Serum and Pituitary Prolactin Changes in the Band-tailed Pigeon (Columba fasciata) in Relation to the Reproductive Cycle

1973 ◽  
Vol 51 (8) ◽  
pp. 583-589 ◽  
Author(s):  
G. L. March ◽  
B. A. McKeown
Keyword(s):  
Reproductive Cycle ◽  
Serum Prolactin ◽  
Pituitary Prolactin ◽  
Columba Fasciata ◽  
Gland Development

Relative changes in serum and pituitary prolactin in the band-tailed pigeon were measured by radioimmunoassay. It was found that serum prolactin concentrations rose substantially prior to crop gland development and reached a maximum during the period of ovulation. At the same time, there was a corresponding depletion of pituitary prolactin. The reciprocal nature of these changes continued for the remainder of the reproductive cycle. Although the lack of antigonadal response to increased levels of prolactin is clearly demonstrated by the male of this species, this problem remains unresolved in the female.

Potentiation of sulpiride-induced prolactin secretion by sodium deprivation in man

1980 ◽  
Vol 94 (1) ◽  
pp. 25-29 ◽  
Author(s):  
Masatomo Mori ◽  
Isao Kobayashi ◽  
Kihachi Ohshima ◽  
Sakae Maruta ◽  
Yohnosuke Shimomura ◽  
...  
Keyword(s):  
Control Diet ◽  
Normal Subjects ◽  
Sodium Content ◽  
Prolactin Secretion ◽  
Serum Prolactin ◽  
Aldosterone Secretion ◽  
Low Sodium Diet ◽  
Specific Radioimmunoassay ◽  
Prolactin Response ◽  
Pituitary Prolactin

Abstract. Previous studies suggest that prolactin is not an important osmoregulatory hormone in man, while aldosterone is well known to be important in osmoregulation. The present investigation was undertaken to ascertain whether serum osmotic changes affect pituitary prolactin secretion following sulpiride administration. Five normal subjects were placed on a constant isocaloric diet with different sodium content. Serum prolactin and aldosterone level were measured by specific radioimmunoassay. The basal serum level of prolactin was unaffected by changes in sodium content of the diet, in contrast to the basal level of aldosterone. On the other hand, the maximum levels of serum prolactin in response to sulpiride (50 mg, im) were significantly higher on a low sodium diet (3 g of salt/day) than on a control diet (12– 15 g of salt/day). When the content of diet changed from low salt to high salt (25 g of salt/day), sulpiride-induced prolactin response decreased, though it was not significantly lower than that on a control diet. However, sulpiride administration could not stimulate aldosterone secretion under any of the various sodium contents of the diet. The present study provides evidence that lowering of serum osmolarity stimulates serum prolactin response to sulpiride administration in man and this response is not modulated by aldosterone secretion.

ONSET OF OESTROGEN-INDUCED PROLACTIN SECRETION AND DNA SYNTHESIS BY THE RAT PITUITARY GLAND

1977 ◽  
Vol 72 (1) ◽  
pp. 35-39 ◽  
Author(s):  
JOAN JACOBI ◽  
H. M. LLOYD ◽  
J. D. MEARES
Keyword(s):  
Dna Synthesis ◽  
Pituitary Gland ◽  
Prolactin Secretion ◽  
Male Rat ◽  
Serum Prolactin ◽  
Rat Pituitary ◽  
The Times ◽  
Pituitary Prolactin

SUMMARY The times of onset of oestrogen-induced prolactin secretion and DNA synthesis were studied in the pituitary gland of the male rat. At intervals from 3 to 96 h after injection of 10 mg diethylstilboestrol dipropionate, serum and pituitary prolactin concentrations were measured by radioimmunoassay and pituitary DNA synthesis by incorporation of [3H]thymidine in vitro. Serum prolactin was raised significantly from 6 h onwards and DNA synthesis was increased from 30 h onwards. Pituitary prolactin concentration began to increase at 30 h. Significant correlations were obtained between serum prolactin and DNA synthesis from 24 to 72 h but not during the period of prolactin secretion from 6 to 24 h.

THE STIMULATION OF PROLACTIN SECRETION BY SULPIRIDE IN "ADOLESCENT GYNAECOMASTIA"

1977 ◽  
Vol 85 (4) ◽  
pp. 692-697
Author(s):  
R. D'Agata ◽  
S. Andó ◽  
S. Gulizia ◽  
L. Condorelli ◽  
C. Paci ◽  
...  
Keyword(s):  
Baseline Level ◽  
Prolactin Secretion ◽  
Serum Prolactin ◽  
Maximum Increase ◽  
The Mean ◽  
Pituitary Prolactin ◽  
Stimulation Of

ABSTRACT In order to evaluate the function of the hypothalamic-pituitary-prolactin axis in "adolescent gynaecomastia" (AG), sulpiride was administered to 7 normal boys and 7 boys with AG. The maximum increase in serum prolactin (PRL) above the mean baseline level (Δmax) was used as index of response. The sulpiride induced a greater PRL release in boys with gynaecomastia than in the controls. Our data indicate that boys with gynaecomastia may have a greater pituitary prolactin pool. The results also illustrate the usefulness of specific neurotrophic agents such as sulpiride as important tools for evaluating the function of the hypothalamic-pituitary-PRL axis.

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.

Studies on the band-tailed pigeon (Columba fasciata) in British Columbia. 1. Seasonal changes in gonadal development and crop gland activity

1970 ◽  
Vol 48 (6) ◽  
pp. 1353-1357 ◽  
Author(s):  
G. L. March ◽  
R. M. F. S. Sadleir
Keyword(s):  
British Columbia ◽  
Breeding Season ◽  
Seasonal Changes ◽  
Gonadal Development ◽  
Hunting Season ◽  
Breeding Condition ◽  
Columba Fasciata ◽  
Gland Development ◽  
Breeding Status ◽  
Do So

Band-tailed pigeons ovulate in British Columbia from May through July although apparently not all females do so early in the breeding season. Males are in breeding condition when they arrive after the northward migration in April and remain so until late July. Evidence suggests that two clutches (one egg each) may be produced during the breeding season. The female's ability to ovulate white crop feeding the squab provides additional evidence of two clutches. Four stages of crop gland development are described in detail and the usefulness of this gland to indicate breeding status is demonstrated. Many birds had active crops when shot during the hunting season indicating a potentially reduced recruitment of the squabs being fed at this time.

PROLACTIN AND LUTEINIZING HORMONE LEVELS BEFORE AND AFTER PARTURITION IN RATS BEARING EITHER SINGLE OR MULTIPLE EMBRYOS

1977 ◽  
Vol 73 (2) ◽  
pp. 257-262 ◽  
Author(s):  
I. NIR ◽  
G. GOLDHABER ◽  
N. HIRSCHMANN ◽  
J. SHANI
Keyword(s):  
Prolactin Level ◽  
Post Partum ◽  
Serum Prolactin ◽  
Serum Prolactin Level ◽  
Steroid Production ◽  
Sharp Drop ◽  
Serum Lh ◽  
Before And After ◽  
Prolactin Synthesis ◽  
Pituitary Prolactin

SUMMARY Levels of prolactin and LH were determined in serum and pituitary during the last days of pregnancy and post partum in rats bearing single and multiple embryos. In rats with a single embryo serum prolactin and LH levels were significantly lower during the last 2 days of pregnancy and post partum than in rats bearing multiple embryos. While large increases were recorded in serum prolactin and LH levels in the rats with multiple embryos between days 21 and 22 of gestation, in the group with single embryos changes occurred in LH level only. Throughout the experiment pituitary prolactin was lower in rats with a single embryo than in those with multiple embryos in spite of the sharp drop in prolactin level in the group with multiple embryos from day 21 to 22. No differences were observed in the pituitary LH levels of either group during the days preceding parturition, but in the rats with multiple embryos there was a sharp drop in LH level post partum. It seems that the reduced serum prolactin level in the rats with a single embryo was associated with inhibition of pituitary prolactin synthesis and release, whereas the decreased serum LH level resulted from impaired release but not synthesis. These results support the hypothesis of a regulatory role for the placenta in pituitary prolactin and LH synthesis and release, either by hypothalamus– pituitary stimulation, or perhaps by way of the ovaries, through regulation of ovarian steroid production.

scholarly journals Accelerated Mammary Gland Development during Pregnancy and Delayed Postlactational Involution in Vitamin D3 Receptor Null Mice

2004 ◽  
Vol 18 (9) ◽  
pp. 2208-2223 ◽  
Author(s):  
Glendon M. Zinser ◽  
JoEllen Welsh
Keyword(s):  
Vitamin D ◽  
Mammary Gland ◽  
Reproductive Cycle ◽  
Mammary Gland Development ◽  
Metabolic Activation ◽  
Calcium Content ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Autocrine Signaling ◽  
Postlactational Involution ◽  
Gland Development

Abstract The vitamin D receptor (VDR) is present in mammary gland, and VDR ablation is associated with accelerated glandular development during puberty. VDR is a nuclear receptor whose ligand, 1,25-dihydroxyvitamin D [1,25-(OH)2D] is generated after metabolic activation of vitamin D by specific vitamin D hydroxylases. In these studies, we demonstrate that both the VDR and the vitamin D 1-α hydroxylase (CYP27B1), which produces 1,25-(OH)2D are present in mammary gland and dynamically regulated during pregnancy, lactation, and involution. Furthermore, we show that mice lacking VDR exhibit accelerated lobuloalveolar development and premature casein expression during pregnancy and delayed postlactational involution compared with mice with functional VDR. The delay in mammary gland regression after weaning of VDR knockout mice is associated with impaired apoptosis as demonstrated by reductions in terminal deoxynucleotidyl transferase-mediated deoxyuridine nick-end labeling staining, caspase-3 activation and Bax induction. Under the conditions used in this study, VDR ablation was not associated with hypocalcemia, suggesting that altered mammary gland development in the absence of the VDR is not related to disturbances in calcium homeostasis. Furthermore, in the setting of normocalcemia, VDR ablation does not affect milk protein or calcium content. These studies suggest that the VDR contributes to mammary cell turnover during the reproductive cycle, and its effects may be mediated via both endocrine and autocrine signaling pathways. Unlike many mammary regulatory factors that exert transient, stage-specific effects, VDR signaling impacts on mammary gland biology during all phases of the reproductive cycle.

PROLACTIN RELEASE IN RESPONSE TO INFUSION OF ISOTONIC OR HYPERTONIC SALINE

1982 ◽  
Vol 92 (2) ◽  
pp. 273-NP ◽  
Author(s):  
D. J. BLISS ◽  
C. J. LOTE
Keyword(s):  
Hypertonic Saline ◽  
Volume Expansion ◽  
Secretory Activity ◽  
Serum Prolactin ◽  
Prolactin Cells ◽  
Prolactin Release ◽  
Fluid Load ◽  
Anaesthetized Rats ◽  
Pituitary Prolactin ◽  
Hypertonic Saline Infusion

In ketamine-anaesthetized rats, the infusion of 10 ml either isotonic (0·9%) or hypertonic (3·0%) saline over a 30-min period was associated with a decrease in the secretory activity of the anterior pituitary prolactin cells (assessed morphologically by electron microscopy), and a decrease in the serum prolactin concentration (determined by radioimmunoassay). The hypertonic saline infusion significantly (P<0·01) increased the serum osmolality whereas the isotonic infusion did not. The results indicated that prolactin release is reduced in response to volume expansion regardless of whether the fluid load is isotonic or hypertonic, and suggested that, in the rat, the hormone may play a role in volume regulation rather than osmoregulation.

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