Prolactin - Other Regulation

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来自 University of Illinois at Urbana-Champaign 的课程

Lactation Biology

5 个评分

University of Illinois at Urbana-Champaign

Lactation Biology

5 个评分

Lactation and especially milk, which is the product of that unique mammalian process, are routinely encountered within our daily lives. Nevertheless, they often are poorly understood by many, even including many who are engaged in the business of producing milk. The overall course goal is to introduce fundamental concepts that form the basis for understanding the biology of lactation, the biology of the mammary gland, and the products of that important physiological process. As a learner in this course, you will be provided with a series of easily understood presentations that collectively will help you build a foundation for greater understanding of lactation. You will be able to engage with other learners so that you can extend your learning beyond the video presentations. Ultimately, you will be able to construct your own mental model for understanding the wide range of topics that relate to the biology of lactation. Upon completion of the course, you will be prepared to expand your knowledge and understanding of lactation from other sources and experiences as you pursue your individual interests. Before you start the course, I suggest that you identify a question or several questions about lactation that you already have on your mind. This could be from your own experiences, something you read about or saw, or something you have wondered about. Write down your question(s) and use that to help you decide how to engage with the content of this course. You might engage with the modules in the order they are presented, or start with a module that is of particular interest to you, or pick and choose modules in any order. I encourage you to engage in all of the types of learning activities that this course has to offer, including but not limited to, the discussion forums, quizzes, peer-review assignments, and concept maps and other learning aids.

从本节课中

Module 5: Mother & Neonate

The peripartum period, the time shortly before, during, and after giving birth, is a time of rapid changes in the mammary gland, the mother, and the neonate. Extensive physiological coordination occurs between the processes leading up to and giving birth, the formation of colostrum, the initiation of lactation in the mammary gland, and the subsequent removal of milk by the neonate. In this module, we explore how the mammary gland changes around the time of giving birth when the gland transitions from a non-lactating to a lactating state. Part of this transition is the production of colostrum, the first mammary secretion produced by the gland after giving birth. Another part of the transition is the changing regulation of mammary gland function from one being driven primarily by hormones associated with pregnancy and parturition to one where milk removal, by the neonate or milking machine, is the driving force in gland function after birth. In this module, we examine some basic characteristics of the neonate, how lactation is initiated (lactogenesis), and the formation and special components of colostrum (immunoglobulins) and their impact on the neonate.

Prolactin - Sources4:36

Prolactin - Control of Secretion5:55

Prolactin - Other Regulation5:26

与讲师见面

Dr. Walter Hurley, PhD
Professor Emeritus
Department of Animal Sciences

[SOUND] So there's one

more factor that I want to

kind of throw in here.

And that is in addition to the things that I've talked about here,

this is this negative inhibitory factors, the dopamine on the lactose,

the releasing factor it looks like, potentially oxytocin.

There's one another key thing, and

that is there seems to be a kind of a feedback loop of prolactin.

It's actually taken back up into the brain and then can stimulate these cells,

the cells in the nuclei to make more prolactin inhibiting factor.

So we have a negative feedback.

Negative feedback loop.

So the more prolactin is produced, the more it gets back here, the more it

stimulates these cells to secrete dopamine to shut down further prolactin.

So it's regulating itself in that sense.

So again it's very, very complex regulatory system for prolactin.

Let's take a look at some of the things that modulate this process that's going on

in the hypothalamus and pituitary gland.

Remember, again dopamine is the inhibitory factor being synthesized and

released by these axons from these cells up in the hypothalamus.

It's negative to negative effector, meaning it shuts down prolactin secretion.

Other things will stimulate prolactin secretion, so

let's look at some of these kinds of modulation.

Estrogen, so particularly during a prepartum surge.

Remember in late pregnancy, estrogen's increasing.

It's getting pretty high.

That actually will modify this system so

that prolactin, the inhibitory factor of these is dampened down.

And so you get a prepartum surge of prolactin,

which is very much involved in lactogenesis.

Suckling, every time the animal suckles or the cow is milked,

the goat's milk whatever the case may be, you get this surge of prolactin.

Again, that's impacting this so the prolactin secretion is increased.

A range of different kinds of drugs and medicines can impact prolactin.

So there is a dopamine antagonist that increased prolactin.

Reserpine is one of those, comes from a plant.

Domperidone is another one that will increase.

That's a drug that's sometimes used in humans, can increase prolactin secretion.

Again, it's modifying the system, it's impacting the effect of the dopamine.

And then we also have other drugs that will decrease prolactin secretion,

so these are dopamine agonists, so

they act like dopamine and shut down prolactin secretions.

So we have bromocriptine is one of those.

Cabergoline is another one.

And there are some other ones that are being used for that as well.

So, a variety of kinds of drugs that are used to either increase prolactin or

decrease prolactin.

And again, they're impacting the system of the prolactin inhibiting factor or

dopamine and how that's impacting or

effecting the secretion of prolactin from the lactotrophs, mammotrophs.

Another one down here we haven't really talked about just mentioned in passing,

is daylight or day length will impact prolactin secretion.

So longer days or more daylight increases prolactin, shorter days or

more darkness, will decrease prolactin.

So let's briefly review what we talked about in terms of prolactin.

Again, it's a major hormone as we think about mammary growth, lactation, etc.

So, again it's created from the lactotrophs in the anterior pituitary.

There are also sources of prolactin like activity in terms of placental lactogen,

coming from the placenta.

A lot of species variability there.

So if you're interested in that, you really kind of have to dig down to each

individual species and look at how that plays out in terms of mammary growth,

mammary development, and lactogenesis, and so on.

And then also, a source of prolactin from the mammary gland itself.

And again,

this is one that we really don't have a lot of tremendous amount of information on

what it's doing in the mammary gland, and how it's impacting the mammary gland.

Prolactin's involved in again, in all stages of mammary development,

lactogenesis, maintenance of lactation the key hormone.

Certainly there are many other hormones involved in all those processes, but

a key hormone in these various processes.

Prolactin secretion pituitary is inhibited by a factor called dopamine or

prolactin inhibiting factor, and it comes from

several nuclei up in the hypothalamus and then released down the pituitary.

One way or the other, there's several mechanisms by which that happens.

It inhibits those lactotrophs from secreting prolactin.

The modulation of this process,

the modulation of the dopamine and how it impacts the lactotrophs

is occurring by a number of mechanisms action of other hormones.

Action of suckling,

action of various kinds of drugs, day length, and a variety of other factors.

So there's a lot of things that go into regulating this particular hormone, and

therefore, those things will one way or

the other, potentially Initially impact lactation as

well as the other functions of prolactin in terms of reproduction and so on.

[SOUND]

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