Cellular mechanisms mediating the stimulation of ovine endometrial secretion of prostaglandin F2α in response to oxytocin: role of phospholipase C and diacylglycerol

1994 ◽  
Vol 141 (3) ◽  
pp. 481-490 ◽  
Author(s):  
W J Silvia ◽  
J-S Lee ◽  
D S Trammell ◽  
S H Hayes ◽  
L L Lowberger ◽  
...  
Keyword(s):  
Time Course ◽  
Prostaglandin F2α ◽  
Endometrial Tissue ◽  
Indole Derivatives ◽  
Cellular Mechanisms ◽  
Response Curves ◽  
The Relationship ◽  
Stimulation Of

Abstract The first objective was to describe and evaluate the relationship between the ability of oxytocin to stimulate the activity of phospholipase (PL) C and its ability to stimulate the release of prostaglandin (PG) F2α in ovine endometrial tissue. Caruncular endometrial tissue was collected from ovariectomized ewes after completion of an 11-day steroid replacement protocol. In experiment 1, explants were incubated either in the presence (10−6 m) or absence of oxytocin for 0, 1, 3, 10, 30 or 100 min to examine the time-course for activation of PLC and release of PGF2α in response to oxytocin. An increase in the activity of PLC was detected at 3 min while an increase in the release of PGF2α was not detected until 10 min (P<0·05). In experiment 2, explants were incubated in the presence of various oxytocin analogues (10−6 m) to compare their abilities to activate PLC and release PGF2α. Oxytocin and three receptor angonists stimulated the activity of PLC and the release of PGF2α (P<0·05) while two oxytocin receptor antagonists had no effect on either response. In experiment 3, explants were incubated in the presence of oxytocin or arginine vasopressin at 10−9 to 10−6 m to establish dose–response curves for the activation of PLC and release of PGF2α. For both hormones, significant increases (P<0·05) in the release of PGF2α were observed at 10−8 m while increases in PLC activity were not detected until 10−7 m was used. In experiment 4, explants were pretreated with either U-73122 (an inhibitor of PLC activity) or U-73343 (an inactive analogue of U-73122). Explants were then treated with control medium, oxytocin or AlF4−. Both oxytocin and AlF4− stimulated the activity of PLC and the release of PGF2α (P<0·05). U-73122 blocked the ability of oxytocin to stimulate the release of PGF2α (P<0·05) but had no effect on its ability to stimulate the activity of PLC (P>0·1). Based on the results from these experiments, the role of PLC in mediating the stimulatory effect of oxytocin on the release of PGF2α remains unclear. The second objective was to evaluate the role of diacylglycerol (DAG) in mediating the stimulatory effect of oxytocin on endometrial secretion of PGF2α. In experiment 5, explants were incubated in vitro with varying doses of two DAG analogues. Both analogues stimulated the release of PGF2α at 10−6 m (P<0·05), the highest dose tested. Corresponding inactive control compounds had no stimulatory effect. In experiment 6, explants were incubated with two synthetic DAGs and two indole-derived analogues of DAG. The indole derivatives stimulated the release of PGF2α. The synthetic DAGs were less effective in stimulating the release of PGF2α at the doses tested. In experiment 7, explants were preincubated with R59022 or LiCl. R59022 enhanced both the basal and oxytocin-stimulated released of PGF2α (P=0·07). LiCl promoted an increase in the accumulation of inositol trisphosphate (P<0·05) but had no effect on the release of PGF2α (P>0·5). These data indicate that DAG stimulates release of PGF2α from ovine endometrial tissue and may mediate the stimulatory effect of oxytocin on release of PGF2α. Journal of Endocrinology (1994) 141, 481–490

Cellular mechanisms mediating the stimulation of ovine endometrial secretion of prostaglandin F2α in response to oxytocin: role of phospholipase A2

1994 ◽  
Vol 141 (3) ◽  
pp. 491-496 ◽  
Author(s):  
J-S Lee ◽  
W J Silvia
Keyword(s):  
Aristolochic Acid ◽  
Prostaglandin F2α ◽  
Inhibitory Effect ◽  
Endometrial Tissue ◽  
Cellular Mechanisms ◽  
Stimulate Activity ◽  
Basal Release ◽  
Stimulation Of

Abstract Four experiments were conducted to determine whether phospholipase (PL) A2 mediates the stimulatory effect of oxytocin on the release of prostaglandin (PG) F2α from ovine endometrial tissue. Caruncular endometrial tissue was collected from ovariectomized ewes on the day after a steroid replacement protocol had been completed. The replacement protocol consisted of progesterone for 10 days (12 mg/day) followed by oestradiol on days 10 and 11 (100 μg/day) and had been shown previously to provide endometrial tissue that would release PGF2α in response to oxytocin in vitro. In experiment 1, oxytocin (10−7 m) and melittin (1·76 × 10−6 m; a stimulator of PLA2) stimulated release of PGF2α from tissue explants (P<0·05). Aristolochic acid (10−4 m; an inhibitor of PLA2) decreased oxytocin-and melittin-induced release of PGF2α by 77% and 71% respectively (P<0·05). Experiment 2 was conducted to establish the minimum inhibitory dose of aristolochic acid. Basal release of PGF2α was inhibited at 10−5 m aristolochic acid, but 10−4 m was required to block the stimulatory effect of oxytocin. Experiment 3 was carried out to identify the precise intracellular locus at which aristolochic acid was exerting its effect. Oxytocin (10−7 m), AlF4− (5 × 10−2m NaF, 10−5m AlCl3), melittin (1·76 × 10−6 m) and arachidonic acid (AA; 20 μg/ml) stimulated release of PGF2α (P<0·05). Aristolochic acid (10−4 m) blocked the release of PGF2α stimulated by oxytocin, AlF4− or melittin by >80% (P<0·05). However, aristolochic acid reduced AA-induced release by only 22% (P=0·09). Thus, aristolochic acid blocked responsiveness to stimulatory agents that act on, or proximal to, PLA2 but not responsiveness to AA whose stimulatory effect is exerted distal to PLA2. Experiment 4 was intended to establish the specificity of the inhibitory effect of aristolochic acid. This was accomplished by examining the effect of aristolochic acid on the ability of oxytocin to stimulate activity of PLC. Aristolochic acid (10−4 m) increased basal PLC activity by 29% (P<0·05) but had no effect on the activity induced by oxytocin (P>0·1). Thus, aristolochic acid blocked the ability of oxytocin to stimulate PGF2α release (experiments 1–3) but not its ability to stimulate the activity of PLC (experiment 4). The effects of melittin and aristolochic acid are consistent with the hypothesis that the stimulatory effect of oxytocin on PGF2α release from ovine endometrial tissue is mediated through PLA2. Journal of Endocrinology (1994) 141, 491–496

Epithelial vs. serosal stimulation of tracheal muscle: role of epithelium

1989 ◽  
Vol 67 (6) ◽  
pp. 2522-2526 ◽  
Author(s):  
D. Pavlovic ◽  
M. Fournier ◽  
M. Aubier ◽  
R. Pariente
Keyword(s):  
Time Course ◽  
Muscle Tension ◽  
Active Role ◽  
Force Transducer ◽  
Tension Development ◽  
In Vitro System ◽  
Pharmacological Stimulation ◽  
Stimulation Of

There is evidence implying an active role of airway epithelium in the modulation of bronchomotor tone. To study this phenomenon, we designed an in vitro system allowing pharmacological stimulation of either the inside or outside of the airway lumen. Rat tracheas were excised, cannulated, and their inside and outside perfused independently with Krebs solution. Two hooks were inserted through opposite sides of the tracheal wall, the lower one was attached to a fixed point, while the upper one was connected to a force transducer. Isometric contractions of the tracheal muscle were elicited by carbachol solution perfused in single and cumulative concentrations. In one-half of the preparations the epithelium was mechanically removed. Stimulation of the inside or outside of the trachea produced equal maximal tracheal muscle tension [1.55 +/- 0.14 and 1.2 +/- 0.09 (SE) g in and out, respectively]. The time course of tension development was longer when carbachol was administered inside the trachea: an effect that was abolished when the epithelium was removed. In addition, removal of the epithelium was found 1) to increase the maximal tension irrespective of the route of carbachol perfusion and 2) to increase the sensitivity of the preparation to carbachol stimulation.

scholarly journals Role of interleukins in the pathogenesis of pulmonary fibrosis

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Yi Xin She ◽  
Qing Yang Yu ◽  
Xiao Xiao Tang
Keyword(s):  
Pulmonary Fibrosis ◽  
Therapeutic Strategy ◽  
Future Directions ◽  
Regulation Mechanisms ◽  
Underlying Mechanisms ◽  
Multiple Cells ◽  
The Relationship

AbstractInterleukins, a group of cytokines participating in inflammation and immune response, are proved to be involved in the formation and development of pulmonary fibrosis. In this article, we reviewed the relationship between interleukins and pulmonary fibrosis from the clinical, animal, as well as cellular levels, and discussed the underlying mechanisms in vivo and in vitro. Despite the effects of interleukin-targeted treatment on experimental pulmonary fibrosis, clinical applications are lacking and unsatisfactory. We conclude that intervening in one type of interleukins with similar functions in IPF may not be enough to stop the development of fibrosis as it involves a complex network of regulation mechanisms. Intervening interleukins combined with other existing therapy or targeting interleukins affecting multiple cells/with different functions at the same time may be one of the future directions. Furthermore, the intervention time is critical as some interleukins play different roles at different stages. Further elucidation on these aspects would provide new perspectives on both the pathogenesis mechanism, as well as the therapeutic strategy and drug development.

scholarly journals Amphetamine-Decreased Progesterone and Estradiol Release in Rat Granulosa Cells: The Regulatory Role of cAMP- and Ca2+-Mediated Signaling Pathways

Biomedicines ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 493
Author(s):  
 Chung-Yu Chen ◽  
Chien-Rung Chen ◽  
Chiao-Nan Chen ◽  
Paulus S. Wang ◽  
Toby Mündel ◽  
...  
Keyword(s):  
Granulosa Cells ◽  
Prostaglandin F2α ◽  
Inhibitory Effect ◽  
Inhibitory Effects ◽  
Steroidogenic Enzyme ◽  
Estradiol Secretion ◽  
Basal Release ◽  
Ca2 Channels

The purpose of this study is to evaluate the amphetamine effects on progesterone and estradiol production in rat granulosa cells and the underlying cellular regulatory mechanisms. Freshly dispersed rat granulosa cells were cultured with various test drugs in the presence of amphetamine, and the estradiol/progesterone production and the cytosolic cAMP level were measured. Additionally, the cytosolic-free Ca2+ concentrations ([Ca2+]i) were measured to examine the role of Ca2+ influx in the presence of amphetamine. Amphetamine in vitro inhibited both basal and porcine follicle-stimulating hormone-stimulated estradiol/progesterone release, and amphetamine significantly decreased steroidogenic enzyme activities. Adding 8-Bromo-cAMP did not recover the inhibitory effects of amphetamine on progesterone and estradiol release. H89 significantly decreased progesterone and estradiol basal release but failed to enhance a further amphetamine inhibitory effect. Amphetamine was capable of further suppressing the release of estradiol release under the presence of nifedipine. Pretreatment with the amphetamine for 2 h decreased the basal [Ca2+]i and prostaglandin F2α-stimulated increase of [Ca2+]i. Amphetamine inhibits progesterone and estradiol secretion in rat granulosa cells through a mechanism involving decreased PKA-downstream steroidogenic enzyme activity and L-type Ca2+ channels. Our current findings show that it is necessary to study the possibility of amphetamine perturbing reproduction in females.

scholarly journals The Role of Interleukin-23 in the Early Development of Emphysema in HIV1+Smokers

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Igor Z. Barjaktarevic ◽  
Ronald G. Crystal ◽  
Robert J. Kaner
Keyword(s):  
Tissue Destruction ◽  
Epithelial Lining Fluid ◽  
Protein Levels ◽  
Knowing That ◽  
Lung Epithelial ◽  
Interleukin 23 ◽  
Metalloproteinase 9 ◽  
Stimulation Of

Rationale.Matrix metalloproteinase-9 (MMP-9) expression is upregulated in alveolar macrophages (AM) of HIV1+smokers who develop emphysema. Knowing that lung epithelial lining fluid (ELF) of HIV1+smokers contains increased levels of inflammatory cytokines compared to HIV1−smokers, we hypothesized that upregulation of lung cytokines in HIV1+smokers may be functionally related to increased MMP-9 expression.Methods.Cytokine arrays evaluated cytokine protein levels in ELF obtained from 5 groups of individuals: HIV1−healthy nonsmokers, HIV1−healthy smokers, HIV1−smokers with low diffusing capacity (DLCO), HIV1+nonsmokers, and HIV1+smokers with lowDLCO.Results. Increased levels of the Th17 related cytokine IL-23 were found in HIV1−smokers with lowDLCOand HIV1+smokers and nonsmokers. Relative IL-23 gene expression was increased in AM of HIV1+individuals, with greater expression in AM of HIV1+smokers with lowDLCO. Infection with HIV1in vitroinduced IL-23 expression in normal AM. IL-23 stimulation of AM/lymphocyte coculturesin vitroinduced upregulation of MMP-9. Lung T lymphocytes express receptor IL-23R and interact with AM in order to upregulate MMP-9.Conclusion. This mechanism may contribute to the increased tissue destruction in the lungs of HIV1+smokers and suggests that Th17 related inflammation may play a role.

scholarly journals Enhanced phosphorylation of Na+–Cl− co-transporter in experimental metabolic syndrome: role of insulin

2012 ◽  
Vol 123 (11) ◽  
pp. 635-647 ◽  
Author(s):  
Radko Komers ◽  
Shaunessy Rogers ◽  
Terry T. Oyama ◽  
Bei Xu ◽  
Chao-Ling Yang ◽  
...  
Keyword(s):  
Metabolic Syndrome ◽  
Time Course ◽  
Kinase Inhibitor ◽  
Endogenous Expression ◽  
The Metabolic Syndrome ◽  
Mammalian Cell Lines ◽  
Phosphoinositide 3 Kinase

In the present study, we investigated the activity of the thiazide-sensitive NCC (Na+–Cl− co-transporter) in experimental metabolic syndrome and the role of insulin in NCC activation. Renal responses to the NCC inhibitor HCTZ (hydrochlorothiazide), as a measure of NCC activity in vivo, were studied in 12-week-old ZO (Zucker obese) rats, a model of the metabolic syndrome, and in ZL (Zucker lean) control animals, together with renal NCC expression and molecular markers of NCC activity, such as localization and phosphorylation. Effects of insulin were studied further in mammalian cell lines with inducible and endogenous expression of this molecule. ZO rats displayed marked hyperinsulinaemia, but no differences in plasma aldosterone, compared with ZL rats. In ZO rats, natriuretic and diuretic responses to NCC inhibition with HCTZ were enhanced compared with ZL rats, and were associated with a decrease in BP (blood pressure). ZO rats displayed enhanced Thr53 NCC phosphorylation and predominant membrane localization of both total and phosphorylated NCC, together with a different profile in expression of SPAK (Ste20-related proline/alanine-rich kinase) isoforms, and lower expression of WNK4. In vitro, insulin induced NCC phosphorylation, which was blocked by a PI3K (phosphoinositide 3-kinase) inhibitor. Insulin-induced reduction in WNK4 expression was also observed, but delayed compared with the time course of NCC phosphorylation. In summary, we report increased NCC activity in hyperinsulinaemic rodents in conjunction with the SPAK expression profile consistent with NCC activation and reduced WNK4, as well as an ability of insulin to induce NCC stimulatory phosphorylation in vitro. Together, these findings indicate that hyperinsulinaemia is an important driving force of NCC activity in the metabolic syndrome with possible consequences for BP regulation.

scholarly journals cAMP induces a rapid and reversible modification of the chemotactic receptor in Dictyostelium discoideum.

1985 ◽  
Vol 100 (3) ◽  
pp. 715-720 ◽  
Author(s):  
C Klein ◽  
J Lubs-Haukeness ◽  
S Simons
Keyword(s):  
Dictyostelium Discoideum ◽  
Concentration Dependence ◽  
Time Course ◽  
Camp Synthesis ◽  
Sds Page ◽  
Reversible Modification ◽  
Camp Receptor ◽  
Camp Stimulation ◽  
Stimulation Of

Stimulation, within 1 min after cAMP stimulation, of aggregation-competent Dictyostelium discoideum amebae was found to cause a rapid (within 1 min) modification of the cell's surface cAMP receptor. The modified receptor migrated on SDS PAGE as a 47,000-mol-wt protein, as opposed to a 45,000-mol-wt protein labeled on unstimulated cells. The length of time this modified receptor could be detected depended upon the strength of the cAMP stimulus: 3-4 min after treatment with 10(-7) M cAMP, cells no longer possessed the 47,000-mol-wt form of the cAMP receptor. Instead, the 45,000-mol-wt form was present. Stimulation of cells with 10(-5) M cAMP, however, resulted in the persistent (over 15 min) expression of the modified receptor. The time course, concentration dependence, and specificity of stimulus for this cAMP-induced shift in the cAMP receptor were found to parallel the cAMP-stimulated phosphorylation of a 47,000-mol-wt protein. In addition, both phenomena were shown to occur in the absence of endogenous cAMP synthesis. The possibility that the cAMP receptor is phosphorylated in response to cAMP stimulation, and the role of this event in cell desensitization, are discussed.

Protective role of epithelium in the guinea pig airway

1989 ◽  
Vol 66 (4) ◽  
pp. 1547-1552 ◽  
Author(s):  
M. Munakata ◽  
I. Huang ◽  
W. Mitzner ◽  
H. Menkes
Keyword(s):  
Guinea Pig ◽  
Protective Role ◽  
Airway Epithelial ◽  
Serosal Side ◽  
Epithelial Surface ◽  
Airway Responses ◽  
Airway Tone ◽  
Stimulation Of

We developed an in vitro system to assess the role of the epithelium in regulating airway tone using the intact guinea pig trachea (J. Appl. Physiol. 64: 466–471, 1988). This method allows us to study the response of the airway when its inner epithelial surface or its outer serosal surface is stimulated independently. Using this system we evaluated how the presence of intact epithelium can affect pharmacological responsiveness. We first examined responses of tracheae with intact epithelium to histamine, acetylcholine, and hypertonic KCl when stimulated from the epithelial or serosal side. We then examined the effect of epithelial denudation on the responses to these agonists. With an intact epithelium, stimulation of the inner epithelial side always caused significantly smaller changes in diameter than stimulation of the outer serosal side. After mechanical denudation of the epithelium, these differences were almost completely abolished. In the absence of intact epithelium, the trachea was 35-fold more sensitive to histamine and 115-fold more sensitive to acetylcholine when these agents were applied to the inner epithelial side. In addition, the presence of an intact epithelium almost completely inhibited any response to epithelial side challenge with hypertonic KCl. These results indicate that the airway epithelial layer has a potent protective role in airway responses to luminal side stimuli, leading us to speculate that changes in airway reactivity measured in various conditions including asthma may result in part from changes in epithelial function.

scholarly journals Cellular adaptations in fat tissue of exercise-trained miniature swine: role of excess energy intake

2000 ◽  
Vol 88 (3) ◽  
pp. 881-887 ◽  
Author(s):  
Gale B. Carey
Keyword(s):  
Adipose Tissue ◽  
Energy Intake ◽  
Excess Energy ◽  
Fat Tissue ◽  
Cellular Mechanisms ◽  
Miniature Swine ◽  
Extracellular Adenosine

This study examined the influence of energy expenditure and energy intake on cellular mechanisms regulating adipose tissue metabolism. 1 Twenty-four swine were assigned to restricted-fed sedentary, restricted-fed exercise-trained, full-fed sedentary, or full-fed exercise-trained groups. After 3 mo of treatment, adipocytes were isolated and adipocyte size, adenosine A1 receptor characteristics, and lipolytic sensitivity were measured. Swine were infused with epinephrine during which adipose tissue extracellular adenosine, plasma fatty acids, and plasma glycerol were measured. Results revealed that adipocytes isolated from restricted-fed exercised swine had a smaller diameter, a lower number of A1 receptors, and a greater sensitivity to lipolytic stimulation, compared with adipocytes from full-fed exercised swine. Extracellular adenosine levels were transiently increased on infusion of epinephrine in adipose tissue of restricted-fed exercised but not full-fed exercised swine. These results suggest a role for adenosine in explaining the discrepancy between in vitro and in vivo lipolysis findings and underscore the notion that excess energy intake dampens the lipolytic sensitivity of adipocytes to β-agonists and adenosine, even if accompanied by exercise training.

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