Prenatal development of gonadotropin-releasing hormone receptors in the rat anterior pituitary

Journal Article · Wed Jan 31 23:00:00 EST 1990 · Endocrinology; (USA)

DOI:https://doi.org/10.1210/endo-126-2-942· OSTI ID:7027455

Jennes, L ^[1]

---

1. Wright State Univ. School of Medicine, Dayton, OH (USA)

The development of pituitary GnRH receptors was studied in the rat with in vitro and in vivo autoradiography. GnRH receptors were first seen in pituitary primordia of 13-day-old fetuses. The binding was specific and saturable and was abolished in the presence of 10 microM synthetic GnRH. To examine whether GnRH was available to the fetus, amnionic fluid was collected on days E 12-18. RIA analyses showed that GnRH levels in the amnionic fluid were low on days 12 and 13 (0-20 pM/ml) and rose to 225 pM/ml on day E 16 before they declined to 110 pM/ml on fetal day E 18. The highest levels of GnRH in the amnionic fluid on day E 16 coincided with the first appearance of immunoreactive LH cells, as determined by immunohistochemistry. Intravenous injection of 500 microliters amnionic fluid into pentobarbital-anesthetized adult rats caused a transient 40-60% increase in circulating serum LH in the recipient animal. To show that GnRH from the amnionic fluid has access to the developing pituitary, the 125I-labeled GnRH agonist Buserelin was injected into the amnionic fluid of 13-, 14-, and 15-day-old fetuses in the presence or absence of 10 microM unlabeled GnRH. Autoradiographic analysis of the fetal tissue indicated that the labeled GnRH agonist bound to specific receptors in the primordial pituitaries. The results suggest that the pituitary gonadotropes are differentiated before day E 13 because the expression of GnRH receptors is already an indication of cell determination. Since GnRH is present in the amnionic fluid in a biologically active form and can reach the fetal pituitary, it is concluded that GnRH may be an important factor determining the onset LH synthesis, but not the differentiation, of primordial pituitary cells.

• OSTI ID: 7027455
• Journal Information: Endocrinology; (USA), Journal Name: Endocrinology; (USA) Vol. 126:2; ISSN ENDOA; ISSN 0013-7227
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
AUTORADIOGRAPHY
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BODY
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ENDOCRINE GLANDS
FETUSES
GLANDS
GONADOTROPINS
HORMONES
IN VITRO
IN VIVO
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPES
KINETICS
MAMMALS
MEMBRANE PROTEINS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HORMONES
PITUITARY GLAND
PITUITARY HORMONES
PROTEINS
RADIOISOTOPES
RATS
REACTION KINETICS
RECEPTORS
RODENTS
VERTEBRATES