Testicular but not ovarian hormones shape patch-leaving adaptation and impulsive choice in rats

Abstract

Hormonal regulation of patch-leaving decision-making remains poorly understood. Here, young adult male and female Long-Evans rats were tested in a patch-leaving task before and after orchiectomy (ORCH), ovariectomy (OVX), or sham surgery, and were subsequently assessed in an impulsive-choice task. Patch leaving was measured under long- and short-travel conditions. Before surgery, males showed longer overstay than females during long-travel sessions, whereas no clear sex difference was detected during short-travel sessions. After surgery, orchiectomy did not produce a uniform shift in patch leaving but selectively disrupted the progressive reduction in overstay that normally emerged across repeated long-travel sessions. By contrast, ovariectomy produced weaker effects and did not reveal a comparably robust change in female patch leaving. Spatial and idle occupancy analyses showed that gonadectomy also altered within-patch behavior, with orchiectomy most strongly increasing idling-related measures in males, whereas ovariectomy more strongly redistributed female patch occupancy. Estrous stage did not significantly organize pre-surgical female overstay. Greater impulsive choice was associated with smaller post-surgical reductions in long-travel overstay in the unadjusted analysis. Together, these findings indicate that testicular hormones selectively support patch-leaving adaptation under high travel cost.