Hormones & Signal Transduction 5 Sections28 LessonsLifetime

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Lecture 01
2 Items
- 1.1
  Introduction to Hormones
- 1.2
  Signal Transduction – Hormones
Signaling and Signal Transduction
7 Items
Hypothalamic & Pituitary Hormones
3 Items
In this section we will discuss the hypothalamic endocrine control on varoius hormones secretin. After that the hormones of the posterior pituitary gland, the antidiuretic hormone and oxytocin, will be discussed individually.
Hormones of the Anterior Pituitary Gland
12 Items
Here we will discuss the Hormones of Anterior Pituitary gland, their secretion, functions and control in various organs
Steroid Hormones
4 Items
This section will be on the steroid hormones, their synthesis, secretion, transport, actions on different organs, mechanism of action of steroid hormones, abnormalities of steroid hormones and their management.

Prolactin – Somatomammotropin

Prolactin (PRL) secreted by lactotropic cells of adenohypophysis under the control of hypothalamus.
Lactotrope hyperplasia is induced by estrogen (during last two trimesters of pregnancy).
Its secretion is primarily controlled by inhibitory effect of dopamine and GABA.
Its release is stimulated by TRH and vasoactive intestinal peptide (VIP).
It controls the initiation and maintenance of lactation.
The Prolactin secretion is pulsatile; highest levels during rapid eye movement sleep and peak serum level occurs between 04:00–06:00 hours.
Prolactin stimulates lactation on estrogen primed breast. It increases synthesis of milk protein and fat.
Hyperprolactinemia is a cause of infertility in females.
Secretion of Prolactin is stimulated by TRH and inhibited by PIF.
The main function of Prolactin is to stimulate mammary growth and the secretion of milk.
It stimulates mRNA synthesis.
This ultimately leads to enlargement of breasts during pregnancy (mammotropic action).
The synthesis of milk proteins such as lactalbumin, & casein takes place after parturition (lactogenic action).
Estrogens, thyroid hormones and glucocorticoids increase the number of prolactin receptors on the mammary cell membrane.
Progesterone has the opposite effect.

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