Abstract
Comfort eating during periods of stress is a common phenomenon observed in both animals and humans. However, the underlying mechanisms of stress‐induced food intake remain elusive. The amygdala plays a central role in higher‐order emotional processing and the posterodorsal subnucleus of the medial amygdala (MePD), in particular, is involved in food intake. Extra‐hypothalamic corticotrophin‐releasing factor (CRF) is well recognised for mediating behavioural responses to stress. To explore the possible role of amygdala CRF receptor activation in stress‐induced food intake, we evaluated whether a stressor such as tail‐pinch, which reliably induces food intake, would fail to do so in animals bearing bilateral neurotoxic lesions of the MePD. Our results showed that ibotenic acid induced lesions of the MePD markedly reduced tail‐pinch induced food intake in ovariectomised, 17β‐oestradiol replaced rats. In addition, intra‐MePD (right side only) administration of CRF (0.002 or 0.02 ng) via chronically implanted cannulae resulted in a dose‐dependent increase in food intake, although higher doses of 0.2 and 2 ng CRF had less effect, producing a bell shaped curve. Furthermore, intra‐MePD (bilateral) administration of the CRF receptor antagonist, astressin (0.3 μg per side) effectively blocked tail‐pinch induced food intake. These data suggest that the MePD is involved in stress‐induced food intake and that the amygdala CRF system may be a mediator of comfort eating.
Highlights
To explore the possible role of amygdala corticotrophin-releasing factor (CRF) receptor activation in stressinduced food intake, we evaluated whether a stressor such as tail-pinch, which reliably induces food intake, would fail to do so in animals bearing bilateral neurotoxic lesions of the MePD
Intra-MePD administration of the CRF receptor antagonist, astressin (0.3 lg per side) effectively blocked tail-pinch induced food intake. These data suggest that the MePD is involved in stress-induced food intake and that the amygdala CRF system may be a mediator of comfort eating
Microinjection of CRF-R1 antagonist into the central nucleus (CeA) completely blocks the excessive intake of palatable food, as well as anxiety-like behaviour [14], suggesting that intra-amygdala CRF mediates comfort eating during stress
Summary
Intra-MePD (bilateral) administration of the CRF receptor antagonist, astressin (0.3 lg per side) effectively blocked tail-pinch induced food intake. These data suggest that the MePD is involved in stress-induced food intake and that the amygdala CRF system may be a mediator of comfort eating. I.c.v. administration of CRF was shown to increase food intake, an effect that was blocked by selective CRF type 1 receptor (CRF-R1) antagonism [4] These results suggest that CRF is involved in food intake (both hyperphagia and anorexia) in a stressor-dependent manner. Microinjection of CRF-R1 antagonist into the CeA completely blocks the excessive intake of palatable food, as well as anxiety-like behaviour [14], suggesting that intra-amygdala CRF mediates comfort eating during stress
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