Neurobiološka osnova spolne orijentacije

undergraduate thesis

• Title (english): Neurobiological basis of sexual orientation
• Author: Valentina Lipovec
• Mentor: Dubravka Hranilović (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2010, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Iako je spolna orijentacija ljudske populacije varijabilna, većina ljudi prednost daje suprotnom spolu (heteroseksualna orijentacija). Postoji tek manjina koja pokazuje homoseksualnu orijentaciju. Dugo se godina glavno objašnjenje homoseksualnosti temeljilo na utjecaju psiholoških faktora. Danas postoji nešto drugačije shvaćanje homoseksualnosti. Jedna od teorija smatra da je homoseksualnost zapisana u genima. Istraživanja provedena na braći, uključujući i blizance, dokazala su da genetski čimbenik igra ulogu u muškoj, ali i ne ženskoj homoseksualnosti. Homoseksualnost vjerojatno ide ženskom linijom, pošto muškarci primaju svoj jedini X kromosom od majke, pa svako svojstvo koje je vezano uz X kromosom prenosi se sa majki na sinove u svakoj sljedećoj generaciji. Glavni ishod istraživanja je pronalazak povezanosti između homoseksualne orijentacije i markera u regiji Xq28 na X kromosomu. No, naknadno su neki znanstvenici otkrili određene nepravilnosti u toj teoriji. Osim te teorije, postoji i ona o povezanosti utjecaja hormona i spolne orijentacije. Najprije je na životinjskim modelima, a kasnije i na ljudima pokazano da androgeni steroidi koji djeluju prije rođenja mogu utjecati na spolnu orijentaciju odraslih ljudi. Postoje brojni nalazi koji pokazuju da je kod nekih vrsta aromatizacija (pretvorba testosterona u estradiol) kritični korak za maskulinizaciju mozga testosteronom. S obzirom da hormoni u perinatalnom razvoju utječu na razvoj mozga, oni također utječu i na razvoj ponašanja. Perinatalna kastracija mužjaka štakora i primjena testosterona na ženke uzrokovala je preferenciju istog spola. Iako je malo dokaza postoje neke naznake da perinatalni hormoni utječu i na seksualnu orijentaciju kod ljudi. Prema trećoj teoriji, mozgovi homoseksualaca i heteroseksualaca strukturno se razlikuju. Razlike se očituju u veličini treće intersticijske jezgre hipotalamusa, veličini suprahijazmatske jezgre te prednje komisure. Nakon različitih mišljenja o nastanku i uzrocima homoseksualnosti, znanstvenici su pokazali da je homoseksualnost orijentacija koja je nepromjenjiva. Ona nije izbor.

Abstract (english)

Although sexual orientation of the human population is variable, most people give priority to the opposite sex (heterosexual orientation). There are only a minority of people who show homosexual orientation. For many years psychological factors were hold responsive for homosexuality. Understanding of homosexuality is today somewhat different. One of the theories believes that homosexuality is influenced by genes. Researches that were conducted on brothers, including twins, have proved that genetic factors play a role in male but not in female homosexuality. Homosexuality is probably transmitted across female line. Since males receive their single X chromosome exclusively from their mothers, any trait that is influenced by an X-linked gene will be preferentially passed through the mother’s side of the family. The main outcome of the research is finding of link between homosexual orientation and markers in the Xq28 region on the X chromosome. But later, some scientists have discovered certain irregularities in the theory. In addition to these theories, there is one suggested a connection between influence of hormones and sexual orientation. The influence of prenatal androgen steroids on the sexual orientation of adults was demonstrated first on animal models, and later in humans. Numerous findings indicate that in some species, aromatization (conversion of testosterone to estradiol) is a critical step for brain masculinization with testosterone. Since hormones dump the prenatal development affect brain development, they also affect the development of behavior. Perinatal castration of male rats and application of testosterone to females caused a preference for the same sex. There are some indications that perinatal hormones affect sexual orientation in humans, but there is still little evidence to support that. According to the third theory, brains of homosexuals and heterosexuals are structurally different. The differences are reflected in the size of the third interstitial nucleus of hypothalamus, size of suprachiasmatic nucleus and anterior commissure. After various opinions about the origin and causes of homosexuality, scientists have shown that homosexuality is not a choice, but an unchangeable orientation.

• Keywords: spolna orijentacija
• Keywords (english): sexual orientation
• Language: croatian
• URN:NBN: urn:nbn:hr:217:334986
• Study programme: Title: Ecology; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) biologije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-03-27 11:53:38