[SOUND] Welcome. We're going to continue talking about lactation, so this course is about lactation, we're finally kind of getting down to what is this thing called lactation. Recall that lactogenesis is the initiation of lactation, the beginning of lactation. How do you get the gland going from a non-lactating state to a lactating state? So functionally, and growth-wise, and so on and so forth. Once lactation's established, we have to keep it going. And so that process is called galactopoiesis, maintenance of lactation. How does that happen? And over the next number of videos, we're going to talk about different kinds of things involved in that. And then a lot of times we think in terms of enhancement of lactation, when lactation function is limiting, whether that's in cattle and lactating women, any species. So, how do we enhance lactation once it's establish, again, both of those terms are galactopoiesis, basically, mean both of those kinds of terms. So let's go to the next slide. And I need to remind you some things we talked about in an earlier video. And then this idea that there's a balance between systemic factors and particularly hormones and prolactins, a key example of that are probably or the most clear cut example, there's a stimulatory to lactation. And then we have local factors which are typically inhibitory. I've introduced to you to this idea of feedback inhibitor of lactation. So these are produced actually by the cells in the tissue. Secreted out into lumen, feed back, and then shut lactation down or lactation functional cells down. These are stimulatory, and again, every time milk is removed, you get the balance or the shifting back and forth between which one is more immediately happening. Remove the milk, you get this spike of prolactin. You've remove the feedback over to lactation. Over time though, this shifts so that this becomes the major factor that the effective prolactin is waned and are pretty much gone, and then accumulation of the feedback over lactation. So, keep in mind that milk removal is very important. Again, we'll talk about that in later videos. Right now, for this video, we want to start focusing on some of the hormones, and kind of going into that, especially we're going to talk a bit about prolactin. So let's go to the next slide. So, how do we know, so many times what we're talking about here is blood concentrations of hormones. Now there are other factors that come into play like receptor numbers and those kinds of things in tissue. But here we're going to focus mostly on blood concentration hormones. And one of the things we need to kind of think a little bit about is, is the blood concentration in that lactating animal limiting? That is to say, if we added more of those hormone, would their milk production go up? Or is not limiting or is it sufficient? So, is it just high enough? And if you add more, you don’t get more milk, but if you decrease that level of blood concentration of that particular hormone, does lactation go down? So, this idea of limiting or sufficient, kind of keep that in the back of our minds as we're thinking about things. Galactogogues is a word that is used for whatever the substance is to promote or enhance lactation. And there's a whole range of galactogogues, factors that will come into play and affect lactation function in an animal, so let's take some look at those. So I've kind of grouped these into several different general groups. Hormones, we'll talk about those very briefly overall, and we'll get into some more details on some of those here in a bit. Drugs that release, that stimulate release of prolactin from the pituitary. A lot of galactogogues, that's what their function seems to be, and we'll get into more details of that here in a moment. Several herbs that people say, well, yeah it looks like they might have galactogogue type activity, and then there's some other kinds of factors, we'll just very briefly touch on that. So let's go to the hormones. Prolactin. The word is prolactin, so it makes sense that that has a lot to do with lactation, and we'll spend a bit of time on that over the next several videos. Growth Hormone, we'll get into Growth Hormone later on. Thyroid hormone, so coming from the thyroid gland. Thyroid stimulating hormone, which comes from pituitary to the thyroid gland, releasing thyroid hormones. And then we also know that TRH or thyroid releasing hormone, thyrotropin releasing hormone, comes from the hypothalamus to the pituitary causing release of TSH, thyroid stimulating hormone, which goes to the thyroid releasing thyroid hormones. So, all these factors, the thyroid certainly comes into play here regardless of what level you're trying to regulate that stimulation of secretion of thyroid hormone. Oxytocin, we know this involves in milk ejection. Also, remember, though, that oxytocin is involved in regulation of prolactin secretion. So back in the Mother Neonate Module, we talked a little bit about regulation of prolactin secretion from the pituitary, and oxytocin is a stimulator, to some degree, of prolactin secretion. Oxytocin doesn't directly impact, other than milk ejection, doesn't directly impact the mammary tissue. But it can also have more of an indirect effect by causing prolactin secretion. So these are just a few of the hormones that we could think of as galactogogues. There is certainly some others. Next slide. So drug is a stimulate release of prolactin from the pituitary, again, prolactin being one of our key examples, one of the most obvious examples of regulation of prolactin. And a lot of these are, what they do is they block specific dopamine receptors. I recall that prolactin secretion from the pituitary is inhibited by factors, dopamine particularly, coming from the hypothalamus and other parts of the brain. And so it's usually suppressed. You release that, so if you block those dopamine receptors, dopamine can't do its job. The pituitary cells then start producing and secreting lots of prolactin. A range of these kinds of things are known and a lot of these come into play in human medicine in various ways. So dopamine antagonists, they antagonize the effect of dopamine. So if they antagonize a negative effect, that means prolactin will be released. Domperidone, metoclopromide are two examples of that that are oftentimes used in human medicine. And sometimes in lactating women that have lactation insufficiency. They're not producing enough milk. Sometimes they will use these drugs to enhance lactation. Antipsychotic drugs, because a lot of times those have the same effects. They're basically dopamine antagonists but they're used for different reasons than lactation, but they have indirect impacts on lactation. Respiridone, Chlorpromazine, Sulpiride, just a few examples of those kinds of drugs, again, oftentimes used in human medicine that directly or indirectly will impact lactation. And so we can think of those as galactogogues. Go to the next slide where we're thinking about herbs. So, then there's a big long list of herbs that have been ascribed, have galactogogue-type activity ascribed to them. I just listed four of them here, blessed thistle, milk thistle, fennel, fenugreek. To be very honest with you, there's not a lot of really good data of experimental data at any rate that demonstrates that these have galactogogue activities. Lot of anecdotal data, or a lot of anecdotes that say, yes, I took that, I had, I wasn't lactating very well, again, a lot of times in lactating women. And I took advantage of blessed thistle, and yes, my milk production increased. Again, not a lot of scientific, really hard core experimental work that demonstrates these things, so we really don't know, first of all, do they really work? And then, secondly, if they do, then how they work? Other factors that are sometimes have galactogogue-type activity ascribed to them, a wide range of those kinds of things. And I don't really want to spend some time going over those now. These are the, typically, the key things that we talk about, think about hormones, those kinds of factors that are regulating prolactin secretion in particularly. And then, sometimes we talk a little bit about herbs as being galactogogues. [SOUND]
