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Male Hormones 101

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>> Hi there. I'm Dr. Susie Gronski. And I'm so glad to be here with you today. I'm a doctor of physical therapy and a certified pelvic rehabilitation practitioner specializing in men's holistic pelvic health and lifestyle medicine. I've been focused on pelvic health for over five years and specializing in male pelvic health for the last three years. Now I know what you are thinking, "How did I ever get involved in exploring the 'down below'?" There's a growing need to help men suffering with pelvic pain, and my mission is to help them get their lives back. In fact, I've even written a book about this. But enough about me, let's get started. In this lecture, you are going to learn all about the guys, hormones that is. Yes, even men have their fare share of hormone fluctuations that can seriously impact brain, muscles, cognitive function, mood, and sexual function. You're going to learn about the key players involved in male sexual health and wellbeing. So what are we waiting for? Let's get to know down below. To get started, let's review the function and the role of androgens. Androgens are steroid hormones produced by the testes and adrenal cortex that help sustain and maintain male sexual characteristics. Androgens are needed to sustain sexual reproductive health. The four major androgens produced by men include testosterone, this is the most abundant sex steroid, and it's produced in Leydig cells of the testes, dehydroepiandrosterone, DHEA, a hormone secreted by the adrenal glands, dihydrotestosterone, DHT, this is the most important and active hormone involved in genital tissue development, but it also plays a minor role in male sexual desire, and lastly, androstenedione which is produced in the testes and the adrenal cortex. It has effects on estrogen and testosterone levels. Androgens have two effects on the body, androgenic and anabolic. Androgenic effects are responsible for the development of masculine characteristics that are usually seen after puberty and anabolic effects are the effects of androgens that promote the growth of muscle, hair, and bone. So for example, when you hear an athlete's been taking anabolic steroids, they're usually taking the androgen testosterone to build more muscle, power, and stamina. Of course, it's worth saying that any synthetic form to boost skeletal muscle formation and power doesn't come without undesirable and dangerous side effects. Androgen receptors are also found in the brain with distinct areas responsible for the male sexual experience. I'm going to do a quick run-through of the most important areas of the brain where androgen receptors are located with a brief description of each. This will seem like a ton of info, so don't worry about memorizing all of this. Ready? Temporal lobe which is responsible for speech, hearing, memory, and emotional response. The preoptic hypothalamus, the region of the hypothalamus that's related to sexual behavior. Hypothalamus, the part of the brain that receives messages from the nervous system to maintain balance within the endocrine system. The hypothalamus is crucial for maintaining balance in the entire body by regulating heart rate, respiratory rate, temperature, sleep patterns, blood pressure, and fluid balance. The amygdala, the integrating center in the brain for processing emotional and arousing stimuli such as fear. The midbrain, the part of the brainstem that's associated with vision, hearing, motor control, alertness, and temperature regulation. Frontal and prefrontal cortex which are responsible for emotional drive, motivation, impulse control, planning, reasoning skills, mood, and activating gross and fine motor control. The cingulate gyrus is an important part of the limbic system which is involved in emotion, memory, and learning. You can see how important androgens are as we just began to appreciate the vital role that reproductive hormones have on brain function and overall health and wellbeing. So you may be wondering, "Where are these androgens produced?" Androgens are made from their precursor cholesterol and produced in the testes and adrenals. Androgen production and secretion is controlled by luteinizing hormone, LH, and follicle stimulating hormone, FSH, which come from the anterior pituitary. You'll recall from the beginning of the course that the anterior pituitary is part of the pituitary gland that makes and releases hormones. Now I'm going to break down the male sex hormone pathway for you. But don't worry if you get a brain freeze. I know I did when I first started learning about the complex life of hormones. So stay with me on this one. The hypothalamus secretes gonadotropin-releasing hormone, GNRH, which stimulates the anterior pituitary gland to produce LH and FSH. LH then has the job of waking up the Leydig cells which are found in the interstitial cells of the testes to produce testosterone. LH pretty much knocks on the Leydig cell's door to say, "Hey, we're getting low on T, wake up." Leydig cells get to work by producing testosterone which is then released into the bloodstream carried by a sex hormone binding globulin. This is a protein produced by the liver that binds to testosterone to transport it through the blood to various targeted tissues in the body including muscle, bone, brain, and genital organs. Hello, sex drive. FSH's job is to stimulate Sertoli cells found in the seminiferous tubules of the testes which are responsible for making sperm. But for all this to happen, the body first needs cholesterol to be converted into pregnenolone, and then into DHEA, and finally into androstenedione which are all precursors for the production of testosterone, estradiol, and DHT, which is the most active form of androgen. Wait a second, did I just say estradiol? Yes, men produce estrogen too. Aromatase, an adrenal enzyme converts circulating testosterone to estrogen. It acts locally and is metabolized in tissue, mostly adipose tissue, AKA fat, but it's also found in the testes, sperm, bone, and cartilage. For guys who carry more weight around their hips and belly, this could seriously affect levels of testosterone production. Next on the agenda is andropause. You know, just like how women go through menopause. Does male menopause exist? Andropause otherwise known as late-onset hypogonadism, LOH, is actually rare, occurring in about 2% of the male population according to a newly conducted study in the New England Journal of Medicine, but it does exist. Suggested causes of andropause include a decline in the function of both the Leydig cells and hypothalamic-pituitary axis, an increase in sex hormone-binding globulin, SHBG, which increases with age and leads to less free testosterone. This refers to unattached testosterone that's hanging out in the blood stream. And lastly, an increase in excess adipose tissue. Recall that aromatase which converts testosterone to estrogen is typically found in adipose tissue. A combination of clinical symptoms and serum T levels are both needed to confirm a diagnosis of andropause. However, it's worth noting that laboratory references and ranges are not individually specific. For example, there are men who have low T according to the tests but don't have any symptoms. The most common sexual symptoms associated with lower total and free T levels are decreased frequency of morning erections, decreased frequency of sexual thoughts, and erectile dysfunction. You might be asking yourself, "What are normal T levels?" Well, there's no straight answer for that. Testosterone levels typically plateau around 30 years old and vary per individual. It's common for T levels to then decrease 1% to 2% per year from baseline. But when it comes to male sexual function, there are other hormones at play to make the magic happen, wink, wink, like oxytocin and prolactin. Wait a second, aren't those female hormones? You're right, they are female hormones, but men have them too. The impact of these hormones only recently has been studied to show their effect on erectile function and libido. So let's go ahead and see how oxytocin and prolactin impact male sexual health. Oxytocin is a hormone released by the posterior pituitary gland. In women, it regulates milk production, uterine contractility, and modulates the stress response. In men, the actual physiological impact of oxytocin is unclear. Animal studies have shown oxytocin to play a direct role in erectile function by increasing dopamine which is a neurotransmitter responsible for stimulating the reward and pleasure centers of the brain including sexual activity. It also has been shown to stimulate the activation of nitric oxide which helps increase blood flow to erectile tissue. Prolactin is a hormone typically recognized in females for the production of milk. For men, prolactin has been gaining some attention as well. Prolactin plays an important role in regulating male sexual desire, and things can go awry when there's too much of it because this can inhibit dopamine receptors in the brain. Hyperprolactinemia, which is a fancy word for a condition where too much prolactin is produced, can inversely impact dopamine receptors in the preoptic hypothalamus which for men can result in decreased testosterone levels, low libido, and decreased sexual arousal. Like oxytocin, further studies are needed to truly understand the impacts of prolactin on male sexual function. So the next time you go on a date and feel butterflies, know that oxytocin is pulsing through your bloodstream to help you fall in love and pair up. You might be asking yourself, "Well, what about thyroid hormones?" Thyroid hormones affect every cell in your body, including reproductive health. Some studies have suggested that hypothyroidism is associated with low libido in men by increasing prolactin levels. We also know that thyroid hormones directly impact serotonin production and serotonin receptors are mostly found in the frontal lobe. As we recall, the frontal lobe is a part of the brain where androgen receptors flourish. This is why when you're depressed, sad, anxious, or angry, feeling sexy is not that easy. Okay, now it's time to recap all of this scientific information. Remember, the main male androgens are testosterone, DHEA, DHT, and andro. There are many receptor sites for these hormones that influence cognitive function, mood, sexual and musculoskeletal health. Andropause is rare, occurring in only 2% of the male population. Hormone testing alone is not valid enough to determine andropause as laboratory tests have very large reference ranges and aren't individually specific. Testosterone level fluctuations are multifactorial. Other hormones like prolactin and oxytocin play an important role in male sexual health and function too. All of these hormones are dependent on the function and health of the entire body. They work together to maintain optimal health. If one doesn't play so nice, other systems have to work harder, creating an imbalance which will disrupt the production of reproductive hormones. You'll start putting all the pieces together in the next lecture when we discuss the impact that stress has on the male reproductive hormones so don't sweat it if you're scratching your head, trying to figure this all out, it's completely normal. I've included a male hormone flowchart to help you digest all of this information. If you have any questions and still find yourself scratching your head, the Education Team is available in the Facebook group to mentor you and answer any questions you have. Thanks so much for watching, and I look forward to seeing you in the next lecture.

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Duration: 13 minutes and 20 seconds
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Language: English
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Posted by: ninaz on Mar 31, 2018

Male Hormones 101

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