BEHAVIORAL AND NEUROENDOCRINE REACTIVITY TO STRESS IN THE WKHA WKY INBRED RAT STRAINS - A MULTIFACTORIAL AND GENETIC-ANALYSIS/

Genetic factors have been shown to influence the nature and the intens ity of the stress responses. In order to understand better the genetic mechanisms involved, we have studied the behavioral and neuroendocrin e responses to novel environments in the WKHA/WKY inbred strains and w e have investigated the genetic relationships between these traits in a segregating F2 intercross. The animals were submitted to behavioral tests known to provide both indices of activity and fear (activity cag es, open field and elevated plus-maze). The plasma levels of prolactin , ACTH, corticosterone, glucose and renin activity were determined aft er a 10-min exposure to novelty. Our results showed that WKHA rats, co mpared to WKYs, were more active in a familiar as well as in novel env ironments. They exhibited also less anxiety-related behaviors and lowe r neuroendocrine responses. A principal component analysis performed o n the behavioral F2 results defined three independent factors: general activity, anxiety and defecation, none of them being correlated with the neuroendocrine measures. Thus this study suggests that these diffe rent responses to stress are independent components that may have dist inct molecular bases.