Prostaglandins (PGs)

Introduction

PGs include PGF2a (important for animal reproduction) and PGE2.
These two are arachidonic acid derivatives (20-C polyunsaturated fatty acids). PG is released from every cell of the body and affects every function of the body.
Source of PGF2a in females: It is released from endometrial glands, ovaries (graffian follicles), myometrium, and placenta are also sources but only during parturition.
Source of PGF2a in males: Seminal vesicles, present in semen. Male camels have no seminal vesicles, so the other source is the prostate gland.

Functions of PGF2a

In males, it is responsible for

  • Sperm metabolism.
  • Smooth muscle contraction (epididymis); involved in ejaculation.
  • It can not be used to increase sperm numbers in natural mating.

In females

  • PGF2a that comes from endometrium causes the lysis of CL.
  • OT triggers the release of PGF2a. This happens only in cyclic animals.
  • PGF2a during parturition causes lysis of CL.
  • It opens/softens or relaxes the cervix.
  • Contraction of myometrium during or after parturition, this contraction of myometrium expels the fetus out.
  • PG in semen causes the contraction of female tubular genitalia for gametes transfer (Oocyte and spermatozoa to the site of fertilization)
Mature CL => OT => Endometrium => PGF2a => Lysis of CL

PGF2a transportation in the body

PGF2a does not go to the systemic circulation. In broad ligament, the uterine vein forms a specific complex with the ovarian artery. PGF2a goes from the uterine vein to the ovarian artery through the local current mechanism. PGF2a is metabolized by the lungs. 90 %  will be metabolized by the lungs in 1st passage. This is why it does not go to the systemic circulation.

Ovulation

Muscles around the ovary cause ovulation.

 Note: We must wear gloves when we inject PGF2a because its size is too small and when it absorbs from the hand surface, it causes contraction of bronchioles, and uterus in human females at any time.

Clinical uses

  • Used for the treatment of persistent CL in the case of pyometra.
  • It is used to shorten the estrus cycle in females. (to have estrus of predictable time).
  • Used in the estrus synchronization protocol.
  • It is used for the treatment of endometritis.
  • It is used for the treatment of open cervix pyometra in bitch (as it causes contraction of uterus).
  • It can be used to cause abortion in all species at some stage of pregnancy (at least early pregnancy).

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