Role of corticotropin-releasing factor, vasopressin and the autonomic nervous system in learning and memory

Learning and memory are essential requirements for every living organism in order to cope with environmental demands, which enables it to adapt to cha nges in the conditions of life. Research on the effects of hormones on memo ry has focused on hormones such as adrenocorticotropic hormone (ACTH), gluc ocorticoids, vasopressin, oxytocin, epinephrine, corticotropin-releasing fa ctor (CRF) that are released into the blood and brain following arousing or stressful experiences. Most of the information have been derived from studies on conditioned behav ior, in particular, avoidance behavior in rats. In these tasks, an aversive situation was used as a stimulus for learning. Aversive stimuli are associ ated with the release of stress hormones and neuropeptides. Many factors pl ay a role in different aspects of learning and memory processes. Neuropepti des not only affect attention, motivation concentration and arousal or vigi lance, but also anxiety and fear. In this way, they participate in learning and memory processes. Furthermore, neuropeptides such as CRF and vasopress in modulate the release of stress hormones such as epinephrine. In turn, sy stemic catecholamines enhance memory consolidation. CRF and vasopressin are colocalized in neurons from the nucleus paraventricularis, which project t o nuclei in the brainstem involved in autonomic regulation. The objective o f this paper is to discuss the role of CRF, vasopressin, and the autonomic nervous system (ANS) in learning and memory processes. Both CRF and vasopre ssin have effects in the same direction on behavior, learning and memory pr ocesses and stress responses (release of catecholamines and ACTH). These ne uropeptides may act synergistically or in a concerted action aimed to learn to adapt to environmental demands. (C) 2000 Elsevier Science B.V. All righ ts reserved.