Porcine maternal infanticide as a model for puerperal psychosis

Abstract

Childbirth is a period of substantial rapid biological and psychological change and a wide range of psychotic disorders can occur ranging from mild 'baby blues' to severe episodes of psychotic illnesses. Puerperal psychosis is the most extreme form of postnatal psychosis, occurring in 1 in 1,000 births. In this study, we have used the pig as an animal model for human postnatal psychiatric illness. Our aim was to identify quantitative trait loci (QTL) associated with maternal (infanticide) sow aggression. This is defined by sows attacking and killing their own newborn offspring, within 24 hr of birth. An affected sib pair whole genome linkage analysis was carried out with 80 microsatellite markers covering the 18 porcine autosomes and the X chromosome, with the aim of identifying chromosomal regions responsible for this abnormal behavior. Analysis was carried out using the non-parametric linkage test of Whittemore and Halpern, as implemented in the Merlin software. The results identified 4 QTL mapping on Sus scrofa chromosomes 2 (SSC2), 10 (SSC10), and X (SSCX). The peak regions of these QTL are syntenic to HSA 5q14.3-15, 1q32, Xpter-Xp2.1, and Xq2.4-Xqter, respectively. Several potential candidate genes lie in these regions in addition to relevant abnormal behavioral QTL, found in humans and rodents.

Gene expression profiling in porcine maternal infanticide: A model for puerperal psychosis

“…The frequency of occurrence in primiparous sows has been estimated in large surveys of commercial pig farms to be 8% [Knap and Merks, 1987] and 7-12% [ Van der Steen et al, 1988]. General behavior shown in these animals and factors affecting it are discussed in more detail elsewhere [Quilter et al, 2007]. However, porcine maternal behavior seems to be mostly influenced by genetic predisposition and the sows' previous experiences.…”

“…It is our hypothesis that pigs can be used as a model for human postnatal illness, particularly puerperal psychosis, as maternal infanticidal aggression in pigs has many features in common [Quilter et al, 2007]. Childbirth in women can be a trigger for a wide range of psychotic disorders ranging from mild ''baby blues'' to severe episodes of psychotic illnesses .…”

“…Furthermore, family studies consistently demonstrate a difference in the risk of puerperal psychosis in individuals with a first degree relative with bipolar disorder and puerperal psychosis compared to those without . The general behavior presented by women with this condition is discussed in more detail elsewhere [Quilter et al, 2007].…”

Genetics of behavioural adaptation of livestock to farming conditions

“…This could be a sign of a higher genetic predisposition to react to involuntary crushing in some sows, and these sows also benefit from a higher genetic merit for progeny growth (Grandinson et al, 2002). Several QTL related to maternal cannibalism have been observed, with a promising one on the X chromosome (Quilter et al, 2007;Chen et al, 2009). In hens, Xu et al (2010) found three QTL involved in egg incubation behaviour, which was put at a disadvantage by selective breeding; among these QTL one was linked to the DRD1 gene, which encodes a dopamine receptor.…”

Selection for pure- and crossbred performance in Charolais

“…In pigs, two studies found QTL located on chromosome X and associated with extreme form of failure of maternal behavior, i.e. sow maternal aggression to their own new born piglets (Quilter et al, 2007;Chen et al, 2009). To our knowledge, the present study is the first GWAS for type traits in beef cattle.…”