Brief Summary
This video explains how GnRH analogs work to suppress the production of sex hormones, such as estrogen and testosterone, by affecting the hypothalamic-pituitary-gonadal axis. It describes how these medications, initially causing a flare-up of hormone production, ultimately lead to a desensitization of the pituitary gland, reducing hormone output.
- GnRH analogs are used to treat conditions like prostate cancer and endometriosis by reducing sex hormone production.
- Examples of GnRH analogs include goserelin (Zoladex) and leuprorelin (Prostap).
- The medications initially cause a surge in LH and FSH, leading to a temporary increase in sex hormones, followed by a desensitization of the pituitary gland and a reduction in hormone production.
The video introduces GnRH analogs and their use in suppressing the production of sex hormones to treat conditions like prostate cancer and endometriosis. These conditions rely on sex hormones to develop and produce symptoms, making GnRH analogs an effective treatment option. Examples of GnRH analogs include goserelin (brand name Zoladex) and leuprorelin (brand name Prostap).
To understand how GnRH analogs work, it's important to understand the hypothalamic-pituitary-gonadal axis. The hypothalamus produces gonadotropin-releasing hormone (GnRH), which stimulates the anterior pituitary gland to produce LH and FSH. In females, LH and FSH stimulate the development of follicles in the ovaries, which then release estrogen. Estrogen has a negative feedback effect on the hypothalamus and pituitary gland. In males, LH stimulates the testicles to produce testosterone, which also has a negative feedback effect on the hypothalamus and anterior pituitary gland.
GnRH analogs are agonists of the GnRH receptors on the anterior pituitary gland. They bind to these receptors and stimulate the release of LH and FSH, similar to the natural GnRH hormone. However, these medications cause a much more powerful stimulation, leading to a large release of LH and FSH. This results in an initial flare of sex hormones, such as estrogen and testosterone, which can last from a few days to a few weeks. This initial surge can temporarily worsen symptoms of conditions like prostate cancer.
GnRH analogs are administered via subcutaneous or intramuscular injection, slowly releasing the hormone into the body over a period of one to three months, depending on the dose. Continuous stimulation of the GnRH receptors leads to desensitization of these receptors on the anterior pituitary gland. Over time, the pituitary gland reduces its production of LH and FSH, leading to a reduction in estrogen or testosterone production, resulting in hypogonadotropic hypogonadism. The effects of GnRH analogs wear off over time, and the pituitary gland becomes more sensitized to GnRH again. Therefore, repeated doses are necessary to maintain the desired effects.
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Transcript
Full transcript of “How do GnRH analogues work? Zoladex, Prostap and other GnRH analogues”. Click a timestamp to open the video at that moment. Need another video? Use the YouTube transcript generator.
0:04 hi this is tom from zero finals comm I wanted to do a video about gnrh analogs and how we use them to shut down the production of the male and female sex hormones in order to treat conditions like prostate cancer and endometriosis these GnRH analogs are effective in treating these conditions because they rely in some way on the sex hormone to develop and produce their symptoms firstly I give you a couple of examples of these GnRH analogs the first one being user Ellen which is under the brand name of Solid X and the other one is looper Ellen which is under the brand name of Pro step to understand how these men
0:52 you need to have a basic understanding of the hypothalamic pituitary gonadal access in the male and female bodies so here we have a basic diagram showing the hypothalamus the anterior pituitary gland and then the gonads in this case the ovaries the hypothalamus produces gonadotrophins releasing hormone or GnRH and the TN rh stimulates the anterior pituitary gland to produce LH and FSH LH and FSH then stimulate the development of the follicles and the ovaries and the follicles themselves and the ovaries release East region and then estrogen goes on to have a negative feedback effect on the hypothalamus and the
1:40 pituitary gland the system is very similar in males except that LH stimulates the testicles to produce testosterone and this testosterone goes on to have a negative feedback effect on the hypothalamus and the anterior pituitary gland so now let's look at how the GnRH analogues work these medication are agonists of the receptors of gnrh on the anterior pituitary gland so the anterior pituitary gland has receptors that sit and wait for gnrh hormones to come along and stimulate them and it's them that trigger the release of the LHIN FSH or the gonadotropins and these receptors on
2:26 the anterior pituitary gland are the targets for these gnrh agonists so these agonists act exactly like the gnrh hormone and target these receptors and stimulate them to produce LH and FSH the medications cause a very powerful stimulation of these receptors so more powerful than natural and cause a large release of the LH and FSH this causes an initial flare of the sex hormones that causes a rise in East region and testosterone this can last a few days to a few weeks and they can have side effects such as temporarily worsening the symptoms of prostate cancer such as growth of the tumor or the metastasis
3:11 for example causing urinary retention or spinal cord compression the injections are given as a subcutaneous or intramuscular injection and that slowly releases the hormone into the body over a period of time and this could be between a month or three months depending on the dose these gnrh analogues are also good at sticking to the receptors for some time and causing continuous stimulation after continuous stimulation of the GnRH receptors these receptors on the anterior pituitary gland become desensitized to the GnRH hormone so over time the pituitary shuts down its production of LH and FSH
3:56 because it's become so desensitized to the effects of the hormone that it no longer responds at all this leads to a reduction in the production of estrogen or testosterone and so you get something called a hypo gonadotropin ad ISM so this is logan a detroy finn's LH and FSH causing a low output of the hormones from the gonads over time the gnrh analogues will wear off and in the absence of this continuous stimulation the pituitary gland will start to become more sensitized to gnrh again and the whole system will come back online therefore the dose needs to be repeated to maintain these effects so thanks for watching I hope you found
4:42 this video helpful if you did don't forget there's plenty of other resources on the zero to finals website including loads and loads of notes on various different topics that you might cover in medical school with specially made illustrations there's also a whole test section where you can find loads of questions to test your knowledge and see where you're up to in preparation for your exams there's also a blog where I share a lot of my ideas about a career in medicine and tips on how to have success as a doctor and if you want to help me out on YouTube you can always leave me a thumbs up give me a comment or even subscribe to the channel so that you can find out when the next videos are coming out so I'll see you again soon
