Time-dependent effects of oestradiol and progesterone on hypothalamic catecholamine turnover in ovariectomized rats

1985 ◽  
Vol 106 (3) ◽  
pp. 303-309 ◽  
Author(s):  
C. Hiemke ◽  
D. Bruder ◽  
M. C. Michel ◽  
R. Ghraf
Keyword(s):  
Turnover Rate ◽  
Brain Area ◽  
Serum Levels ◽  
Time Dependent ◽  
Ovariectomized Rats ◽  
Dopamine Turnover ◽  
Turnover Rates ◽  
Noradrenaline Turnover ◽  
Time Element ◽  
Increased Sensitivity

ABSTRACT Long-term ovariectomized rats received a single injection of 20 μg oestradiol benzoate (OB) which reduced the serum levels of LH for at least 3 days. The inhibitory effects were accompanied by time-dependent alterations of noradrenaline and dopamine turnover rates in the mediobasal hypothalamus (MBH) and the preoptic-anterior hypothalamic brain area (POAH). Oestradiol markedly interfered with the time-dependent variations of noradrenaline and dopamine turnover seen in the MBH of untreated ovariectomized animals during daylight hours. In the POAH the turnover rate of noradrenaline decreased 2 days after priming with OB and then increased in the afternoon of day 3. The increase of noradrenaline turnover in the POAH was accompanied by a low afternoon turnover rate of dopamine in the M BH and by an increased sensitivity of the LH secretory system to progesterone. Dopamine and noradrenaline turnover involve a time element. While the negative feedback actions of oestradiol do not seem to be associated with changes in dopamine or noradrenaline turnover, the results support the view that the induction of LH afternoon surges depends upon an increase of stimulatory noradrenergic inputs to the POAH and a decrease of inhibitory dopaminergic inputs in the MBH. J. Endocr. (1985) 106, 303–309

Effects of oestradiol benzoate and progesterone on luteinizing hormone release and catecholamine turnover in the preoptic-hypothalamic brain area of ovariectomized rats

1983 ◽  
Vol 97 (3) ◽  
pp. 437-445 ◽  
Author(s):  
C. Hiemke ◽  
D. Frohne ◽  
D. Bruder ◽  
R. Ghraf
Keyword(s):  
Brain Area ◽  
Serum Levels ◽  
Ovariectomized Rats ◽  
Time Interval ◽  
Dopamine Turnover ◽  
Noradrenaline Turnover ◽  
Serum Lh ◽  
Short Term Exposure ◽  
Oestradiol Benzoate

At noon, long-term (4–6 weeks) ovariectomized rats were exposed for 6–78 h to a single subcutaneous injection of oestradiol benzoate (20 μg) which significantly reduced the serum levels of LH over the whole time-interval investigated. The negative feedback action of oestradiol was accompanied by reduced turnover of both noradrenaline and dopamine in the preoptic-anterior hypothalamic brain area (POAH), but not in the mediobasal hypothalamus, 6, 68 and 72 h after administration of the hormone. Between 72 and 78 h after oestradiol-priming an afternoon increase of noradrenaline turnover was observed in the POAH. In rats primed with oestradiol benzoate for 72 h, short-term exposure (6 h) to progesterone (2·5 mg) induced a marked surge of serum LH and FSH in the late afternoon. In the POAH of these rats progesterone did not interfere with the afternoon increase of noradrenaline turnover induced by oestradiol-priming. However, it markedly increased the dopamine turnover rate of primed rats, thus reversing the inhibitory action of oestradiol benzoate on the dopaminergic system of the POAH. It is concluded that both the noradrenergic and the dopaminergic neurones of the POAH are involved in the negative and positive feedback actions of oestradiol and progesterone on LH and FSH release. The paper discusses whether the oestradiol-induced afternoon increase in noradrenaline turnover represents a prerequisite for the induction of LH surges by progesterone.

Antioestrogen inhibition of oestradiol-induced alterations in hypothalamic noradrenaline turnover

1985 ◽  
Vol 106 (1) ◽  
pp. 37-42 ◽  
Author(s):  
C. Hiemke ◽  
B. Poetz ◽  
R. Ghraf
Keyword(s):  
Brain Area ◽  
Serum Levels ◽  
Ovariectomized Rats ◽  
Noradrenaline Turnover ◽  
Stimulatory Action ◽  
Enhanced Sensitivity ◽  
Oestradiol Benzoate ◽  
Lh Release ◽  
Secretory System

ABSTRACT Long-term (4–6 weeks) ovariectomized rats were injected with either oestradiol benzoate (OB; 20 μg s.c.) or monohydroxytamoxifen (MTAM; 0·2 mg i.p.) plus OB. Oestradiol benzoate was administered at 12.00 h on day 0 and MTAM was given immediately before OB, followed by further injections twice daily to maintain sufficiently high antioestrogen levels. When given alone, OB reduced the serum levels of LH during the morning (08.00–09.00 h) and afternoon (17.30–18.30 h) hours of day 3 after priming. The feedback actions of OB on LH release were accompanied by time-dependent alterations of noradrenaline turnover in the preoptic–anterior hypothalamic brain area (POAH). On day 3 after priming the noradrenaline turnover rate was reduced in the morning and increased in the afternoon. The increase correlated with an enhanced sensitivity of the LH secretory system to progesterone. The antioestrogen MTAM blocked the OB-induced sensitization of LH release to the stimulatory action of progesterone and interfered with the stimulatory long-term effect of oestradiol on hypothalamic noradrenaline turnover. The data strongly support the view that the oestrogen-induced afternoon increase of noradrenaline turnover in the POAH represents a pre-requisite for the induction of LH surges. The stimulatory effect of oestradiol on hypothalamic noradrenaline turnover seems to be mediated by a classical oestrogen receptor mechanism. J. Endocr. (1985) 106, 37–42

AN EVALUATION OF THE RELATIONSHIPS BETWEEN DIETARY PARAMETERS AND RUMEN LIQUID TURNOVER RATE

1981 ◽  
Vol 61 (1) ◽  
pp. 91-96 ◽  
Author(s):  
ESSI EVANS
Keyword(s):  
Feed Intake ◽  
Turnover Rate ◽  
Energy Content ◽  
Energy Concentration ◽  
Dietary Energy ◽  
Regression Analyses ◽  
Turnover Rates ◽  
Independent Variables ◽  
Independent Variable ◽  
Ration Composition

Data were accumulated from published sources and were combined in order to estimate the effects of level of feed intake, dietary energy concentration, energy intake level and dietary forage percentage on rumen liquid turnover rates in sheep and cattle. The effects of the dietary parameters on liquid turnover rates were estimated by regression analysis, where all possible combinations of independent variables were considered. It was found that rumen liquid turnover rates increased (P < 0.05) as feed intake increased with both sheep (r = 0.610) and cattle (r = 0.715). From multiple regression analyses it was learned that the inclusion of independent variables that were related to the physical composition of the diet along with variables for intake improved the estimation of liquid turnover rates, although the independent variable related to ration composition differed between sheep and cattle. With data from sheep experiments, elevations in the digestible energy content of the diet depressed (P < 0.05) liquid turnover rate. Based upon data from cattle, decreases in the forage portion of the diet had a similar depressing (P < 0.05) effect.

Reasons for Women to Leave the IT Workforce

2011 ◽  
pp. 1068-1074 ◽  
Author(s):  
Peter Hoonakker ◽  
Pascale Carayon ◽  
Jen Schoepke
Keyword(s):  
Gender Differences ◽  
Labor Force ◽  
Turnover Rate ◽  
Meta Analysis ◽  
Turnover Rates ◽  
It Workforce ◽  
Individual Variables ◽  
The 1960S ◽  
It Personnel ◽  
Annual Turnover

Turnover has been a major issue among information technology (IT) personnel since the very early days of computing as well as nowadays (Moore, 2000; Niederman & Summer, 2003). IT personnel have a strong tendency to frequently switch employers. Annual turnover in the information systems (IS) field ranged between 15% and 20% during the 1960s and the early 1970s. In the late 1970s, the turnover was as high as 28% annually and around 20% in the early 1980s. By the 1990s, the turnover rate reached 25 to 33% annually (Jiang & Klein, 2002). Many large American companies had a 25 to 33% turnover rate among their IS personnel in the late 1990s (Hayes, 1998). Although women represent an increasingly important segment of the labor force, their turnover rate can exceed 2½ times the turnover rate of men (Chusmir, 1982; Cotton & Tuttle, 1986; Davis & Kuhn, 2003; Giacobbe Miller & Wheeler, 1992; Schwarz, 1989). A meta-analysis by Cotton & Tuttle (1986) of 120 datasets showed strong evidence for gender differences in turnover: women are more likely to leave their job than men. Gender differences in turnover are less consistent among nonmanagerial and nonprofessional employees, and are stronger among professional (Cotton & Tuttle, 1986). However, recent evidence suggests that educated women start resembling men with regard to turnover rate and pattern (Griffeth, Hom, & Gaertner, 2000; Royalty, 1998). Educated women are more likely to leave to take on another job, while less educated women are more likely to abandon the labor force (Royalty, 1998). Furthermore, part of the higher turnover rates for women can be explained by individual variables that turnover studies conducted by economists and focused on industry do not consider, such as age, tenure, marital status, occupation and salary (Giacobbe Miller & Wheeler, 1992). In this chapter, we look at gender differences in reasons why IT personnel want to leave their job, and in their intentions once they have left their job.

The effects of soy on scopolamine-induced spatial learning and memory impairments are comparable to the effects of estradiol

2019 ◽  
Vol 39 (3) ◽  
Author(s):  
Narges Marefati ◽  
Amin Mokhtari-Zaer ◽  
Farimah Beheshti ◽  
Sareh Karimi ◽  
Zahra Mahdian ◽  
...  
Keyword(s):  
Learning And Memory ◽  
Spatial Learning ◽  
Serum Levels ◽  
Ovariectomized Rats ◽  
Control Group ◽  
Spatial Learning And Memory ◽  
Protective Effects ◽  
Memory Impairments ◽  
The Central Nervous System ◽  
Higher Doses

Abstract Background Modulatory effects of soy extract and estradiol on the central nervous system (CNS) have been reported. The effect of soy on scopolamine-induced spatial learning and memory in comparison to the effect of estradiol was investigated. Materials and methods Ovariectomized rats were divided into the following groups: (1) control, (2) scopolamine (Sco), (3) scopolamine-soy 20 (Sco-S 20), (4) scopolamine-soy 60 (Sco-S 60), (5) scopolamine-estradiol 20 (Sco-E 20) and (6) scopolamine-estradiol 60 (Sco-E 60). Soy extract, estradiol and vehicle were administered daily for 6 weeks before training in the Morris water maze (MWM) test. Scopolamine (2 mg/kg) was injected 30 min before training in the MWM test. Results In the MWM, the escape latency and traveled path to find the platform in the Sco group was prolonged compared to the control group (p < 0.001). Treatment by higher doses of soy improved performances of the rats in the MWM (p < 0.05 – p < 0.001). However, treatment with both doses of estradiol (20 and 60 μg/kg) resulted in a statistically significant improvement in the MWM (p < 0.01 – p < 0.001). Cortical, hippocampal and serum levels of malondialdehyde (MDA), as an index of lipid peroxidation, were increased which was prevented by soy extract and estradiol (p < 0.001). Cortical, hippocampal as well as serum levels of the total thiol, superoxide dismutase (SOD) and catalase (CAT) in Sco group were lower than the control group (p < 0.001) while they were enhanced when the animals were treated by soy extract and estradiol (p < 0.01 – p < 0.001). Conclusions It was observed that both soy extract and estradiol prevented learning and memory impairments induced by scopolamine in ovariectomized rats. These effects can be attributed to their protective effects on oxidative damage of the brain tissue.

Acetoacetate turnover and oxidation rates in ovine pregnancy ketosis

1964 ◽  
Vol 206 (2) ◽  
pp. 449-452 ◽  
Author(s):  
E. N. Bergman ◽  
K. Kon
Keyword(s):  
Turnover Rate ◽  
Ketone Bodies ◽  
Plasma Concentrations ◽  
Turnover Rates ◽  
Acetoacetic Acid ◽  
Oxidation Rates ◽  
Tracer Dose ◽  
Pregnant Sheep ◽  
The Mean ◽  
Normal Twin

Labeled acetoacetic acid (AcAc) was administered as a tracer dose and as a continuous infusion to 24 twin-pregnant ewes with varying degrees of spontaneous or fasting hypoglycemic ketosis. The mean AcAc turnover rate of five normal twin-pregnant sheep (plasma AcAc < 1 mg/100 ml) was only 0.04 g/hr kg3/4 or 1.0 g/sheep hr. During ketosis the turnover rate of AcAc was directly proportional to the plasma AcAc concentration until a maximal concentration of about 10 mg/100 ml was attained (total ketone bodies, expressed as acetone, would be about 20 mg/100 ml). At higher plasma concentrations, the AcAc turnover rates remained constant at nearly 0.4 g/hr kg3/4 (9 g/sheep hr). About one-half of this AcAc was oxidized to CO2 regardless of the actual amount utilized. The mean percentage of the total exhaled CO2 derived from AcAc metabolism increased from 2% in normal ewes to a maximum of about 20% during pregnancy ketosis. Comparisons of these data to values obtained in previous experiments on artificially ketotic nonpregnant sheep indicate that an overproduction of ketone bodies, rather than an underutilization, is the major cause of ruminant ketosis.

scholarly journals Time-Dependent Changes in Local and Serum Levels of Inflammatory Cytokines as Markers for Incised Wound Aging of Skeletal Muscles

2018 ◽  
Vol 245 (1) ◽  
pp. 29-35 ◽  
Author(s):  
Mohammed Hassan Gaballah ◽  
Tetsuya Horita ◽  
Masataka Takamiya ◽  
Keisuke Yokoji ◽  
Mamiko Fukuta ◽  
...  
Keyword(s):  
Inflammatory Cytokines ◽  
Skeletal Muscles ◽  
Serum Levels ◽  
Time Dependent ◽  
Incised Wound

Lactate and pyruvate isotopic enrichments in plasma and tissues of postabsorptive and starved rats

1995 ◽  
Vol 268 (5) ◽  
pp. E880-E888 ◽  
Author(s):  
V. Large ◽  
M. Soloviev ◽  
H. Brunengraber ◽  
M. Beylot
Keyword(s):  
Turnover Rate ◽  
Surprising Result ◽  
Plasma Lactate ◽  
Turnover Rates ◽  
Isotopic Enrichment ◽  
Isotopic Equilibrium ◽  
Anesthetized Rats ◽  
Lactate Turnover ◽  
Lactate And Pyruvate

It has been proposed that plasma pyruvate isotopic enrichment (IE) during infusion of labeled lactate could be used to estimate the intracellular IE of lactate and pyruvate and thus to calculate their turnover rate. We determined the relations of plasma and tissue IE of lactate and pyruvate in anesthetized rats infused with [3-13C]lactate in an artery and sampled from a vein (A-V mode) or infused in a vein and sampled from an artery (V-A mode). In both groups of rats, the ratio of tissue to plasma lactate IE was < 1 with large differences between tissues: the highest ratio was observed in heart and the lowest in soleus. With the exception of liver, this ratio was higher in the A-V than in the V-A mode. Pyruvate IE was lower than lactate IE in tissues, with a few exceptions, and in plasma. This ratio of pyruvate to lactate IE was approximately 0.70 in plasma in A-V and V-A modes. Moreover pyruvate IE was also always higher in plasma than in tissues. This seemingly surprising result could be explained by the production of labeled pyruvate from labeled lactate inside the circulation by erythrocytes, because we observed a rapid isotopic equilibrium between lactate and pyruvate in blood "in vitro." Apparent lactate turnover was higher in the A-V than in the V-A mode when it was calculated using lactate as well as pyruvate IE. Therefore plasma pyruvate IE cannot be used in rats to estimate tissue IE and did not reconcile turnover rates measured using the A-V or V-A mode.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals A Study of Fibrinogen Turnover in Classical Hemophilia and Congenital Afibrinogenemia

Blood ◽  
1961 ◽  
Vol 18 (6) ◽  
pp. 710-716 ◽  
Author(s):  
AARON R. RAUSEN ◽  
ANDRE CRUCHAUD ◽  
CAMPBELL W. McMILLAN ◽  
DAVID GITLIN
Keyword(s):  
Half Life ◽  
Turnover Rate ◽  
Turnover Rates ◽  
Congenital Afibrinogenemia ◽  
Normal Adults

Abstract The rate of disappearance from the plasma of intravenously administered I131-labeled fibrinogen was studied in six patients with classical hemophilia and in one patient with congenital afibrinogenemia. The six patients with hemophilia had radioiodinated fibrinogen half-lives ranging from 2.8 to 3.6 days, while the patient with congenital afibrinogenemia had a labeled fibrinogen half-life of 3.0 days. These results compare favorably with fibrinogen turnover rates measured in normal adults by others and were similar to the normal fibrinogen turnover rate determined in the patient with congenital afibrinogenemia in a previous study. This failure to demonstrate a prolongation of survival of fibrinogen in patients with hemophilia suggests that in vivo clotting, if it occurs at all normally, is not a major factor in the turnover of fibrinogen.

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