Biomedical subjects

J P Bouquin

Publications and source records attributed to J P Bouquin.

3 recordsLinked to original sources

PubMed1988

Changes in the cAMP synthesis by fetal thyroid during the 5 last days of the intrauterine life in the rat.

The cAMP synthesis by fetal rat thyroids is stimulated in vitro by thyrotropin (TSH) or forskolin during the 5 last days of intrauterine life. The effects are TSH- or forskolin-dose-dependent with equal responses to 20 mIU.ml-1 TSH or to 1 microM forskolin. The magnitude of the responses to TSH or to forskolin decreases significantly as the fetus is ageing. Since forskolin effects bypass hormone receptors, the adenylate cyclase activity can be concluded to decrease during the end of gestation probably in relation with thyroid iodine accumulation. The responses to TSH and forskolin becoming synergic between 19 1/2 and 21 1/2 days indicate modifications of adenylate cyclase properties probably related to some maturation of the enzyme.

Animals↗

PubMed1986

Fetal hypophysis as the main source of serum TSH in fetal rat.

Decapitation performed at days 17-18 leads to a drastic drop (82%) in blood TSH of 19 and 21-day-old rat fetuses below the mother's level. 125I-TSH injected at 21 days into the mother's bloodstream is not found in fetal blood. The fetal hypophysis is the main source of fetal plasmatic TSH.

Animals↗

PubMed1985

Thyrotropic hormone and thyroidal function initiation in fetal rat.

In rat fetus thyrotropic hormone (TSH) is present in the blood as early as day 16 and reaches maximum on day 18. On day 21, TSH level falls off to an intermediate value. Thyroxine is detected in the plasma of fetuses from day 18; the subsequent increase in T4 concentration until day 21, probably generates the negative feedback controlling TSH secretion. The observed increase and maximum in plasma TSH are concomitant with the highest concentrations of cAMP in the thyroid. There may be a causal relationship behind this concomitance since TSH stimulates in vitro the accumulation of cAMP in explanted thyroid from 17 days-old fetuses. The implications of these findings on the role of TSH in the developing rat thyroid are discussed.

Animals↗