CSF somatostatin in anorexia nervosa and bulimia: relationship to the hypothalamic pituitary-adrenal cortical axis

The eating disorders, anorexia nervosa and normal weight bulimia, are associated with disturbances of hypothalamic-pituitary-adrenal cortical (HPA) and growth hormone function. Because somatostatin (SRIF) is one of the neuropeptides known to modulate feeding behavior and neuroendocrine systems, we measured cerebrospinal fluid (CSF) concentrations of this peptide in patients with eating disorders. CSF SRIF concentrations in patients with anorexia nervosa, both at low weight and after weight recovery, were similar to those in controls. When normal weight bulimic women stopped binging, they had a modest but significant increase in CSF SRIF. CSF SRIF was not related to plasma growth hormone concentrations but did show relationships to HPA axis hormones. Healthy volunteer women had a significant positive relationship between CSF SRIF and CSF corticotropin releasing hormone (CRH). In underweight anorectics, CSF SRIF was negatively related to both 24-hr urinary free cortisol and plasma cortisol concentrations after dexamethasone, but it was not significantly related to CSF CRH. These relationships more closely resembled those of healthy controls after weight correction. In bulimics, CSF SRIF was positively related to CSF CRH and negatively related to plasma cortisol. Our findings support a previously described relationship between CSF SRIF and HPA axis activity. The differences in SRIF-HPA relationships in anorectics and bulimics may constitute or reflect pathophysiological distinctions between these disorders.