Title Hormonski nadzor nad razvojem mliječne žlijezde
i proizvodnjom mlijeka Title (english) Hormonal regulation of the developement of the mammary gland and milk synthesis Author Kristian Nikolić Mentor Jasna Aladrović (mentor)Mentor Lana Pađen (mentor)Committee member Martina Lojkić (predsjednik povjerenstva)Committee member Jasna Aladrović (član povjerenstva)Committee member Lana Pađen (član povjerenstva)Granter University of Zagreb Defense date and country 2021, Croatia Scientific / art field, BIOMEDICINE AND HEALTHCARE Abstract Izrazito brz razvoj mliječne
žlijezde možemo uočiti u pubertetu i bređosti. Endokrini sustav koordinira razvoj mliječne
žlijezde s reproduktivnim sustavom i potrebom potomaka za mlijekom. Razvoj mliječne
žlijezde do početka stvaranja mlijeka naziva se mamogeneza. Za mamogenezu izuzetno su bitni
hormon rasta, IGF-1, glukokortikoidi, hormoni štitaste žlijezde i spolni hormoni. Tijekom
bređosti za rast i razvoj mliječne žlijezde potrebni su progesteron, estrogen, prolaktin, hormon
rasta, placentalni laktogen, inzulin i kortikosteroidi. Početak proizvodnje mijeka naziva se
laktogeneza. Prvi sekret koji alveolarne stanice mliječne žlijezde proizvedu se naziva
kolostrum. Održavanje proizvodnje mlijeka naziva se galaktopoeza pri čemu su broj sekretornih
epitelnih stanica i proizvodnja mlijeka u korelaciji. Laktogenezu primarno kontrolira prolaktin,
a otpuštanje mlijeka oksitocin. Prolaktin ima mnogobrojne funkcije i luči se iz prednjeg režnja
hipofize. Ključan je za ekspresiju gena za sintezu bjelančevina mlijeka. Oksitocin je bitan za
kontrakciju mioepitelnih stanica na površini alveola i duž kanalića mliječne žlijezde. Obrazac
otpuštanja oksitocina je pulzatoran. Ostali hormoni koji su bitni za laktaciju su kortizol, koji
ima opći učinak na metabolizam, progesteron čija je funkcija stimulacija razvoja vimena tokom
bređosti, hormon rasta, estrogeni koji povećavaju broj prolaktinskih receptora i pojačava
otpuštanje prolaktina. Glavni dio organskih sastojaka mlijeka sintetizira se samo u epitelnim
stanicama mliječne žlijezde. Četiri glavne komponente u mlijeku su bjelančevine, masti, laktoza
i minerali. Nalazimo još i vitamine i druge organske molekule koje prelaze u mlijeko iz krvi.
Epitelne stanice mliječne žlijezde imaju vrlo brz metabolizam. Od bjelančevina najzastupljeniji
su kazeini, proteini sirutke, imunoglobulini i enzimi. U mliječnih krava dobre plodnosti
laktacija traje 305 dana. Vrhunac laktacije kod krava je 4-6 tjedana nakon teljenja. Ako se vime
ne prazni do kraja, proizvodnja mlijeka opada jer alveole i sekretorno tkivo involuiraju.
Involucija je također pod endokrinom kontrolom i korelira s odgovarajućim pražnjenjem
vimena.
Abstract (english) The growth and development of the mammary gland starts before the animal is born. The
development is especially fast during puberty and gestation. The endocrine system coordinates
the development of the mammary gland with the reproductive system and the metabolic needs
of their offspring. The development of the mammary gland before it starts producing milk is
called mammogenesis. Crucial hormones for mammogenesis are: growth hormone, IGF-1,
glucocorticoids, thyroid gland hormones and sex hormones. For its development during
pregnancy progesterone, estrogen, prolactin growth hormone, placental lactogen, insulin and
corticosteroids are of great importance. Lactogenesis is the beginning of milk production. The
first milk that the mammary gland produces is called colostrum. The process of maintaining
milk production is called galactopoiesis and during that process the number of epithelial cells
and milk production are correlated. Lactogenesis is primarily controlled by prolactin, and milk
ejection is dependent on oxytocin. Prolactin has many biological functions inside the organism
and it is released by the anterior lobe of the pituitary gland. Its main function is expression of
genes necessary for milk protein synthesis. Oxytocin is most important for the contraction of
myoepithelial cells that are found on the surface of alveoli and milk ducts. Oxytocin is secreted
in a pulsating pattern. Other hormones that are important for lactogenesis are: cortisol, which
has a general effect on the animal’s metabolism, progesterone whose function is stimulating the
development of the mammary gland prepartum, growth hormone, estrogens which are
important for the production of prolactin receptors and they increase the secretion of prolactin.
Most of the organic milk compounds are synthetized only in epithelial cells of the mammary
gland. The four main constituents of milk are proteins, fats, lactose and minerals. We can also
find vitamins and other molecules which are taken from blood by the mammary gland.
Epithelial cells have a very fast metabolism. Main proteins found in milk are caseins, whey
proteins, immunoglobulins and enzymes. Standard cattle lactation lasts 305 days. Peak of the
lactation curve is observed 4-6 weeks after giving birth. If the udder is not emptied properly,
milk production will drop because alveoli and secretory tissue of the udder will undergo the
process of involution. After weening off their young the mammary gland goes through the
process of involution. It is also controlled by hormones.
Keywords
mliječna žlijezda
oksitocin
prolaktin
mlijeko
laktacija
Keywords (english)
mammary gland
oxytocin
prolactin
milk
lactation
Language croatian URN:NBN urn:nbn:hr:178:502525 Study programme Title: Veterinary Medicine Type of resource Text File origin Born digital Access conditions Open access Terms of use Created on 2021-07-12 11:05:55
