Effects of various melatonin treatments on plasma prolactin concentrations in the ewe

1986 ◽  
Vol 108 (2) ◽  
pp. 287-292 ◽  
Author(s):  
A. L. Poulton ◽  
J. English ◽  
A. M. Symons ◽  
J. Arendt
Keyword(s):  
Plasma Prolactin ◽  
Melatonin Treatment ◽  
Blood Samples ◽  
Serial Blood ◽  
Artificial Photoperiod ◽  
Oral Doses

ABSTRACT Ewes were treated with s.c. implants of melatonin in mid-April, mid-May and mid-June. From mid-June, other animals were given oral doses of melatonin daily at 16.30 h and another group was maintained under a short (8 h light: 16 h darkness) artificial photoperiod (lights out 16.30 h). Serial blood samples were taken from all animals in June and July. Plasma prolactin concentrations were significantly reduced in ewes treated in May and June (implant, oral and photoperiod treatments) but not in those treated in April. After treatment in June, prolactin levels were significantly suppressed after 7 days of oral and implant melatonin therapy, and after 28 days of a short artificial photoperiod. Melatonin treatment appeared more efficient than an artificial photoperiod in reducing plasma prolactin concentrations. J. Endocr. (1986) 108, 287–292

A note on the effect of melatonin feeding on the initiation of ovarian activity and on plasma prolactin levels in lactating and non-lactating red deer hinds

1985 ◽  
Vol 40 (3) ◽  
pp. 515-518 ◽  
Author(s):  
Rachel Nowak ◽  
R. N. Elmhirst ◽  
R. G. Rodway
Keyword(s):  
Detection Limit ◽  
Corpus Luteum ◽  
Red Deer ◽  
Inhibitory Effect ◽  
Ovarian Activity ◽  
Plasma Prolactin ◽  
Melatonin Treatment ◽  
Plasma Progesterone ◽  
Blood Samples

ABSTRACTMelatonin was fed daily at 14.00 h to eight non-lactating and six lactating hinds. Feeding was begun on 27 July 1983 (day 1) and continued until 21 September (day 57). Six non-lactating hinds were used as controls. Blood samples were taken about every 10 days from day 42 until day 73. Plasma progesterone and prolactin were determined by radioimmunoassay. Progesterone values of greater than 0·63 μg/1 were taken to indicate the presence of a corpus luteum and that the animal had ovulated. In the melatonintreated, non-lactating group seven of the eight hinds showed ovarian activity compared with two of the six controls (P < 0·01). None of the lactating hinds treated with melatonin showed evidence of ovarian activity. In both the lactating and non-lactating hinds treated with melatonin, prolactin levels were never greater than the detection limit of the assay (7·4 μg/l), while, in the control hinds mean prolactin levels were elevated on all but the last sampling day. It is, therefore, possible to induce early ovarian activity in non-lactating red deer hinds by feeding melatonin. However, although melatonin treatment similarly depressed plasma prolactin levels in both lactating and non-lactating hinds, it was unable to overcome the inhibitory effect of lactation on reproduction.

Changes in plasma concentrations of LH, FSH and prolactin in ewes receiving melatonin and short-photoperiod treatments to induce early onset of breeding activity

1987 ◽  
Vol 112 (1) ◽  
pp. 103-111 ◽  
Author(s):  
A. L. Poulton ◽  
J. English ◽  
A. M. Symons ◽  
J. Arendt
Keyword(s):  
Plasma Concentrations ◽  
Pulse Frequency ◽  
Short Photoperiod ◽  
Plasma Prolactin ◽  
Significant Group ◽  
Blood Samples ◽  
Serial Blood ◽  
Breeding Activity ◽  
Before And After ◽  
Natural Photoperiod

ABSTRACT Breeding activity was similarly advanced in ewes given continuous (s.c. implant) or timed (oral dose at 15.30 h) melatonin treatments or subjected to a short (8 h light: 16 h darkness) artificial photoperiod. Treatments commenced in mid-June and were terminated in mid-November. Weekly and serial blood samples were collected before and after treatments commenced, to ascertain the effects on plasma prolactin, LH and FSH concentrations. In addition, serial blood samples were collected for 24 h plasma prolactin and melatonin estimations before and after cessation of the treatments. Plasma prolactin levels were significantly reduced immediately following the start of the melatonin (implant and oral) and short-photoperiod treatments but 'rebounded' to levels greater than control values. The normal seasonal (spring) rise in plasma prolactin was noted in the following year. Before the onset of breeding activity, mean plasma LH and FSH concentrations and LH pulse frequency did not change following any of the treatments. The 24-h plasma melatonin profile accurately reflected the various applied treatments but had re-entrained to the prevailing (natural) photoperiod 1 week after termination of the treatments. There were no significant group differences in 24-h plasma prolactin levels 1 week before or 1 and 11 weeks after the treatments had ceased. Such treatments, although successfully advancing the onset of breeding activity and modifying the seasonal plasma prolactin rhythm, were not manifested through any apparent change in peripheral LH or FSH. J. Endocr. (1987) 112, 103–111

scholarly journals Consumption of Cross-Linked Resistant Starch (RS4XL) on Glucose and Insulin Responses in Humans

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Enas K. Al-Tamimi ◽  
Paul A. Seib ◽  
Brian S. Snyder ◽  
Mark D. Haub
Keyword(s):  
Dietary Fiber ◽  
Resistant Starch ◽  
Area Under The Curve ◽  
Postprandial Glucose ◽  
Wheat Starch ◽  
Blood Samples ◽  
Serial Blood ◽  
Insulin Levels ◽  
Insulin Responses ◽  
First Time

Objective. The objective was to compare the postprandial glycemic and insulinemic responses to nutrition bars containing either cross-linked RS type 4 (RS4XL) or standard wheat starch in normoglycemic adults (n= 13; age = 27±5 years; BMI = 25±3 kg/m2).Methods. Volunteers completed three trials during which they consumed a glucose beverage (GLU), a puffed wheat control bar (PWB), and a bar containing cross-linked RS4 (RS4XL) matched for available carbohydrate content. Serial blood samples were collected over two hours and glucose and insulin concentrations were determined and the incremental area under the curve (iAUC) was calculated.Results. TheRS4XLpeak glucose and insulin concentrations were lower than the GLU and PWB (P<.05). The iAUC for glucose and insulin were lower following ingestion of RS4 compared with the GLU and PWB trials.Conclusions. These data illustrate, for the first time, that directly substituting standard starch withRS4XL, while matched for available carbohydrates, attenuated postprandial glucose and insulin levels in humans. It remains to be determined whether this response was due to the dietary fiber and/or resistant starch aspects of theRS4XLbar.

Photoacoustic detection of circulating melanoma cells as a predictor of metastasis in stage III patients.

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. e21053-e21053
Author(s):  
John Andrew Viator ◽  
Martin Sanders ◽  
Ahmad A. Tarhini ◽  
Cindy Sander ◽  
Robert Hugh Edgar ◽  
...  
Keyword(s):  
Laser Light ◽  
Melanoma Cells ◽  
Ultrasonic Waves ◽  
Flow Cytometer ◽  
Disease State ◽  
Stage Iii ◽  
Blood Samples ◽  
Serial Blood ◽  
Melanoma Patients ◽  
Stage Iii Melanoma

e21053 Background: Circulating tumor cells have been correlated with disease state and distant metastatic spread in cancer patients. We postulated that enumerating circulating melanoma cells (CMCs) may predict the onset of distant metastasis in Stage III patients. We detected CMCs using our photoacoustic flow cytometer, in which we irradiated enriched blood samples with nanosecond pulsed laser light. While there is no effect on non-optically active leukocytes, absorption of laser light by pigmented melanoma cells resulted in robust ultrasonic waves that indicated CMCs in the sample. Methods: We tested 32 archived samples from 9 Stage III melanoma patients using our photoacoustic flow cytometer. Each patient had between 2 and 6 serial blood samples. We used a pulsed Nd:YAG laser to irradiate mononuclear cells in suspension and under flow. The number of CMCs detected after testing was recorded, indicating the time sequence of circulating tumor cell activity. Results: The numbers of CTCs for each sample is shown in the table below. The ultimate disease state, whether the patient became metastatic or not, was blinded to the investigators who performed the photoacoustic tests. One sample for patient 3 indicated 63 CMCs, though this test was known to be contaminated and had an unknown number of false detections. Conclusions: We found that patients who had a series of more than 4 CMCs were more likely to become metastatic than those patients who tested for 4 CMCs for fewer, indicating that a sequence of CMC detections in serial blood draws provides a potentially strong predictor of metastasis in Stage III melanoma patients warranting further investigation at this and lower stages of melanoma. We are developing a more rigorous model based on time series analysis of CMCs for prediction of metastasis. [Table: see text]

Effects of melatonin implantation on cashmere growth, hormone concentrations and cashmere yield in cashmere-perennial-type Liaoning cashmere goats

2017 ◽  
Vol 57 (1) ◽  
pp. 60 ◽  
Author(s):  
Chunhui Duan ◽  
Jianhai Xu ◽  
Yu Zhang ◽  
Wei Zhang ◽  
Yabo Sun ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Growth Rate ◽  
Fibre Diameter ◽  
Control Group ◽  
Plasma Prolactin ◽  
Blood Samples ◽  
Growing Period ◽  
Plasma Melatonin ◽  
Cashmere Goats ◽  
Slow Growing

The aim of the present study was to investigate the effects of melatonin implants on cashmere growth, the concentrations of plasma melatonin and prolactin and the total cashmere yield in cashmere-perennial-type Liaoning cashmere goats. Twenty female goats were assigned to two treatments (n = 10) including a control and a treatment in which melatonin (2 mg/kg bodyweight) was implanted in March and May, respectively. The experiment lasted for 153 days. Fibre samples were collected in July, August and April the following year (before cashmere harvest). Blood samples were taken monthly from March to August. Cashmere yield was recorded after harvest. In melatonin-treated goats, cashmere length and cashmere growth rate from April to July were significantly increased (P < 0.05), but no influence was observed (P > 0.05) in August. Implantation of melatonin significantly increased plasma melatonin concentrations (P < 0.05) and decreased prolactin concentrations from April to July compared with the control group (P < 0.05), but no difference was observed in August (P > 0.05). Administration of melatonin increased the cashmere yield by 6.2% and the maximum cashmere length by 8.4%, but the differences were not significant (P > 0.05). Moreover, the cashmere fibre diameter was not influenced by melatonin implantation (P > 0.05). The results also indicated that plasma melatonin concentrations were correlated with plasma prolactin in the regulation of cashmere growth. Implantation of melatonin was an effective way to promote cashmere growth, and administration during the cashmere slow-growing period improved cashmere production without changing cashmere fibre diameter in cashmere-perennial-type Liaoning cashmere goats.

PATTERNS OF PLASMA PROLACTIN IN POST-PARTUM SUCKLED COWS

1981 ◽  
Vol 90 (3) ◽  
pp. 391-396 ◽  
Author(s):  
R. WEBB ◽  
G. E. LAMMING
Keyword(s):  
Post Partum ◽  
Significant Negative Correlation ◽  
Prolactin Secretion ◽  
The Other ◽  
Plasma Prolactin ◽  
Blood Samples ◽  
Biphasic Pattern ◽  
Stage Of Lactation ◽  
Low Concentrations ◽  
High Concentrations

Blood samples taken on alternate days through indwelling jugular venous catheters from 12 suckled cows between days 14 and 48 post partum contained significantly less prolactin than samples collected on intermediate days by jugular venepuncture. Samples taken through the catheter every 2 h for 72 h periods revealed a repetitive daily biphasic pattern of prolactin secretion with low concentrations at 09.00 and 19.00 h and high concentrations at 13.00 and 23.00 h. In two groups of cows, one group calving at the beginning of March (increasing photoperiod) and the other calving during June (decreasing photoperiod), there was a significant negative correlation between stage of lactation and plasma prolactin concentrations in samples taken by venepuncture.

Differences in the seasonal rhythmicity of plasma prolactin in elderly human subjects: detection in women but not in men

1983 ◽  
Vol 96 (1) ◽  
pp. 65-71 ◽  
Author(s):  
Yvan Touitou ◽  
Alain Carayon ◽  
Alain Reinberg ◽  
André Bogdan ◽  
Hervé Beck
Keyword(s):  
Sex Difference ◽  
Elderly Women ◽  
Human Subjects ◽  
Mental Condition ◽  
Elderly Subjects ◽  
Plasma Prolactin ◽  
Elderly Men ◽  
Blood Samples ◽  
Young And Elderly Subjects ◽  
Seasonal Rhythmicity

Effects of age, sex and mental condition on the circadian and circannual rhythmicity of plasma prolactin in human subjects were investigated. Circannual changes were recorded on a circadian basis in January, March, June and October in four groups of subjects: seven young men, six elderly men, six elderly women and six senile demented patients (two men and four women). Blood samples were drawn every 4 h over a 24-h period at the four sampling sessions. Circadian rhythms of the hormone were validated in all groups and at all sampling sessions except twice in elderly demented subjects. The 24-h mean levels of prolactin in plasma were approximately the same in young and elderly subjects. The circadian acrophases were most often located in the vicinity of 02.00–04.00 h. The circannual rhythmicity of the hormone showed a sex difference; the rhythm was not validated in either young or elderly men but was detected in the groups of elderly women and elderly demented patients (mainly women). The acrophases were located in May. This paper strongly suggests a sex difference in the circannual rhythmicity of plasma prolactin levels in elderly subjects.

A study of the luteolytic mechanism of the antiprogesterone RU486 during the late-luteal phase in pseudopregnant rats

1996 ◽  
Vol 150 (1) ◽  
pp. 93-98 ◽  
Author(s):  
Y Nakamura ◽  
H Tamura ◽  
M Ono ◽  
K Shimamura ◽  
N Sugino ◽  
...  
Keyword(s):  
Subcutaneous Injection ◽  
Luteal Phase ◽  
Treated Group ◽  
Sesame Oil ◽  
Serum Prolactin ◽  
Control Group ◽  
Serum Progesterone ◽  
Blood Samples ◽  
Serial Blood ◽  
Late Luteal Phase

Abstract The purpose of this study was to examine the possible mechanism through which RU486 induces luteolysis during the late-luteal phase in pseudopregnant (PSP) rats. PSP rats received a subcutaneous injection of RU486 in sesame oil (5 mg/kg body weight) or sesame oil alone once a day between day 9 and day 11 of pseudopregnancy. Serial blood samples were collected on days 5, 9, 10, 11 and 12 and assayed for progesterone content. To examine the possible action of RU486 through a uterine and/or a pituitary (prolactin-dependent) mechanism, PSP rats and chronic hysterectomized PSP rats which had been hysterectomized before PSP induction received a subcutaneous injection of RU486 in sesame oil (5 mg/kg body weight), sesame oil alone, prolactin in 50% polyvinylpyrrolidone (15 IU/day), or RU486 and prolactin once a day between day 9 and day 11 of pseudopregnancy. Serial blood samples were collected on days 5, 9, 10 and 11 and assayed for progesterone content. Blood samples were also collected at 0400 h on day 12 and used for prolactin and progesterone determinations. To examine the direct effect of RU486 on corpus luteum and/or pituitary, hysterectomized rats underwent hypophysectomy and pituitary autotransplantation on dioestrus 1 and received a subcutaneous injection of RU486 in sesame oil or sesame oil alone for 3 days between day 21 and day 23 after surgery. Serial blood samples were collected on days 10, 21, 22, 23 and 24 and assayed for progesterone and prolactin contents. In ordinary PSP rats, serum progesterone levels were significantly (P<0·01) lower in the RU486-treated group than in the control group (9 ± 1 vs 53 ± 7 ng/ml; mean ± s.e.m.) on day 11. Serum prolactin levels at 0400 h on day 12 of pseudopregnancy were significantly (P<0·05) lower in the RU486-treated group than in the control group (16 ±4 vs 154 ±44 ng/ml; mean ± s.e.m.). The concomitant prolactin treatment reversed the luteolytic effects of RU486 on day 11 of pseudopregnancy. In hysterectomized PSP rats, RU486 also suppressed serum prolactin levels, and the concomitant prolactin treatment again reversed the luteolytic effects of RU486. In hysterectomized rats which were hypophysectomized and pituitary autotransplanted, RU486 treatment did not induce any significant changes in serum progesterone and prolactin levels. These results indicated that RU486 induced luteolysis during the late-luteal phase in PSP rats by suppressing prolactin secretion via a hypothalamic mechanism. Journal of Endocrinology (1996) 150, 93–98

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