The Biosynthesis of Prolactin | SpringerLink

To determine whether PRL affects the synthesis of specific luteal protein(s), corpora lutea were obtained from rats hypophysectomized on day 3 of pregnancy and then treated with or without PRL (125µg x 2/day) for 4 days.

04/01/2018 · The Biosynthesis of Prolactin

Leptin Affects Prolactin Action on Milk Protein and Fat Synthesis in the Bovine Mammary Gland

Prolactin - Colorado State University

The rates of synthesis and release of growth hormone (GH), prolactin, and whole protein of the rat anterior pituitary were determined using an method.
1. Thyroidectomy caused a marked decrease in both synthesis and release of GH. Decreased synthesis was restored by a single injection of T3 (20μg/100g body weight) within 12hr. Decreased GH release was also increased gradually by T3 injection. The percentage release of GH was increased by thyroidectomy and the increase was depressed by T3 injection.
2. Prolactin synthesis was increased by thyroidectomy, and the increased synthesis was suppressed as early as 3 hr after T3 injection. Prolactin release was not affected by thyroidectomy. The percentage release decreased significantly after thyroidectomy.
3. Whole protein synthesis was increased by thyroidectomy and the increase was suppressed by T3 injection. The whole protein release and the percentage release were not influenced by thyroidectomy and decreased significantly within 3 hr after T3 injection.
4. Added , T3 had no effect on synthesis of whole pituitary protein, but whole protein release was clearly suppressed at concentrations as low as 10-7m.
These results indicated that thyroid hormone stimulated GH synthetic processes and depressed GH release processes. Prolactin synthetic processes were depressed by thyroid hormone. The mechanisms of the thyroid hormone action and the physiological significance of the facts observed are discussed.

Effects of prostaglandins on prolactin and growth …

In summary, the results of this investigation demonstrate that PRL substantially down-regulates the expression of the abundant 37, 000 MW protein(s) in the corpus luteum.


Prolactin: Synthesis, Fate and Actions | SpringerLink

The synthesis of anterior pituitary proteins was examined in a double label experiment in which pituitaries from ovariectomized, female rats were incubated with [14C]leucine and pituitaries from rats receiving estradiol injections were incubated with [3H]leucine.

stimulates the release of prolactin from the pituitary

This 37K protein, which is remarkably regulated by PRL, can serve as a marker for both PRL action in the corpus luteum as well as luteal regression.AB - Although it is well established that PRL is essential for luteal cell steroidogenesis and growth in the rat, its exact mechanism of action remains unknown.

Endocrine System - Hormones Flashcards | Quizlet

Human is synthesised in and secreted from lactotroph cells in the anterior pituitary. These cells constitute about 15-25% of functioning anterior pituitary cells. The lactotrophs differ from the other pituitary cells in that they have a high basal secretory activity and secretion is mainly under a tonic inhibition by hypothalamic dopamine (DA). DA reaches
the pituitary via the hypothalamic-pituitary portal system and inhibits by binding to type 2 dopaminergic (D2) receptors on the lactotrophs, leading to a rapid suppression of release from secretory vesicles, inhibition of gene expression and lactotroph proliferation. This mechanism is the rationale for treating patients suffering from hyperprolactinemia with DA agonists. In addition, other potential inhibiting factors on release are somatostatin and γ-aminobutyric acid (GABA). Furthermore, exerts a negative feedback on its own release, by stimulating hypothalamic DA synthesis. Although the control of secretion is mainly inhibitory, there are several known -releasing factors, including thyreotropinreleasing hormone (TRH), vasoactive intestinal polypeptide (VIP), oxytocin, endothelin and estrogens. Moreover, estrogens activate secondary responses that may influence gene transcription. Indeed estrogens inhibit dopaminergic hypothalamic activity and upregulate receptors. Furthermore, secretion is increased by different forms of stressors. A summary of the regulation of secretion is presented in Figure 3. In humans, is secreted episodically during the day with the highest concentrations occurring at sleep ().

Prolactin (PRL) Growth hormone ..

The synthesis of anterior pituitary proteins was examined in a double label experiment in which pituitaries from ovariectomized, female rats were incubated with [14C]leucine and pituitaries from rats receiving estradiol injections were incubated with [3H]leucine.