Regulation in pregnant mink (Mustela vison) of plasma progesterone and prolactin concentrations and regulation of onset of the spring moult by daylight ratio and melatonin injections

1983 ◽  
Vol 61 (9) ◽  
pp. 1959-1963 ◽  
Author(s):  
L. Martinet ◽  
D. Allain ◽  
M. Meunier
Keyword(s):  
Prolactin Secretion ◽  
The Other ◽  
Short Photoperiod ◽  
Plasma Prolactin ◽  
Positive Relation ◽  
Vernal Equinox ◽  
Plasma Progesterone ◽  
Progesterone Secretion ◽  
The One ◽  
L 13

In pregnant or pseudopregnant mink maintained under natural daylight conditions and mated early in March, plasma prolactin and progesterone levels began to increase after the vernal equinox. The onset of spring moult was observed a few days later. When the females were transferred to a 15 h light (L): 9 h dark (D) photoperiod just after mating, prolactin and progesterone increase was advanced by several days; when the mink were transferred to an 11 h L: 13 h D schedule, these increases, as well as the onset of spring moult, were delayed or inhibited. A daily afternoon injection of melatonin mimicked the effects of short photoperiod. A positive relation was observed between plasma prolactin on the one hand and progesterone secretion or onset of moulting on the other. These results suggest that short photoperiod or melatonin effects might act by inhibiting prolactin secretion.

PLASMA PROLACTIN AND PROGESTERONE RESPONSES TO MATING ARE ALTERED IN AGED RATS

1981 ◽  
Vol 90 (2) ◽  
pp. 179-191 ◽  
Author(s):  
S. HENDRICKS ◽  
C. A. BLAKE
Keyword(s):  
Plasma Concentrations ◽  
External Jugular Vein ◽  
Female Rats ◽  
Plasma Prolactin ◽  
Aged Rats ◽  
Pregnant Rats ◽  
Pregnant Rat ◽  
Plasma Progesterone ◽  
The One ◽  
The Right

The effects of varying amounts of copulatory stimulation on patterns of plasma concentrations of prolactin and progesterone were evaluated in 3- and 12-month-old female rats. The 12-month-old group included rats which still exhibited oestrous cycles and rats in persistent vaginal oestrus (PVO). The extent of copulatory stimulation was defined by the number of intromissions received during mating: ≤5,15 or > 50. Blood samples were drawn over the 8 days after mating through a cannula inserted into the right external jugular vein. Plasma from the samples was assayed for prolactin and progesterone. In aged but still cyclic rats, pregnancy rates were positively correlated with the number of intromissions received during mating. Only one rat in PVO became pregnant. All animals which became pregnant and rats in PVO which, after mating, exhibited a disruption of the pattern of PVO, showed the nocturnal surge of plasma prolactin characteristic of pregnant and pseudopregnant rats. While these surges persisted until day 8 after mating in pregnant animals, they were absent by this time in the rats in PVO. Prolactin surges were present in some but not all of the aged rats which did not become pregnant. Progesterone concentrations were raised in all pregnant animals except the one pregnant rat in PVO and, while not related to the number of intromissions, concentrations were higher 8 days after mating in young compared with those in aged pregnant rats. Plasma progesterone was low in rats in PVO regardless of disruption of the pattern of PVO. We have concluded that the failure of limited copulatory stimulation to induce pregnancy in older rats results, at least in part, from its failure to initiate nocturnal prolactin surges. Nevertheless, our data suggest that matings which are not experimentally limited should provide ample stimulation to establish such surges. Although reduced plasma concentrations of prolactin and progesterone at pro-oestrus and reduced plasma progesterone through part of gestation may contribute to decreasing fertility in aged rats, other unidentified factors appear to be involved in mediating the capacity of extensive copulatory stimulation to induce pregnancy in these animals.

Seasonal patterns of luteal cyclicity in young red deer (Cervus elaphus) and sambar deer (Cervus unicolor)

1997 ◽  
Vol 9 (6) ◽  
pp. 587 ◽  
Author(s):  
G. W. Asher ◽  
P. D. Muir ◽  
G. Semiadi ◽  
K. T. O'Neill ◽  
I. C. Scott ◽  
...  
Keyword(s):  
Cervus Elaphus ◽  
Red Deer ◽  
Prolactin Secretion ◽  
Seasonal Patterns ◽  
Plasma Prolactin ◽  
Reproductive Seasonality ◽  
Plasma Progesterone ◽  
The Mean ◽  
Sambar Deer ◽  
Cervus Unicolor

Seasonal onset of pubertal ovulation and incidence of luteal cyclicity was assessed from plasma progesterone proles over 15 months for tame red deer (n = 7) and sambar deer (n = 7) hinds. Seasonal responses to photoperiod were determined from plasma prolactin proles. All red deer attained puberty at 17-18 months of age in May-June and expressed 3-6 luteal cycles of length 20·0 ± 10·4 days (mean ± s.e.m.) over 52-102 days. Six sambar deer attained puberty at 7-19 months of age, between August and December. Duration of luteal cyclicity was variable. While one animal remained continuously cyclic for 13 months, most entered anoestrus between November and February. The mean length of the luteal cycle was 17·2 ± 0·3 days. While red deer exhibited strongly seasonal patterns of prolactin secretion, sambar deer showed no such seasonal trends. The data collectively indicate that young sambar hinds at temperate latitudes exhibit loosely dened patterns of reproductive seasonality that are 4-6 months out of phase with those of red deer, although some individuals may be non-seasonal. Failure to express seasonal patterns of prolactin secretion indicates that sambar deer may not perceive photoperiodic cues to the same extent as do red deer.

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.

This Drives Me Nuts!

2016 ◽  
pp. 266-289 ◽  
Author(s):  
Stefano Triberti
Keyword(s):  
Video Games ◽  
Negative Emotions ◽  
Well Being ◽  
The Other ◽  
Positive Experience ◽  
Positive Relation ◽  
Complex Emotions ◽  
Video Gamers ◽  
The One ◽  
Anxiety And Fear

Video games are an interesting example of technologies/media able to generate complex emotions. Indeed, part of the emotions commonly arising in the experience of video gamers are quite negative. On the one hand, video gamers may feel frustration and anger due to the difficulty of the gameplay. On the other hand, they may experience sadness, anxiety and fear due to the immersion into emotionally rich narratives. Yet, video gamers seem to appreciate gaming technologies generating negative emotions, and the research on media frequently highlights a counterintuitive positive relation between negative affect and enjoinment/well-being outcomes. Starting from these premises, the present chapter is aimed to review the negative emotions typical of video games, in order to understand in what ways they can concur in generating an overall positive experience. Then, the chapter discusses implications for research on video games as positive technologies, namely technologies able to promote well-being in their users.

This Drives Me Nuts!

2016 ◽  
pp. 271-294 ◽  
Author(s):  
Stefano Triberti
Keyword(s):  
Video Games ◽  
Negative Emotions ◽  
Well Being ◽  
The Other ◽  
Positive Experience ◽  
Positive Relation ◽  
Complex Emotions ◽  
Video Gamers ◽  
The One ◽  
Anxiety And Fear

Video games are an interesting example of technologies/media able to generate complex emotions. Indeed, part of the emotions commonly arising in the experience of video gamers are quite negative. On the one hand, video gamers may feel frustration and anger due to the difficulty of the gameplay. On the other hand, they may experience sadness, anxiety and fear due to the immersion into emotionally rich narratives. Yet, video gamers seem to appreciate gaming technologies generating negative emotions, and the research on media frequently highlights a counterintuitive positive relation between negative affect and enjoinment/well-being outcomes. Starting from these premises, the present chapter is aimed to review the negative emotions typical of video games, in order to understand in what ways they can concur in generating an overall positive experience. Then, the chapter discusses implications for research on video games as positive technologies, namely technologies able to promote well-being in their users.

Seasonal variation and circadian rhythmicity of the prolactin profile during the summer months in repeat-breeding Murrah buffalo heifers

2007 ◽  
Vol 19 (4) ◽  
pp. 569 ◽  
Author(s):  
Kajal S. Roy ◽  
Bukkaraya S. Prakash
Keyword(s):  
Prolactin Secretion ◽  
Circadian Rhythmicity ◽  
Oestrous Cycle ◽  
Gonadal Hormone ◽  
Plasma Prolactin ◽  
Murrah Buffalo ◽  
Progesterone Secretion ◽  
Endocrine Profile ◽  
Severe Heat Stress ◽  
The Mean

The present study was undertaken to determine a detailed endocrine profile for prolactin and progesterone during the oestrous cycle in repeat-breeding Murrah buffalo heifers during summer and winter. Hormone concentrations were quantified in blood plasma samples collected over the oestrous cycle in both winter and summer, as well as in samples collected during the summer months to observe circadian rhythmicity. The mean plasma prolactin concentration during the winter months ranged from 3.10 ± 0.48 to 9.17 ± 1.39 ng mL–1; during the summer months, plasma prolactin concentrations ranged from 248.50 ± 16.03 to 369.63 ± 25.13 ng mL–1. During the winter months, the mean plasma progesterone concentration ranged from 0.20 ± 0.00 to 3.04 ± 0.34 ng mL–1, which was significantly higher (P < 0.01) than the prolactin concentrations recorded in the summer months (range 0.20 ± 0.00 to 1.48 ± 0.13 ng mL–1). Plasma prolactin and progesterone concentrations were negatively correlated (r = –0.24) during the summer oestrous cycle, which indicates prolactin-induced suppression of progesterone secretion through poor luteal development. During the summer, a circadian rhythmicity was observed in buffaloes and the results indicate that high prolactin secretion contributes to poor fertility by lowering gonadal hormone (progesterone) secretion. It was concluded from the present study that prolactin and progesterone profiles during the summer and winter months are directly correlated with the reproductive performance of buffaloes. The finding also validates the hypothesis that hyperprolactinaemia may cause acyclicity/infertility in buffaloes during the summer months due to severe heat stress.

Factors affecting prolactin secretion during the breeding cycle of the ring dove (Streptopelia risoria) and its possible role in incubation

1986 ◽  
Vol 110 (3) ◽  
pp. 447-458 ◽  
Author(s):  
R. W. Lea ◽  
D. M. Vowles ◽  
H. R. Dick
Keyword(s):  
Visual Stimulation ◽  
Prolactin Secretion ◽  
Nest Defence ◽  
Breeding Cycle ◽  
Plasma Prolactin ◽  
Plasma Progesterone ◽  
Factors Affecting ◽  
Streptopelia Risoria ◽  
Ring Dove ◽  
Defence Behaviour

ABSTRACT Plasma prolactin began to increase significantly about 5 days after the onset of incubation in both sexes of the dove to reach a peak at the time of hatch. At this time, the concentration of prolactin in the plasma of the female was significantly higher than in the male. In the middle of the incubation period prolactin levels measured over a 24-h period remained constant in both sexes, although the male sits during the middle of the day and the female for the rest of the time. Nest deprivation resulted in a sharp, significant decline in the concentration of prolactin in both sexes. Newly hatched squabs stimulated the release of prolactin only in those doves which had been incubating eggs for several days. A distinct sex difference was observed in the expression of nest defence behaviour of the ring dove during the breeding cycle. At the time of laying, the female was significantly more aggressive than the male and her aggression increased only slightly up to the time of hatching. In contrast, male aggression increased gradually from a low level at laying to reach a peak at the time of hatching. The levels of plasma progesterone in the female showed a significant increase around the time of lay. No significant changes occurred in the plasma concentration of either progesterone or 17α-hydroxyprogesterone in the male. Administration of prolactin increased the length of time of incubation of infertile eggs. Nest manipulations which had the effect of inducing the doves to begin incubation 4 days before laying showed that (1) the length of time of incubation of infertile eggs is fixed and independent of events which occur at courtship or oviposition, (2) the initiation of the increase in plasma prolactin concentration during incubation is independent of events which occur at courtship and oviposition and (3) the termination of incubation is always preceded by a fall in the concentration of plasma prolactin. It is concluded that the length of time of incubation is dependent upon sustained raised levels of plasma prolactin. The concentration of plasma prolactin increases several days after the onset of incubation in response to the tactile stimulation of sitting. High levels, if maintained by visual stimulation from the nest, maintain incubation for a fixed period. After this, if the eggs fail to hatch, prolactin levels fall and the doves cease incubation and begin a new cycle. J. Endocr. (1986) 110, 447–458

scholarly journals Efecto de la intensificación sobre la eficiencia de las explotaciones lecheras

2011 ◽  
Vol 7 (13) ◽  
pp. 91 ◽  
Author(s):  
Antonio Álvarez ◽  
Julio Del Corral ◽  
José Antonio Pérez ◽  
Daniel Solís
Keyword(s):  
Production Cost ◽  
Dairy Farms ◽  
The Other ◽  
Cost Functions ◽  
Empirical Literature ◽  
Positive Relation ◽  
Methodological Issues ◽  
Ex Post ◽  
Ex Ante ◽  
The One

This study analyzes the differences on production cost associated with the intensification of production for a sample of dairy farms in Asturias. In doing so, we account for two methodological issues which are not usually considered in the empirical literature. On the one hand, we allow for different technologies within the sample. On the other hand, we estimate ex ante cost functions, which use ‘planned output’ instead of the traditional ex post approach which uses the ‘observed output’. Our results show a positive relation between intensification and efficiency.

Note on Selection of Coordinate Systems for Geodynamics

1975 ◽  
Vol 26 ◽  
pp. 395-407
Author(s):  
S. Henriksen
Keyword(s):  
Sea Level ◽  
The Other ◽  
Coordinate Systems ◽  
Mean Sea Level ◽  
The Earth ◽  
The One ◽  
Static Systems ◽  
Selection Of

The first question to be answered, in seeking coordinate systems for geodynamics, is: what is geodynamics? The answer is, of course, that geodynamics is that part of geophysics which is concerned with movements of the Earth, as opposed to geostatics which is the physics of the stationary Earth. But as far as we know, there is no stationary Earth – epur sic monere. So geodynamics is actually coextensive with geophysics, and coordinate systems suitable for the one should be suitable for the other. At the present time, there are not many coordinate systems, if any, that can be identified with a static Earth. Certainly the only coordinate of aeronomic (atmospheric) interest is the height, and this is usually either as geodynamic height or as pressure. In oceanology, the most important coordinate is depth, and this, like heights in the atmosphere, is expressed as metric depth from mean sea level, as geodynamic depth, or as pressure. Only for the earth do we find “static” systems in use, ana even here there is real question as to whether the systems are dynamic or static. So it would seem that our answer to the question, of what kind, of coordinate systems are we seeking, must be that we are looking for the same systems as are used in geophysics, and these systems are dynamic in nature already – that is, their definition involvestime.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

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