Differences in the responses of the pituitary beta-endorphin and cardiovascular system to ethanol and stress as a function of family history.

Abstract

Genetic and environmental factors, such as stress, are important for the initiation and maintenance of heavy drinking, whereas beta-endorphin may be important in controlling alcohol consumption. These studies investigated the response of pituitary beta-endorphin to stress and the effect of alcohol on the stress response in subjects at low (LR) and high (HR) risk of alcoholism, as determined from their family history. Twenty LR and 20 HR subjects were exposed to stress 30 min after ingestion of either a placebo or an alcohol drink. Plasma beta-endorphin was measured before and for 4 hr after the drink. Changes in the concentration of plasma beta-endorphin after ingestion of the placebo or alcohol drink alone served as controls to compare the stress-induced changes. Pulse and diastolic and systolic blood pressure were also measured. HR subjects presented higher baseline values of pulse and systolic blood pressure and lower plasma beta-endorphin than LR subjects. Stress induced a small increase in cardiovascular activity, whereas alcohol induced a stronger stimulation. Alcohol before stress did not prevent the stress-induced increase in cardiovascular activity. Stress, but not alcohol, increased the plasma beta-endorphin concentration. LR subjects presented a higher stress-induced increase in plasma beta-endorphin and a faster recovery than HR subjects. Alcohol before stress attenuated the stress-induced increase in plasma beta-endorphin in both LR and HR subjects. This attenuation was stronger in LR subjects. Thus, there are differences in the response of beta-endorphin to stress and the effect of ethanol on stress responses as a function of a family history of alcoholism.