Regulation of the TRH-like peptide pyroglutamyl-glutamyl-prolineamide in the rat anterior pituitary gland

1995 ◽  
Vol 145 (1) ◽  
pp. 43-49 ◽  
Author(s):  
J M M Rondeel ◽  
W Klootwijk ◽  
E Linkels ◽  
G A C van Haasteren ◽  
W J de Greef ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Sex Difference ◽  
Anterior Pituitary ◽  
Biological Significance ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Anterior Pituitary Gland ◽  
Female Rats ◽  
Male Rats ◽  
Rat Pituitary

Abstract TRH-like peptides share the N- and C-terminal amino acids with TRH (pGlu-His-Pro-NH2) but differ in the middle amino acid residue. One of them, pGlu-Glu-Pro-NH2 (<EEP-NH2; EEP) is present in the rat pituitary gland, but its biological significance is unknown. We investigated the localization and regulation of this tripeptide in the rat pituitary gland. To distinguish between TRH and EEP two antisera were used for RIA: specificity of antiserum 4319 for the TRH-like peptides pGlu-Phe-Pro-NH2 and EEP was equal to or greater than that for TRH, whereas antiserum 8880 is TRH-specific. Our RIA data showed the presence of a TRH-like peptide in the anterior pituitary gland (AP) and of TRH in the posterior pituitary gland (PP). The TRH-like peptide in the AP was identified on anion-exchange chromatography and subsequent HPLC as EEP. Pathophysiological conditions such as altered thyroid and adrenal status and suckling did not affect pituitary gland levels of EEP. In general, however, there is a clear sex difference: levels of EEP are higher in male than in female rats. In both sexes gonadectomy leads to a substantial two- to threefold rise in EEP levels, abolishing the sex difference. Testosterone administration to gonadectomized male rats normalizes levels of EEP again. Disulfiram, an inhibitor of the enzyme peptidylglycine α-amidating monooxygenase, reduced levels of EEP in the AP by approximately 50%. In conclusion: 1) the TRH-like peptide EEP is present in the AP, whereas TRH is confined to the PP, 2) levels of EEP in the AP are regulated by sex steroids, 3) EEP is actively amidated in the AP and thus seems to be produced from a glycine-extended progenitor sequence. Journal of Endocrinology (1995) 145, 43–49

Urinary excretion of the TRH-like peptide pyroglutamyl-glutamyl-prolineamide in rats

1997 ◽  
Vol 153 (3) ◽  
pp. 411-421 ◽  
Author(s):  
W Klootwijk ◽  
R D H de Boer ◽  
E Sleddens-Linkels ◽  
S M Cockle ◽  
W W de Herder ◽  
...  
Keyword(s):  
Urinary Excretion ◽  
Anterior Pituitary ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Female Rats ◽  
Male Rats ◽  
Rat Tissues ◽  
Rat Serum ◽  
Methanolic Extracts ◽  
Gonadotrophin Secretion

Abstract TRH-like immunoreactivity (TRH-LI) was estimated in methanolic extracts of rat tissues and blood by RIA using antiserum 4319, which binds most peptides with the structure pGlu-X-ProNH2, or antiserum 8880, which is specific for TRH (pGlu-His-ProNH2). TRH-LI (determined with antiserum 4319) and TRH (determined with antiserum 8880) contents were 8 and 8 ng/g in brain, 216 and 222 ng/g in hypothalamus, 6·5 and 6 ng/g in pancreas, 163 and 116 ng/g in male pituitary, 105 and 77 ng/g in female pituitary, 1 and 0·1 ng/g in salivary gland, 61 and 42 ng/g in thyroid, 12 and 3 ng/g in adrenal, 3 and 0·3 ng/g in prostate, and 11 and 0·8 ng/g in ovary respectively. Blood TRH-LI (antiserum 4319) and TRH (antiserum 8880) levels were 31 and 18 pg/ml in male rats, and 23 and 10 pg/ml in female rats respectively. Unextracted serum obtained from blood kept for at least 1 h at room temperature no longer contained authentic TRH but still contained TRH-LI (males 20·3 ± 3·1, females 15·9 ± 3·0 pg/ml; means ± s.e.m.). Isocratic reverse-phase HPLC showed that TRH-LI in serum is largely pGlu-Glu-ProNH2 (<EEP-NH2), a peptide previously found in prostate and anterior pituitary. In urine, TRH-LI (antiserum 4319) and TRH (antiserum 8880) levels were 3·21 ± 0·35 and 0·32 ± 0·04 ng/ml in male rats and 3·75 ± 0·22 and 0·37 ± 0·04 ng/ml in female rats respectively (means ± s.e.m.). Anion-exchange chromatography on QAE-Sephadex showed that urine of normally fed rats contains both basic/neutral TRH-LI (b/nTRH-LI) and acidic TRH-LI (aTRH-LI) in a ratio of ≈ 40:60, and further analysis by HPLC indicated that aTRH-LI represents <EEP-NH2. Analysis of food extracts and urine from fasted rats demonstrated that b/nTRH-LI is derived from food particles spilled by the rats during urine collection, while aTRH-LI is endogenously produced. While urinary aTRH-LI levels were higher in female than in male rats (2·99 ± 0·41 vs 2·04 ± 0·20 ng/ml), the daily urinary excretion was similar in both sexes (females 15·6 ± 1·4, males 19·5 ± 2·0 ng/day). Intravenously injected <EEP-NH2 disappeared from serum with a half-life of ≈ 1 h, and was recovered unchanged and quantitatively in urine. In contrast, when <EEP-NH2 was administered with food, only ≈ 0·5% was recovered in urine. The urinary clearance rate of serum TRH-LI amounted to 0·52 ± 0·10 ml/min in males and 0·34 ± 0·05 ml/min in females. In view of the presence of <EEP-NH2 in the anterior pituitary gland, and the regulation of its content in parallel with gonadotrophins, we examined the possibility that serum <EEP-NH2 is of pituitary origin and correlates with gonadotrophin secretion. However, treatments that alter pituitary <EEP-NH2 content and gonadotrophin release had no effect on serum TRH-LI or urinary aTRH-LI. In conclusion, the TRH-like peptide <EEP-NH2 is present in rat serum and is excreted into the urine. Moreover, <EEP-NH2 in serum and urine is not derived from rat food and is probably not of pituitary origin. Journal of Endocrinology (1997) 153, 411–421

scholarly journals The hormonal status modulates the effect of neurokinin A on prolactin secretion in female rats

1998 ◽  
Vol 159 (3) ◽  
pp. 389-395 ◽  
Author(s):  
D Pisera ◽  
S Theas ◽  
A De Laurentiis ◽  
M Lasaga ◽  
B Duvilanski ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
In Vitro Release ◽  
Anterior Pituitary Gland ◽  
Female Rats ◽  
Male Rats ◽  
Neurokinin A ◽  
Pituitary Cells ◽  
Anterior Pituitary Cells ◽  
Ovx Rats

We have previously reported that neurokinin A (NKA), a tachykinin closely related to substance P, increases the release of prolactin (PRL) from the anterior pituitary gland of male rats, but not from pituitaries of ovariectomized (OVX) female rats. In this study, we evaluated the influence of estrogens in the action of NKA on PRL secretion in female rats. NKA stimulated the in vitro release of PRL from pituitary glands of OVX-chronically estrogenized rats, and of proestrus and estrus rats, but had no effect in anterior pituitaries of diestrus rats. In addition, we observed that cultured anterior pituitary cells of OVX rats responded to NKA only when they were incubated for 3 days in the presence of estradiol 10(-9) M. This effect was blocked by L-659,877, an NK-2 receptor antagonist. We also studied the action of NKA on PRL release during lactation. The response of anterior pituitary cells to NKA was variable over this period. The maximal sensitivity to NKA was observed at day 10 of lactation. Furthermore, the blockade of endogenous NKA by the administration of an anti-NKA serum to lactating rats reduced the PRL surge induced by the suckling stimulus. These results show that the responsiveness of the anterior pituitary gland of female rats to NKA is modulated by the endocrine environment, and suggest that NKA may participate in the control of PRL secretion during the estrus cycle and lactation.

DIRECT ANTIPROLIFERATIVE EFFECT OF DOPAMINE AGONISTS ON THE ANTERIOR PITUITARY GLAND IN ORGAN CULTURE

1978 ◽  
Vol 79 (2) ◽  
pp. 245-246 ◽  
Author(s):  
M. PAWLIKOWSKI ◽  
J. KUNERT-RADEK ◽  
H. STĘPIEŃ
Keyword(s):  
Pituitary Gland ◽  
Dopamine Receptor ◽  
Mitotic Activity ◽  
Anterior Pituitary ◽  
Anterior Pituitary Gland ◽  
Antiproliferative Effect ◽  
Male Rats ◽  
Pars Intermedia ◽  
Pituitary Tumours ◽  
Rat Pituitary

Department of Experimental Endocrinology, Institute of Endocrinology, Medical Academy of Łódź, Dr Sterling sir. 3, 91–425 Łódź, Poland (Received 22 May 1978) Lloyd, Meares & Jacobi (1975) observed inhibition of mitotic activity in the anterior pituitary gland by the dopamine receptor agonist, bromocriptine, in oestrogen-treated male rats. This observation has been confirmed in our laboratory (Stępień, Wolaniuk & Pawlikowski, 1978). Suppression of mitotic activity in the pars intermedia of the rat pituitary gland by bromocriptine has also been observed (Rychter & Stępień, 1977). Furthermore, it has been found that the dopamine receptor blocker, pimozide, enhances mitotic activity in the rat anterior pituitary gland (Stępień et al. 1978). By the use of various ergot alkaloids, MacLeod & Lehmeyer (1973) succeeded in inhibiting the growth of transplantable rat pituitary tumours. There have also been observations suggesting an antiproliferative effect of bromocriptine on human pituitary tumours (Wass, Thorner, Morris, Rees, Mason, Jones &

Prolactin release, oestrogens and proliferation of prolactin-secreting cells in the anterior pituitary gland of adult male rats

1986 ◽  
Vol 108 (3) ◽  
pp. 399-403 ◽  
Author(s):  
R. L. Pérez ◽  
G. A. Machiavelli ◽  
M. I. Romano ◽  
J. A. Burdman
Keyword(s):  
Cell Proliferation ◽  
Pituitary Gland ◽  
Adult Male ◽  
Anterior Pituitary ◽  
Pituitary Hormones ◽  
Anterior Pituitary Gland ◽  
Male Rats ◽  
Serum Prolactin ◽  
Prolactin Release ◽  
Experimental Conditions

ABSTRACT Relationships among the release of prolactin, the effect of oestrogens and the proliferation of prolactin-secreting cells were studied under several experimental conditions. Administration of sulpiride or oestradiol released prolactin and stimulated cell proliferation in the anterior pituitary gland of adult male rats. Clomiphene completely abolished the rise in cell proliferation, but did not interfere with the sulpiride-induced release of prolactin. Treatment with oestradiol plus sulpiride significantly increased serum prolactin concentrations and the mitotic index compared with the sum of the stimulation produced by both drugs separately. Bromocriptine abolished the stimulatory effect of oestradiol on the serum prolactin concentration and on cell proliferation. In oestradiol- and/or sulpiride-treated rats, 80% of the cells in mitoses were lactotrophs. The remaining 20% did not stain with antisera against any of the pituitary hormones. The number of prolactin-secreting cells in the anterior pituitary gland significantly increased after the administration of oestradiol or sulpiride. The results demonstrate that treatment with sulpiride and/or oestradiol increases the proliferation and the number of lactotrophs in the anterior pituitary gland of the rat. J. Endocr. (1986) 108, 399–403

Effects of Angiotensin II on LHRH Release, as Measured by in vivo Microdialysis of the Anterior Pituitary Gland of Conscious Female Rats

1992 ◽  
Vol 55 (3) ◽  
pp. 276-281 ◽  
Author(s):  
Marianne K. Steele ◽  
Kate N. Stephenson ◽  
John M. Meredith ◽  
Jon E. Levine
Keyword(s):  
Angiotensin Ii ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
In Vivo Microdialysis ◽  
Anterior Pituitary Gland ◽  
Female Rats ◽  
Lhrh Release

Cyproheptadine and desmethylcyproheptadine directly inhibit the release of adrenocorticotrophin and β-lipotrophin/β-endorphin activity from the neurointermediate lobe of the rat pituitary gland

1983 ◽  
Vol 96 (3) ◽  
pp. 395-400 ◽  
Author(s):  
S. W. J. Lamberts ◽  
E. G. Bons ◽  
P. Uitterlinden ◽  
W. H. Hackeng
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Serotonin Receptor ◽  
Direct Action ◽  
Anterior Pituitary Gland ◽  
Hormone Release ◽  
Neurointermediate Lobe ◽  
Rat Pituitary

Cyproheptadine and its metabolite desmethylcyproheptadine were shown to suppress directly the release of adrenocorticotrophin (ACTH) and β-lipotrophin/β-endorphin activity from the neurointermediate lobe of the pituitary gland incubated in vitro. Neither compound affected the release of ACTH from the anterior pituitary gland. Serotonin stimulated the release of ACTH and β-lipotrophin/β-endorphin activity from the neurointermediate lobe, but did not influence the (desmethyl)cyproheptadine-mediated inhibition of hormone release. These results indicate that serotonin and cyproheptadine affect hormone release by the neurointermediate lobe by a direct action. The effect of cyproheptadine, however, might not be exerted by a serotonin receptor.

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