Hypothalamic input is required for development of normal numbers of thyrotrophs and gonadotrophs but not other anterior pituitary cells in late gestation sheep

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dc.contributor.authorSzarek, E.
dc.contributor.authorFarrand, K.
dc.contributor.authorMcMillen, I.
dc.contributor.authorYoung, I.
dc.contributor.authorHoughton, D.
dc.contributor.authorSchwartz, J.
dc.date.issued2007
dc.descriptionCopyright © 2008 The Physiological Society.
dc.description.abstractTo evaluate the hypothalamic contribution to the development of anterior pituitary (AP) cells we surgically disconnected the hypothalamus from the pituitary (hypothalamo-pituitary disconnection, HPD) in fetal sheep and collected pituitaries 31 days later. Pituitaries (n = 6 per group) were obtained from fetal sheep (term = 147 ± 3 days) at 110 days (unoperated group) of gestation and at 141 days from animals that had undergone HPD or sham surgery at 110 days. Cells were identified by labelling pituitary sections with antisera against the six AP hormones. Additionally, we investigated the colocalization of glycoprotein hormones. The proportions of somatotrophs and corticotrophs were unchanged by age or HPD. Lactotrophs increased 80% over time, but the proportion was unaffected by HPD. Thyrotrophs, which were unaffected by age, increased 70% following HPD. Gonadotrophs increased with gestational age (LH+ cells 55%; FSH+ cells 19-fold), but this was severely attenuated by HPD. We investigated the possible existence of a reciprocal effect of HPD on multipotential glycoprotein-expressing cells. Co-expression of LH and TSH was extremely rare (< 1%) and unchanged over the last month of gestation or HPD. The increase of gonadotrophs expressing FSH only or LH and FSH was attenuated by HPD. Therefore, the proportions of somatotrophs, lactotrophs and corticotrophs are regulated independently of hypothalamic input in the late gestation fetal pituitary. In marked contrast, the determination of the thyrotroph and gonadotroph lineages over the same time period is subject to complex mechanisms involving hypothalamic factors, which inhibit differentiation and/or proliferation of thyrotrophs, but stimulate gonadotrophs down the FSH lineage. Development of a distinct population of gonadotrophs, expressing only LH, appears to be subject to alternative mechanisms.
dc.description.statementofresponsibilityEva Szarek, Kirsten Farrand, I. Caroline McMillen, I. Ross Young, Daniel Houghton and Jeffrey Schwartz
dc.identifier.citationThe Journal of Physiology, 2007; 586(4):1185-1194
dc.identifier.doi10.1113/jphysiol.2007.141523
dc.identifier.issn0022-3751
dc.identifier.issn1469-7793
dc.identifier.urihttp://hdl.handle.net/2440/43190
dc.language.isoen
dc.publisherBlackwell Publishing Ltd
dc.source.urihttp://jp.physoc.org/cgi/content/abstract/586/4/1185
dc.subjectHypothalamo-Hypophyseal System
dc.subjectPituitary Gland, Anterior
dc.subjectHypothalamus
dc.subjectFetus
dc.subjectAnimals
dc.subjectSheep
dc.subjectFollicle Stimulating Hormone
dc.subjectLuteinizing Hormone
dc.subjectThyrotropin
dc.subjectCell Count
dc.subjectFetal Development
dc.subjectPregnancy
dc.subjectFemale
dc.subjectGonadotrophs
dc.subjectThyrotrophs
dc.titleHypothalamic input is required for development of normal numbers of thyrotrophs and gonadotrophs but not other anterior pituitary cells in late gestation sheep
dc.typeJournal article
pubs.publication-statusPublished

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