Anterior Pituitary Transcriptome Suggests Differences in ACTH Release in Tame and Aggressive Foxes

Abstract

Domesticated species exhibit a suite of behavioral, endocrinological, and morphological changes referred to as “domestication syndrome.” These changes may include a reduction in reactivity of the hypothalamic-pituitary-adrenal (HPA) axis and specifically reduced adrenocorticotropic hormone release from the anterior pituitary. To investigate the biological mechanisms targeted during domestication, we investigated gene expression in the pituitaries of experimentally domesticated foxes (Vulpes vulpes). RNA was sequenced from the anterior pituitary of six foxes selectively bred for tameness (“tame foxes”) and six foxes selectively bred for aggression (“aggressive foxes”). Expression, splicing, and network differences identified between the two lines indicated the importance of genes related to regulation of exocytosis, specifically mediated by cAMP, organization of pseudopodia, and cell motility. These findings provide new insights into biological mechanisms that may have been targeted when these lines of foxes were selected for behavior and suggest new directions for research into HPA axis regulation and the biological underpinnings of domestication.

Genomic signatures of domestication in Old World camels

“…Like several of the genes found in dromedaries, defects in KDM1A cause craniofacial disorders and psychomotor retardation 49 again, signature features of DS. Furthermore, KDM1A is required for pituitary organogenesis 50 , and stress hormone activity regulated by the hypothalamic-pituitary-adrenal axis is also tightly correlated with both thyroid hormone activity 51 and tameness in foxes 52 . The genes LUZP1 and NLK both function in neural development.…”

Highly heritable and functionally relevant breed differences in dog behaviour

“…Importantly, a reduction in stranger-directed aggression is thought to be the unifying factor in (early) dog domestication and human self-domestication [52], making GRM8 an interesting candidate gene for these processes. Similarly, PDE7B, which is differentially expressed in the brains of tame and aggressive foxes [53], has been identified as a target of selection during domestication, and is highly expressed in the brain [54], where it functions in dopaminergic pathways [55]. In our analyses, SNPs in this gene were associated with breed differences in aggression, which is consistent with data from experimentally bred foxes, as well as hypotheses that selection against aggression was the primary evolutionary pressure during initial domestication events [56][57][58].…”

Hypothalamic transcriptome of tame and aggressive silver foxes (Vulpes vulpes) identifies gene expression differences shared across brain regions

“…24,25 However, the gene expression of corticotrophin releasing factor by the hypothalamus did not differ between the two fox groups. 25,26 Differences in serotonergic and catecholaminergic systems have been reported in the hypothalamus of tame compared with aggressive foxes, with the latter having a reduced density of serotonin 1A (5-HT1A) receptors in this brain region, but demonstrating greater amounts of serotonin and noradrenaline in the anterior hypothalamus. [27][28][29][30] Recently, global transcriptomic changes have been identified in the prefrontal cortex (PFC), basal forebrain (BFB) and anterior pituitary gland of tame vs aggressive foxes.…”