HOME

TheInfoList



OR:

Progesterone devices are broadly used in the control of reproductive management in
livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to ani ...
. They work by increasing circulating plasma progesterone levels with the following consequences: # Progesterone suppresses the secretion of
gonadotropin-releasing hormone Gonadotropin-releasing hormone (GnRH) is a releasing hormone responsible for the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. GnRH is a tropic peptide hormone synthesized and released ...
(GnRH) from the
hypothalamus The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus ...
. This is done via a negative feedback to the hypothalamus
neuroendocrine cell Neuroendocrine cells are cells that receive neuronal input (through neurotransmitters released by nerve cells or neurosecretory cells) and, as a consequence of this input, release messenger molecules (hormones) into the blood. In this way they bri ...
s, by inhibition of KiSSpeptin
KiSS1-derived peptide receptor The KiSS1-derived peptide receptor (also known as GPR54 or the Kisspeptin receptor) is a G protein-coupled receptor which binds the peptide hormone kisspeptin (metastin). Kisspeptin is encoded by the metastasis suppressor gene KISS1, which is ex ...
, a protein needed for the release of GnRH. # Low levels of GnRH prevent the emergence of a dominant follicle by reducing the release of LH and FSH hormones. Current follicular waves cease and a new wave emerges 3–5 days after implant. # A dominant follicle develops but there is no
ovulation Ovulation is the release of eggs from the ovaries. In women, this event occurs when the ovarian follicles rupture and release the secondary oocyte ovarian cells. After ovulation, during the luteal phase, the egg will be available to be fertilize ...
as LH release is prevented by suppression of GnRH. # Removal of progesterone device produces a surge of GnRH, generating a pulse of LH that induces ovulation.


Methods of progesterone administration

* Progesterone Releasing Intravaginal Device (PRID). For use in cattle and buffalo. They consist on a stainless spiral coil coated with an inert silicone rubber matrix impregnated in progesterone (1.55g). It has a nylon string that is placed hanging out of the vagina. Tying a loop on the string can facilitate removal of the device in the event the string is shortened to prevent rogue heifers or cows pulling them out. The coil has been commercially available since the mid 1970s. It originally included a capsule of oestradiol valerate. The use of o
estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...
s in the food producing industry in the EU was banned in 1981 because of their suggested
carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive sub ...
ic effects. These substances are still approved for use in the US and many other countries, including Australia, Canada and New Zealand. The coil is licensed to use with fixed time
artificial insemination Artificial insemination is the deliberate introduction of sperm into a female's cervix or uterine cavity for the purpose of achieving a pregnancy through in vivo fertilization by means other than sexual intercourse. It is a fertility treatment ...
* Controlled Internal Drug Release (CIDR). For use in cattle and buffalo. This is a T-shaped silicone elastomer device impregnated in progesterone (1.38g). It has a plastic tail to ease removal. The curve of plasma progesterone in ovariectomised cows fitted with either PRID or CIDR show similar overall levels with a more obvious initial peak in the coil versus the t-shaped device. It has been suggested that this increased level of plasma progesterone is due to optimal contact of the coil with the vaginal walls. Some heifers resent insertion of either device as it involves penetration of the hymen. Device retention is high (around 98%) in both PRID and CIRD. Reasons for loss include overlubrication, pneumovagina, rogue cows pulling out the nylon string or plastic tail and slack cows, large breeds after several calvings.


Other devices

*
Progestogen Progestogens, also sometimes written progestagens or gestagens, are a class of natural or synthetic steroid hormones that bind to and activate the progesterone receptors (PR). Progesterone is the major and most important progestogen in the bod ...
ear implant. * Progestogen impregnated intravaginal sponge. For use mainly in sheep.


Clinical uses of Progesterone devices

*Synchronisation of
oestrus The estrous cycle (, originally ) is the set of recurring physiological changes that are induced by reproductive hormones in most mammalian therian females. Estrous cycles start after sexual maturity in females and are interrupted by anestrou ...
in conjunction with
prostaglandin F2α Prostaglandin F2α (PGF2α in prostanoid nomenclature), pharmaceutically termed carboprost is a naturally occurring prostaglandin used in medicine to induce labor and as an abortifacient. Prostaglandins are lipids throughout the entire body that ...
. The PGF2α injection helps to ensure there is no residual CL and the potentially ovulating follicle has been held primed for less time, enhancing its viability. Protocol: Progesterone for 9 days. PGF2α injection on days 5-8. Serve on observed oestrus or fixed time once at 56h or twice at 48h and 72h. *Induction of oestrus in anoestrus cows. *Treatment of follicular cysts *Persistent ovarian folliclesLópez-Gatius et al. (2001). Persistent ovarian follicles in dairy cows: a therapeutic approach. Theriogenology, 56 (4), p649-59 *Improve
oocyte An oocyte (, ), oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female ...
quality *Reduction of early embryonic death and improved fertility *Treatment of repeat breeders *Increased fertility in embryo transfer protocols


References

{{Reflist Theriogenology Veterinary drugs