CSF isatin is elevated in bulimia nervosa

Isatin (2,3-dioxoindole) is one component of tribulin (Glover et al 1988; Halket et al 1991), the name given to endogenous monoamine oxidase (MAO) inhibitory activity with associated benzodiazepine receptor binding activity (Glover et al 1980, 198l; Sandier 1982; Clow et al 1983; Armando et al 1983, 1986; Elsworth et al 1986). Increased urinary tribulin has been reported in both animals and man in association with several types of stress, including alcohol and benzodiazepine withdrawal (Petursson et al 1981, 1982; Bhattacharya et al 1982, 1988); however, isatin does not account for all the activity previously ascribed to tribulin, which also includes a selective MAO A inhibitory component, recently purified in part (unpublished observations), lsatin is known to be a selective MAO B inhibitor (Glover et a11988), with a discrete distribution in tissues and brain (Watkins et al 1990). The anxiogenic agent pentylenetetrazole provokes an isatin increase in rat (Bhattacharya et al 1991a) and rabbit (Clow et al 1989) brains. Isatin is anxiogenic in a range of animal models (Bhattacharya et al 1991b; Bhattacharya and Acharya 1993). Patients with bulimia nervosa (BN) engage in stressful behaviors such as dieting, binge eating, and purging, are more likely to have experienced stressful life events, and are often more anxious. Therefore, we measured cerebrospinal fluid (CSF) isatin levels in a group of bulimics and controls.