hormones

• GnRH is produced in the hypothalamus. It drives release of LH and FSH from the gonadotrophs in the anterior pituitary gland
• Oxytocin is released from the posterior pituitary gland, placenta and the gonads. It induces uterine contractions for parturition and expulsion of the placenta. It is also involved in the milk ejection reflex and ejaculation.

  Plays a role in maternal, social and sexual behaviour.

  Increases production of prostaglandins
• LH is released from the anterior pituitary gland. In females it stimulates ovulation and the formation of the progesterone secreting luteal cells in the ovary. In males it stimulates the leydig cells of the testes to secrete testosterone.
• FSH is released from the anterior pituitary gland. It promotes the development and maturation of the gametes and the secretion of gonadal hormones. In females it promotes primary follicle growth and oestrogen secretion. In males it stimulates spermatogenesis and acts on the sertoli cells of the testes to release inhibin.
• Activin is released from the anterior pituitary gland. It stimulates FSH synthesis and secretion
• Follistatin is released from the anterior pituitary gland. It inhibits activin, thus impacting FSH production
• Prolactin is released from the anterior pituitary gland. It is involved in milk production, mammary tissue development and parental behaviour.

  Is under the control of the dopamine break
• In reproduction, growth hormone stimulates milk production. It is released from the anterior pituitary gland
• Oestrogen is released from the gonads, adrenal glands and placenta. It is involved in the control of reproduction through:

  • Oestrus cycling
  • Development of secondary sexual characteristics
  • Behaviour - sexual, social, aggressive, parental
  • Inhibits GnRH (except during oestrus)
  • Promotes embryo development
  • Increases uterine contractility prior to parturition
• Progestins are produced in the gonads, adrenal glands and the placenta. They:

  • inhibit GnRH secretion
  • development of secondary sexual characteristics
  • behaviour - sexual, social, aggressive, parental
  • blocks uterine contractility during pregnancy
  • blocks lactation
• Androgens are produced in the gonads, adrenal glands and placenta. They are responsible for development of secondary sexual characteristics and sexual, social, aggressive and parental behaviours
• Inhibin is produced by the gonads. It:

  • inhibits FSH biosynthesis and secretion
  • is also stimulated by FSH in granulosa cells
  • stimulated by androgens

  Secreted from sertoli cells in males
• Relaxin is produced in the female gonads and placenta. It prepares the birth canal for parturition through cervical softening (increases flexibility of cervical ligaments) . Also:

  • relaxes the myometrium to synchronise contractions during birth
  • stimulates mammary tissue development
  • is driven by prostaglandins
• Placental gonadotrophins provide support for, and stimulates, the CL during pregnancy so it doesn't regress.

  Has potent LH like activity and can be used clinically to stimulate ovulation
• Placental lactogens have a similar biological action to prolactin and growth hormone.

  • Promotes foetal growth
  • Promoted development of mammary tissue
  • Promotes lactogenisis
• Prostaglandins produced by the placenta induce myometrial contractions. Also induces cervical softening and drives relaxin production
• Cortisol is produced in the adrenal glands. In reproduction it:

  • Induces parturition
  • Drives foetal maturation
  • Activates the foetal HPA axis at the end of pregnancy to drive oestrogen production from the placenta (inducing contractions)
  • Initiates and maintains lactation
• Aldosterone is produced in the adrenal glands. It ensures proper electrolyte and mineral metabolism during lactation
• Thyroid hormones are produced by principle cells in the thyroid gland. They increase metabolism and drive development of the foetus, especially its nervous system.
• Calcitonin is produced by C cells in the thyroid gland. It decreases plasma calcium levels which is important for calcium homeostasis during lactation or egg laying
• Parathyroid hormone is produced by chief cells in the parathyroid glands. It increases plasma calcium levels which is important for calcium homeostasis during lactation or egg laying
• Insulin is produced in the pancreas and is important in reproduction for glucose metabolism during lactation. It promotes the absorption of glucose from the blood into storage in the liver, fat and skeletal muscle