Differential prolactin responsiveness to stress in left- and right-pawed mice.

Behavioral laterality has been shown to be related to immunological and endocrinological responsiveness in mice. The current study extended these findings by examining the pituitary hormone prolactin, and its response to stress, in left- and right-pawed mice. In two experiments, mice were tested on two measures of behavioral laterality, the Collins paw preference test and the Lateral Paw Preference (LPP) test. Circulating PRL levels were then measured in all subjects under baseline and stressed conditions. In Experiment 1, the PRL stress response was related to Collins paw preference in interaction with coat-color among females of a genetically heterogeneous group. Left-pawed black females showed a significant increase in PRL, while right-pawed black females did not. Among agouti mice, left-pawed females showed a significant decrease, while right-pawed did not. Experiment 2 used a genetically homogeneous group of agouti C3H mice. Again there were effects of Collins paw preference among females, with the right-pawed showing a significant increase in PRL following stress. In neither experiment were there effects of LPP. In neither experiment were there lateralized differences among males. These results indicate lateralized regulation of PRL among females, similar to that previously observed for ACTH regulation.