0:08 all right Ninja nerds so what we're
0:09 going to do in this video is we're going
0:12 to talk about prolactin okay so if you
0:13 guys remember from the hypothalamic
0:16 pituitary axis video we discussed what
0:17 were the stimuli and what were some of
0:19 the inhibiting factors for prolactin
0:20 we're going to get into a little bit
0:21 more detail on that and look at its
0:24 effect on target organs all right so
0:26 first off what is the function of
0:28 prolactin prolactin is designed to be
0:30 able to promote what's called lactation
0:33 right or milk production so it's working
0:34 on the actual mamory gland so if you
0:37 look here we have a mamory gland right a
0:39 mamory gland is really just a modified
0:41 aicr gland which is a type of sweat
0:44 gland right so it's a modified aicr
0:46 gland and what it's designed to do is
0:47 it's designed to be able to produce milk
0:49 if you look here at the actual mammory
0:52 gland you see these blue tube like
0:54 structures right there these are called
0:56 your lobules and your lobules are
0:58 consisting of these cells which are
1:00 called your alveolar cells and those
1:01 alveolar cells are the cells that are
1:03 making milk and we'll zoom in on one to
1:05 look at its action if you look in
1:08 between there's all this interlobar
1:10 connective tissue and then uh at the end
1:11 of the interlobar connective tissue
1:13 there's these little ligaments called
1:14 suspensories ligaments or Cooper
1:17 ligaments and they anchor the breast to
1:19 the actual posterior wall right so the
1:20 pectoralis Mage and some of the actual
1:22 tissue behind that then you got some
1:25 superficial fascia and you got these
1:27 little tubes draining these actual
1:29 glands here what are these tubes here
1:30 called these tubes are called the
1:33 lactiferous Ducks and then there's
1:34 actually a dilation of the lactiferous
1:36 ducts just behind the nipple and that's
1:38 called the lactiferous sinus and then
1:39 again here's the nipple and then there's
1:42 a little bit of areola around that okay
1:43 so that's our mamry gland and again what
1:45 does prolactin do it's going to
1:48 stimulate these alveolar glands to start
1:50 producing milk and we'll take a look at
1:51 that before we do that though let's see
1:53 what's the actual stimuli and inhibiting
1:54 factors for
1:56 prolactin okay so if we look here we
1:59 have the hypothalamus right okay and
2:00 then right here is going to be your
2:02 infundibulum and then here's your poster
2:05 pituitary and here's your anti pituitary
2:07 right we had some cells before that we
2:09 were talking about that release specific
2:13 types of chemicals right so these two
2:16 guys right here are a group of neurons
2:17 right so we're going actually going to
2:18 call these as a group here so let's say
2:20 I actually group them
2:22 together these guys are a bunch of cell
2:24 bodies that are collectively in together
2:26 in the hypothalamus they're called
2:34 nucleus now the aru nucleus is a group
2:36 of cell bodies in the central nervous
2:38 system right and what happens is their
2:40 axons come together and they actually
2:42 secrete different types of chemicals but
2:44 one of the main chemicals that we're
2:45 going to look at here is actually going
2:47 to be called
2:48 called
2:52 prolactin inhibiting hormone and over
2:53 here what would be secreted over here
2:56 prolactin inhibiting hormone now
2:58 prolactin inhibiting hormone let's
3:01 actually show that as a black dot here
3:02 so let's say there's the black dot right
3:04 there there's the black dot right there
3:06 I want to define something before I keep
3:08 going into showing this axis here I want
3:09 to say something about prolactin
3:11 inhibiting hormone I know I mentioned it
3:12 before but you know there's actually
3:13 another name that we can actually give
3:17 prolactin inhibiting hormone it's called
3:20 dopamine so dopamine is actually just
3:23 another name for prolactin inhibiting
3:27 hormone now prolactin inhibiting hormone
3:29 does what it circulates down through
3:30 this actual portal system the
3:33 hypophysial portal system right so let's
3:34 show it actually circulating down
3:38 through the hypo fisal portal system
3:40 then what happens it comes out of the
3:43 hypohyal portal system into the anterior
3:46 pituitary so when it gets out here into
3:47 the anterior pituitary look what's going
3:50 to happen the prolactin is going to come
3:52 over and it's going to act on these
3:54 different types of receptors present on
3:57 this cell what is this cell here called
3:59 lactotrope or sometimes they even call
4:00 them lact tropes right but I'm going to
4:02 put lacto
4:06 Trope what happens is this actual
4:09 prolactin inhibiting hormone is going to
4:10 act on this receptor and again what's
4:12 prolactin inhibiting hormone called it's
4:15 called dopamine it actually acts on D2
4:16 receptors but neither here nor there
4:20 what's the effect it inhibits this cell
4:22 from releasing prolactin so prolactin
4:23 won't be
4:26 released okay well that doesn't help me
4:27 how do I know what's going to stimulate
4:29 the release of prolactin okay there
4:32 there is other nuclei in the vicinity
4:34 here so there actually is other nuclei
4:36 here one of them that we can take a look at
4:38 at
4:42 here is actually called look at this guy
4:45 he's got a mouth like no other right so
4:47 what does he do he secretes certain
4:49 types of chemicals what are these
4:50 chemicals that he's secreting he's
4:53 secreting chemicals for example this one
4:55 chemical that he secretes is actually called
4:56 called
4:59 trh you might have heard of that before
5:00 remember remember that from thyroid
5:01 hormone it's called thyrotropin
5:04 releasing hormone this nucleus right
5:07 here is called the par
5:10 par ventricular
5:12 ventricular
5:15 nucleus and what does he do he secretes
5:17 thyrotropin releasing hormone guess what
5:19 thyrotropin releasing hormone does it
5:22 can actually circulate down through the
5:24 hypo fical portal system and then it can
5:26 come out right it can come out here into
5:29 the anti pituitary and it can bind on to
5:32 some specific receptors present on this
5:35 actual lactotrope and look it binds onto
5:37 the lactotrope and guess what kind of
5:39 signals it gives to this lactotrope it
5:42 gives stimulatory signals okay that's another
5:43 another
5:45 thing other things that can actually
5:48 trigger this pathway besides thyrotropin
5:49 releasing hormone because we need to
5:51 know all the things that are stimulatory
5:52 and all the things that are inhibitory
5:54 so again what's this inhibitory one here
5:56 this black dot right here this is
5:59 Prolactin inhibiting hormone and once
6:01 this red dot right here this is called
6:04 thyrotropin releasing hormone he's one
6:06 of the types of prolactin releasing
6:08 hormones what are some other things that
6:10 can stimulate this prolactin release
6:12 okay so let's show him he's giving the
6:14 stimulatory signal and now look what
6:15 this guy's going to do he's going to
6:17 start uh undergoing some specific type
6:19 of transcription and translation and
6:21 look what he's going to produce out of
6:25 this he's going to produce Pro lactin
6:27 the hormone that we care about right so
6:31 TR is stimulating this path way what are
6:33 some other things that can stimulate
6:35 prolactin production because we need to
6:37 know those you know females they they
6:39 usually have a lot of estrogen right so
6:40 they make a lot of estrogen where do you
6:42 make estrogen from you make it from the
6:44 ovaries right so when the estrogen is
6:46 produced during the actual uh pregnancy
6:48 process and even actually during the
6:50 birthing process and after the birthing
6:53 process what happens is estrogen levels
6:57 are extremely important for prolactin
6:59 production so what does it do estrogen
7:00 can actually
7:03 stimulate prolactin production but you
7:05 know what else it can do it can come
7:07 over here and act on these neurons right
7:09 here you know the arcu nucleus it
7:10 actually can come over here and look
7:11 what it can
7:15 do it actually can inhibit the arcu
7:17 nucleus from producing prolactin
7:19 inhibiting hormone so what happens if
7:20 you produce very little prolactin
7:22 inhibiting hormone little prolactin
7:24 inhibiting hormone is going to have less
7:26 of a negative effect on this lactotrope
7:27 and that's going to start producing
7:29 prolactin so there's two stimulate
7:32 effects of estrogen one is it's going to
7:34 stimulate prolactin production directly
7:36 as well as inhibit the release of
7:39 dopamine okay there's other things that
7:40 can also do this too I'm just going to
7:43 mention uh one more and that is
7:46 breastfeeding okay because there's a lot
7:47 of things that we could mention here but
7:48 we're just going to mention the most
7:50 significant and the most important ones
7:52 so breastfeeding also has a direct
7:57 stimulus on prolactin production okay so
7:58 whenever there's the suckling of the
8:00 baby it can act activate mechano
8:01 receptors and that can trigger the
8:04 production of oxytocin but it also can
8:06 stimulate the production of so it also
8:07 where else could it work here the
8:14 what the pair of ventricular nucleus to
8:16 release more thyrotropin releasing
8:18 hormone more thyrotropin releasing
8:19 hormone will actually stimulate this
8:22 lactotrope to make more prolactin okay
8:23 now we got that now so we know what
8:25 stimulates the release of prolactin we
8:26 know what inhibits the releas of
8:28 prolactin inhibit inhibitory dopamine
8:31 stimulatory is estrogen breastfeeding
8:33 and thyroid troping releasing hormone
8:35 we're done okay let's come over here to
8:38 the mammory gland in the mamory gland
8:39 like we said there's a whole bunch of
8:41 alveolar cells over here and these
8:42 alveolar cells are the ones that are
8:44 making the milk what we're going to do
8:46 is we're going to zoom in on an alveolar
8:47 cell and take a deeper look at how prolactin
8:50 prolactin
8:53 works okay so if we look over here
8:55 prolactin is actually circulating in the
8:57 blood now so let's say here this Green
9:00 Dot right here is actually going to be
9:02 prolactin and prolactin is being
9:05 transported in the bloodstream right and
9:06 what happens is this prolactin so again
9:09 what is this chemical here called called
9:11 prolactin what will happen is Prolactin
9:14 will act on these alveolar cells which
9:16 are part of your mammory glands within
9:18 your lobules right what is it going to
9:21 do it's going to act on these receptors
9:23 because this is an alveolar cell so
9:25 again what is this cell here called This
9:27 is an
9:29 Alvar cell and it's one of the
9:31 components of the lobules right so this
9:33 is a component of the
9:36 lobules now what happens prolactin comes
9:39 out of the bloodstream and activates
9:41 some specific receptors that are present
9:43 on this alviar cell we're not going to
9:45 go into detail on it just remember we'll
9:46 cover this when we talked about the
9:49 receptor pathway but it activates what's
9:52 called jonis kinas which is a jack which
9:54 then activates what's called stat and
9:57 Stat is a signal transducer that
9:59 activates transcription transcription
10:01 for what multiple different types of
10:03 things so what is this going to activate
10:07 it's going to activate genes to make
10:10 mRNA and that mRNA is then going to get
10:13 what translated into proteins via the
10:16 ribosomes and what are these proteins
10:18 going to do they can do so many
10:19 different things some of these proteins
10:21 might be milk proteins so for example we
10:24 might actually do what we might actually
10:25 excrete these proteins out into the
10:27 Lumen what kind of proteins could this
10:30 be this could be things like casine this
10:33 could be things like lacto Farin lot of
10:35 different types of proteins right what
10:37 else can it do you know these proteins
10:38 can also come over here and maybe
10:41 phosphorate specific types of channels
10:44 what type of channels maybe channels for
10:46 certain types of uh ions so maybe this
10:48 one could be for certain types of ions
10:51 so what could this one be for ions maybe
10:53 this channels for other different types
10:54 of proteins let's say that this channel
10:56 is opening up for uh other different
10:58 types of proteins so let's say that this
11:01 is like IG antibodies or other different
11:02 types of proteins
11:05 right and let's say that this one is for
11:07 uh cholesterol so let's say that this is
11:10 a pathway for cholesterol or different
11:12 types of lipids right and really they
11:14 don't need a transport receptor uh
11:16 really cholesterol and lipid soluble
11:17 substances don't really need a
11:19 transporter because they can move
11:20 through the membrane I'm just showing it
11:22 as with respect to the diagram so again
11:26 what could be brought in ions what else
11:27 could be brought in certain types of
11:29 amog globulins like IG GA and certain
11:32 types of proteins as well as cholesterol
11:34 or different types of lipids as well as
11:35 making your own proteins and then what's
11:37 going to happen all of these things are
11:39 going to get pushed out where out into
11:42 the actual Lumen right so again what's
11:44 this going to come out here IGA proteins
11:46 and other different types of things and
11:50 also a lot of lipids and cholesterol
11:51 okay all right so again what are these
11:52 chemicals that are going to be present
11:54 in Lum Lumen a lot of different types of
11:56 ions and electrolytes right what else
11:58 could be present here bunch of different
12:00 types of proteins what kind of proteins
12:03 we could have things like casine or
12:06 renin or lacto Farin right what else
12:08 could you have you could also have other
12:11 different types of proteins like IGA
12:13 antibodies or as well as plasma proteins
12:16 that you filtered out right okay what
12:17 else could you have you could also have
12:19 a lot of different types of lipids and
12:21 cholesterol right so we could also have
12:24 a lot of different types of
12:26 lipids and
12:28 cholesterol as well as vitamins there's
12:30 so many different things that are
12:32 present within the actual milk that it
12:33 would take forever to go through all of
12:35 them okay but just know that basically
12:36 that's what it's doing it's stimulating
12:37 the production of a whole bunch of
12:39 different types of proteins some of the
12:40 proteins are going to be direct milk
12:42 proteins other things are going to
12:44 activate certain types of channels or
12:46 other different types of Pathways to
12:49 bring in substances from the plasma
12:51 right like IGA antibodies or certain
12:54 types of ions or cholesterol or vitamins
12:56 or minerals all these different types of
12:57 things to provide nutrient support to
12:59 the baby
13:01 okay now that we know that we know what
13:03 what have we been able to accomplish
13:05 throughout this whole thing here we've
13:08 been able to say what is the stimulus
13:09 for prolactin production what is it what
13:11 are the three stimuli for prolactin
13:13 production so again if I were to kind of
13:15 highlight here the big ones we'd say
13:19 estrogen is a very powerful stimulus
13:21 what else did we say we also said
13:27 stimulus and what else did we say we
13:30 also said thyrotropin releasing hormone
13:32 is a very positive stimulus so all of
13:35 these things are stimulating what
13:37 prolactin production what are the things
13:39 that are inhibiting prolactin production
13:41 this would be
13:45 dopamine okay so dopamine is a very very
13:47 powerful inhibitor
13:50 of prolactin production oh one more
13:52 thing that I want to mention here and
13:53 that's going to finish up our video here
13:55 guys let's come back over here for a
13:58 second here um I remember I told you
13:59 that estrogen is a very strong
14:01 stimulator right well estrogen is a
14:04 stimulator of prolactin production but
14:06 when estrogen is produced right after
14:09 the actual birthing process the estrogen
14:10 levels drop a little bit and as the
14:12 estrogen levels drop a little bit what
14:14 happens is because normally like let's
14:17 imagine here's this receptor right
14:18 estrogen is going to work through
14:20 different types of Pathways to inhibit
14:23 the action of prolactin on this alol
14:25 cell so even though prolactin levels can
14:28 be high it won't be able to exert its
14:30 effects inside of the cell because why
14:32 the reason why this wouldn't happen is
14:36 because of extremely high estrogen
14:39 levels so with extremely high estrogen
14:41 levels it can stimulate prolactin
14:43 production but inhibit the action of
14:46 prolactin on the Alvar cells so what has
14:49 to happen is is after after the birthing
14:51 process the estrogen levels start coming
14:52 down a little bit coming down a little
14:53 bit coming down a little bit and then
14:56 what happens then prolactin can act on
14:59 the specifically the Alvar cells to
15:00 produce all the different types of
