Ontogeny of hypothalamic pituitary function in the pig: pituitary thyrotrophin in the fetus and neonate

Abstract

Thyrotrophin in individual pituitaries obtained from fetal and prepubertal pigs was quantified by homologous radioimmunoassay (RIA) and heterologous radioreceptor assay (RRA). Relative evolution of pituitary TSH contents and concentrations with age were in good agreement as measured by both assay systems although the quantity of TSH detected by RRA appeared consistently lower than that measured by RIA. Thyrotrophin was first detected in pituitaries of fetal pigs at day 75 of gestation. Thereafter the pituitary content of TSH increased to approximately 45 micrograms/pituitary in the oldest group tested (6 weeks of age). The pituitary TSH concentration rose sharply until birth (114 +/- 1 day post coitum) and thereafter remained increased at a concentration of approximately 400 ng/mg wet weight.

Developmental aspects of prolactin receptor gene expression in fetal and neonatal mice

“…Renal PRL-R is regulated in part by thyroid status, with hypothyroidism reducing and hyperthyroidism increas¬ ing PRL-R (36). Concentrations of TSH rise during gestation and the first week of life (37,38). In our qualitative study, the abundance of mRNA for PRL-R in older fetuses may reflect the continual rise in plasma TSH and subsequently the thyroxine levels.…”

Fetal development and regulation of pituitary cell types

“…In the human fetus, at 28 weeks of gestation, TSH serum levels are consistently elevated above material values Kaplan et al, 1972Kaplan et al, ,1976 and decrease slowly from 32 weeks of gestation. In the pig, the pituitary content and concentration increase regularly during gestation and the first weeks of life (McNamara et al, 1986).…”