ACh also regulates glutamatergic transmission in other neuronal subtypes involved in food intake. Stimulation of nAChRs on orexin-positive neurons in the LH induces concurrent release of glutamate and ACh, which could lead to feed-forward stimulation of this circuit once activated (Pasumarthi and Fadel, 2010). There is also some indication from studies of hypothalamic neurons in culture that ACh signaling can be upregulated to compensate for prolonged blockade of glutamatergic signaling (Belousov et al., 2001). Thus, ACh acting through nAChRs may also potentiate glutamate signaling in particular neuronal subtypes of the hypothalamus, although the functional consequences of this regulation are not yet known.
