Endogenous opioids and feeding behavior: A decade of further progress (2004–2014). A Festschrift to Dr. Abba Kastin

• Food intake is stimulated by mu opioid receptor agonists in the nucleus accumbens.
• Limbic, hypothalamic and brain stem sites also support this stimulatory effect.
• General and selective opioid receptor subtype antagonists decrease food intake.
• Mice lacking specific opioid receptors show mixed intake and body weight effects.
• Opioid peptide and receptor gene expression are altered across intake situations.

Functional elucidation of the endogenous opioid system temporally paralleled the creation and growth of the journal, Peptides, under the leadership of its founding editor, Dr. Abba Kastin. He was prescient in publishing annual and uninterrupted reviews on Endogenous Opiates and Behavior that served as a microcosm for the journal under his stewardship. This author published a 2004 review, “Endogenous opioids and feeding behavior: a thirty-year historical perspective”, summarizing research in this field between 1974 and 2003. The present review “closes the circle” by reviewing the last 10 years (2004–2014) of research examining the role of endogenous opioids and feeding behavior. The review summarizes effects upon ingestive behavior following administration of opioid receptor agonists, in opioid receptor knockout animals, following administration of general opioid receptor antagonists, following administration of selective mu, delta, kappa and ORL-1 receptor antagonists, and evaluating opioid peptide and opioid receptor changes in different food intake models.