Fig. 7.
NPY inhibits glutamatergic hypocretin cells by multiple mechanisms. NPY acts on Y1 postsynaptic receptors to inhibit the hypocretin cell, and acts on Y2 presynaptic receptors to attenuate release of GABA and glutamate. Different actions of NPY are shown by the red arrows, with a downward arrow indicating a decrease, and upward arrow an increase. These NPY axons also contain GABA. Based on Fu et al, 2004; Horvath et al,1999. NPY probably has similar effect on many of its target neurons, including the POMC cell (Cowley et al, 2001), although the subset of NPY receptors expressed in cell bodies or terminals may differ from cell to cell.