Prolactin, Pain, Fertility, and Endometriosis: Understanding the Possible Connection

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Full transcript of the original video, lightly edited for readability.

That is a great point. So let's talk about it. You've probably heard of prolactin before, and most people know it as a hormone that helps women produce breast milk after pregnancy. But what if I told you that's only one small part of what prolactin actually does? Because in endometriosis, prolactin appears to become something completely different. It behaves more like an inflammatory signaling molecule, a cytokine, if you will. One that can influence pain, fertility, blood vessel growth, and immune dysfunction. And possibly even how aggressively the disease behaves.

So let's start to connect some dots. One of the biggest misconceptions about prolactin is that it only comes from the pituitary gland. That's not true. Yes, your pituitary makes prolactin, but immune cells can make prolactin, the uterus can make prolactin, and endometrial tissue can make prolactin. Even inflammatory cells inside the pelvic cavity can release prolactin locally. So now think about endometriosis. You already have chronic inflammation, activated macrophages, elevated IL-6, elevated TNF-alpha, activated immune cells constantly communicating with one another. Those same immune cells can begin producing prolactin inside the inflammatory environment itself.

Now, prolactin isn't simply circulating through the bloodstream. It's being produced exactly where the disease is occurring. And that's where things become dangerous. Because prolactin has receptors throughout the body. Once prolactin binds its receptor, it activates multiple survival pathways. Jack 2 stat 5, MAPK, PI3K, and AKT. If those Names sound familiar. They should, because they're the exact same pathways we've talked about repeatedly in endometriosis. The pathways that help cells survive, avoid apoptosis, continue dividing, continue producing inflammatory proteins, continue resisting normal biological shutdown.

Prolactin doesn't create those pathways. It feeds directly into them. Now let's talk about pain. This is where prolactin becomes incredibly interesting. Most people assume endometriosis hurts because lesions bleed. That's only part of the story. Pain is determined by nerves, specifically how sensitive those nerves become. Normally, your pain fibers require a fairly strong stimulus before they fire. But prolactin lowers that threshold. It makes peripheral nociceptors far easier to activate. In other words, stimuli that normally wouldn't hurt now hurt. Pressure becomes pain.

Normal bowel movement becomes pain. A full bladder becomes pain. Intercourse becomes pain. Even gentle movement can become painful. This process is called peripheral sensitization. The nerve isn't damaged. It's simply been reprogrammed to fire more easily. And prolactin is one of the molecules capable of doing exactly that. But that's not all. Endometriotic lesions don't just inflame tissue. They actually recruit nerves. The lesions release neurotrophic factors that encourage new sensory nerve fibers to grow directly into them. Now, combine that with prolactin, you now have more nerves embedded inside inflammatory tissue that have become dramatically more sensitive.

It's almost like turning up the volume while simultaneously adding more speakers. That's why pain often becomes progressively worse over time. Not because the lesion necessarily becomes much larger, but Because the nervous system becomes increasingly amplified. Now let's move into fertility. High prolactin doesn't just affect the pelvis. It affects the brain, specifically, the hypothalamus. Inside the hypothalamus are neurons that produce kisspeptin. Kisspeptin is one of the most important signals controlling reproduction. It stimulates GnRH. GnRH. Stimulates LH. And FSH. LH. And FSH.

Regulate ovulation. But elevated prolactin suppresses kisspeptin. When kisspeptin drops, GnRH. Signalling weakens. LH. Becomes abnormal. Ovulation becomes less reliable. Some women stop ovulating altogether. Others still ovulate but develop what's called a luteal phase defect. That means the corpus luteum doesn't produce enough progesterone after ovulation. Without adequate progesterone, the uterine lining never fully prepares for implantation. So fertilization may occur, but implantation becomes much less successful, or pregnancy is lost very early. Now, combine that with progesterone resistance already present in endometriosis, and you've created another layer of infertility.

Then we arrive at angiogenesis. Every lesion needs oxygen. Every lesion needs nutrients. Without blood vessels, lesions can't survive. One of prolactin's lesser known roles is promoting vascular signaling. It increases VEGF. Activity. VEGF. Stimulates new blood vessel formation. More blood vessels mean more oxygen, more nutrients, more support for lesion survival. You're literally helping the disease build its own infrastructure. Then comes the immune system. One of the most fascinating things I found is that prolactin doesn't simply respond to inflammation. It helps perpetuate it.

Activated macrophages produce prolactin. Prolactin activates macrophages. Those macrophages produce more inflammatory cytokines like IL-6 and TNF-alpha. Those cytokines recruit additional immune cells, which produce even more prolactin. You've now created a self sustaining inflammatory feedback loop. The disease isn't simply surviving, it's communicating with itself. And perhaps one of the most interesting findings is that prolactin levels actually tend to increase with disease severity. Women with more advanced endometriosis often demonstrate significantly higher prolactin concentrations than women with milder disease. Researchers have even proposed prolactin as part of future biomarker panels because elevated levels correlate with pain severity, infertility, and more advanced disease stages.

Now here's where treatment starts becoming exciting. Instead of only suppressing estrogen, researchers have begun targeting prolactin itself. Drugs like cabergoline and quinagolide, which activate dopamine receptors, reduce prolactin production. But they also do something even more interesting. They interfere with VEGF. Signalling. They reduce angiogenesis. Multiple studies have demonstrated reductions in lesion size, improvements in pain, and preservation of fertility without inducing the hypoestrogenic state caused by many traditional hormonal therapies. Even newer therapies are now being developed that don't lower prolactin. They block the prolactin receptor itself.

In experimental models, blocking the prolactin receptor dramatically reduced inflammation, reduced pain, and prevented lesion establishment altogether. That's remarkable because instead of shutting down the reproductive system, they're targeting one of the diseases communication networks directly. And I think that's the biggest takeaway. Prolactin Isn't just a breastfeeding hormone. In endometriosis, it becomes part of a much larger signaling network. It amplifies inflammation, it sensitizes nerves, promotes angiogenesis, and contributes to infertility. It feeds directly into the survival pathways like MAPK, Jack, stat. The lesion isn't simply responding to hormones, it's exploiting them.

Which is exactly why I keep saying endometriosis isn't just a hormonal disease. It's a signaling disease that manipulates hormones. The immune system, nervous system, and blood vessels are all talking to each other. And prolactin maybe one of the molecules that keeps it alive.