Drug addiction is a chronic, relapsing disorder characterized by compulsive drug seeking and use, linked to dysregulation of brain regions involved in reward and stress. Brain stress systems, including corticotropin-releasing factor (CRF), norepinephrine, orexin, vasopressin, and dynorphin, and antistress systems, such as neuropeptide Y (NPY) and nociceptin, play key roles in drug dependence. These systems, particularly in the extended amygdala, are involved in the transition to and maintenance of addiction. Understanding these systems provides insights into the emotional circuitry underlying addiction and offers new targets for treatment. Drug addiction involves three stages: preoccupation/anticipation, binge/intoxication, and withdrawal/negative affect. Stress and negative reinforcement drive drug seeking, especially during withdrawal and craving. Animal models show that stress can reinstate drug-seeking behavior, highlighting the role of brain stress systems in relapse. The hypothalamic-pituitary-adrenal (HPA) axis is central to stress responses, and its dysregulation contributes to addiction. The extended amygdala, including the bed nucleus of the stria terminalis, central medial amygdala, and posterior shell of the nucleus accumbens, is a key region involved in stress and addiction. CRF systems are activated during withdrawal and contribute to anxiety-like behaviors and increased drug-seeking. CRF receptor antagonists reduce withdrawal symptoms and ethanol self-administration. Norepinephrine, through α2 and β-adrenergic receptors, modulates stress-induced reinstatement of drug-seeking behavior. Dynorphin, a κ opioid system, is involved in negative emotional states and dysphoria, with dynorphin antagonists reducing cocaine-seeking behavior. Orexin neurons in the lateral hypothalamus are activated by cues and contribute to reward and arousal, while those in the perifornical-dorsomedial hypothalamus mediate stress. Vasopressin systems in the amygdala are involved in aversive emotional responses to opioid withdrawal. Neuropeptide Y (NPY) has anxiolytic and orexigenic effects, reducing excessive ethanol intake in dependent animals. NPY receptor subtypes Y1 and Y2 are involved in alcohol dependence, with Y1 knockout mice showing increased alcohol consumption and Y2 knockout mice showing decreased consumption. NPY administration reduces alcohol intake in dependent animals, suggesting a role in modulating drinking behavior. These findings highlight the complex interactions between brain stress and antistress systems in addiction, offering potential therapeutic targets for treatment and prevention.Drug addiction is a chronic, relapsing disorder characterized by compulsive drug seeking and use, linked to dysregulation of brain regions involved in reward and stress. Brain stress systems, including corticotropin-releasing factor (CRF), norepinephrine, orexin, vasopressin, and dynorphin, and antistress systems, such as neuropeptide Y (NPY) and nociceptin, play key roles in drug dependence. These systems, particularly in the extended amygdala, are involved in the transition to and maintenance of addiction. Understanding these systems provides insights into the emotional circuitry underlying addiction and offers new targets for treatment. Drug addiction involves three stages: preoccupation/anticipation, binge/intoxication, and withdrawal/negative affect. Stress and negative reinforcement drive drug seeking, especially during withdrawal and craving. Animal models show that stress can reinstate drug-seeking behavior, highlighting the role of brain stress systems in relapse. The hypothalamic-pituitary-adrenal (HPA) axis is central to stress responses, and its dysregulation contributes to addiction. The extended amygdala, including the bed nucleus of the stria terminalis, central medial amygdala, and posterior shell of the nucleus accumbens, is a key region involved in stress and addiction. CRF systems are activated during withdrawal and contribute to anxiety-like behaviors and increased drug-seeking. CRF receptor antagonists reduce withdrawal symptoms and ethanol self-administration. Norepinephrine, through α2 and β-adrenergic receptors, modulates stress-induced reinstatement of drug-seeking behavior. Dynorphin, a κ opioid system, is involved in negative emotional states and dysphoria, with dynorphin antagonists reducing cocaine-seeking behavior. Orexin neurons in the lateral hypothalamus are activated by cues and contribute to reward and arousal, while those in the perifornical-dorsomedial hypothalamus mediate stress. Vasopressin systems in the amygdala are involved in aversive emotional responses to opioid withdrawal. Neuropeptide Y (NPY) has anxiolytic and orexigenic effects, reducing excessive ethanol intake in dependent animals. NPY receptor subtypes Y1 and Y2 are involved in alcohol dependence, with Y1 knockout mice showing increased alcohol consumption and Y2 knockout mice showing decreased consumption. NPY administration reduces alcohol intake in dependent animals, suggesting a role in modulating drinking behavior. These findings highlight the complex interactions between brain stress and antistress systems in addiction, offering potential therapeutic targets for treatment and prevention.