Phytoestrogen

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Lactation Biology

11 classificações

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University of Illinois at Urbana-Champaign

Lactation Biology

11 classificações

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.

Na lição

Module 8: Atypical Lactation

We typically assume that development of the mammary gland and production of milk are closely regulated by and are coordinated with the reproductive functioning of the animal. Most often that is true. From the knowledge gained from other modules in this course, it is clear that mammary gland development and lactogenesis are heavily regulated by hormones. As it turns out, the presence of mammary gland-regulating hormones is not always directly associated with the reproductive status of the animal. If the hormone activity is present, regardless of its source, it may impact mammary gland development and function. The series of videos in this module presents an overview of what we are calling atypical lactation. That is when the mammary gland undergoes development and lactation in the absence of the usual physiological cues that we associate with the process, such as an animal giving birth.

Induced Lactation11:41

Phytoestrogen7:04

Zearalenone7:05

Elevated Prolactin14:23

Relactation, Allosucking, Communal Nursing12:46

Lactation in Males15:34

Conheça os instrutores

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

[SOUND] So here's some examples

of where elevated estrogen might

be coming from internally.

So again, our two unusual situations are Cystic ovaries and particularly,

Ovarian tumors.

Let's think about where are there might be some external sources of estrogen so

to everyone talk about very briefly your files and selling them to look at

this is a wide range of kinds of compounds coming from the wide range of plants.

So a diverse group of plant-derived compounds that have estrogenic activity.

These were discovered back in the 1930s, so

a lot is known about them at this point.

Structural similarities, so these things, many of these compounds have structural

similarities to estradiol, which is kind of the major estrogen.

That has an impact in mammals.

And the structural similarity actually allows them to bind to estrogen receptors

and this is how they have one type of function or another.

Different general types of these.

Isoflavones, coumestans and a whole wide range of these kind of compounds.

The key to these though in terms of thinking about mammary development is

that they are fairly weak estrogens.

So 1/1000 to 1/10,000 times as potent as estradiol 17Beta.

Again estradiol 17Beta being like the most potent type of

estrogen in terms of the kinds of functions that we're talking about.

So they're fairly weak.

They also preferentially bind beta estrogen receptors,

versus the alpha receptors, so it depends which tissue you're talking about.

A wide range of kinds of things will come into play as to whether these are actually

having an impact on the mammary tissue.

Let's go to the next slide.

So as we think about this because they are coming from plants, again a wide range of,

these are found in a wide range of plants species especially legumes.

So beans, soybeans, alfalfa, clover, things like that,

a lot of those kinds of types of agronomic crops that we use for animals.

But they're also found in grasses.

Fruits, just a wide range of plant species have some sort of estrogenic or

potentially have some sort of estrogenic activity.

Components that have estrogenic activity.

Plant strains.

Different kinds of strains of plants may have more or less.

Growing conditions can impact the concentration of phytoestrogens in

the plant.

The quantity ingested obviously is going to impact potentially the animal.

I call it animal metabolism here because a lot of these things, once they're

ingested, they circulate through the body they're actually converted into

metabolized into and some other component which may be more or less active.

So it's not just in the plant but

also helps metabolize an animal may impact that.

Ratios a different kinds of plants have several different phytoestrogens so

what's the ratio is a different ones and how the biological activity.

And then tissue sensitivity that gets back to the burning to the beta

receptor versus alpha receptor.

A wild wide range of this kind of things.

the key to this though is again they are fairly their

potency are very low compared to estrodial.

And so what a lot of times we find is, that the amount of estrogen,

estradiol in the animal is high enough that it really overshadows,

it doesn't allow these things to have an impact, particularly on the mammary gland.

We can find such situations where it does have an impact, and certainly the original

observations of these, the original characterization of phytoestrogens.

Done in Australia back in the 1940s where they were

grazing sheep on something called subterranean clover.

And the sheep were grazing.

This is basically all they were eating and

over a period of time it had very high levels of phytoestrogens.

They realized not only the animals were infertile,

they had a lot of reproductive issues.

Well they also started developing mammary glands even though they were not pregnant.

That's a situation were we're getting very very high levels of phytoestrogren

over a period of time and causing development of the mammary gland.

Let's go to the next slide.

But a lot of the times what we find is that experimentally,

the way we can characterize these phytoestrogens is

through taking out the internal source of estrogen.

So ovariectomized.

So this is an example of the effects of genistein.

Genistein is the major phytoestrogen in say soybeans and ovariectomized gilts,

see we're looking at the uterine horns here, not the mammary gland.

Take a look at the uterus.

This is an ovariectomized animal.

So pretty much be like an animal that you'd see prior to puberty.

This is estrogen treated, okay?

Not genistein treated, this is estrogen treated.

And you can see the massive growth of the two uterine horns here.

Again these gilts compared to the non-treated and

genistein treated would be kind of in between.

In terms of the, I didn't have a picture of the genistein ones here but

it kind of be in between here, but clearly much bigger than, much more developed.

So then the ovariectomized one without anything without any

estrogen or genistein.

The key is that the uterus of the pig is extremely sensitive to estrogen.

So that's why you get the massive growth of the uterine horns here.

If we look at the mammary gland in these same kinds of animals,

ovariectomized, we see the base of the nipple.

The pink part is the,

the stained is the kind of the collagenous tissue at the base of the nipple.

The nipple would be up here.

Genistein, really only see a little bit of development of lobules and LVI compared to

when treated with estrogen, where we see a lot more of the lobules and LVI.

The lobules being formed in this tissues, so again the genistein treatment,

even at the level we were giving, was kind of in between.

So it's estrogenic but

you're not getting massive mammary gland development with the way this was done.

This was only injected for 15 days or something like that.

So clearly some tissues are much more reactive,

responsive, than the mammary gland in this particular case.

So that gives you just one example of thinking about vital estrogens.

Very very effective in ovariectomized animal when we take out

the internal source of estrogen.

Again it just depends upon the animal depends upon so

many circumstances as to whether it's going to have an impact on the mammary

gland when the animal is intact and there's endogenous estrogen.

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