which express cholinergic markers, were activated in response to presentation of food when the animals were hungry (Rolls et al., 1979). Consistent with a potential role for ACh in coordinating caloric need with food-seeking behaviors, long-term maintenance on a high-fat/high-sugar diet significantly down-regulated levels of ACh-esterase (AChE) in a number of brain areas that was particularly pronounced in the hypothalamus (Kaizer et al., 2004). One possibility is that the role of ACh in the hypothalamus is to integrate the interoceptive cues related to hunger with exteroceptive cues of food availability, threat or other salient conditions, a function consistent with the role of the hypothalamus in integration of interoceptive and exteroceptive conditions (Craig, 2002, 2003), but this remains to be tested.
