PLASMA TESTOSTERONE LEVELS ARE RELATED TO VARIOUS ASPECTS OF LOCOMOTOR-ACTIVITY IN WILD-CAUGHT MALE MEADOW VOLES (MICROTUS-PENNSYLVANICUS)

The relationship between plasma testosterone levels and locomotor acti vity in wild-caught sexually mature male meadow voles (Microtus pennsy lvanicus) was assessed in the laboratory. Several aspects of locomotor activity were monitored for 1 h on two consecutive days using the aut omated Digiscan activity monitoring system. Plasma testosterone levels were determined immediately following the second day of activity moni toring. Significant Pearson correlations were obtained between plasma testosterone levels and total distance traveled [r(10) = 0.55, p < 0.0 5] and amount of time spent in movement [r(10) = 0.55, p < 0.0.5] on t he second day. The wild voles showed a reduction in activity levels fr om the first to the second day of activity monitoring, which is indica tive of habituation to a novel environment. This study provides direct evidence for a significant correlation between laboratory measures of behavioral activity and plasma testosterone levels in a wild-caught r odent. These findings indicate that previous assessments of hormone-be havior relationships in laboratory-bred rodents are consistent with th e relationship between hormones and behavior in wild rodents. (C) 1998 Elsevier Science Inc.