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Bakgrund: Oxytocin är ett naturligt hormon under förlossning som påverkar uterus att kontrahera sig och det främjas av lugn och ro och trygghet. Det kan även administreras i syntetisk form t ex när värksvaghet föreligger, men World Health Organisation (WHO) anser att det används i alltför stor utsträckning. Värkstimulering med syntetiskt oxytocin är en av de vanligaste interventionerna vid förlossningsenheter i Sverige.   Motiv: Förlossningsvården i Sverige idag är hårt pressad och barnmorskor hanterar ibland fler än en födande i aktiv fas. Detta medför att möjligheten att ge kontinuerligt stöd minskar, och samtidigt ses en ökad medikaliserad vård med stort fokus på risker där fler interventioner utförs, bland annat överanvändningen av syntetiskt oxytocin som värkstimulering.   Syfte: Syftet med denna intervjustudie var att belysa barnmorskor uppfattning om syntetiskt och naturligt oxytocin under förlossning.    Metod: Studien genomfördes med kvalitativ metod där semistrukturerade intervjuer analyserades genom tematisk analys med teoretisk ansats. Birth Territory används som teoretisk referensram.   Resultat: Analysen resulterade i två teman med sex subteman. Barnmorskans önskan att bevara sin kompetens för att främja det normala, belyser begränsningar och förutsättningar i miljö och organisation som barnmorskan har för att utöva sin unika yrkeskunskap. Syntetiskt oxytocin som ersättning för barnmorskans närvaro, beskriver hur verksamhetens organisation, men även attityder kring syntetiskt oxytocin har lett till att närvaro hos den födande ersätts med bl. a syntetiskt oxytocin.   Konklusion: Barnmorskor beskriver att syntetiskt oxytocin används i för stor utsträckning och att det till viss del beror på organisationens uppbyggnad men även barnmorskans egna inställning. Det syntetiska oxytocinet har normaliserats och ersätter det naturliga oxytocinet och en barnmorskas närvaro.

Steroid hormones are reported to increase oxytocin (OXT) expression in skeletal muscle. It is possible that OXT may play essential roles in satellite cell (SC) proliferation and differentiation, which further contribute to skeletal muscle development and growth. In this dissertation, we tested this hypothesis with in-vivo and in-vitro studies in intrauterine growth restriction (IUGR) sheep, caloric restricted (CR) calves, tamoxifen (TAM) treated heifers, and bovine satellite cells (BSCs), respectively. In the in-vivo studies, we collected (1) longissimus dorsi muscle (LM) from IUGR sheep; (2) infraspinatus muscle (INF), LM, and semitendinosus muscle (ST) from CR calves; (3) LM muscle from TAM heifers. In all samples, mRNA abundance of targeted genes, such as OXT, were measured. Muscle fiber size and BSC number were also determined in skeletal muscle from TAM treated heifers. For the in-vitro studies, different treatments including 17β-estradiol (E2), trenbolone (TBA), TAM, OXT, and atosiban were applied to wild-type BSC and OXT knockout BSC (CRISPR-OXT) separately to investigate OXT's functions on BSC activity. For in-vivo studies, OXT expression significantly decreased (P<0.05) in IUGR LM muscle. Caloric restriction decreased OXT expression (P<0.05) in INF, LD, and ST muscle. Expression of OXT in LM from TAM animals decreased 50% (P<0.05). Moreover, TAM caused a small statistical reduction (P<0.05) in cross-sectional area (CSA). In in-vitro studies, OXT alone increased (P<0.05) fusion index but not proliferation in the wild-type BSC, whereas both proliferation and differentiation were stimulated (P<0.05) by OXT treatment in the CRISPR-OXT cell. By contrast, E2 and TBA increased (P<0.05) both proliferation rate and fusion index in wild-type BSC. However, E2 and TBA only stimulated proliferation rate (P<0.05) but not fusion index for CRISPR-OXT cells. Atosiban treatment resulted in lower proliferation and differentiation (P<0.05) in both wild-type BSC and CRISPR-OXT cell compared with OXT and E2 treatment groups. Together, our in-vivo studies indicate that OXT may play important roles in skeletal muscle development and growth. Our in-vitro studies demonstrate that OXT plays important roles in BSC proliferation and differentiation, and it is involved in steroid hormone stimulated BSC activity. / PHD / Oxytocin (OXT) is a mammalian neurohypophysial hormone. It has been demonstrated that OXT is highly expressed in skeletal muscle and satellite cell (SC) by steroid hormone administration. However, the role of OXT in SC proliferation and differentiation is not elucidated. In this dissertation, the in-vivo and in-vitro studies are combined and used to investigate if OXT is involved in bovine SC (BSC) activity. In the in-vivo studies, we collected muscle samples from intrauterine growth restriction (IUGR) sheep, caloric restricted (CR) calves, and tamoxifen (TAM) treated heifers. In all samples, mRNA abundance of OXT was measured. For the in-vitro studies, wild-type BSC and OXT knockout BSC (CRISPR-OXT) were treated with different factors including 17β-estradiol (E2), trenbolone (TBA), TAM, OXT, and atosiban separately to investigate OXT's functions on BSC activity. For in-vivo studies, OXT expression significantly decreased (P<0.05) in IUGR, CR, and TAM muscle. In in-vitro studies, OXT alone increased (P<0.05) fusion index but not proliferation in the wild-type BSC, whereas both proliferation and differentiation were stimulated (P<0.05) by OXT treatment in the CRISPR-OXT cell. By contrast, E2 and TBA, which can stimulate OXT expression in cultured BSC, increased (P<0.05) both proliferation rate and fusion index in wild-type BSC. However, E2 and TBA only stimulated proliferation rate (P<0.05) but not fusion index for CRISPR-OXT cells. Atosiban treatment resulted in lower proliferation and differentiation (P<0.05) in both wild-type BSC and CRISPR-OXT cell compared with OXT and E2 treatment groups. Together, our studies indicate that OXT plays important roles in BSC proliferation and differentiation, and it is involved in steroid hormone stimulated BSC activity. Studies to investigate specific biological mechanisms of steroid hormone stimulated OXT expression in SC are needed in the future.

The present study was designed to measure levels of oxytocic activity in the blood of cows before, during, and after physical stimulation to the teats and udder. It was also designed to determine the relationship between these levels and intramammary pressure. Knowledge in both these areas has been lacking up to the present. Some information in these areas was obtained as a result of this study. It was found that a wide variation existed in the levels of oxytocic activity between cows. In most cows, a bulk of oxytocic activity was detected in the interval of one to four minutes after stimulation began. The activity rapidly declined to low levels, with some exceptions, between the third and fourth minute post-stimulation. This information indicates that no specific changes need to be made in the present milking procedures. / Master of Science