Role of pituitary and related neuropeptides in alcoholism and pharmacodependence.

Evidence is accumulating that hormonal systems present in the pituitary and the brain play a critical role in behavioral homeostase. The hormones and their fragments, called neuropeptides, produced by these systems modulate neurotransmitter activity and thereby control brain functions. Disturbances in this hormonal control may result in psychopathology, including addiction. Vasopressin and related peptides decrease under certain conditions addictive behavior of experimental animals and humans and brain reward. The pituitary and brain opioid peptides are candidates to play an essential role in reward processes and may be common factors in addiction to various psychoactive drugs, including heroin and alcohol, and to habits. Other pituitary hormones, like ACTH, gamma 2-MSH and prolactin have also been implicated in brain reward and drug addiction. It is postulated that disturbances in the hormonal and neuropeptide systems may lead to a state in which addiction behavior can easily be elicited and that the hormonal climate in the body may be of relevance for the individual susceptibility to addictive drugs. It is proposed to analyse the relation between hormonal systems and addictive behavior.