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Article: Thyrotropin: α- and β-subunits of thyrotropin, and prolactin responses to four-hour constant infusions of thyrotropin-releasing hormone in normal subjects and patients with pituitary-thyroid disorders

TitleThyrotropin: α- and β-subunits of thyrotropin, and prolactin responses to four-hour constant infusions of thyrotropin-releasing hormone in normal subjects and patients with pituitary-thyroid disorders
Authors
Issue Date1979
PublisherThe Endocrine Society. The Journal's web site is located at http://jcem.endojournals.org
Citation
Journal Of Clinical Endocrinology And Metabolism, 1979, v. 49 n. 1, p. 127-131 How to Cite?
AbstractTRH was administered as a 4-h constant rate iv infusion (0.4 μg/min) to eight healthy euthyroid volunteers, three euthyroid females on estrogen, eight hyperthyroid patients, eight patients with primary hypothyroidism, and five patients with hypothalamic and pituitary disorders. Blood was collected at regular intervals for the measurements of TSH, α- and β-TSH subunits, T3 and PRL. Healthy euthyroid subjects exhibited biphasic increases in intact TSH as well as in α- and β-TSH subunits. Circulating TSH levels rose rapidly within 10 min of infusion to a peak in 45 min. Levels were then stable or decreasing until 90 min, when a second phase of increase occurred which was maximal at 160 min. Greater responses were observed in females than in males. Primary hypothyroid patients exhibited similar biphasic increases in TSH and its subunits as did euthyroid subjects. Patients with hypothalamic and pituitary disorders had delayed and diminished responses, while thyrotoxic patients did not respond at all. In euthyroid subjects, significant increases in serum T3 levels as a result of thyroidal stimulation by TSH occurred within 60-120 min and continued steadily until the end of infusion when they declined. In patients with hypothalamic and pituitary disorders, T3 levels began to rise at 180 min and continued for 2 h after stopping the infusion. The PRL response in normal subjects showed a rapid increase to maximum levels within 30-45 min, followed by a gradual decrease despite continued TRH stimulation. This pattern was maintained in women on estrogen who had higher basal PRL levels. The biphasic response pattern of TSH and its subunits to TRH reflects the probable existence of two pools of TSH in the pituitary. The first is a readily releasable pool of presynthesized hormone, and the second, which required longer stimulation before release, represented newly synthesized hormone. The pattern of PRL secretion differs from that of TSH. The biphasic response of PRL is not clearly differentiated. This may be explained by an initial release phase greater than the second biosynthetic phase.
Persistent Identifierhttp://hdl.handle.net/10722/161649
ISSN
2015 Impact Factor: 5.531
2015 SCImago Journal Rankings: 2.940
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorChan, Ven_US
dc.contributor.authorWang, Cen_US
dc.contributor.authorYeung, RTTen_US
dc.date.accessioned2012-09-05T05:13:29Z-
dc.date.available2012-09-05T05:13:29Z-
dc.date.issued1979en_US
dc.identifier.citationJournal Of Clinical Endocrinology And Metabolism, 1979, v. 49 n. 1, p. 127-131en_US
dc.identifier.issn0021-972Xen_US
dc.identifier.urihttp://hdl.handle.net/10722/161649-
dc.description.abstractTRH was administered as a 4-h constant rate iv infusion (0.4 μg/min) to eight healthy euthyroid volunteers, three euthyroid females on estrogen, eight hyperthyroid patients, eight patients with primary hypothyroidism, and five patients with hypothalamic and pituitary disorders. Blood was collected at regular intervals for the measurements of TSH, α- and β-TSH subunits, T3 and PRL. Healthy euthyroid subjects exhibited biphasic increases in intact TSH as well as in α- and β-TSH subunits. Circulating TSH levels rose rapidly within 10 min of infusion to a peak in 45 min. Levels were then stable or decreasing until 90 min, when a second phase of increase occurred which was maximal at 160 min. Greater responses were observed in females than in males. Primary hypothyroid patients exhibited similar biphasic increases in TSH and its subunits as did euthyroid subjects. Patients with hypothalamic and pituitary disorders had delayed and diminished responses, while thyrotoxic patients did not respond at all. In euthyroid subjects, significant increases in serum T3 levels as a result of thyroidal stimulation by TSH occurred within 60-120 min and continued steadily until the end of infusion when they declined. In patients with hypothalamic and pituitary disorders, T3 levels began to rise at 180 min and continued for 2 h after stopping the infusion. The PRL response in normal subjects showed a rapid increase to maximum levels within 30-45 min, followed by a gradual decrease despite continued TRH stimulation. This pattern was maintained in women on estrogen who had higher basal PRL levels. The biphasic response pattern of TSH and its subunits to TRH reflects the probable existence of two pools of TSH in the pituitary. The first is a readily releasable pool of presynthesized hormone, and the second, which required longer stimulation before release, represented newly synthesized hormone. The pattern of PRL secretion differs from that of TSH. The biphasic response of PRL is not clearly differentiated. This may be explained by an initial release phase greater than the second biosynthetic phase.en_US
dc.languageengen_US
dc.publisherThe Endocrine Society. The Journal's web site is located at http://jcem.endojournals.orgen_US
dc.relation.ispartofJournal of Clinical Endocrinology and Metabolismen_US
dc.subject.meshAdulten_US
dc.subject.meshCraniopharyngioma - Blooden_US
dc.subject.meshEstradiol - Pharmacologyen_US
dc.subject.meshFemaleen_US
dc.subject.meshHumansen_US
dc.subject.meshHyperthyroidism - Blooden_US
dc.subject.meshHypopituitarism - Blooden_US
dc.subject.meshHypothyroidism - Blooden_US
dc.subject.meshMaleen_US
dc.subject.meshMiddle Ageden_US
dc.subject.meshPituitary Diseases - Blooden_US
dc.subject.meshPituitary Neoplasms - Blooden_US
dc.subject.meshProlactin - Blooden_US
dc.subject.meshThyroid Diseases - Blooden_US
dc.subject.meshThyrotropin - Blooden_US
dc.subject.meshThyrotropin-Releasing Hormone - Pharmacologyen_US
dc.subject.meshTriiodothyronine - Blooden_US
dc.subject.meshTuberculosis, Meningeal - Blooden_US
dc.titleThyrotropin: α- and β-subunits of thyrotropin, and prolactin responses to four-hour constant infusions of thyrotropin-releasing hormone in normal subjects and patients with pituitary-thyroid disordersen_US
dc.typeArticleen_US
dc.identifier.emailChan, V:vnychana@hkucc.hku.hken_US
dc.identifier.authorityChan, V=rp00320en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1210/jcem-49-1-127-
dc.identifier.pmid109462-
dc.identifier.scopuseid_2-s2.0-0018756932en_US
dc.identifier.volume49en_US
dc.identifier.issue1en_US
dc.identifier.spage127en_US
dc.identifier.epage131en_US
dc.identifier.isiWOS:A1979HB64200022-
dc.publisher.placeUnited Statesen_US
dc.identifier.scopusauthoridChan, V=7202654865en_US
dc.identifier.scopusauthoridWang, C=7501631357en_US
dc.identifier.scopusauthoridYeung, RTT=7102833337en_US

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