Differences in the Responses of the Pituitary β‐Endorphin and Cardiovascular System to Ethanol and Stress as a Function of Family History

Abstract

Background Genetic and environmental factors, such as stress, are important for the initiation and maintenance of heavy drinking, whereas β‐endorphin may be important in controlling alcohol consumption. These studies investigated the response of pituitary β‐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 β‐endorphin was measured before and for 4 hr after the drink. Changes in the concentration of plasma β‐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 β‐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 β‐endorphin concentration. LR subjects presented a higher stress‐induced increase in plasma β‐endorphin and a faster recovery than HR subjects. Alcohol before stress attenuated the stress‐induced increase in plasma β‐endorphin in both LR and HR subjects. This attenuation was stronger in LR subjects.Conclusions Thus, there are differences in the response of β‐endorphin to stress and the effect of ethanol on stress responses as a function of a family history of alcoholism.