Early social deprivation shapes neuronal programming of the social decision-making network in a cooperatively breeding fish

The early social environment an animal experiences may have pervasive
effects on its behaviour. The Social Decision-Making network (SDMN),
consisting of interconnected brain nuclei from the forebrain and midbrain,
is involved in the regulation of behaviours during social interactions. In
species with advanced sociality such as cooperative breeders, offspring
are exposed to a large number and a great diversity of social interactions
every day of their early life, which may have life-long consequences on
the development of several neurophysiological systems within the SDMN,
although these effects are largely unknown. We studied these life-long
effects in a cooperatively breeding fish, Neolamprologus pulcher, focusing
on the expression in the SDMN of genes involved in the monoaminergic and
stress response systems. N. pulcher fry were raised until an age of two
months either with their parents, subordinate helpers and same clutch
siblings (+F), or with same clutch siblings only (-F). Analysis of the
expression of glucocorticoid receptor (GR), mineralcorticoid receptors
(MR), corticotropin releasing factor (CRF), dopamine receptors 1 and 2,
serotonin transporter (SERT) and DNA methyltransferase I (DNMT1) genes
showed that early social experiences altered the neurogenomic state of the
preoptic area (POA) of the hypothalamus. The dopamine receptor 1 gene was
up-regulated in the POA of -F fish, compared to +F fish. -F fish also
showed up-regulation of GR1 expression in the dorsal medial telencephalon
(homologous to the basolateral amygdala). Our results suggest that early
social environment has life-long effects on the development of several
neurophysiological systems within the SDMN. --