A closer look at alcohol-induced changes in the ghrelin system: novel insights from preclinical and clinical data.

Ghrelin is a gastric-derived peptide hormone with demonstrated impact on alcohol intake and craving, but the reverse side of this bidirectional link, that is, the effects of alcohol on the ghrelin system, remains to be fully established. To further characterize this relationship, we examined (1) ghrelin levels via secondary analysis of human laboratory alcohol administration experiments with heavy-drinking participants; (2) expression of ghrelin, ghrelin receptor, and ghrelin-O-acyltransferase (GOAT) genes (GHRL, GHSR, and MBOAT4, respectively) in post-mortem brain tissue from individuals with alcohol use disorder (AUD) versus controls; (3) ghrelin levels in Ghsr knockout and wild-type rats following intraperitoneal (i.p.

Nicotine serves as an effective reinforcer of intravenous drug-taking behavior in human cigarette smokers.

Rationale: Although numerous studies have documented that nicotine can function as an effective reinforcer of intravenous self-administration behavior in animals, it has not been clearly shown to maintain intravenous self-administration behavior above vehicle placebo levels in humans.

Objectives: To compare the reinforcing effectiveness of nicotine versus saline placebo in human research volunteers responding under fixed-ratio (FR) schedules of intravenous drug self-administration while systematically increasing response requirements.

Methods: Eight male cigarette smokers resided in an inpatient research unit.