Changes

===Prolactin (PRL)===

===Prolactin (PRL)===

PRL is a protein that is produced  from the '''Anterior Pituitary''' via '''lactotroph cells'''. In males the target tissues are the testes and the brain whilst in females the target tissue are cells located within the mammary tissues and the corpus luteum in rodents. In the male PRL induces maternal behaviour whilst it also does this in the female together with lactation and ensuring functionality of the corpora lutea in some species.

Prolactin is a protein that is produced  from by the '''anterior pituitary''' via '''lactotroph cells'''. This hormone exerts a stimulatory effect on milk synthesis within the mammary glands. It has also been shown to have some degree of gonadal function in some domestic species and rodents. In birds increased concentrations of prolactin have been linked with brooding behaviours and the associated metabolic changes that birds undergo during brooding.

Prolactin secretion is regulated by the hypothalamus which produces several neurohormones that affect prolactin concentrations. The most important within this is '''dopamine''' (or prolactin inhibitory hormone, PRL-IH) which exerts a totally dominant inhibitory action on prolactin synthesis. The hypothalamic regulation of prolactin secretion is via signals from the central nervous system. Prolactin synthesis is increased when the mother is suckling via a reflex stimulation of the teats. This stimulation reflex reduces the secretion of dopamine and increases the hormone '''prolactin releasing hormone''' (PRL-RH). Once prolactin binds to it's target receptors within the mammary gland cells, it activates an intracellular tyrosine kinase. When this occurs in the developing animal this binding can also cause the differentiation of mammary epithelial cells during pregnancy. The half-life of prolactin is approximately 20mins.

Estradiol can also have an effect on the prolactin producing cells within the anterior pituitary and is responsible for increased concentrations of prolactin in females undergoing puberty and may also contribute to the increased concentrations during late pregnancy.

 

===Oxytocin (OT)===

===Oxytocin (OT)===

OT is a neuropeptide (a octapeptide) which is synthesised in the '''hypothalamus''' and stored in the posterior pituitary. OT can also be synthesised by the corpus luteum. In males the target tissue for OT is smooth muscle within the epididymal tail, ductus deferens and the ampulla. In females OT targets the uterine myometrium and endometrium together with cells of the mammary glands. In the male OT stimulates PGF2α synthesis and facilitates the pre-ejaculatory movement of spermatozoa. In females, OT stimulates uterine motility and the synthesis of PGF2α from the uterus. It also begins milk 'let-down' or ejection.

OT is a neuropeptide (a octapeptide) which is synthesised in the '''hypothalamus''' and stored in the posterior pituitary. OT can also be synthesised by the corpus luteum. In males the target tissue for OT is smooth muscle within the epididymal tail, ductus deferens and the ampulla. In females OT targets the uterine myometrium and endometrium together with cells of the mammary glands. In the male OT stimulates PGF2α synthesis and facilitates the pre-ejaculatory movement of spermatozoa. In females, OT stimulates uterine motility and the synthesis of PGF2α from the uterus. It also begins milk 'let-down' or ejection.