Possible loci of nicotine effects on feeding behavior. The brain receives a multitude of signals from the periphery reporting on adequacy of food intake and energy balance. These include humoral signals (red ribbon arrow) such as hormones and cytokines (e.g., leptin, TNFα, insulin, cholescystokinin, norepinephrine) and metabolites (e.g., glucose and fatty acids) as well as neural signals (green ribbon arrow). Within the hypothalamus (HYP) and the nucleus of the tractus solitarius (NTS) this information is integrated and transmitted to multiple brain regions (dark blue arrows), and the appropriate behavior is elicited. In addition to these central responses, the PNS (light blue) neurons including sympathetic, parasympathetic, and enteric, innervate the gastrointestinal tract, adipose depots, and endocrine organs. Possible sites at which nicotine might modify feeding behavior or energy balance are indicated with stars. A number of non-neural tissues express nAChRs, and could repsond directly to nicotine. In the CNS, nicotine could act within the hypothalamus, the NTS, and in the regions throughout the neuroaxis to which these structures project (mPFC, medial septal, and basal forebrain nuclei; VTA, ventral tegmental area; NTS, nucleus tractus solitarius; PBr, parabrachial nucleus; VLM, ventrolateral medullary nucleus; CrN, cranial nerve nuclei; VISC. SENS and VISC MTR, visceral sensory and motor neurons; NE, norephnephrine, ENT, N's, enteric neurons; CCK, cholecystokinin; FAs, fatty acids).