Endorphins in inbred mice with variable sensitivity to ethanol: effect of acute ethanol treatment

Resting levels of beta-endorphin like immunoreactivity were determined in the hypothalamus, neurointermediate lobe and anterior lobe of the pituitary gland and the serum of inbred mice strains (C57BL/6, BALB/C and DBA/2). C57BL/6 mice showed the highest content of beta-endorphin like immunoreactivity in the neurointermediate lobe, anterior lobe and serum. Animals were injected i.p. with either an ethanol solution (3g ethanol/Kg b. wt.) or saline. 45 minutes post ethanol treatment the beta-endorphin like immunoreactivity content was increased in the serum of all three strains of mice studied and was decreased in the hypothalamus of the C57BL/6 mice. Studies with reverse phace HPLC indicated some differences in the relative proportions of the various forms of beta-endorphin in some tissues among the three strains of mice. These results suggest that genetically determined differences in endorphin levels may be involved in some of the genetically determined differences in responses to ethanol.