Table 2.

Neurotransmitters implicated in drug-seeking behaviours that have also been found to influence food intake

Neurotransmitter	Origin	Mechanism	Drugs and food
Dopamine	VTA, SN, hypothalamus	Enhances incentive salience, conditioning	All drugs Increased prevalence of DRD2 Taq1A A1 allele in obese patients with other drug dependencies compared to non-abusing obese patients (203)
Opioids	Throughout the brain	Hedonic responses, pain modulation. Interacts with ghrelin and NPY1 to modulate food reward (204)	All drugs most prominent heroin and opiate analgesics Endogenous opioids facilitate intake of sweet and fat tastants (205). In a targeted study of food addiction, the functional A118G polymorphism of the muopioid receptor gene was associated with binge eating disorders (206)
Cannabinoids	Throughout the brain	Reward and homeostatic regulation, short-term and long-term synaptic plasticity throughout the brain (207)	All drugs most prominent marihuana Endocannabinoids interact with peripheral signals, like leptin, insulin, ghrelin and satiety hormones affecting energy balance and adiposity (208)
Serotonin	Raphe nuclei	Control of behavioural, perceptual (e.g. olfaction) and regulatory systems, including mood, hunger, body temp. Sexual behaviour, muscle control and sensory perception. Hypothalamic control of food intake (209)	Ecstasy, hallucinogens (LSD, mescaline, psilocybin) 5-HT drugs reduce food intake in rodents in a manner consistent with an enhancement of satiety (210).
Histamine	Tuberomamillary nucleus (TMN) of the posterior hypothalamus	Regulation of the sleep-wake cycle, appetite, endocrine homeostasis, body temperature, pain perception, learning, memory and emotion (211).	Alcohol and nicotine (212,213) (214). Sustained histaminergic blockade in rats is associated with decreased body weight (215).
Cholinergic (216)	Nicotine receptors in VTA and hypothalamus	Regulates activity in DA neurons and in MCH neurons. Nicotine administration into the lateral hypothalamus significantly decreases food intake (217)	Nicotine. Hyperphagia: a major deterrent to smoking cessation (218)
Glutamate	Throughout the brain	Perception of pain, responses to the environment and memory. Injection of glutamate into the lateral hypothalamus elicits an intense feeding in satiated rats (219)	All drugs most prominent PCP and ketamine Selective stimulation of AMPAR in the LH is sufficient to elicit feeding (220).
GABA	Throughout the brain	Modulates striatal signalling from D1R and D2R expressing neurons and modulates reactivity of DA neurons in midbrain	Alcohol, opiates, inhalants, benzodiazepines (171). When released from leptin-inhibited neurons, GABA can promote weight gain (221).
Norepinephrine	Locus coeruleus	NE (like NPY and AGRP) reported to modulate the circuitry of consummatory ingestive responses via its actions in both hypothalamic and hindbrain sites (222).	Memory to drugs (223) Memories to food properties (224)