ReviewCurrent findings on the role of oxytocin in the regulation of food intake
Introduction
The hypothalamic neuropeptide oxytocin, besides its physiological function in parturition and lactation, is primarily known for its role in psychosocial and affective processing, e.g., in bonding behavior, emotion regulation, and sexual function [1], [2], [3], [4]. Oxytocin is released into the circulation by axonal terminals in the posterior pituitary and, in addition, acts directly on central nervous receptors. Interestingly, oxytocin is produced in hypothalamic regions that also regulate appetite and metabolism and are targets of appetite-regulating hormones like leptin, cholecystokinin (CCK) and ghrelin [5], [6]. Important insights into the role of oxytocin in the central nervous regulation of metabolic functions have been obtained in animal experiments (e.g., [7], [8], [9]; for review see [10], [11]) which indicate that oxytocin contributes to the control of food intake, energy expenditure and glucose homeostasis [12], [13]. In recent years, first experiments to investigate respective effects in the human organism have been performed, primarily relying on the intranasal pathway of neuropeptide delivery to the brain. Intranasal administration of oxytocin in humans has been repeatedly shown to inhibit eating behavior driven by hunger due to energy depletion as well as by more reward-related, ‘hedonic’ factors associated with food intake [14], [15], [16]. This short review summarizes the effects of oxytocin on ingestive behavior in healthy humans and subjects with obesity or eating disorders, with the aim of providing an update on current research and future directions, and looks at possible links between oxytocin's eating-related function and its role in psychosocial regulation (see Fig. 1 for an overview of oxytocin effects).
Section snippets
The neuropeptide oxytocin
Oxytocin is a nine-amino acid neuropeptide hormone that is predominantly produced in two hypothalamic regions, the paraventricular nucleus (PVN) and the supraoptic nucleus [17]. PVN oxytocin neurons project to the pituitary gland (about 40%) and a number of brain areas including the brainstem. Around 10% of PVN neurons project to three core areas of the brainstem that play an important role in the regulation of food intake: nucleus tractus solitarius, dorsal motor nucleus of the vagus nerve
Oxytocin's impact on cognition and emotion
The role of oxytocin in psychosocial, cognitive and emotional processes has become increasingly clear in recent years (see ref. [3], [51] for reviews). A rapidly growing number of studies provides evidence that intranasally administered oxytocin enhances empathy [52], the perception of emotional facial expressions as well as covert attention to happy faces [53], [54], [55], [56] and increases trust in others [2]. Oxytocin also enhances the recognition of emotional states expressed in body
Oxytocin's impact on eating behavior and energy homeostasis in animals
Thanks to research efforts in the past two to three decades, the contribution of oxytocin to the regulation of eating behavior and metabolism has gained increasing attention, and it seems like oxytocin is now not only recognized as a social peptide, but also as a messenger with relevance for food intake control. First hints at a role of oxytocin in the regulation of food intake came from animal studies where lesions of the oxytocin-expressing hypothalamic PVN resulted in increases in food
Oxytocin as a link between psychosocial mechanisms and eating behavior
The findings discussed above open up an interesting new perspective for oxytocin as a regulator of eating behavior in humans, although the mechanisms underlying oxytocin's hypophagic effect are only poorly understood. In particular, it is unknown why oxytocin in contrast to other satiating messengers is effective in obese humans. It might even be proposed that the impact of oxytocin on eating behavior is tightly interrelated with or even dependent on its psychosocial function, so that a
Acknowledgments
This work was supported by a Junior grant to M.S.S from the fortüne program of the Faculty of Medicine of the University of Tübingen, by grants from the Deutsche Forschungsgemeinschaft (DFG; SFB 654 “Plasticity and Sleep”), from the German Federal Ministry of Education and Research (BMBF) to the German Center for Diabetes Research (DZD e.V.; 01GI0925), and the Helmholtz Alliance ICEMED—Imaging and Curing Environmental Metabolic Diseases (ICEMED), through the Initiative and Networking Fund of
References (166)
- et al.
Genes, brains and mammalian social bonds
Trends Ecol. Evol.
(2005) - et al.
Oxytocin role in enhancing well-being: a literature review
J. Affect. Disord.
(2011) - et al.
Oxytocin innervation of caudal brainstem nuclei activated by cholecystokinin
Brain Res.
(2003) - et al.
Oxytocin and an oxytocin agonist administered centrally decrease food intake in rats
Peptides
(1991) - et al.
Oxytocin and appetite
Prog. Brain Res.
(2008) - et al.
Translational and therapeutic potential of oxytocin as an anti-obesity strategy: insights from rodents, nonhuman primates and humans
Physiol. Behav.
(2015) - et al.
Oxytocin-messages via the cerebrospinal fluid: behavioral effects; a review
Physiol. Behav.
(2010) - et al.
The organization of noradrenergic pathways from the brainstem to the paraventricular and supraoptic nuclei in the rat
Brain Res.
(1982) - et al.
Penetration of neurohypophyseal hormones from plasma into cerebrospinal fluid (CSF): half-times of disappearance of these neuropeptides from CSF
Brain Res.
(1983) - et al.
The oxytocin receptor
Trends Endocrinol. Metab.
(2003)