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Veterinary/zoology session

Examination of gluco- and mineralocorticoid effects in perinatal and adult vasopressin deficient Brattleboro rats
Varga János - year 5
SzIE, Faculty of Veterinary Science, Ecology Department; MTA-KOKI Laboratory of Behavioural and Stress Studies
Supervisors: Dóra Zelena, Péter Kabai


We proved previously that vasopressin takes part in the regulation of the hypothalamo-pituitary-adrenal axis (HPA axis) in age-related manner. The glucocorticoids, responsible for the effects of the axis, are structurally very similar to the mineralocorticoids, and they act on the same receptors.

The aim of our work was to examine if vasopressin has age-related influence on the level of gluco- and mineralocorticoids, on their receptors and prereceptor enzymes. We compared vasopressin deficient Brattleboro rats to their heterozygote siblings. We used 10 days and 10 weeks old male animals.

We decapitated the four groups at rest, than we measured the levels of corticosterone (HPA-axis) and aldosterone (mineralocorticoid effect) with radioimmunassay from their blood. We defined mRNA levels of gluco- (GR) and mineralocorticoid receptors (MR), of hydroxisteroid dehidrogenase (HSD) 1 and 2 (glucocorticoide activating-inactivating enzymes) from the hypothalamus and from the liver with quantitative PCR. we measured the hormon levels in stressed animals too.

The corticosterone levels of the vasopressin deficient animals were higher without reference to the age, while the elevation of aldosterone level was more pronounced in the small rats. The level of GR and MR decreased in the hypothalamus and in the liver of the 10 years old rats. We found lower receptor levels in the liver of the vasopressin deficient animals in accordance with their higher hormone levels. An unexpected result was that the HSD 1 level rose in the hypothalamus of the vasopressin deficient pups.

Our results are in agreement with the hypothesis of stress hyporesponsive period, and they demonstrated that the small rats are less sensitive to the perinatal hormone changes at the level of receptors as well. In general, the deficiency of vasopressin caused bigger changes in 10 days old than adult animals. These support the theory that this molecule plays a more considerable regulatory role during the perinatal period.

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