Activation of the immune-endocrine system with lipopolysaccharide reduces affiliative behaviors in voles

In Experiment I, individually housed mate meadow voles (Microtus pennsylvan icus) and prairie voles (Microtus ochrogaster) were injected with lipopolys accharide (LPS) and exhibited the expected decrease in testosterone and inc rease in corticosterone and interleukin-1 beta concentrations 3 hr later, i ndicating activation of the endocrine and immune systems. In Experiment 2, LPS- and saline-injected males were tethered in a 3-chamber partner prefere nce apparatus. The time females spent in each chamber with a male, as well as the amount of time spent in social contact, was monitored. Female prairi e votes, but not meadow voles, spent more time in the chamber with saline- than with LPS-injected males. LPS-injected male prairie and meadow votes en gaged in less social contact with female conspecifics than did saline-injec ted males. These data suggest that LPS modifies physiology and behavior in male voles and that females may use these changes to discriminate healthy f rom potentially infected males.