Urinary Excretion of Oestrone Sulphate and Cortisol in Early Pregnant Gilts Treated with Glucocorticoids

Abstract

The aim of this study was to determine rates of urinary excretion of oestrone sulphate and Cortisol in early pregnant gilts that were untreated or treated with either dexamethasone, corn oil or hydrocortisone. Twenty Polish Landrace gilts were used. They were grouped immediately after mating as follows: Experiment I — Group 1 (5 gilts), control animals and Group 2 (5 gilts), injected i.m. with dexamethasone (30 μg/kg) at 12-h intervals from day 13 to day 22 of pregnancy; Experiment II — Group 3 (5 gilts), injected i.m. with corn oil at 12-h intervals from day 13 to day 22 of pregnancy and Group 4 (5 gilts), injected i.m. with hydrocortisone acetate (250 mg) at 12-h intervals from day 11 to day 20 of pregnancy. Gilts were placed in metabolic cages, and 24-h urine aliquots were collected from day 6 to day 32 of pregnancy. On days 34–36 of pregnancy gilts were slaughtered and clinical data were collected. Rates of urinary excretion of oestrone sulphate and Cortisol were determined by enhanced chemiluminescence immunoassays. The urinary excretion of oestrone sulphate expressed in nmol/24 h and μmol/mol creatinine were significantly correlated. There was no correlation between Cortisol expressed in nmol/24 h and μmol/mol creatinine (p>0.5). A first significant increase of urinary oestrone sulphate excretion, expressed in nmol/24 h, on days 13–14 and a second one on days 19–20 of gestation occurred in control untreated and oil-treated gilts. The urinary excretion of oestrone sulphate reached maximum values between days 25 and 32 of gestation. In dexamethasone-treated gilts Cortisol excretion significantly decreased on day 16, i.e. 3 days after injections of dexamethasone had commenced. The treatment with hydrocortisone resulted in a significantly increased Cortisol excretion after the last injection of hydrocortisone. There were no relations between levels of urinary oestrone sulphate excretion expressed in nmol/24 h and the number of foetuses. When the urinary excretion of oestrone sulphate was expressed in mol/mol creatinine we found a positive relation between concentrations on day 20 of pregnancy and the number of foetuses. In one untreated gilt with a relatively high urinary excretion of Cortisol (more than 200 nmol/24 h) a lower number of foetuses was found at autopsy.

In conclusion, both dexamethasone and hydrocortisone treatment seemed to delay the first observed peak in oestrone sulphate in gilts without affecting the embryonic survival and the number of viable foetuses. kw|Keywords|k]stress; k]foetus; k]chemiluminescence immunoassay

Sammanfattning

Studien omfattade 20 polska Lantrasgyltor, som uppstallades vid The Kielanowski Institute of Animal Physiology and Nutrition, Jablonna, Polen. Efter betäckning placerades gyltorna i metabolismburar. För att undvika den stress som kan uppkomma vid blodprovstagning samlades urinprover för att följa insatt behandling. Vi behandlade dräktiga gyltor med upprepade doser av dexametason, vegetabilisk olja respektive hydrokortison från dag 11–13 t.o.m. dag 20–22 efter betäckning. Urinprover, som togs från dag 6 t.o.m. dag 32, analyserades med avseende på östronsulfat, kortisol och kreatinin. Det förelåg en hög korrelation mellan urinutsöndringen av östronsulfat uttryckt i nmol/24 timmar och μmol/mol kreatinin. Däremot fanns det ingen korrelation när det gäller exkretionen av kortisol. Den första ökningen av östronsulfat, uttryckt i nmol/24 timmar, påvisades dag 13–14 och den andra dag 19–20 av dräktigheten i de båda kontrollgrupperna. Resultatet av studien tyder på att den första ökningen av östronsulfat hämmades efter dexametason- och hydrokortisonbehandlingen. Urinutsöndringen av östronsulfat uppnådde sitt maximum mellan dag 25 och 32 av dräktigheten. Urinutsöndringen av kortisol hos dexametasonbehandlade gyltor sjönk dag 16, dvs. 3–5 dagar efter påbörjad behandling med dexametason. Behandling av gyltor med hydrokortison resulterade i en ökad utsöndring av kortisol efter den sista injektionen. Det fanns ingen relation mellan östronsulfatmängden i urinen, uttryckt i nmol/24 timmar, och antalet funna foster. Däremot kunde man påvisa en sådan korrelation mellan östronsulfat uttryckt i mol/mol kreatinin under dag 20 av dräktigheten. Hos en kontrollgylta, vars exkretion av kortisol var högre än 200 nmol/24 timmar fanns, endast 8 levande foster av 18 möjliga. Hos en annan kontrollgylta, där alla 18 foster var levande, var exkretionen av kortisol väsentligt lägre.