Maternal Deprivation in Rats is Associated with Corticotrophin-Releasing Hormone (CRH) Promoter Hypomethylation and Enhances CRH Transcriptional Responses to Stress in Adulthood
Article first published online: 19 JUN 2012
Published 2012. This article is a US Government work and is in the public domain in the USA.
Journal of Neuroendocrinology
Volume 24, Issue 7, pages 1055–1064, July 2012
How to Cite
Chen, J., Evans, A. N., Liu, Y., Honda, M., Saavedra, J. M. and Aguilera, G. (2012), Maternal Deprivation in Rats is Associated with Corticotrophin-Releasing Hormone (CRH) Promoter Hypomethylation and Enhances CRH Transcriptional Responses to Stress in Adulthood. Journal of Neuroendocrinology, 24: 1055–1064. doi: 10.1111/j.1365-2826.2012.02306.x
- Issue published online: 19 JUN 2012
- Article first published online: 19 JUN 2012
- Accepted manuscript online: 29 FEB 2012 12:17PM EST
- Received 13 January 2012, revised 21 February 2012, accepted 22 February 2012
- maternal deprivation;
- corticotrophin-releasing hormone;
- DNA methylation;
- hypothalamic pituitary adrenal axis
Exposure to stress during early development causes long-lasting alterations in behaviour and hypothalamic pituitary adrenal (HPA) axis activity, including increased expression of corticotrophin-releasing hormone (CRH). To determine whether early-life stress causes epigenetic changes in the CRH promoter leading to increased CRH transcription, 8-week old female and male rats, subjected to maternal deprivation (MD) between days 2 and 13 post-birth, were studied for HPA axis responses to stress and CRH promoter methylation in the hypothalamic paraventricular nucleus (PVN) and central nucleus of the amygdala (CeA). Plasma corticosterone and PVN CRH heteronuclear (hn)RNA responses to acute restraint stress were higher in MD rats of both sexes. DNA methylation analysis of the CRH promoter revealed a significantly lower percentage of methylation in two CpGs preceding (CpG1) and inside (CpG2) the cyclic AMP-response element (CRE) at −230 bp in the CRH promoter in the PVN but not the CeA of MD rats. Gel-shift assays, using nuclear proteins from forskolin-treated hypothalamic 4B cells and CRH promoter CRE oligonucleotides, unmethylated or methylated at CpG1, revealed a strong band that was supershifted by phospho-cAMP response element-binding antibody. This band was 50% weaker using oligonucleotides methylated at CpG2 (intra-CRE), or methylated at both CpG1 and CpG2. These findings demonstrate that HPA axis hypersensitivity caused by neonatal stress causes long-lasting enhanced CRH transcriptional activity in the PVN of both sexes. Hypomethylation of the CRH promoter CRE, a region critical for CRH transcriptional activation, could serve as a mechanism for the increased transcriptional responses to stress observed in MD rats.