Biokemijski mehanizmi sinteze spolnih hormona u domaćih životinja

master's thesis

• Title (english): Biochemical Mechanisms of Sex Hormones Synthesis in Domestic Animals
• Author: Erika Gamulin
• Mentor: Marko Samardžija (mentor)
• Mentor: Jelka Pleadin (mentor)
• Committee member: Ivan Folnožić (predsjednik povjerenstva)
• Committee member: Marko Samardžija (član povjerenstva)
• Committee member: Jelka Pleadin (član povjerenstva)
• Granter: University of Zagreb; Faculty of Veterinary Medicine; (Reproduction and Obstetrics Clinic); Zagreb
• Defense date and country: 2018-04-26, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Veterinary Medicine

Abstract

Spolni hormoni su steroidi koji se preko višestrukih biokemijskih mehanizama sintetiziraju u gonadama. U sustavima sisavaca, postoji šest obitelji steroidnih hormona koji se mogu klasificirati na strukturnoj i biološkoj (hormonskoj) osnovi. To su: estrogeni i progestini (ženski spolni steroidi), androgeni (muški spolni steroidi), mineralokortikoidi (aldosteron), glukokortikoide (kortizol) i vitamin D. Svi navedeni steroidi nastaju iz kolesterola.
Glavna struktura prstena za kolesterol je potpuno zasićena kolestanska struktura prstena. Steroidni hormoni su topljivi u mastima, tako da mogu ulaziti u sve stanice tijela, jer lipidne stanične barijere ne predstavljaju pravu barijeru. Regulacijski ciklus proizvodnje spolnih hormona je složen proces, a svi mehanizmi se odvijaju preko osovine hipotalamus – hipofiza – jajnici. Biosinteza hormona uvjetuje spolni ciklus životinje, ali i ovisi o spolnom ciklusu same jedinke, odnosno biosinteza kod gravidnih razlikuje se od one u reproduktivnoj dobi. U gravidnih životinja je glavni izvor estrogena posteljica. Muški spolni hormoni (androgeni) su steroidi s 19 C-atoma, a ženski s 18 C-atoma (estrogeni) i 21 C-atomom (progesteron). Androgeni se sintetiziraju u Leydigovim stanicama iz kolesterola, progesteron u žutom tijelu (corpus luteum), a estrogeni u jajnicima i žutom tijelu, manje u testisima i nadbubrežnoj žlijezdi. Tijekom biosinteze pregnenolon je važan prekursor koji je potreban za stvaranje svih steroidnih hormona. Reakcije kataliziraju enzimi kao što su: P450scc, StAR, 5α-reduktaza. Najaktivniji estrogen je 17β-estradiol, a testosteron 5α-dihidrotestosteron (5α-DHT). Progesteron, testosteron i estradiol imaju višestruke uloge u spolnim ciklusima, a njihova funkcija u organizmu u ovisnosti je o fiziološkoj sintezi samih hormona.

Abstract (english)

Sex hormones are steroids synthesized by gonads through multiple biochemical mechanisms. In mammalian systems, there are six families of steroid hormones that can be classified on both a structural and a biological (hormonal) basis. They are the estrogens and progestins (female sex steroids), androgens (male sex hormones), mineralocorticoids (aldosterone), glucocorticoids (cortisol) and vitamin D. They are all derived from cholesterol. The parent ring structure for cholesterol is the fully saturated ring structure cholestane. Steroid hormones are fat-soluble so they can enter all body cells because lipid cellular barriers are not a barrier for them. Regulatory cognitive production of sex hormones is a complex process, and all mechanisms take place through the hypothalamus-pituitary-ovarian linkages. The hormone biosynthesis determines the sex cycle of the animals, but also depends on the sex cycle of the same individuals, therefore the biosynthesis in pregnancy is different from the one in the reproductive age. Pregnancy is characterized by a massive increase in the production of both progesterone and estrogen. The increase in progesterone and estradiol production occurs only in the placenta. Male sex hormones (androgens) are steroids with 19 C-atoms, and female with 18 C-atoms (estrogens) and 21 C-atoms (progesterone). Androgens are synthesized in Leydig's cells from cholesterol, progesterone in the corpus luteum, and estrogen in the ovaries and corpus luteum, while less amounts are produced in the testicles and the adrenal gland. In the mitochondria, cholesterol is converted into pregnenolone, the precursor steroid required for synthesis of all steroid hormones. The reactions catalyze enzymes such as: P450scc, StAR, 5α-reductase. The most active estrogen is 17β-estradiol, and testosterone 5α-dihydrotestosterone (5α-DHT). Progesterone, testosterone and estradiol have multiple roles in sex cycles, and their function will depend on the physiological synthesis of the hormones themselves.

• Keywords: spolni hormoni; androgeni; estrogeni; progesteron; biokemija
• Keywords (english): sex hormones; androgens; estrogens; progesterone; biochemistry
• Language: croatian
• URN:NBN: urn:nbn:hr:178:843863
• Study programme: Title: Veterinary Medicine; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: doktor/doktorica veterinarske medicine (doktor/doktorica veterinarske medicine)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-07-24 06:39:59