Effects of intranasal oxytocin on satiety signaling in people with schizophrenia.

Overweight and obesity in schizophrenia are prevalent, affecting half to three-quarters of people with schizophrenia. Hyperphagia and increased meal size have also been implicated as significant contributors to the weight gain problem. Oxytocin has shown to play a role in appetite control in humans and is considered an anorexigenic peptide. This two-day, within-subjects, challenge study involved the examination of satiety after administration of 24 IU oxytocin (intranasal) vs. placebo in participants with a DSM-IV diagnosis of schizophrenia (N = 16). Self reported satiety along with a preload-test meal paradigm were utilized as well as related laboratory measures (insulin, glucose, and leptin), and measures of taste and smell. There were no statistically significant differences between the groups on self-reported satiety or test meal consumption, insulin or glucose levels, or sensory measures. A significant treatment difference was found (F = 5.22, df = 1,97.6, p = 0.025), with a decrease in leptin in the oxytocin group post-administration, but no time effect (F = 1.67, df = 6,95.1, p = 0.180) or treatment by time interaction (F = 1.36. df = 3,4.16, p = 0.261). Despite the small sample and mostly negative findings, we encourage more work to use higher and repeated doses of oxytocin, and to further examine the effect of oxytocin on leptin in schizophrenia as this may be important for understanding both weight control and psychopathology.