scholarly journals Kisspeptin Is Present in Ovine Hypophysial Portal Blood But Does Not Increase during the Preovulatory Luteinizing Hormone Surge: Evidence that Gonadotropes Are Not Direct Targets of Kisspeptin in Vivo

Endocrinology ◽  
2007 ◽  
Vol 149 (4) ◽  
pp. 1951-1959 ◽  
Author(s):  
J. T. Smith ◽  
A. Rao ◽  
A. Pereira ◽  
A. Caraty ◽  
R. P. Millar ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Culture Media ◽  
Pituitary Cell ◽  
Portal Blood ◽  
Lh Surge ◽  
Lh Release ◽  
Cell Fractions ◽  
Hypophysial Portal

There is strong evidence that kisspeptin acts to regulate GnRH secretion, but whether there is also a component of action on the gonadotropes is not clear. Using quantitative RT-PCR, we found that G protein-coupled receptor-54 mRNA is expressed in ovine pituitary cell fractions enriched for gonadotropes as well as in somatotropes and lactotropes. To test whether kisspeptin acts directly on the pituitary gonadotropes, we first examined LH release from primary ovine pituitary cell cultures treated with kisspeptin. We found that kisspeptin treatment increased the concentration of LH in culture media by 80%, compared with control, but only in pituitary cultures from ewes during the follicular phase of the estrous cycle. After this, we determined whether kisspeptin acts on the pituitary gland in vivo. Using GnRH-replaced ovariectomized hypothalamo-pituitary-disconnected ewes, we were not able to achieve any effect of kisspeptin on LH under steady-state conditions or during the period of an estrogen-induced LH surge. Finally, we collected hypophysial portal blood samples from ovariectomized ewes and measured kisspeptin levels. Low but detectable amounts of kisspeptin were found in portal plasma, but levels were similar in ovariectomized ewes that were untreated or given estrogen to elicit an LH surge. Thus, although we observed an effect of kisspeptin on LH release in vitro in some situations, similar findings were not obtained in vivo. Moreover, the low concentrations of kisspeptin in hypophysial portal blood and the lack of any change during the period of an estrogen-induced GnRH/LH surge suggest that action on the pituitary gland is not of major consequence in terms of LH release.

Oxytocin has a role in gonadotrophin regulation in rats

1990 ◽  
Vol 125 (3) ◽  
pp. 425-432 ◽  
Author(s):  
G. Robinson ◽  
J. J. Evans
Keyword(s):  
Follicular Development ◽  
Pituitary Cells ◽  
Lh Surge ◽  
Rat Pituitary ◽  
Lh Release ◽  
Rat Pituitary Cells ◽  
Dose Dependent ◽  
In Vivo Administration

ABSTRACT We previously demonstrated that oxytocin stimulates LH release from rat pituitary cells in vitro and advances follicular development and ovulation in mice in vivo. This study reports an investigation of rat LH levels following in-vivo administration of oxytocin. Injection of oxytocin (10 mIU/g, i.p.) to rats at 07.00, 08.00 and 09.00 h of pro-oestrus or at 09.00, 10.00 and 11.00 h of pro-oestrus advanced the onset of the LH surge (P<0.005) and attainment of peak concentrations of LH (P<0.02) in peripheral blood. On the other hand, the descending phase of the LH surge and the surge amplitude were not altered by oxytocin. Treatment at 05.00, 06.00 and 07.00 h of pro-oestrus or at 11.00, 12.00 and 13.00 h of pro-oestrus had no effect on the LH profile. A higher oxytocin dose (20 mIU/g) inhibited LH release when treatment was begun at 05.00, 07.00 or 09.00 h of pro-oestrus. A lower dose (5 mIU/g) was ineffective in altering LH concentrations. In addition, injections of oxytocin (10 mIU/g) at oestrus, metoestrus or dioestrus had no effect on the release of LH. Thus the efficacy of oxytocin in altering concentrations of LH was dose dependent and also critically affected by the day of the oestrous cycle and the time of pro-oestrus. Removal of endogenous oxytocin activity by the use of an oxytocin receptor antagonist abolished the pro-oestrous LH surge, indicating that oxytocin is a vital physiological component of the LH-releasing mechanism in rats. The study provides unequivocal evidence that oxytocin induces LH release in vivo, but the manifestation of oxytocin activity is dependent upon conditions of exposure. Journal of Endocrinology (1990) 125, 425–432

In-vivo inhibition of the preovulatory LH surge by substance P and in-vitro modulation of gonadotrophin-releasing hormone-induced LH release by substance P, oestradiol and progesterone in the female rat

1991 ◽  
Vol 130 (2) ◽  
pp. 169-175 ◽  
Author(s):  
T. Battmann ◽  
S. Mélik Parsadaniantz ◽  
B. Jeanjean ◽  
B. Kerdelhué
Keyword(s):  
Substance P ◽  
Inhibitory Effect ◽  
Female Rat ◽  
Neuroendocrine Control ◽  
Lh Surge ◽  
Releasing Hormone ◽  
Lh Release ◽  
Gonadotrophin Releasing Hormone

ABSTRACT The effects of substance P (SP) on the preovulatory surge of LH and on the inhibitory and stimulatory effects of oestradiol-17β and progesterone on gonadotrophin-releasing hormone (GnRH)-induced LH release were investigated in vivo and in vitro in the rat. A single s.c. injection of 100 μg SP at 12.00 h on the day of pro-oestrus significantly decreased the preovulatory surge of LH. In vitro, the inhibitory effect of oestradiol-17β on GnRH-induced LH release was not modified by treatment with SP. The stimulatory effect of progesterone on GnRH-induced LH release was reduced by treatment with SP. It is concluded that SP may play a modulatory role in the neuroendocrine control of the preovulatory LH surge. Journal of Endocrinology (1991) 130, 169–175

EFFECTS OF OESTRADIOL, HYPOTHALAMIC EXTRACTS AND LUTEINIZING HORMONE RELEASING HORMONE ON RAT ANTERIOR PITUITARY GLAND GONADOTROPHIN RELEASE IN VITRO BEFORE AND AFTER THE PREOVULATORY LUTEINIZING HORMONE SURGE AT PRO-OESTRUS

1981 ◽  
Vol 90 (3) ◽  
pp. 345-354 ◽  
Author(s):  
KATHLEEN A. ELIAS ◽  
C. A. BLAKE
Keyword(s):  
Luteinizing Hormone ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Anterior Pituitary Gland ◽  
Lh Surge ◽  
Releasing Hormone ◽  
Lh Rh ◽  
Lh Releasing Hormone

Changes at the anterior pituitary and/or hypothalamic levels which result in selective FSH release during late pro-oestrus in the cyclic rat were investigated. The possible involvement of decreasing serum concentrations of oestrogen during pro-oestrus in such changes was studied. Rats were decapitated at 12.00 h on pro-oestrus, before the onset of the LH surge and first phase of FSH release, or at 24.00 h on pro-oestrus, shortly after the onset of the second or selective phase of FSH release. Other rats were given oestrogen (OE2) at 14.00 h and killed at 24.00 h pro-oestrus. Paired hemi-anterior pituitary glands were incubated with vehicle or OE2 with or without synthetic LH-releasing hormone (LH-RH) or hypothalamic acid extracts prepared from rats killed at 12.00 or 24.00 h on pro-oestrus. At 24.00 h pro-oestrus, serum FSH concentration was high while serum LH concentration was low regardless of whether rats were given OE2. Glands collected and incubated at 24.00 h released more FSH and less LH than did glands collected and incubated at 12.00 h pro-oestrus. Administration of OE2 in vivo and/or in vitro did not affect these responses. The increments in LH and FSH release attributed to LH-RH or hypothalamic extracts in the glands incubated at 24.00 h were not different from those of the glands incubated at 12.00 h. Also, the hypothalamic extracts prepared from rats killed at 24.00 h were no more effective than the extracts prepared from rats killed at 12.00 h in releasing LH or FSH from glands incubated at 12.00 or 24.00 h pro-oestrus. Administration of OE2 in vivo caused a small suppression of LH-RH-induced FSH release. We suggest that a change occurs at the level of the anterior pituitary gland during the period of the LH surge and first phase of FSH release to increase basal FSH secretion selectively and cause, at least in part, the second phase of increased serum FSH. This change is not mediated by a decrease in serum oestrogen concentration. We failed to observe any evidence that LH-RH causes preferential FSH release during late pro-oestrus or that a hypothalamic peptide with a preferential FSH releasing ability is involved in FSH release at this time.

Suppression by LRH of the stimulatory effect of oestradiol on the secretion of LH by the rat pituitary gland

1987 ◽  
Vol 114 (4) ◽  
pp. 488-496
Author(s):  
G. A. Schuiling ◽  
H. Moes ◽  
J. de Koning ◽  
T. R. Koiter
Keyword(s):  
Luteinizing Hormone ◽  
Pituitary Gland ◽  
Secretion Rate ◽  
Ovariectomized Rats ◽  
Release Mechanisms ◽  
Lh Release ◽  
Lh Secretion ◽  
Positive Effect

Abstract. Ovariectomized rats were infused with varying doses of luteinizing hormone-releasing-hormone (LRH). Some of the rats were also treated with oestradiol benzoate (EB). The effects of these pre-treatments on the in vitro release of luteinizing hormone (LH) were studied. The following parameters of in vitro LH release were measured: a) the autonomous secretion rate; b) the secretion rate following maximum stimulation with LRH, and c) the total quantity of LH released during the 6-hour experiment. The in vivo pre-treatments with LRH and EB dose-dependently decreased the pituitary LH content as well as all three of the above parameters of in vitro LH secretion. There was a linear relationship between the pituitary LH content and the three parameters of in vitro LH release. These parameters were therefore expressed as percentage of the pituitary LH content to give the relative LH secretion rates. The three parameters were thereby corrected for LRH/EB-induced changes in the pituitary LH content. In this way we obtained information on the effects of LRH and EB on the state of the LH release mechanisms of the gonadotropes. EB potentiated the LRH-induced depletion of the pituitary LH stores at all in vivo LRH infusion rates. The effect of EB on the quantity of LH released during perifusion in vitro, however, varied with the previous LRH infusion rates. After LRH infusion rates lower than about 120 ng/h (which establishes plasma concentrations of about 70 ng/l) EB enhanced the stimulated quantity of LH released. After higher rates of LRH infusion, EB lowered the amount of LH released. The effect of EB on the relative secretion of LH in vitro, i.e. on the LH release mechanisms, however, was positive irrespective of the prior in vivo LRH infusion rates, although the effect of EB was greater at the lower rates of LRH infusion. The effect of EB on the autonomous, in vitro, LH secretion rate was positive irrespective of the prior in vivo LRH infusion rates. The positive effect of EB on the mechanism underlying this component of LH secretion was LRH-independent. The effect of EB on the mechanism underlying the LRH-stimulated component of LH release appeared to be strongly LRH-dependent. The effect of EB was maximal if the LRH infusion rate had been lower than about 50 ng/h. With higher infusion rates it became increasingly smaller and was zero at the rate of about 180 ng/h or more. The LRH infusion rates of 50 and 180 ng/h establish plasma LRH concentrations of about 30 and 90 ng/l. Thus, the positive effect of EB on the LRH-stimulated component of LH secretion can be regulated by LRH at the plasma concentration interval of 30–90 ng/l. This study demonstrates that the 'overall' effect of EB on the LH secretion rate is determined by the 'balance' between the effect of EB on the pituitary LH content (the potentiation of the LRH-induced depletion of the LH stores) and the effect of EB on the LH release mechanisms (which effect, in the case of the LRH-stimulated component of LH secretion, can be suppressed by LRH). If the former effect dominates, the effect of EB on the secretion of LH is negative, if the latter dominates, the effect of EB is positive. The LRH concentration at which the positive effect turns into the negative effect is about 70 ng/l. We suggest that the ability of LRH and EB to influence each others' effect on the pituitary gland at physiological concentrations of the two hormones, plays a role in the regulation of the secretion of LH.

scholarly journals Influence of Light Conditions and Medium Composition on Morphophysiological Characteristics of Stevia rebaudiana Bertoni In Vitro and In Vivo

Horticulturae ◽  
2021 ◽  
Vol 7 (7) ◽  
pp. 195
Author(s):  
Alla A. Shulgina ◽  
Elena A. Kalashnikova ◽  
Ivan G. Tarakanov ◽  
Rima N. Kirakosyan ◽  
Mikhail Yu. Cherednichenko ◽  
...  
Keyword(s):  
Culture Media ◽  
Stevia Rebaudiana ◽  
Adventitious Shoot ◽  
Optimal Growth ◽  
Medium Composition ◽  
Light Spectra ◽  
Stevia Rebaudiana Bertoni ◽  
Multiplication Coefficient

We investigated the influence of different conditions (light composition and plant growth regulators (PGRs) in culture media) on the morphophysiological parameters of Stevia rebaudiana Bertoni in vitro and in vivo. Both PGRs and the light spectra applied were found to significantly affect plant morphogenesis. During the micropropagation stage of S. rebaudiana, optimal growth, with a multiplication coefficient of 15, was obtained in an MS culture medium containing 2,4-epibrassinolide (Epin) and indole-3-acetic acid (IAA) at concentrations of 0.1 and 0.5 mg L−1, respectively. During the rooting stage, we found that the addition of 0.5 mg L−1 hydroxycinnamic acid (Zircon) to the MS medium led to an optimal root formation frequency of 85% and resulted in the formation of strong plants with well-developed leaf blades. Cultivation on media containing 0.1 mg L−1 Epin and 0.5 mg L−1 IAA and receiving coherent light irradiation on a weekly basis resulted in a 100% increase in the multiplication coefficient, better adventitious shoot growth, and a 33% increase in the number of leaves. S. rebaudiana microshoots, cultured on MS media containing 1.0 mg L−1 6-benzylaminopurine (BAP) and 0.5 mg L−1 IAA with red monochrome light treatments, increased the multiplication coefficient by 30% compared with controls (white light, media without PGRs).

In-vivo and in-vitro secretion of prolactin by lactating rat adenohypophyses as a function of intracellular age

1984 ◽  
Vol 101 (1) ◽  
pp. 27-32 ◽  
Author(s):  
F. Mena ◽  
G. Martínez-Escalera ◽  
C. Clapp ◽  
C. E. Grosvenor
Keyword(s):  
Pituitary Gland ◽  
Incubation Period ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Polyacrylamide Gel ◽  
Pituitary Glands ◽  
H 26

ABSTRACT Adenohypophysial prolactin of lactating rats was pulse-labelled by [3H]leucine injected i.v. at the time of removal of the pups. The [3H]prolactin concentration in the pituitary gland, analysed by polyacrylamide-gel electrophoresis, progressively fell as the time from labelling to removal of the pituitary gland increased from 8 to 24 h, which suggests that there was a loss of hormone as it aged within the gland. Suckling effectively provoked the depletion–transformation of total and [3H]prolactin (extracted at pH 7·2) when applied after 8 h but not when applied after either 16 or 24 h after removing the pups. In rats whose pups were removed for 8 h, suckling also depleted–transformed [3H]prolactin labelled 4 h, but not that labelled 1 h before suckling. The pituitary glands of other lactating rats were labelled with [3H]leucine injected i.v. at various times before removing the glands and incubating them in medium 199. The secretion into the medium of [3H]prolactin labelled either 4, 8, 16 or 24 h beforehand was maximal during the first 30 min then declined from 30 to 240 min of incubation. However, secretion of prolactin labelled 1 h and 10 min beforehand reached a maximum after 0·5–1 h and 2 h of incubation respectively, then remained constant during the remainder of the 4-h incubation period. The total 4-h secretion of [3H]prolactin was greatest (65% of preincubation concentration) from those glands labelled 4 h before in contrast to those labelled 10 min (15%) or 1 (38%), 8 (34%), 16 (18%) or 24 h (26%) before incubation. Taken together, these data suggest that prolactin synthesized 4 h earlier is more likely to be released in response to physiological stimuli than is more recently formed prolactin or prolactin which has remained in the pituitary gland for 16 h or longer. J. Endocr. (1984) 101, 27–32

scholarly journals Astrocyte-Derived CCL2 is Associated with M1 Activation and Recruitment of Cultured Microglial Cells

2016 ◽  
Vol 38 (3) ◽  
pp. 859-870 ◽  
Author(s):  
Mingfeng He ◽  
Hongquan Dong ◽  
Yahui Huang ◽  
Shunmei Lu ◽  
Shu Zhang ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Microglial Activation ◽  
Culture Media ◽  
Microglial Cells ◽  
Migration Ability ◽  
Migration Assay ◽  
Tnf Α

Background/Aims: Microglia are an essential player in central nervous system inflammation. Recent studies have demonstrated that the astrocytic chemokine, CCL2, is associated with microglial activation in vivo. However, CCL2-induced microglial activation has not yet been studied in vitro. The purpose of the current study was to understand the role of astrocyte-derived CCL2 in microglial activation and to elucidate the underlying mechanism(s). Methods: Primary astrocytes were pre-treated with CCL2 siRNA and stimulated with TNF-α. The culture medium (CM) was collected and added to cultures of microglia, which were incubated with and without CCR2 inhibitor. Microglial cells were analyzed by quantitative RT-PCR to determine whether they polarized to the M1 or M2 state. Microglial migratory ability was assessed by transwell migration assay. Results: TNF-α stimulated the release of CCL2 from astrocytes, even if the culture media containing TNF-α was replaced with fresh media after 3 h. CM from TNF-α-stimulated astrocytes successfully induced microglial activation, which was ascertained by increased activation of M1 and enhanced migration ability. In contrast, CM from astrocytes pretreated with CCL2 siRNA showed no effect on microglial activation, compared to controls. Additionally, microglia pre-treated with RS102895, a CCR2 inhibitor, were resistant to activation by CM from TNF-α-stimulated astrocytes. Conclusion: This study demonstrates that the CCL2/CCR2 pathway of astrocyte-induced microglial activation is associated with M1 polarization and enhanced migration ability, indicating that this pathway could be a useful target to ameliorate inflammation in the central nervous system.

scholarly journals Cathepsin B Localizes in the Caveolae and Participates in the Proteolytic Cascade in Trabecular Meshwork Cells. Potential New Drug Target for the Treatment of Glaucoma

2020 ◽  
Vol 10 (1) ◽  
pp. 78
Author(s):  
April Nettesheim ◽  
Myoung Sup Shim ◽  
Angela Dixon ◽  
Urmimala Raychaudhuri ◽  
Haiyan Gong ◽  
...  
Keyword(s):  
Trabecular Meshwork ◽  
Cathepsin B ◽  
Molecular Mechanisms ◽  
Culture Media ◽  
Ecm Remodeling ◽  
Trabecular Meshwork Cells ◽  
Proteolytic Cascade

Extracellular matrix (ECM) deposition in the trabecular meshwork (TM) is one of the hallmarks of glaucoma, a group of human diseases and leading cause of permanent blindness. The molecular mechanisms underlying ECM deposition in the glaucomatous TM are not known, but it is presumed to be a consequence of excessive synthesis of ECM components, decreased proteolytic degradation, or both. Targeting ECM deposition might represent a therapeutic approach to restore outflow facility in glaucoma. Previous work conducted in our laboratory identified the lysosomal enzyme cathepsin B (CTSB) to be expressed on the cellular surface and to be secreted into the culture media in trabecular meshwork (TM) cells. Here, we further investigated the role of CTSB on ECM remodeling and outflow physiology in vitro and in CSTBko mice. Our results indicate that CTSB localizes in the caveolae and participates in the pericellular degradation of ECM in TM cells. We also report here a novel role of CTSB in regulating the expression of PAI-1 and TGFβ/Smad signaling in TM cells vitro and in vivo in CTSBko mice. We propose enhancing CTSB activity as a novel therapeutic target to attenuate fibrosis and ECM deposition in the glaucomatous outflow pathway.

Age-dependent changes in volume and haemoglobin content of erythrocytes in the carp (Cyprinus carpio L.)

1989 ◽  
Vol 141 (1) ◽  
pp. 133-149 ◽  
Author(s):  
W. Speckner ◽  
J. F. Schindler ◽  
C. Albers
Keyword(s):  
Gel Filtration ◽  
Linear Increase ◽  
Human Erythrocytes ◽  
Main Peak ◽  
Red Cell ◽  
Human Haemoglobin ◽  
Cell Fractions ◽  
Haemoglobin Content

Carp erythrocytes were fractionated by angle-head centrifugation which yielded fractions with a linear increase in density. Haematological examinations revealed that the heavier red blood cells of carp had greater volumes (MCV), more haemoglobin (MCH) and higher haemoglobin concentrations (MCHC) than light ones. The same experiments with human red cell fractions yielded a decrease in MCV, constant MCH and an increase in MCHC. Haemoglobin content in individual erythrocytes was also determined by scanning stage absorbance cytophotometry to establish the frequency distribution of the cellular haemoglobin contents. In carp, the distribution was symmetrical with the means increasing with density. No such change with cell density was found in human erythrocytes. Both carp and human erythrocytes incorporated [2-14C]glycine in vitro. After gel filtration, radioactivity was detected in carp, but not in human, haemoglobin fractions. 14C was found in all three haemoglobin fractions, obtained by isoelectric focusing, and was present in the haem and in the globin. [2-14C]glycine-labelled erythrocytes were reinjected into chronically cannulated carp and followed in vivo for several months. With time, the main peak of scintillation counts shifted from red cell fractions of low to high density. This is considered as evidence that density and age of red cells in carp are positively correlated and that erythrocytes can synthesize haemoglobin while circulating in the peripheral blood.

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