Stress-related gene expression in brain and adrenal gland of porcine fetuses and neonates

Feb 16, 2005Theriogenology

Stress-related gene activity in the brain and stress hormone gland of pig fetuses and newborns

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Abstract

Maternal deprivation in neonatal pigs resulted in a significant increase in c-fos and CRH transcript levels in the brain.

Maternal deprivation led to down-regulation of CRHR1 mRNA and up-regulation of c-jun in the pituitary gland.
Pregnant sows treated with 100 IU ACTH every two days increased mRNA expression of c-fos in the fetal brain.
ACTH treatment did not significantly affect CRH mRNA levels in the fetal brain but decreased MC2R mRNA expression in the adrenal gland.
Fetal pituitary CRHR1 and POMC mRNA expression was low in most fetuses, indicating incomplete development of the HPA axis.
Prenatal stress in pigs may affect HPA axis activity in the offspring, as suggested by the observed changes in gene expression.

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This study was conducted to examine stress-induced effects on gene expression of specific markers for HPA axis and neuronal activity in fetuses and neonatal pigs. Brain, pituitary gland, and adrenal gland were obtained to determine the mRNA levels for corticotropin-releasing hormone (CRH), CRH receptor 1 (CRHR1), pro-opiomelanocortin (POMC), ACTH receptor (MC2R), c-jun and c-fos. The suitability of these molecular markers was determined in neonatal pigs which were maternally deprived for two hours. It was found that maternal deprivation caused significantly higher transcript levels of c-fos and CRH in brain accompanied by a down-regulation of CRHR1 mRNA and an up-regulation of c-jun in the pituitary gland. To determine the effect of elevated maternal cortisol levels on gene expression of these molecular markers in fetuses, pregnant sows were treated with 100 IU ACTH (Synacthen Depot) s.c. every two days between Day 49 and Day 75 of gestation (normal gestation length 114 days). Animals were killed 48 hours after the last ACTH administration and fetuses of each sow were isolated. The ACTH treatment of sows significantly increased mRNA expression of c-fos but not of CRH in the fetal brain, and significantly decreased MC2R mRNA expression in the adrenal gland. However, HPA axis seems not to be fully developed in Day 77-fetuses because fetal pituitary CRHR1 and POMC mRNA expression was low in most of the fetuses. Although the expression of endocrine regulatory factors was partially incomplete in fetuses at the beginning of the third-trimester, ACTH dependent activation of c-fos mRNA in brain indicates a stress-related increase of neuronal activity. Based on these results it is assumed that prenatal stress in pigs may also have effects on the activity of the HPA axis in the offspring.

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Stress-related gene expression in brain and adrenal gland of porcine fetuses and neonates

Abstract

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