Effects of Alcohol on the Endocrine System. Lecture Summary

Introduction:
Endocrinology is the branch of biological science that concerns itself with the actions of hormones (chemical messengers) and the organs in which the hormones are formed. Hormones have multiple functions in the body, including ensuring a constant internal environment and enabling the organism to respond appropriately to changes in both the internal and external environments. Alcohol can act on endocrine systems to influence synthesis, storage, release and transport of hormones as well as hormonal regulation and mechanisms of action, and thus can have a wide range of adverse effects.

Overview of endocrine systems:
Description of major endocrine glands and hormones released. Discussion of chemical nature and functions of hormones. Overview of hypothalamic-pituitary axis, with particular focus on the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes and the hormones they secrete.

Influence of alcohol on endocrine systems:
Discussion of general mechanisms through which alcohol can alter endocrine function including effects on hormone synthesis, storage and release; effects on hormone transport in plasma and on transport proteins; effects on hormone regulation by feedback mechanisms; and effects on hormone receptors and second messenger systems.

Specific influence of alcohol on the HPA and HPG axes:
Specific examples of alcohol's actions on the HPA axis demonstrate that alcohol stimulates the release of adrenocorticotropic hormone (ACTH) from the pituitary in a dose dependent and time dependent manner, and acts primarily at the level of the hypothalamus to have these effects. In addition, alcohol appears to alter the response of the HPA axis to subsequent stimuli, which in itself will have significant consequences for the ability of the organism to respond to environmental challenges. Specific examples of alcohol's actions on the HPG axis demonstrate that, in contrast to its effects on the HPA axis, alcohol inhibits synthesis and release of hypothalamic releasing hormones that activate the HPG axis. Furthermore, alcohol appears to have direct effects in inhibiting hormone release at the level of the pituitary and the testes. Effects of alcohol on these endocrine systems will have significant implications for both behavioral and physiological function of the organism.