THE EFFECTS OF RESTRAINT OR HYPERTONIC SALINE STRESS ON CORTICOTROPIN-RELEASING FACTOR, ARGININE-VASOPRESSIN, AND PROENKEPHALIN-A MESSENGER-RNAS IS THE CFY, SPRAGUE-DAWLEY AND WISTAR STRAINS OF RAT

It is generally assumed that the stress response of different strains of rat will be identical following exposure to acute stress. In the pr esent study we have examined the activation of the hypothalamo-pituita ry-adrenal axis in the Wister, Sprague-Dawley and CFY strains of rat f ollowing exposure to either the predominantly psychological stress of restraint or the physical stress of i.p. hypertonic saline injection. We have investigated the hypothalamic activation of corticotrophin-rel easing factor (CRF) and proenkephalin A (PEA) mRNAs in the parvocellul ar cells of the paraventricular nucleus (PVN) and arginine vasopressin (AVP) in both the magnocellular and parvocellular regions in the PVN following acute stress. In addition we have measured corticosterone as an index of end-point activation. Circulating corticosterone and CRF mRNA were increased in all three strains following either stress. AVP and PEA mRNAs were increased following hypertonic saline but only in t he CFY strain following restraint. Overall the relative increase in th e parameters measured was greater in the CFY strain of rat than the ot her strains. These data demonstrate marked differences in response to acute stress in the three strains of rat examined. These varying respo nses must be taken into consideration when designing or interpreting a ny study investigating the stress response.