Central Peptidergic Mechanisms in Autonomic Control

Since the recognition in the 1970s that peptides may play more diverse physiological roles than suggested by their original recognition as circulating hormones, there has been an explosion of information regarding the potential central nervous system actions of these substances. Pharmacological binding studies have described an extensive distribution of many different groups of peptidergic receptors suggesting potential sites of action for specific peptides within the brain. Many of these receptor localizations were found within the blood brain barrier indicating that these substances were released locally and perhaps acted as neurotransmitters. Over the years, experiments demonstrating physiological effects of locally administered peptides in regions where receptors for that molecule are localized have added credibility to such a hypothesis. The explosion of interest in the peptides as potential chemical messengers within the brain has since led to the description of multiple peptidergic neuronal systems within the brain. In addition, there are now many different reports of postsynaptic effects of exogenous administration of peptides on single neurons. Similarly, many studies have reported more broad-based physiological effects resulting from actions of peptides within the central nervous system.The manuscripts that follow summarize presentations in a symposium to examine the "Central Peptidergic Mechanisms in Autonomic Control," which was part of the program at the Canadian Federation of Biological Sciences annual meeting held at Queen's University in Kingston in July of 1991. The express purpose of this symposium in its inception was to provide a forum for consideration of the CNS actions of peptides in the context of a systems physiology approach. We hoped to consider our current knowledge of the roles of peptides in the brain as they relate to the control of specific physiological systems. Therefore rather than presenting a consideration of individual peptides, and each one's multitude of potential roles, the manuscripts presented in the following section have addressed what is known of central peptidergic involvement in the physiological control of reproductive function (W. K. Samson), cardiovascular regulation (A. V. Ferguson), thermoregulatory control (Q. J. Pittman), and drinking (M. Evered).I should like to take this opportunity to thank all who contributed to this symposium, in particular the speakers without whose cooperation it would not have been possible. I am also indebted to the sponsors of the symposium: Merck Frosst, Warner Lambert, Sandoz, the Canadian Physiological Society, and the Faculty of Medicine at Queen's University, whose generous support permitted such a highly qualified group of invited speakers to attend.