The effect of acute social isolation on neural molecular responses in components of the social decision-making network

Abstract

Prolonged or chronic social isolation has pronounced effects on animals, ranging from altered stress responses, increased anxiety and aggressive behaviour, and even increased mortality. The effects of shorter periods of isolation are much less well researched; however, short periods of isolation are used routinely for testing animal behaviour and physiology. Here, we studied how a 3 h period of isolation from a cagemate affected neural gene expression in three brain regions that contain important components of the social decision-making network, the hypothalamus, the nucleus taeniae of the amygdala, and the bed nucleus of the stria terminalis, using a gregarious bird as a model (zebra finches). We found evidence suggestive of altered neural activity, synaptic transmission, metabolism, and even potentially pain perception, all of which could create cofounding effects on experimental tests that involve isolating animals. We recommend that the effects of short-term social isolation need to be better understood and propose alternatives to isolating animals for testing.

Keywords: Acute; Chronic; Social decision-making network; Social isolation.

Fig. 1

Differentially expressed genes in response to acute isolation in the hypothalamus (A), nucleus taeniae (B), and the bed nucleus of the stria terminalis (C). Genes with p-adjust < 0.05 without a symbol do not have a HUGO Gene Nomenclature Committee (HGNC) Symbol

Fig. 2

Gene Set Enrichment Analysis results. Results show all enriched pathways detected within each GO category, for each brain region. The absence of a GO category plot indicates that no pathway was detected for that category. The size of the circles corresponds to the number of genes that responded to the Isolation treatment in a given pathway

Fig. 3

Behaviours (A-C) (isolated: n = 6; paired: n = 5) and circulating corticosterone (D) (isolated: n = 4; paired: n = 5) of animals in Isolated relative to Paired treatment. ** used for p < = 0.01, * used for p < = 0.05, ns used for p > 0.05