Autosomal and Y chromosomal effects on the stereotyped response to apomorphine in wild house mice

The behavioral response to apomorphine, a dopamine agonist, was shown to be different between a selection line characterized by Short Attack Latencies (SAL) and a selection line having Long Attack Latencies (LAL) (4). Aggressive SAL mice were more sensitive to apomorphine than nonaggressive LAL males. The aim of this research was to determine whether the stereotyped response to apomorphine is affected by the Y chromosome in the same way as it influences attack latency. For this purpose, F1 reciprocal hybrids as well as congenic lines (SAL.LY and LAL.SY) were used. The major difference between the congenic and parental lines is the nonpairing part of the Y chromosome (non-PAR). Apomorphine was injected subcutaneously at a preselected dose level of 5.0 mg/kg to induce stereotyped behavior manifested in compulsive sniffing, gnawing, and licking. Both the autosomes and the non-PAR Y chromosome affected the response to apomorphine. The effect of the autosomes was in accordance with the aggression data, whereas the effect of the non-PAR Y chromosome was different, and suggests a specific relation between dopamine systems and the non-PAR Y chromosome.