Background: 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.
Methods: 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.
Results: 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.
Conclusions: 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.