According to the classical concept of Geoffrey Harris the pituitary gland is controlled by the brain by means of blood-borne chemical messengers produced by central neurons. The recent isolation and structural characterization of several such messengers by Roger Guillemin and Andrew Schally and their collaborators brought the final proof for this hypothesis. This also meant that the extensive knowledge collected in the field of neurobiology now became highly relevant for the endocrinologists. For this reason it was felt important to organize a symposium which brought together experts in the fields of neurobiology and endocrinology. The idea was to focus the attention on neuronal mechanisms, particularly those related to chemical transmission, which may be of importance for the central regulation of hormonal secretion patterns. We would like to express our sincere gratitude to the Nobel Founda tion for supporting the organization of the Nobel Symposium 42 on "Principles of the Central Regulation of the Endocrine System". We would also like to express our thanks to all participants, to Professor Carl-Gustaf Bernhard, Permanent Secretary of the Royal Academy of Sciences, for making the facilities of the Academ- available to us, and to the Symposium secretaries Mrs. Gun Hultgren, Mrs. Lena Persson and Mrs. Ulla-Britt Wedin. It is a pleasure to acknowledge the generous financial support from the Nobel Foundation and its Nobel Symposium Committee through grants from the Tercentenary Foundation of the Bank of Sweden, and from the Swedish Medical Research Council, KABI AB, Stockholm, and ASTRA AB, Sodertalje.

Inhalt
Opening address.- Session I. The Peptidergic Neuron.- Neuroendocrine regulation: The peptidergic neuron Introduction and historical background.- The biochemistry of peptidergic neurons.- Hypothalamic hormones regulating pituitary (and other) functions: Their physiology and biochemistry as well as recent studies with their synthetic analogues.- Presynaptic mechanisms in peptidergic neurons.- Neurotransmitters and neuropeptides: Distribution patterns and cellular localization as revealed by immuno-cytochemistry.- Activation of release and mechanism of release of neurohypophyseal hormones.- Studies on the release and degradation of hypothalamic releasing hormones by the hypothalamus and other CNS areas in vitro.- Postsynaptic mechanisms in peptidergic transmission.- The role of GTP in the coupling of hormone receptors and adenylate cyclase.- Interactions between hypothalamic and peripheral hormones at the anterior pituitary level.- Peptide and neurotransmitter receptors in the brain: Regulation by ions and guanyl nucleotides.- Neurophysiology of hypothalamic peptidergic neurons.- The opioid receptors and their ligands.- Session II. Transmitter and Neuropeptide Synaptic Mechanisms.- Regulation of the ?-adrenergic receptor in the pineal gland and red cell membranes.- Cyclic nucleotide and protein phosphorylation mechanisms in the central nervous system.- Contrasting principles of synaptic physiology: Peptidergic and non-peptidergic neurons.- Regulation of neuropeptide release in rat brain.- Studies on interactions of epinephrine neuronal systems with other neuronal systems.- Effect of peptides on brain monoamines and on gross behaviour.- Session III. Hormonal Control of Peptidergic Neurons.- Current approaches to steroid hormone-cell interactions.- Steroid hormone receptorsin brain and pituitary.- Feedback effects on central mechanisms controlling neuroendocrine functions.- Pituitary neuropeptides and behavior.- Sexual differentiating actions of steroids on the hypothalamopituitary-liver axis.- Session IV. Interactions Between Hormones and Neurotransmitters in the Control of Peptidergic Neurons.- Neurotransmitters in the control of anterior pituitary function.- Neurotransmitter mechanisms in the control of the secretion of hormones from the anterior pituitary.- Session V. Controls of Peptidergic Neurons in Humans.- Control of peptidergic neurons in humans. An introduction.- Studies of the role of dopamine in the control of prolactin and gonadotropin secretion in humans.- Neurotransmitter control of growth hormone and prolactin secretion.- Clinical neuroendocrine relationships in normal and disordered prolactin secretion.- Session VI. Reporters' Overviews.- Role and regulation of neuropeptide neurons.- Some principles of neuronal regulation at the postsynaptic level.- Reporter's remarks.- Overview of Session IV: Interactions between hormones and neurotransmitters in the control of peptidergic neurons.- Discussion of clinical neuroendocrinology section.- Participants.