was detected in the serum (p<0.05). The galanin pituitary level was initially increased (6, 12 h) (p<0.05), but as starvation progressed, it first reached (at 24 h) and ultimately fell below the level recorded in the ad libitum rats (at 48 h) (p<0.05). Both prolactin and galanin were elevated in the hypothalamus after 24- and 48-h starvation. The results show that the starvation-induced increase in the pituitary prolactin expression did not lead to the rise in prolactin circulating levels, but rather resulted in the elevation of the prolactin hypothalamic content. Furthermore, the results suggest that under the circumstances of disturbed energy homeostasis, galanin might be responsible for the augmented prolactin production, initially at the pituitary and subsequently at the hypothalamic level.

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