Overview of the Brain, Hormones and Neurotransmitters: PACER Integrative Behavioral Health

Hey there, everybody, and welcome to the overview of the brain hormones and neurotransmitters. This is part of the PACER Integrative Behavioral Health Series. I am your host, Dr. Donnellice Snipes. In this video, we're going to review parts of the brain and get a general understanding of the most important hormones and neurotransmitters as they relate to cognitive and mood functioning. Let's start with the limbic system. Your limbic system is responsible for behavioral and emotional processes, so it's a big deal. The limbic system and the frontal cortex have been implicated in nearly every mental and behavioral disorder due to their influence on hormones and neurotransmitters which impact your appetite, your gut motility, your gut health, your attention, your concentration, your energy, your heart rate, whether you're impulsive or not. Inflammation, mood, pain tolerance, respiration, libido, sleep, and the list goes on. So the limbic system is really important because it helps regulate the hormones and neurotransmitters that make all of those things happen. One part of the limbic system is called the hypothalamus, and we've talked about it before in terms of the hypothalamic pituitary adrenal axis. But the hypothalamus is also involved in a whole bunch of other things. The hypothalamus receives input, for example, from the vagus nerve, which connects your gut to your brain, and it modulates something called the gut brain axis. Now, you will learn, if you didn't already know, that a large proportion of your neurotransmitters are actually made in your gut. So if the vagus nerve tells the brain that something's a miss inside the body, then that is going to trigger the HPA axis activation. The vagus nerve is the main component of the parasympathetic nervous system, which controls mood, immune response and inflammation, digestion, and heart rate. It establishes one of the connections between the brain and the gastrointestinal tract and sends information to the brain about the health and the state of your inner organs and just your general physical health. Vagal tone is correlated with the ability to regulate stress responses and can be influenced by breathing. When you slow your breathing, it triggers the rest and digest. It tamps down that HPA axis. When you breathe more quickly, it triggers potentially the fight or flight reaction. So the way your vagus nerve is responding is important. Vagal tone can actually be improved, just like you can improve the tone of your muscles. The vagal tone can be improved through meditation and Yoga, which assists people in learning how to regulate their breathing. And when they learn how to regulate their breathing, they are one step closer to being able to more effectively regulate their stress, their mood and anxiety symptoms. The hypothalamus also has one of the highest densities of cytokine receptors, which are stimulated by the HPA axis. Now remember, there are pro inflammatory cytokines, the ones that cause inflammation in order to theoretically help the body heal or get the immune system to attack invaders. And then there are anti inflammatory cytokines. The hypothalamus also interacts with the pituitary gland, that p and the HP whatever axes to influence the endocrine system. It does this. The hypothalamus and the pituitary gland kind of team up to form the HPA or the hypothalamic pituitary adrenal axis. So the hypothalamus and pituitary act on the adrenal glands. And we know the adrenal glands in part produce adrenaline. The hypothalamus and pituitary also work together on the thyroid glands, and that is called the HPT axis. And the hypothalamus and pituitary work together on the gonads. So you have the HPG axis. Now, the HPA axis influences the HPT and the HPG axes, but the hypothalamus, those axes also can work independently of one another. The hypothalamic neurons originate in the nose and respond to pheromones as well as other scents by sending a signal to the pituitary gland that communicates with the adrenal glands, the gonads and the thyroids. One way you can think about this is, you know, pheromones tend to be are the chemicals that we put off that stimulate oxytocin and attraction. And some of those things, you really often don't smell those, but your nose picks them up, the hypothalamic neurons picks them up, and then it sends that message to the pituitary gland. And if they are, you know, positive pheromones, if it's a good mix, then it'll communicate with the gonads to say, okay, let's increase libido. So you can see how it's a really interesting system. The hypothalamus also synthesizes vasopressin and oxytocin, which are both chemicals that are involved in bonding and social behavior. We need that hypothalamus to be healthy. And when it's not healthy, it can cause a whole host of problems. Another part of the limbic system is the amygdala, and I'm sure you've heard about this if you work with patients with ptsd. The amygdala is one of the more primitive areas of the brain and is acutely involved in fear processing and initiation of the fear response. If the amygdala receives information that there's a threat, it will trigger that, you know, a cascade effect. It'll send a signal to the hypothalamus, to the HPA axis, to trigger that fight orf flight reaction. The amygdala plays a primary role in processing memories and the formation and storage of memories associated with emotional events and responses, including fear, anxiety, and aggression. So the amygdala is the part of the brain that helps you remember things that could be dangerous to you. The amygdala is not really involved if it's a pleasurable memory, it's involved in fear conditioning. The amygdala can be overactive in people with anxiety or ptsd, and that is something, for example, that they have hypothesized that treatments like EMDR may assist the person with addressing. Now, the hippocampus, not we just talked about the hypothalamus. Now we're going to talk about the hippocampus. The hippocampus is connected to the amygdala and assists with learning and emotional memory formation. The thalamus is a relay station of sorts, involved in sensory processing and adapting cognitive maps. Now, we've talked about schema or cognitive maps before, and the thalamus is part of the brain that is involved in taking in new information, comparing it to what we know, and modifying those schema or cognitive maps to, to best protect the person involved. The thalamus is also involved in the regulation of circadian rhythms. We need to have a healthy brain in order to have a healthy body system to help have a healthy body factory, so to speak. The pituitary gland is located behind your nose and attached to the hypothalamus. The pituitary gland and the adrenals both synthesize inflammatory cytokines, which amplify and maintain elevated HPA axis activity during chronic inflammation. So in people with autoimmune issues or who are recovering from a particularly severe illness and they've got chronic inflammation, inflammation that goes on for, you know, days and days. It's not just something like, you know, when you bump your head and it's swollen for an hour, that chronic inflammation triggers the HPA axis to stay active because there's a threat, the body factory, the, the organism is injured and that will cause the pituitary gland and adrenals to continue to synthesize inflammatory cytokines. The pituitary gland also influences the release of growth and thyroid hormones, gonadal hormones, estrogen, testosterone, oxytocin, human growth hormone and endorphins. Our pituitary gland, which you saw earlier, is involved in a lot of, it's involved in almost everything the limbic system does because it's the hpa, hpg, HPT axes. The pituitary gland is really important. So, you know, we just, we want to be aware of what the parts of the brain do so we can understand, for example, how it might impact somebody if they've got a tumor in a part of their brain or if they are in a car accident and damage a part of their brain. The adrenal glands are, are the, a part of the HPA axis. The adrenal glands produce your gonadal hormones, your estrogen and your testosterone and cortisol. So we need our adrenal glands to be functioning so we can enact that fight or flight response. They are part of the stress response that produces and releases adrenaline. When adrenaline is released, it causes the blood glucose to spike and noradrenaline, which is norepinephrine, and norepinephrine gives us energy, but it's more known for helping us focus. When we are in that fight or flight state, we need to have energy and we need to stay focused on whatever that threat is in order to get away and keep ourselves safe. The adrenal glands also promote proper cardiovascular function and blood pressure control. Adrenaline and norepinephrine help regulate our, our blood pressure. It helps control blood sugar. When the adrenals are pumping out adrenaline because that HPA axis is activated, then blood sugar is going to go way up. When there, when it's not pumping out the adrenaline, then you're not going to have the significant spikes in blood sugar. The adrenals also assist the body in utilization of carbohydrates, which are sugars for short term energy and fats for long term energy. We only have so much glycogen stored in our muscles. We only have so, so much of a reserve of glucose blood blood sugar to help us with that immediate fight or flight reaction. If it goes on for a long time or for you doing some sort of an endurance activity, then the body will switch over and use fat for that long term endurance type of activity that's going on. Because fats Are a much denser source of energy. The adrenal glands also can help distribute stored fat and promote healthy gastrointestinal functions. Now remember, the vagus nerve connects the gastrointestinal system to the brain. And if you the GI system is not healthy, then it sends warning signals to the brain that, you know, something's offline in the body factory. If the adrenal glands are not functioning properly, then you may start seeing mood problems, for example, because the GI system starts getting out of whack and causing cascade effects. Adrenal glands may develop nodules which can potentially produce excessive amounts of certain hormones, leading to various health issues. And doctors will screen for this. But it is important to recognize if the person is experiencing, for example, high levels of anxiety or sudden extreme depression. It something could be involved with the adrenal glands if they suddenly have more difficulty controlling their blood sugar. You know, it could be related to diabetes and panc, or it could be related to adrenal issues. There are a lot of things that are impacted by the adrenal glands. The thyroid, Remember the hypothalamic pituitary thyroid axis. A lot of us are familiar with the thyroid. It's one of those things that gets blamed when we start gaining weight. We say, oh, I must have hypothyroid. Well, let's talk about this thyroid here. The thyroid uses iodine from the food, food we eat to make the thyroid hormones. In the US they found that a lot of people have started, started to become iodine deficient because they've switched to exclusively sea salt and they're not getting iodine enough iodine from the foods they eat. So this is one of those things that doctors can test for with a simple blood test. If the client that you're working with is, for example, eating exclusively sea salt or non iodized salt and starting to feel sluggish, Some depressive symptoms, you know, that might be one, one thing to look at, especially if they're not taking a multivitamin. The thyroid influences how the body use and uses energy and helps to regulate breathing, heart rate, metabolic rate, muscle strength, menstrual cycles, body temperature and cholesterol levels, to name a few things. Chronic elevation of cortisol. So if that hypothalamic pituitary adrenal axis is regularly activated, chronically activated, then the person may have chronically high levels of cortisol. Chronically high levels of cortisol and thyroid stimulating hormone from that HPA axis. Being hyperactive can result in reduced availability of thyroid hormones and, and Ultimately present symptoms of hypothyroid. In states of hypothyroidism, the person may experience a reduced ability to metabolize cortisol, which unfortunately leads to elevated levels of cortisol. So high levels of cortisol reduce the availability of thyroid hormones, and low thyroid hormones increase cortisol levels. So it's working against itself. And that's important to recognize. And this is one of those areas where we can really talk with people about the importance of stress management and trying to reduce those cortisol levels so their thyroid can function effectively. The gonads, Hypothalamic, pituitary, gonadal axis. The gonads are the sex organs. In males, it's the testes which secrete testosterone, and in females, it's the ovaries which produce estrogen and progesterone. The hypothalamus, remember we talked about that earlier? And the pituitary gland, the HP and the HP axis control how much testosterone the testes produce and secrete, and they also control the levels of estrogen and progesterone. Now, my favorite part is the frontal cortex, and this is not part of the limbic system. But the frontal cortex is the part of the brain that is the last to fully develop. It's responsible for reward, emotion and motivation. It's where we do our higher order thinking and processing. We have impulse control, planning, you know, all of the stuff that goes a little wonky when people have dementia or if they have challenges with adhd. A lot of times they will find that there are problems in the functioning in the frontal cortex. The frontal cortex is involved in higher cognitive processes, or what we call executive functions, such as impulse control, goal directed behaviors, problem solving, planning, and organization. A dysfunctional frontal cortex is related to behavioral disinhibition and deficits in self monitoring. That can be a possible cause of substance use disorders, impulse control disorders, adhd, autism spectrum disorders, and even insomnia. Unfortunately, damage to the frontal cortex is very common, especially due to traumatic brain injury from falls, from football, motor vehicle accidents, or even addictive behaviors. Addictive behaviors. The, the surges of glutamate and dopamine from addictive behaviors, especially during the, when the brain is still forming up until age 24, can be very damaging to the frontal cortex. So it's important to protect the brain. When, for example, you hit your head, you know, your, your brain can bounce around a little bit, but if you hit it hard enough, the fluid that's in there to protect your brain may not be enough. And it can result in damage, you know, bruising of those of that brain tissue. So let's move on to talking about some of the big chemicals. And each one of these neurochemicals and hormones will have its own presentation, but just kind of hit the highlights. So you're getting an overview of what we're going to talk about. Acetylcholine is a neurotransmitter that's involved in muscle control, arousal, attention, memory and motivation. Interestingly, as acetylcholine goes up, serotonin goes down, typically. So if you've got a client who's experiencing depression, it could be that acetylcholine is too high, could be that serotonin is too low. It could be serotonin is too low because of acetylcholine. But there are a whole bunch of other reasons that somebody could be experiencing depressive symptoms. And there are a whole bunch of causes for serotonin to be low. It could be completely independent of acetylcholine. Dopamine has long been called our pleasure chemical, and that's misleading. Endorphins are our pleasure chemical. Dopamine is our motivation chemical. I want to do that again. Neurochemical. Dopamine is involved in reward based learning. When we do something that's pleasurable, dopamine is secreted and it says, let's do that some more. And when we start thinking, thinking about things that have caused, created pleasure before, dopamine is secreted, going, yeah, let's go do that now. So dopamine is involved in motivation, executive functioning, mood, movement, and including things like restless leg syndrome and Parkinson's disease. Dopamine is implicated or dop. Problems with dopamine are implicated in that. People who are experiencing erectile dysfunction may be having problems with their dopamine levels. Dopamine is actually very much tied to energy levels. And you'll notice this if you have people who are on antipsychotic medications, for example, that lower dopamine. People who are on antipsychotics and atypical antipsychotics often are very, very sleepy. So energy is really affected by dopamine levels, cognition. So what you're thinking about psychosis, hallucinations and delusions can be impacted by dopamine levels. And ADHD symptoms are also thought to be related to dopamine. Thinking about motivation and executive functioning. Those can be two problems in adhd and so those are directly related to dopamine. Dopamine most of the time inhibits norepinephrine, regulates insulin, reduces intestinal Motility and improves the immune system. This is not always true, but most of the time it's true. There are always some caveats when we're dealing with humans, but the short version is dopamine is really important. Dopamine is also implicated in depression. If people are feeling apathetic, you know, which means. Can mean not motivated. If they are having trouble focusing and concentrating, if they have a low mood, if they have low energy, those are all symptoms of depression. So they have found in some people, their depression may be caused by low levels of dopamine. Most of the time, when serotonin goes up, dopamine also goes up. So we can't necessarily divorce the two of them. It could be that serotonin's low, but it could be that dopamine is low. This is something that the psychiatrist or the physician will work out with the person. But it's important to understand that these neurochemicals are involved in much more than mood and focus. They're involved in all kinds of bodily processes. And if our bodily processes slow down or speed up, that's going to affect a lot of other things. Norepinephrine is produced in the adrenals. We already talked about that. It helps to regulate circadian rhythms. It is your primary attention and focus. Neurochemical Dopamine says, I want to do that again. And norepinephrine is really helpful with attention and focus. It also is very closely involved with blood pressure regulation and mood. Some of your antidepressants are actually norepinephrine reuptake inhibitors. Unfortunately, too much norepinephrine can cause panic. So some of your antidepressants that are selective serotonin and norepinephrine reuptake inhibitors can cause anxiety and panic in people with depression because their norepinephrine levels were already fine. And increasing norepinephrine levels causes them to feel agitated, anxious, or even panicky. Glutamate is a very basic neurochemical. We don't know a whole lot about it yet. We know that it has receptors throughout the body, and it's the main excitatory neurotransmitter. Unfortunately, it can excite cells to their death, which is called excitotoxicity. When there is too much glutamate being released. And I've used the analogy before of running too hot. But when there's too much glutamate going on, it disrupts memory formation. And that can happen during a trauma, which can be beneficial. But if it lasts for too long, it can actually cause neuronal death. And we see people who have been exposed to chronic stress or who have uncontrolled PTSD often have smaller brains. There's actually reduction in their brain density, brain size, and they suspect a lot of that is due to the excitotoxicity of the glutamate. Glutamate is one of the main chemicals that is secreted, if you remember, when the HPA axis is triggered. So if we can help people regulate their HPA axis, we can help them regulate the amount of glutamate. GABA is the main inhibitory neurotransmitter in adults. In children, it actually acts as an excitatory neurochemical. Go figure. But once the brain is developed, GABA is the main calming neurotransmitter. It's created by breaking down glutamate. So people can have difficulty with GABA because there's not enough glutamate to break down to make gaba. Or there maybe they don't have the minerals and substances necessary to break down sufficient glutamate to break it down into gaba. Or the GABA receptors on the other end may not be working. So there's a lot of reasons people may have deficient levels of neurotransmitters. GABA is considered the main excitatory neurotransmitter in many regions of the brain before the maturation of the glutamatergic synapses. So like I was just saying, until the brain matures, GABA is actually excitatory, but once the brain matures, it is inhibitory. GABA is the neurotransmitter that is acted on by a lot of your anti anxiety medications. So you can imagine that people with developing brains will have a different reaction or could have a significantly different reaction to some of the GABAergic medications than people who are adults. GABA assists in neurogeneration. Well, that's good. Glutamate can cause neurotoxicity. GABA actually assists in neurogeneration and development. It assists in reducing anxiety and fear, hence the slang name that it's our natural anti anxiety medication or our natural Valium. It's produced at relatively high levels in the insulin producing beta cells of the pancreas. If you remember, people who have type 1 diabetes have problems with these beta cells. So it is interesting to note the correlation between anxiety issues and people with diabetes. GABA also helps to suppress inflammation and regulate muscle contraction. When people are experiencing, you know, muscle spasms, sometimes they will be Given a muscle relaxant, which also acts on some of the GABA receptors. Serotonin. This is the one that most people know. Well, maybe most people know dopamine too, but serotonin is the one that's usually blamed for mood disorders. But serotonin is involved in almost literally everything that your body does. Serotonin receptors, like all of the others, are found throughout the body. Serotonin is responsible for mood. Now, when we talk, when you learn more about serotonin, you'll learn that there are multiple types of serotonin receptors. Some serotonin receptors are excitatory, some are inhibitory. But serotonin, either way, is involved in mood. It's involved in energy and glutamate release, respiration, blood pressure, appetite, pain, perception, bone density, memory, learning, cognition, motivation, and dopamine release. Acetylcholine, dopamine and norepinephrine. Norepinephrine release in the frontal cortex and GI motility. So it is really interconnected to a lot of stuff. If serotonin levels are out of balance, the person is going to be having some symptoms of something, and. And that's important to recognize. Serotonin, for example, is like most other neurotransmitters are made from the proteins that we eat, but they require a bunch of different vitamins and mineral minerals to break that protein down and convert it to a neurotransmitter. So people who have a crappy diet may not be making enough serotonin. Like I said earlier, they may not have enough. Enough may not get secreted. Even if they've got plenty in storage, enough may not get secreted. Um, it may get taken up or reabsorbed too quickly. The receptors on the other end may not pay any attention to it, or they may just not have enough. So there are a lot of different reasons serotonin can be low. What we can do with people as behavioral health practitioners is help them do everything they can in, in terms of cognitive and lifestyle modification to support healthy serotonin functioning in their system. Progesterone is one of those gonadal hormones, sex hormones, that we talk about, and it is a building block for testosterone. Who knew? We think of progesterone as a female hormone, but it is actually also a building block for testosterone. It is involved in bone density, blood sugar regulation, libido, mood, estrogen balancing, fat metabolism, energy, thyroid functioning, and the prevention of motor, cognitive, and sensory impairments in both men and women. Progesterone is actually a pretty important chemical, but like all other chemicals, Hormones, neurotransmitters. It's needs to be in a very precise balance to all of the other chemicals, including thyroid chemicals and adrenaline and estrogen and testosterone. Estrogen is in both men and women have estrogen. It's involved in mood regulation, female sex characteristics. Estradiol is one type of estrogen, and in balance with testosterone is important for male sexual functioning. So men really do need to have certain, a certain amount of estradiol for effective sexual functioning. Estrogen does or is known to increase serotonin and the number of serotonin receptors in the brain. It modifies the production and the effects of your endorphins. Remember, those are your pleasure chemicals and works to protect nerves from damage, possibly even serving to stimulate nerve growth. Estrogen gets a bad rap because too much of it can be a problem and is related to certain cancers and related, you know, too much estrogen can also be related to mood issues, but not enough estrogen can also cause a problem. Testosterone is yet another one of your gonadal hormones that's present in both men and women. The HPA axis actually plays a major role in regulating testosterone levels. Testosterone is one of those chemicals that kind of spurs on competitive competitiveness and motivation. In men, it is responsible for the development of male sex characteristics. In women, it is balanced, or the development of male sex characteristics is suppressed by the greater amount of the estrogens and that are in a woman's body. In men, testosterone is the primary hormone and estrogen and progesterone are much lower. Testosterone, like the other gonadal hormones, is also involved in bone density, sexual behavior, mood regulation, the availability of serotonin and energy levels. So we really want to look at testosterone levels. If somebody is reporting that they're having challenges with mood regulation, libido, energy levels, it could be depression, it could be testosterone. It is super easy for a doctor to do a blood test to assess thyroid hormone levels, gonadal hormone levels, vitamin D levels, and rule out any imbalances that may be existing there. It's also important if you're working with people who are on hormonal birth control or hormone replacement therapy. Those hormones may need to be adjusted periodically. So if they start experiencing mood or cognitive symptoms, it's important for them to go back to their doctor and get reassessed. Oxytocin is another hormone in our body. It's commonly known as the bonding hormone. Oxytocin receptors are found throughout the body, including in the amygdala. Remember, the amygdala is where they process Fear. Well, it also has oxytocin receptors that make you want to protect other people. When there's a threat, oxytocin receptors in the amygdala may get activated to, you know, make you protect your children. You know, there's just that. We call it an innate response, but it comes from somewhere. Oxytocin is important in the human sexual response. You know, if we want to bond, then it will be involved in libido. It is involved also in the modulation of the HPA axis by indirectly inhibiting cortisol. So as oxytocin goes up, cortisol indirectly goes down. That's a good thing. That's why they've shown that things like petting an animal and massage can increase oxytocin levels and also decrease cortisol levels. Oxytocin increases positive attitudes and bonding with individuals with similar characteristics. And I thought that was kind of interesting that it doesn't just randomly do it. You're not going to walk out and just want to love everybody. But oxytocin does increase positive attitudes with people you find similar to you. So that was kind of one of those interesting things. Vasopressin is, I believe, our final chemical that we're going to talk about. And it is a hormone that increases the amount of water reabsorbed back into circulation after being filtered through the kidneys. Remember, our kidneys are kind of one of our waste processing centers. So the fluid goes through the kidneys, the kidneys pull out out the waste, and then the water, the purified water that comes out, vasopressin, helps it be reabsorbed into the system. It constricts arterioles, which may increase peripheral vascular resistance and raise blood pressure. That can be good. Sometimes we need that blood pressure kicked up a notch, especially when the HPA axis is activated and it's released directly into the brain from the hypothalamus. There's that diagum hypothalamus again. And is involved in social behavior, sexual motivation, pair bonding, and maternal responses to stress. So vasopressin and oxytocin operate a lot of times in very similar ways. Vasopressin has more of a stimulatory or stimulating effect than oxytocin does. Oxytocin tends to be more calming and, you know, peace and love sort of thing. The human body is extremely complex. Symptoms of mood and cognitive disorders can be caused by a variety of problems in a variety of physiological systems. Cognitions and emotions can trigger the HPA axis and altering the function of internal systems setting off a cascade. Effective treatment of mood and cognitive disorders requires addressing all physiological as well as psychological and environmental issues contributing to neurochemical imbalance.