Effects of adrenalectomy and of mineralocorticoid receptor/glucocorticoid receptor ligands in female Brown Norway and Fischer 344 rats and f1 hybrids

Our previous studies suggested that the mineralocorticoid receptor (MR) of Brown Norway (BN) male rats is active independently of the presence of its ligands (i.e. constitutively active), and that glucocorticoid receptor (GR)-mediated mechanisms are more efficient in BN than in Fischer 344 (F344) male rats. Such functional differences in corticosteroid receptors led us to compare the effect of adrenalectomy (ADX) and MR/GR-mediated actions (treatments with deoxycorticosterone, DOC and RU 28362, respectively) on female rats from both strains, and, within the framework of a genetic study, to investigate how these differences were inherited in rats of the first generation (F1) born from the crossbreeding between BN and F344 inbred rats. This study extends our previous hypotheses of a constitutive activation of MR and of a greater efficiency of GR in males to females of the BN strain. In both strains, female rats were less sensitive to ADX and to treatments with DOC or RU 28362 than males. Globally, F1 hybrid BNxF344 rats inherited the functional characteristics of MR and GR of BN rats.