In-vitro effects of corticosterone, synthetic ovine corticotrophin releasing factor and arginine vasopressin on the release of adrenocorticotrophin by fetal rat pituitary glands

1984 ◽  
Vol 101 (3) ◽  
pp. 339-344 ◽  
Author(s):  
J. P. Dupouy ◽  
A. Chatelain
Keyword(s):  
Arginine Vasopressin ◽  
Fetal Life ◽  
Spontaneous Release ◽  
Sharp Rise ◽  
Corticotrophin Releasing Factor ◽  
Fetal Rat ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Acth Release

ABSTRACT The in-vitro release of ACTH by fetal rat pituitary glands on days 17, 19 and 21 of pregnancy was measured using radioimmunoassay. The spontaneous release of ACTH, expressed in pg ACTH/gland per h, increased with fetal age, in correlation with the sharp rise in pituitary ACTH content. However, since pituitary ACTH content was nearly sevenfold higher at term than on day 17, while basal release of ACTH was only threefold higher, one can speculate that the spontaneous release of ACTH was proportionally greater on day 17 than on day 21 of gestation. As corticosterone, at a physiological concentration (865 nmol/l), reduced ACTH release, it was concluded that the pituitary gland was one site of the negative feedback action of the corticosteroids during fetal life. Quantities of synthetic ovine corticotrophin releasing factor (CRF) which gave concentrations of 0·3–30 nmol/l in the incubation medium induced a sharp rise in ACTH release which was log-dose dependent between 0·3 and 3 nmolCRF/1 on day 17 and between 0·3 and 30 nmolCRF/1 on days 19 and 21. The response to CRF increased with fetal age. Quantities of arginine vasopressin (AVP) which gave concentrations of 2–200 nmol/l stimulated ACTH release at all stages of gestation investigated. However, the response to AVP was much lower than that to CRF. Potentiation of CRF-induced ACTH release was not observed when whole pituitary glands from 21-day-old fetuses were incubated with AVP (20 nmol/l) + CRF (3 nmol/l). Such results were correlated with the ontogenesis of immunoreactive vasopressin- and CRF-containing fibres in the median eminence of the rat fetus, as well as with the CRF-like immunoreactivity present in adult rat pituitary portal plasma and the AVP content of the fetal rat hypophysis. J. Endocr. (1984) 101, 339–344

Effects of rat corticotrophin-releasing factor, arginine vasopressin and oxytocin on the secretions of adrenocorticotrophic hormone and corticosterone in the fetal rat in late gestation: in vivo and in vitro studies

1994 ◽  
Vol 130 (3) ◽  
pp. 313-319 ◽  
Author(s):  
S Deloof ◽  
V Montel ◽  
A Chatelain
Keyword(s):  
Arginine Vasopressin ◽  
Anterior Pituitary ◽  
Late Gestation ◽  
Adrenocorticotrophic Hormone ◽  
Rat Fetuses ◽  
Corticotrophin Releasing Factor ◽  
Fetal Rat ◽  
Pituitary Glands

Deloof S, Montel V, Chatelain A. Effects of rat corticotrophin-releasing factor, arginine vasopressin and oxytocin on the secretions of adrenocorticotrophic hormone and corticosterone in the fetal rat in late gestation: in vivo and in vitro studies. Eur J Endocrinol 1994;130:313–19. ISSN 0804–4643 The effects of rat corticotrophin-releasing factor (rCRF), arginine vasopressin (AVP) and oxytocin (OT) were investigated in vivo in 21 -day-old rat fetuses injected through the umbilical vein and in vitro on perifused anterior pituitary glands from 21-day-old rat fetuses. In vivo, rCRF (1.25 pmol • 50 μl−1 • fetus−1), AVP (5 pmol • 50 μl−1 •fetus−1) alone and rCRF in association with AVP or oxytocin (12.5 pmol • 50 μl−1 • fetus−1) increased plasma adrenocorticotrophic hormone (ACTH) and corticosterone levels only 30 min after the start of injection. During the first 10 min of the sampling period, the injection of these peptides alone or in combination and the injection of saline decreased the plasma ACTH concentration, which was lower than that of uninjected fetuses, but had no effect on the plasma corticosterone concentration. In vitro, the release of ACTH by perifused anterior pituitary glands was increased strongly by rCRF (4 pmol/0.5 ml) but only slightly by AVP (92 pmol/0.5 ml) and oxytocin (198 pmol/0.5 ml). Arginine vasopressin and oxytoxin potentiated the release of ACTH stimulated by rCRF in vitro but not in vivo. Our results suggest that rCRF is the major peptide that controls ACTH secretion in the fetal rat at term. In conclusion, the rise of the ACTH level observed only 30 min after injection of rCRF or AVP suggests the existence of a factor able to inhibit the ACTH response after injection of these peptides. This factor might be elicited by the blood volume expansion. A Chatelain, Laboratoire de Neuroendocrinologie du Développement, Université des Sciences et Technologies de Lille, Bâtiment SN4, 59655 Villeneuve d'Ascq cédex, France

Vasopressin-binding sites in the pig pituitary gland: competition by novel vasopressin antagonists suggests the existence of an unusual receptor subtype in the anterior lobe

1994 ◽  
Vol 141 (3) ◽  
pp. 383-391 ◽  
Author(s):  
Y Arsenijevic ◽  
M Dubois-Dauphin ◽  
E Tribollet ◽  
M Manning ◽  
W H Sawyer ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Rat Liver ◽  
Arginine Vasopressin ◽  
Binding Sites ◽  
Anterior Lobe ◽  
Receptor Subtype ◽  
Lower Affinity ◽  
Corticotrophin Releasing Factor ◽  
Rat Pituitary ◽  
Acth Release

Abstract Arginine vasopressin (AVP) acts in the pituitary gland, in synergy with corticotrophin-releasing factor, to induce ACTH release in response to stressful stimuli. Pituitary AVP receptors in the rat are coupled to phospholipase C, as are the so-called V1-type AVP receptors. The present study examined [3H]AVP binding in membranes prepared from the anterior lobe of the pituitary gland of the pig. [3H]AVP, alone or in competition with analogues, bound to sites in the pig anterior lobe which are pharmacologically similar to those described previously by others in the rat pituitary gland. For comparison, the same competition studies were performed on membrane preparations from the rat liver which contain the classic V1-type AVP receptor. Pituitary and liver AVP-binding sites were dissimilar; both cyclic and linear V1 antagonists had, in general, a much lower affinity for pituitary AVP-binding sites than for those in the liver. Thus, Phaa-d-Tyr(Et)-Phe-Gln-Asn-Lys-Pro-Arg-NH2 (Phaa=phenylacetyl) has a 2500-fold greater affinity for the latter (negative logarithm of inhibition constant (pKi)=9·64) than for the former (pKi=6·22). One linear antagonist, Pa-d-Tyr-Phe-Val-Asn-Arg-Pro-Arg-Arg-NH2 (Pa=propionyl) had about equal affinities for liver and pituitary membranes (pKi=6·39 and 6·53 respectively). Another compound, Phaa-d-Tyr-Phe-Val-Asn-Arg-Pro-Arg-Arg-NH2 had the highest affinity found to date for binding to AVP sites in the pituitary (pKi=7·43). These findings suggest some ideas for the design of more potent and/or selective AVP analogues acting in the pituitary gland. Journal of Endocrinology (1994) 141, 383–391

EFFECT OF 6-DEHYDRO-16-METHYLENE-HYDROCORTISONE AND DEXAMETHASONE ON THE RELEASE OF ACTH FROM RAT PITUITARY GLANDS IN VITRO

1970 ◽  
Vol 63 (3) ◽  
pp. 431-436 ◽  
Author(s):  
K. Berthold ◽  
A. Arimura ◽  
A. V. Schally
Keyword(s):  
Pituitary Gland ◽  
Direct Action ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Acth Release

ABSTRACT Direct action of 6-dehydro-16-methylene-hydrocortisone (STC 407) and dexamethasone on the rat pituitary gland was investigated in vitro. CRF-induced ACTH release was suppressed after preincubation of the pituitary gland with 10 μg STC 407/ml or 1 μg dexamethasone/ml. These results suggest that both STC 407 and dexamethasone act directly on the pituitary gland.

Vasopressin receptors influencing the secretion of ACTH by the rat adenohypophysis

1987 ◽  
Vol 113 (3) ◽  
pp. 389-396 ◽  
Author(s):  
J. C. Buckingham
Keyword(s):  
Receptor Antagonist ◽  
Arginine Vasopressin ◽  
Receptor Agonist ◽  
Intrinsic Activity ◽  
Corticotrophin Releasing Factor ◽  
Low Concentrations ◽  
Vasopressin Receptors ◽  
Acth Release

ABSTRACT The effects of selective agonists and antagonists of type 1 (V1) and type 2 (V2) vasopressin receptors on the secretion of ACTH in vitro by segments of adenohypophysial tissue and in vivo in rats pretreated with pentobarbitone and chlorpromazine were studied in the presence and absence of the 41 amino acid-containing peptide, corticotrophin-releasing factor-41 (CRF-41). The non-selective vasopressin receptor agonist, arginine vasopressin (AVP) and the V1-receptor agonist, felypressin caused dose-related increases in ACTH release in vivo and in vitro but the V2-receptor agonist, desmopressin was only weakly active in this respect. Their actions in vitro were antagonized competitively by the V1-receptor antagonist, d(C2H5)2-AVP, but were unaffected by the V2-receptor antagonist, d(CH2)5-d-Iso2-Thr4-AVP. Arginine vasopressin, felypressin and desmopressins in concentrations considerably lower than those necessary to elicit directly the release of ACTH, potentiated, in a dose-related manner, the activity of CRF-41 in vitro. The potentiating effects were not antagonized by the V2-receptor antagonist or by low concentrations of the V1 -receptor antagonist. At a higher concentration, the V1-receptor antagonist reduced, but did not abolish, the potentiating effects of AVP and its analogues. However, at this concentration, it also exhibited weak intrinsic activity and, like the agonists, potentiated the response to CRF-41. The results suggest that the direct effect of AVP on ACTH release is mediated by V1-like receptors. The vasopressin receptors involved in the potentiation of CRF-41 activity appear to be different. J. Endocr. (1987) 113, 389–396

ACTH secretion from isolated hypophysial anterior lobes of male and female newborn rats: effects of corticotrophin-releasing factor, arginine vasopressin and oxytocin alone or in combination

1993 ◽  
Vol 137 (1) ◽  
pp. 123-132 ◽  
Author(s):  
L. Hary ◽  
J. P. Dupouy ◽  
A. Chatelain
Keyword(s):  
Arginine Vasopressin ◽  
Anterior Pituitary ◽  
Newborn Rats ◽  
Acth Secretion ◽  
Peripheral Plasma ◽  
Corticotrophin Releasing Factor ◽  
Males And Females ◽  
Dose Dependent ◽  
Acth Release

ABSTRACT ACTH release by the anterior pituitary lobes of 8-day-old newborn rats (males and females) in the presence of rat corticotrophin-releasing factor (rCRF), arginine vasopressin (AVP) and oxytocin, given alone or in association, was measured in vitro. Rat CRF and AVP induced a dose-dependent release of ACTH in both sexes, while oxytocin was unable to stimulate ACTH secretion except at the highest dose tested. No sex-related difference was noted for any of the responses. Oxytocin (1 nmol/l) potentiated the response to rCRF (0·20 nmol/l) by the anterior pituitary lobes of females but not by those of males. This oxytocin potentiation was abolished when female newborn rats were injected at birth with testosterone (1 mg). AVP (1 nmol/l) alone stimulated ACTH release from the anterior pituitary lobes of the newborn rats of both sexes and markedly potentiated the ACTH response to rCRF. Although no difference between the sexes was noted for basal levels of AVP and oxytocin in the hypothalamus, the neurointermediate lobe and the peripheral plasma, the present data on the sex-related effect of oxytocin on the newborn adenohypophysis could, in part, explain why ACTH release in response to ether stress was previously reported to be more lasting in females than in males on day 8 postpartum. Journal of Endocrinology (1993) 137, 123–132

Early glucocorticoid feedback in anterior pituitary corticotrophs: differential inhibition of hormone release induced by vasopressin and corticotrophin-releasing factor in vitro

1991 ◽  
Vol 129 (2) ◽  
pp. 261-268 ◽  
Author(s):  
M. J. Shipston ◽  
F. A. Antoni
Keyword(s):  
Anterior Pituitary ◽  
Actinomycin D ◽  
Feedback Inhibition ◽  
Female Rats ◽  
Hormone Release ◽  
Type Ii ◽  
Acth Secretion ◽  
Corticotrophin Releasing Factor ◽  
Acth Release

ABSTRACT Vasopressin and 41-residue corticotrophin-releasing factor (CRF-41) are physiological mediators of the hypothalamic control of pituitary ACTH secretion, whilst adrenocortical glucocorticoids are the major inhibitory factors regulating ACTH output. In the present study it was investigated in vitro whether the characteristics of early glucocorticoid inhibition of stimulated ACTH secretion would differ depending on the nature of the stimulus and the temporal relationship between secretagogue and steroid. The experiments were carried out using perifused segments of rat adenohypophysis obtained from randomly cycling female rats. Repeated pulses (5 min) of CRF-41 or vasopressin were given at 1-h intervals for up to 7 h. The net release of ACTH became stable after the second secretagogue pulse. Administration of 0·1 μmol corticosterone/l 30 min before and during a 5-min pulse of 10 nmol CRF-41/l inhibited CRF-41-stimulated ACTH release to 60% of control. Stimulated hormone release remained suppressed at 90 min after the start of the corticosterone infusion and returned to control levels by 150 min. If corticosterone treatment (35 min total exposure) was started simultaneously with the CRF-41 pulse, no inhibitory effect of the steroid was observed at any subsequent time-point examined (60,90,120 and 150 min). In contrast, vasopressin-stimulated ACTH release was inhibited by approximately 50% when corticosterone was applied before, or simultaneously with, a 5-min pulse of 10 nmol vasopressin/l. The synthetic glucocorticoid type II receptor agonist RU28362, administered 30 min before and during a 5-min pulse of 10 nmol CRF-41/l, reduced CRF-41-stimulated ACTH release to 50% of control up to 2·5 h after the start of RU28362 application (although inhibition after 35 min exposure was not statistically significant). Inhibition of ACTH release stimulated by 10 nmol vasopressin/l was observed within 35 min of steroid application and was maintained up to 2·5 h after the initial application of RU28362. The action of RU28362 on CRF-41-stimulated ACTH release was blocked by inhibitors of transcription (actinomycin D) and translation (puromycin); notably these drugs did not modify the ACTH response to CRF-41. In contrast, actinomycin D as well as puromycin reduced vasopressin-stimulated ACTH release. The data suggest that: (1) the timing of steroid application is important in determining the early glucocorticoid inhibition of CRF-41- but not vasopressin-stimulated ACTH secretion; (2) CRF-41 and vasopressin mobilize different pools of ACTH from the anterior pituitary gland; (3) type II glucocorticoid receptors and synthesis of new protein(s) are involved in the early inhibitory action of glucocorticoids; (4) depending on the timing and nature of the incident secretagogue, differential negative feedback inhibition of ACTH secretion may occur at the pituitary level in vivo. Journal of Endocrinology (1991) 129, 261–268

Production and utilization of monoclonal antibodies to human/rat corticotrophin-releasing factor-41

1990 ◽  
Vol 5 (2) ◽  
pp. 159-166 ◽  
Author(s):  
N. G. N. Milton ◽  
E. W. Hillhouse ◽  
S. A. Nicholson ◽  
C. H. Self ◽  
A. M. McGregor
Keyword(s):  
Monoclonal Antibodies ◽  
Enzyme Linked Immunosorbent Assay ◽  
Dependent Manner ◽  
Corticotrophin Releasing Factor ◽  
Tissue Extracts ◽  
Rat Pituitary ◽  
Hypothalamic Tissue ◽  
Dose Dependent

ABSTRACT Murine monoclonal antibodies against human/rat corticotrophin-releasing factor-41 (CRF-41) were produced and characterized for use in the immunological and biological characterization of CRF-41. Spleen cells from BALB/c mice immunized with CRF-41 conjugated to bovine γ-globulin were fused with a BALB/c-derived non-secretor X-63 myeloma line. Hybridomas were selected for CRF antibody production by enzyme-linked immunosorbent assay, and positive hybridomas cloned twice. Three monoclonal antibodies were obtained (KCHMB001, KCHMB002 and KCHMB003) and characterized as IgG1, IgG1 and IgG2a isotypes respectively, with affinity constants for rat CRF-41 of 30, 53 and 34 nmol/l respectively. All three monoclonal antibodies recognize an epitope contained between residues 34 and 41 of the human/rat sequence. The antibodies were able to neutralize the ACTH-releasing activity of rat CRF-41, applied to rat pituitary fragments in vitro, in a dose-dependent manner. Isoelectric focusing showed that KCHMB 003 detected bands of synthetic rat CRF-41 and rat [Met(O)21,38]-CRF-41 at pH 7·1 and 6·8 respectively. Use of KCHMB003 in a two-site enzyme-amplified immunoassay showed that this antibody recognizes both synthetic rat CRF-41 and immunoreactive CRF-41 in rat hypothalamic tissue extracts.

BIOSYNTHESIS OF GONADOTROPHINS BY RAT PITUITARIES IN VITRO

1975 ◽  
Vol 66 (3) ◽  
pp. 369-374 ◽  
Author(s):  
MRIDULA CHOWDHURY ◽  
EMIL STEINBERGER
Keyword(s):  
Comparative Study ◽  
Anterior Pituitary ◽  
Male Rats ◽  
Leucine Incorporation ◽  
Experimental Conditions ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Endogenous Proteases ◽  
Pituitary Homogenate

SUMMARY A method has been developed for studying biosynthesis of FSH in the rat pituitary in vitro. Anterior pituitary glands were incubated with [3H]leucine; a specific and sensitive immunoprecipitation technique was used to isolate FSH from the pituitary homogenate. Total FSH content of the samples was measured by a double-antibody radioimmunoassay technique. Using this technique, a comparative study of LH and FSH synthesis in the same pituitary of adult male rats incubated for various intervals (0·5–6 h) was done. Increased incorporation of [3H]leucine into both LH and FSH with time was noted. The rate and amount of [3H]leucine incorporation into FSH was found to be higher than that into LH, indicating that either the rate of FSH synthesis is higher than that of LH or FSH has more leucine residues than LH. Greater susceptibility of LH to degradation by endogenous proteases during dialysis may also reflect less incorporation of [3H]leucine into LH. This method provides a reliable tool for evaluating FSH synthesis under various experimental conditions.

Dexamethasone inhibits ovine corticotrophin-releasing factor (oCRF), arginine vasopressin (AVP), and oCRF + AVP stimulated release of ACTH during the last third of pregnancy in the sheep fetus

1987 ◽  
Vol 65 (6) ◽  
pp. 1186-1192 ◽  
Author(s):  
Laurie J. Norman ◽  
John R. G. Challis
Keyword(s):  
Negative Feedback ◽  
Arginine Vasopressin ◽  
Late Pregnancy ◽  
Feedback Effect ◽  
Plasma Acth ◽  
Fetal Sheep ◽  
Corticotrophin Releasing Factor ◽  
Basal Release ◽  
Sheep Fetus ◽  
Acth Release

We examined the hypothesis that in fetal sheep during late pregnancy exogenous glucocorticoids might affect differentially the pituitary response, measured as changes in plasma ACTH concentrations, to the systemic administration of ovine corticotrophin-releasing factor (oCRF), arginine vasopressin (AVP), or oCRF + AVP. At d 113–116 of pregnancy, equimolar injections of oCRF and AVP given separately provoked similar significant increases in plasma ACTH; the change in ACTH over basal values was significantly greater than the sum of the two separate responses when AVP + oCRF were given together. Exogenous dexamethasone did not affect basal ACTH concentrations, but suppressed significantly the responses to oCRF, AVP, and oCRF + AVP. At d 126–130, there was a significant ACTH response to CRF alone and to AVP + oCRF, but not to AVP alone. The response during the first 30 min postinjection to oCRF was significantly less than that to AVP + oCRF. Plasma Cortisol rose after each peptide injection. Exogenous dexamethasone suppressed both basal and stimulated responses to each peptide. At the amounts injected, there was no significant ACTH or Cortisol response to oCRF, AVP, or oCRF + AVP at d 136–140, but dexamethasone suppressed basal ACTH and Cortisol concentrations at this time. We conclude that stimulated, but not basal, release of ACTH is subject to the negative feedback effect of exogenous glucocorticoid by d 113–116 of gestation in fetal sheep. Both basal and stimulated release of ACTH and Cortisol are suppressed after d 125. At the amount of exogenous dexamethasone given, oCRF, AVP, and oCRF + AVP-stimulated responses are affected similarly. Our results suggest different controls of basal and stimulated ACTH release from the pituitary at d 113–116 of gestation. Our findings would be consistent with the pituitary as a level of action for the negative feedback effect of corticosteroids on stimulated ACTH release throughout the last third of pregnancy in fetal sheep.

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