Behav Brain Res. 2015 Dec 27. pii: S0166-4328(15)30344-2. doi: 10.1016/j.bbr.2015.12.035.
Stereotypic behaviour (SB) occurs in certain human disorders (e.g. autism), and animals treated with stimulants or raised in impoverished conditions, including laboratory mice in standard cages.
Dysfunctional cortico-basal ganglia pathways have been implicated in these examples, but for cage-induced forms of SB, the relative roles of ventral versus dorsal striatum have not been fully ascertained.
Here, we used immunohistochemical staining of FosB and ΔFosB to assess long-term activation within the nucleus accumbens and caudate-putamen of C57BL/6 mice. Housed in typical laboratory cages, these mice spontaneously developed different degrees of route-tracing, bar-mouthing and other forms of SB (spending 0% to over 50% of their active time budgets in this behaviour).
The most highly stereotypic mice showed the most elevated FosB/ΔFosB activity in the nucleus accumbens. No such patterns occurred in the caudate-putamen.
The cage-induced SB common in standard-housed mice thus involves elevated activity within the ventral striatum, suggesting an aetiology closer to compulsive gambling, eating and drug-seeking than to classic amphetamine stereotypies and other behaviours induced by motor loop over-activation.
KEYWORDS: Stereotypic behaviour; abnormal repetitive behaviour; caudate-putamen; nucleus accumbens; stereotypy; striatum; transcription factor; ΔFosB