Physiological roles of thyrotrophin-releasing hormone and vasoactive intestinal peptide on the pulsatile secretory patterns of prolactin in pituitary-grafted female rats

1994 ◽  
Vol 142 (3) ◽  
pp. 581-586 ◽  
Author(s):  
A Lafuente ◽  
J Marcó ◽  
A I Esquifino
Keyword(s):  
Vasoactive Intestinal Peptide ◽  
Prolactin Secretion ◽  
Female Rats ◽  
Thyrotrophin Releasing Hormone ◽  
Mean Values ◽  
Pulsatile Secretion ◽  
Releasing Hormone ◽  
Absolute Amplitude ◽  
The Mean ◽  
The Absolute

Abstract Much is known about the fact that thyrotrophin-releasing hormone (TRH) and vasoactive intestinal peptide (VIP) stimulate prolactin secretion but areas of uncertainty remain. This work was undertaken to describe the effects of TRH and VIP on the pulsatile secretion pattern of prolactin, in adult sham-operated and pituitary-grafted hyperprolactinaemic female rats. Two pulses of TRH (1 μg/rat) or one pulse of VIP (20 μg/rat) were given 60 or 120 min after the period of blood sampling. Pituitary grafting increased the mean values of prolactin, absolute amplitude and duration of the peaks and decreased their frequency, compared with control animals. In sham-operated rats, TRH elevated prolactin levels by increasing the absolute and relative amplitudes and duration of the pulses, along with a decrease in their frequency. No priming effects of TRH were observed in this study. Hyperprolactinaemia blunted TRH effects on the pulsatile secretion pattern of prolactin. In sham-operated rats, VIP administration increased the absolute and relative amplitudes of the prolactin peaks. None of the other parameters studied were changed. In pituitary-grafted animals, VIP administration increased the absolute and relative amplitudes of the prolactin peaks but to a lesser extent compared with controls. These data suggest that TRH and VIP affect prolactin pulsatility differentially. The effects of TRH and VIP were blunted to some extent by exposure to previously elevated circulating prolactin levels. Journal of Endocrinology (1994) 142, 581–586

Pulsatile prolactin secretory patterns throughout the oestrous cycle in the rat

1993 ◽  
Vol 137 (1) ◽  
pp. 43-47 ◽  
Author(s):  
A. Lafuente ◽  
J. Marcó ◽  
A. I. Esquifino
Keyword(s):  
Adult Female ◽  
Prolactin Secretion ◽  
Oestrous Cycle ◽  
Relative Amplitude ◽  
Female Rat ◽  
Mean Values ◽  
Low Level ◽  
Absolute Amplitude ◽  
The Absolute

ABSTRACT Prolactin secretion throughout the oestrous cycle in the rat remains at a low level and fairly constant, with the exception of the surge at pro-oestrus. The present study was designed to characterize possible changes in pulsatile patterns of prolactin during the oestrous cycle of the adult female rat. Mean values of prolactin increased from dioestrus-2 to pro-oestrus and then decreased to the values found at dioestrus-1. The number of peaks remained fairly constant in any phase of the oestrous cycle. The absolute amplitude of the peaks increased numerically but was not statistically significant from dioestrus-2 to pro-oestrus then decreasing until dioestrus-1. No changes in the relative amplitude or duration of the peaks throughout the oestrous cycle were detected. The results indicated that there is a similar pulsatile pattern of prolactin at any stage of the oestrous cycle, when samples were obtained during the morning. Journal of Endocrinology (1993) 137, 43–47

Intraventricular administration of thyrotrophin-releasing hormone (TRH) suppresses prolactin secretion and synthesis: a possible involvement of dopamine release by TRH from rat hypothalamus

1992 ◽  
Vol 133 (1) ◽  
pp. 59-66 ◽  
Author(s):  
H. Ikegami ◽  
H. Jikihara ◽  
K. Koike ◽  
K. Morishige ◽  
H. Kurachi ◽  
...  
Keyword(s):  
Dopamine Release ◽  
Prolactin Secretion ◽  
Female Rats ◽  
Serum Prolactin ◽  
Dependent Manner ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Rat Hypothalamus ◽  
Prolactin Gene ◽  
Gene Transcripts

ABSTRACT The administration of thyrotrophin-releasing hormone (TRH) causes a variety of dopamine-related biological events. To understand the specific role of TRH on rat hypothalamic dopamine neurones, we examined the in-vivo effects of intraventricular (i.c.v.) infusion of TRH on the release and synthesis of prolactin in the rat pituitary gland and on the changes in binding of [3H]MeTRH and dopamine turnover rates in rat hypothalamus. We have also examined the in-vitro effects of TRH on the release of [3H]dopamine from dispersed tuberoinfundibular dopamine neurones. Female rats were treated with i.c.v. infusions of 1 μmol TRH/l daily for 1, 3 and 7 days using Alzet osmotic pumps. Following 7 days of treatment the serum prolactin concentrations were significantly decreased. A reduction in hypothalamic TRH-binding sites (Bmax) was also apparent but the dissociation constant (Kd) was unaffected. Northern blot analysis of total RNA isolated from the pituitary glands of control animals using 32P-labelled prolactin cDNA as a probe indicated the presence of three species of prolactin gene transcripts of approximately 3·7, 2·0 and 1·0 kb in size, and these were decreased by TRH treatment. We examined the turnover rate of dopamine in the rat hypothalamus when TRH was administered i.c.v. for 7 days. There was a significant increase in 3,4-dihydroxyphenylacetic acid/dopamine ratio with TRH treatment. Moreover, exposure to TRH stimulated [3H]dopamine release from rat tuberoinfundibular neurones in a time- and dose-dependent manner. Dopamine receptor antagonists such as SCH23390 and (−)sulpiride, and other neuropeptides such as vasoactive intestinal peptide and oxytocin did not affect TRH-stimulated [3H]dopamine release. These data suggest that i.c.v. administration of TRH might decrease both prolactin secretion and accumulation of prolactin gene transcripts in the pituitary by stimulating dopamine release from tuberoinfundibular neurones. Journal of Endocrinology (1992) 133, 59–66

SERUM THYROTROPHIN AND THE RESPONSE TO THYROTROPHIN RELEASING HORMONE IN SYMPTOMLESS AUTOIMMUNE THYROIDITIS AND IN BORDERLINE AND OVERT HYPOTHYROIDISM

1974 ◽  
Vol 75 (2) ◽  
pp. 274-285 ◽  
Author(s):  
A. Gordin ◽  
P. Saarinen ◽  
R. Pelkonen ◽  
B.-A. Lamberg
Keyword(s):  
Autoimmune Thyroiditis ◽  
Elevated Serum ◽  
Mean Value ◽  
Primary Hypothyroidism ◽  
Overt Hypothyroidism ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
The Mean ◽  
The Individual ◽  
Serum Tsh

ABSTRACT Serum thyrotrophin (TSH) was determined by the double-antibody radioimmunoassay in 58 patients with primary hypothyroidism and was found to be elevated in all but 2 patients, one of whom had overt and one clinically borderline hypothyroidism. Six (29%) out of 21 subjects with symptomless autoimmune thyroiditis (SAT) had an elevated serum TSH level. There was little correlation between the severity of the disease and the serum TSH values in individual cases. However, the mean serum TSH value in overt hypothyroidism (93.4 μU/ml) was significantly higher than the mean value both in clinically borderline hypothyroidism (34.4 μU/ml) and in SAT (8.8 μU/ml). The response to the thyrotrophin-releasing hormone (TRH) was increased in all 39 patients with overt or borderline hypothyroidism and in 9 (43 %) of the 21 subjects with SAT. The individual TRH response in these two groups showed a marked overlap, but the mean response was significantly higher in overt (149.5 μU/ml) or clinically borderline hypothyroidism (99.9 μU/ml) than in SAT (35.3 μU/ml). Thus a normal basal TSH level in connection with a normal response to TRH excludes primary hypothyroidism, but nevertheless not all patients with elevated TSH values or increased responses to TRH are clinically hypothyroid.

Growth hormone and prolactin secretion by dispersed cell cultures of a normal human pituitary: effects of thyrotrophin releasing hormone, theophylline, somatostatin, and 2-bromo-α-ergocryptine

1981 ◽  
Vol 98 (3) ◽  
pp. 345-351 ◽  
Author(s):  
Eric F. Adams ◽  
Imperia E. Brajkovich ◽  
Keith Mashiter
Keyword(s):  
Cell Culture ◽  
Growth Hormone ◽  
Hormone Secretion ◽  
Prolactin Secretion ◽  
Human Pituitary ◽  
Thyrotrophin Releasing Hormone ◽  
Cell Culture Techniques ◽  
Releasing Hormone ◽  
Culture Techniques ◽  
Normal Human

Abstract. Growth hormone (GH) and prolactin (Prl) secretion by a normal human pituitary in dispersed cell culture has been investigated. Prl secretion was significantly stimulated after 0.5, 1,2 and 4 h exposure to 1, 10, 100 and 1000 ng/ml thyrotrophin releasing hormone (TRH). Maximal effects were obtained with 10 ng/ml TRH at 2 h, higher doses being less effective. GH secretion was unchanged with the exception that 1 ng/ml TRH produced a small decrease at 4 h. GH and Prl secretion was significantly inhibited by incubation with 0.01, 0.1, 1 or 10 μg/ml 2-bromo-α-ergocryptine (bromocriptine). The inhibition persited for a further 24 h after removal of bromocriptine. Theophylline (10−2 m) significantly increased GH and Prl secretion during a 4 h incubation and this effect was blocked by co-incubation with 10 ng/ml somatostatin (SRIF). SRIF also inhibited basal GH and Prl secretion during 4 h and removal of SRIF and incubation for at further 4 h led to a rebound in GH and Prl secretion to levels greater than control. It is concluded that cell culture techniques previously applied to the study of hormone secretion by pituitary adenomas can be equally applied to the normal human pituitary.

EFFECT OF THYROTROPHIN RELEASING HORMONE AND THYROID-STIMULATING HORMONE ON SERUM PROTEIN-BOUND 131I

1972 ◽  
Vol 70 (3) ◽  
pp. 454-462 ◽  
Author(s):  
Egil Haug ◽  
Harald Frey ◽  
Terje Sand
Keyword(s):  
Oral Dose ◽  
Thyroid Stimulating Hormone ◽  
Significant Rise ◽  
Response Relationship ◽  
Dose Response Relationship ◽  
Thyrotrophin Releasing Hormone ◽  
Peak Response ◽  
Releasing Hormone ◽  
Clear Dose Response ◽  
The Mean

ABSTRACT Seventeen subjects without any clinical or laboratory evidence of thyroidal or pituitary disease were given 1.0 mg thyrotrophin-releasing hormone (TRH) as a rapid iv injection 48 hours after an oral dose of 50 μCi 131I-. In all subjects there was a clear rise in serum PB131I. The elevation in the mean serum PB131I was significant (P<0.01) one hour after TRH, and the mean peak response was noted at 4 hours. It is suggested that this elevation in serum PB131I following TRH administration reflects the effect of the TSH released. In order to find the most suitable method of administration, 1.0 mg TRH was given iv, im, or as a 1 hour infusion. The maximal responses seemed to be independent of the mode of administration. Six subjects were given 3.0 mg TRH iv and 4 others 6.0 mg TRH iv. It was not possible to demonstrate a clear dose-response relationship. In five subjects the serum PB127I and the serum PB131I were measured at the same times following administration of TRH. This showed that the serum PB131I was a more sensitive index of TSH release than the serum PB127I. Twenty-four hours after the TRH injection the same subjects were given 5 IU TSH as a rapid iv or im injection. All subjects responded with a significant rise in serum PB131I. In the subjects who did not respond to TRH the response to TSH allows the differentiation between pituitary and thyroid disease.

scholarly journals Measurements of CFC-11, CFC-12, and HCFC-22 total columns in the atmosphere at the St. Petersburg site in 2009–2019

2020 ◽  
Author(s):  
Alexander Polyakov ◽  
Anatoly Poberovsky ◽  
Maria Makarova ◽  
Yana Virolainen ◽  
Yuri Timofeyev
Keyword(s):  
Seasonal Variability ◽  
Climate Model ◽  
Independent Data ◽  
Mean Values ◽  
Absolute Value ◽  
Qualitative And Quantitative ◽  
Observational Site ◽  
Retrieval Strategies ◽  
The Mean ◽  
The Absolute

Abstract. The retrieval strategies for deriving the atmospheric total columns (TCs) of CFC-11 (CCl3F), CFC-12 (CCl2F2), and HCFC-22 (CHClF2) from ground–based measurements of IR solar radiation have been improved. We demonstrate the advantage of using the Tikhonov-Phillips regularization approach for solving the inverse problem of the retrieval of these gases and give the optimized values of regularization parameters. The estimates of relative systematic and random errors amount to 7.61 % and 3.08 %, 2.24 % and 2.40 %, 5.75 % and 3.70 %, for CFC-11, CFC-12, and HCFC-22, respectively. We analyze the time series of the TCs and mean molar fractions (MMFs) of CFC-11, CFC-12, and HCFC-22 measured at the NDACC site St. Petersburg located near Saint Petersburg, Russia for the period of 2009–2019. Mean values of the MMFs for CFC-11, CFC-12, and HCFC-22 total 225, 493, and 238 pptv, respectively. Estimates of the MMFs trends for CFC-11, CFC-12, and HCFC-22 account for −0.40 ± 0.07 %/yr, -0.49  ±0.05 %/yr, and 2.12±0.13 %/yr, respectively. We have compared the mean values, trends and seasonal variability of CFC-11, CFC-12, and HCFC-22 MMFs measured at the St. Petersburg site in 2009–2019 to that of 1) near–ground volume mixing ratios (VMRs) measured at the observational site Mace Head, Ireland (GVMR); 2) the mean in the 8–12 km layer VMRs measured by ACE–FTS and averaged over 55–65° N latitudes (SVMR); and the MMFs of the Whole Atmosphere Community Climate Model for the St. Petersburg site (WMMF). The means of the MMFs are less than that of the GVMR for CFC-11 by 9 pptv (3.8 %), for CFC-12 by 24 pptv (4.6 %); for HCFC-22, the mean MMFs does not differ significantly from the mean GVMR. The absolute value of the trend estimates of the MMFs is less than that of the GVMR for CFC-11 (−0.40 vs −0.53 %/yr) and CFC-12 (−0.49 vs −0.59 %yr); the trend estimate of the HCFC-22 MMFs does not differ significantly from that of the GVMR. The seasonal variability of the GVMR for all three gases is much lower than the MMFs variability. The means of the MMFs are less than that of the SVMR for CFC-11 by 10 pptv (4.3 %), for CFC-12 by 33 pptv (6.3 %), and for HCFC-22 by 2 pptv (0.8 %). The absolute value of the trend estimates of the MMFs is less than that of the SVMR for CFC-11 (−0.40 vs −0.63 %/yr) and CFC-12 (−0.49 vs −0.58 %/yr); the trend estimate of the HCFC-22 MMFs does not differ significantly from that of the SVMR. The MMF and SVMR values show nearly the same qualitative and quantitative seasonal variability for all three gases. The means of the MMFs are greater than that of the WMMF for CFC-11 by 22 pptv (10 %), for CFC-12 by 15 pptv (3.1 %), and for HCFC-22 by 23 pptv (10 %). The absolute value of the trend estimates of the MMFs is less than that of the WMMF for CFC-11 (−0.40 vs −1.68 %/yr), CFC-12 (−0.49 vs −0.84 %/yr), and HCFC-22 (2.12 %/yr vs 3.40 %/yr). The MMFs and WMMF values show nearly the same qualitative and quantitative seasonal variability for CFC-11 and CFC-12, whereas the seasonal variability of the WMMF for HCFC-22 is essentially less than that of the MMFs. In general, the comparison of the MMFs with the independent data shows a good agreement of their means within the systematic error of considered measurements. The observed trends over the St. Petersburg site demonstrate the smaller decrease rates for CFC-11 and CFC-12 TCs than that of the independent data, and the same decrease rate for HCFC-22. The suggested retrieval strategies can be used for analysis of the IR solar spectra measurements using Bruker FS125HR spectrometers, e.g. at other IRWG sites of the NDACC observational network.

Effects of antiserum to thyrotrophin-releasing hormone on the concentrations of plasma prolactin, thyrotrophin and LH in the pro-oestrous rat

1985 ◽  
Vol 104 (2) ◽  
pp. 205-209 ◽  
Author(s):  
A. M. Horn ◽  
H. M. Fraser ◽  
G. Fink
Keyword(s):  
Plasma Concentrations ◽  
Passive Immunization ◽  
Immune Serum ◽  
Female Rats ◽  
Plasma Prolactin ◽  
Thyrotrophin Releasing Hormone ◽  
Blood Samples ◽  
Releasing Hormone ◽  
Sheep Blood

ABSTRACT The possible role of thyrotrophin-releasing hormone (TRH) in causing the pro-oestrous surge of prolactin was investigated in conscious female rats by passive immunization with a specific anti-TRH serum raised in sheep. Blood samples were withdrawn through a previously implanted intra-atrial cannula. The i.p. injection of 1 ml anti-TRH serum, but not non-immune sheep serum, at 13.00 h of pro-oestrus delayed by about 1 h the onset of the prolactin surge, but the peak of the surge was similar to that in animals injected with the non-immune serum. The plasma concentrations of TSH were significantly reduced by the anti-TRH serum, but plasma concentrations of LH were not significantly affected. These results show that TRH may play an important role in the timing and initiation, but not the maintenance of the prolactin surge in the pro-oestrous rat. J. Endocr. (1985) 104, 205–209

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