Hypothalamic expression of Peg3 gene is associated with maternal care differences between SM/J and LG/J mouse strains

• Grant number: 12/06699-3
• Support Opportunities: Regular Research Grants - Publications - Scientific article
• Start date: May 01, 2012
• End date: October 31, 2012
• Field of knowledge: Biological Sciences - Genetics - Animal Genetics
• Principal Investigator: Andréa Cristina Peripato
• Grantee: Andréa Cristina Peripato
• Host Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Maternal care is essential in mammals, and variations in the environment provided by mothers may directly influence the viability of newborns and emotional behavior later in life. A previous study investigated genetic variations associated with maternal care in an intercross of LG/J and SM/J inbred mouse strains and identified two single-locus QTLs. Here, we selected three candidate genes located within these QTLs intervals; Oxt on chromosome 2, and FosB and Peg3 on chromosome 7 and tested their association with maternal care. LG/J females showed impaired postpartum nest building and pup retrieval, a one day delay in milk ejection, reduced exploratory activity and higher anxiety-like behavior when compared to SM/J females. The nucleotide sequences of Oxt and FosB were similar between strains, as were their hypothalamic expression levels. Conversely, Peg3 nucleotide sequences showed four nonsynonymous replacement substitutions on LG/J dams, T11062G, G13744A, A13808G and G13813A, and a 30-base pair (10 aa) in tandem repeat in the coding region with three copies in SM/J and 5 copies in LG/J. Maternal care-impaired LG/J mothers express 37% lower Peg3 mRNA levels in the hypothalamus on the 2nd postpartum day. We also found an association of the Peg3 repeat-variant and poor maternal care in F2 heterozygote females derived from a LG/J x SM/J intercross. These results may suggest that the maternally-imprinted Peg3 gene is responsible for the single-locus QTL on chromosome 7 that has been shown to influence maternal care in these strains. Furthermore, these data provide additional support for an epigenetic regulation of maternal behavior. (AU)