Intrahypothalamic Neuroendocrine Actions of Corticotropin-Releasing Factor
- 28 September 2007
- book chapter
- Published by Wiley
- Vol. 172, 151-172
- https://doi.org/10.1002/9780470514368.ch8
Abstract
Most studies of the neuroendocrine effects of corticotropin-releasing factor (CRF) have focused on its role in the regulation of the pituitary-adrenal axis; activation of this axis follows release of the peptide from CRF-containing terminals in the median eminence. However, a sizeable proportion of CRF fibres terminate within the hypothalamus itself, where synaptic contacts with other hypothalamic neuropeptidergic neurons (e.g. gonadotropin-releasing hormone-containing and opioidergic neurons) have been identified. Here, we summarize physiological and pharmacological data which provide insights into the nature and significance of these intrahypothalamic connections. It is now clear that CRF is a potent secretagogue of the three major endogenous opioid peptides (beta-endorphin, Met-enkephalin and dynorphin) and that it stimulates opioidergic neurons tonically. In the case of beta-endorphin, another hypothalamic peptide, arginine vasopressin, appears to be an essential mediator of CRF's effect, suggesting the occurrence of CRF synapses on, or in the vicinity of, vasopressin neurons; morphological support for this assumption is still wanting. Evidence for direct and indirect inhibitory effects of CRF on sexual behaviour and secretion of reproductive hormones is also presented; the indirect pathways include opioidergic neurons. An important conclusion from all these studies is that, in addition to its better known functions in producing adaptive responses during stressful situations, CRF might also contribute to the coordinated functioning of various components of the neuroendocrine system under basal conditions. Although feedback regulation of hypothalamic neuronal activity by peripheral steroids is a well-established tenet of endocrinology, data on modulation of the intrahypothalamic actions of CRF by adrenal and sex steroids are just emerging. Some of these newer findings may be useful in framing questions related to the mechanisms underlying disease states (such as depressive illness) in which CRF has been strongly implicated.Keywords
This publication has 56 references indexed in Scilit:
- A Role for Vasopressin in the Stress-Induced Inhibition of Gonadotrophin Secretion: Studies in the Brattleboro RatJournal of Neuroendocrinology, 1991
- Repeated Stress-Induced Activation of Corticotropin-Releasing Factor Neurons Enhances Vasopressin Stores and Colocalization with Corticotropin-Releasing Factor in the Median Eminence of RatsNeuroendocrinology, 1991
- Effects of Pituitary Beta-Endorphin Secretagogues on the Concentration of Beta-Endorphin in Rat Cerebrospinal Fluid: Evidence for a Role of Vasopressin in the Regulation of Brain Beta-Endorphin ReleaseNeuroendocrinology, 1990
- Responses to Corticotropin-Releasing Hormone in the Hypercortisolism of Depression and Cushing's DiseaseNew England Journal of Medicine, 1986
- Stress-Induced Inhibition of Reproductive Functions: Role of Endogenous Corticotropin-Releasing FactorScience, 1986
- Combined administration of human corticotropin-releasing factor and lysine vasopressin induces cortisol escape from dexamethasone suppression in healthy subjectsLife Sciences, 1985
- Effect of the long-term administration of corticotropin-releasing factor on the pituitary-adrenal and pituitary-gonadal axis in the male rat.JCI Insight, 1985
- Blunted Corticotropin and Normal Cortisol Response to Human Corticotropin-Releasing Factor in DepressionNew England Journal of Medicine, 1984
- Corticotropin-releasing factor is a potent inhibitor of sexual receptivity in the female ratNature, 1983