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Hypercortisolism is one of the most consistent biological abnormalities seen in patients with major depression, particularly the melancholic subtype. We present preliminary data regarding the effects of electroconvulsive therapy (ECT) on urinary-free cortisol (UFC) excretion and on the secretion of its principal regulatory hormone, corticotropin-releasing hormone (CRH), into the cerebrospinal fluid (CSF) of patients with major depression. Our preliminary results indicate that, while acute elevations in UFC may occur with the initiation of ECT or other antidepressant treatments, successful treatment with ECT is associated with a reduction in both UFC excretion and the diurnal pattern of CSF immunoreactive CRH levels. These findings are compatible with data in experimental animals that show reductions in hypothalamic CRH expression and pituitary-adrenal function with long-term antidepressant treatments.

Data from our group and others suggest that pituitary-adrenal activation in major depression reflects a defect at or above the hypothalamus which results in the hypersecretion of corticotropin-releasing hormone (CRH); some have suggested, however, that elevated indices of cortisol secretion and lack of suppressibility to dexamethasone may be a manifestation of a primary defect in glucocorticoid receptor activation. We report here a study of early morning pituitary-adrenal responses to the glucocorticoid antagonist RU 486 in patients with major depression and healthy volunteers. Previous data suggested that the response to RU 486 could represent an index of endogenous CRH secretory activity. RU 486 produced a robust increase in plasma corticotropin (ACTH) and cortisol secretion in both control subjects and depressed patients. In the controls, however, the increase was confined to the last 2 hours of sampling (6 to 8 am), whereas in the depressed patients the increase occurred throughout the sampling period (3 to 8 am). The ACTH response in the depressed patients exceeded that in the controls during most of the sampling period, including a significant (p less than .005) increase between 3 and 4:30 am. These results are compatible with the idea that hypercortisolism in major depression represents an alteration in the overall set point for hypothalamic CRH secretion rather than a primary alteration at the level of the glucocorticoid receptor.

The role of stress in the natural history of major depression has been a subject of intense scrutiny, particularly in light of the 20th century discoveries of some of the biological mediators of stress responses. In this paper we present evidence suggesting the hypothesis that an abnormality in the counterregulation of generalized stress responses underlies critical aspects of the pathophysiology of major depression. In particular, we focus on the role of inadequate glucocorticoid restraint of the central nervous system (CNS) components of the adrenocortical and adrenergic systems, i.e. the corticotropin releasing hormone (CRH) components of the adrenocortical and adrenergic systems, i.e. the corticotropin releasing hormone (CRH) and locus ceruleus-norepinephrine (LC-NE) systems. We believe that this hypothesis not only helps explain many of the observed abnormalities in the syndrome of major depression, but also provides a biological basis for subtyping this syndrome.

Patients with anorexia nervosa have neuroendocrine and behavioral alterations that starvation and weight loss are thought to cause, or contribute to, since they are reversed by weight restoration. We have found that anorexics have starvation-related disturbances of neuropeptide Y (NPY), corticotropin-releasing hormone (CRH), and beta-endorphin, as determined by their measurements in cerebrospinal fluid. The relationship between these neuropeptides and several symptoms in anorexia, together with findings in experimental animals, raise a possibility that changes in the activity of these neuropeptides contribute to neuroendocrine and behavioral alterations in anorexia. Specifically, a disturbance of central nervous system CRH activity is likely to be responsible for hypercortisolemia, while a disturbance of central nervous system NPY may contribute to amenorrhea. In addition, disturbances of these neuropeptides could contribute to other symptoms such as increased physical activity, hypotension, reduced sexual interest, depression, and pathological feeding behavior.

Vasopressin (AVP) and oxytocin (OT) are hypothalamic neuropeptides having distinct peripherally and centrally directed cell populations. While principally responsible for the regulation of osmotic equilibrium, AVP also participates in stress-mediated adrenocorticotropic hormone (ACTH) release, and in consolidation and retrieval of aversively conditioned behaviors. OT is principally known for its role in parturition and lactation, but also has effects opposite of AVP, antagonizing stress-mediated ACTH release and impairing the consolidation and retrieval of aversively conditioned behaviors. Our group has demonstrated novel peripheral osmoregulatory defects in underweight anorexics, coupled with hypersecretion of AVP into the cerebrospinal fluid (CSF). Conversely, a relative reduction of CSF OT is seen in underweight anorexics. Speculatively, these reciprocal changes in neurohypophyseal peptides in the underweight anorexic may enhance the observed neuroendocrine and cognitive abnormalities. In addition, the alterations in CSF OT may occur as a consequence of the abnormal gastrointestinal function present during the acute stages of anorexia nervosa.

The satiety-inducing effects of centrally and peripherally administered cholecystokinin (CCK) in experimental animals have been well documented. Recently, studies in humans showed that CCK is released into plasma following food ingestion, a phenomenon postulated to promote meal-related satiety. To explore whether abnormal CCK secretion during feeding may be related to pathophysiological mechanisms in disorders associated with appetite abnormalities, we report here studies of the plasma CCK response to a test meal in patients with bulimia nervosa, as well as seasonal (hyperphagic) and melancholic (anorexic) depression. Compared to controls, bulimic patients had impaired meal-related CCK secretion, correlated with an impaired sense of postprandial satiety. This defect resolved with tricyclic antidepressant-induced amelioration of bulimic behavior, suggesting that deficient CCK secretion may constitute a fundamental pathophysiologic derangement in this disorder. In contrast to patients with bulimia nervosa, hyperphagic patients with seasonal affective disorder failed to show abnormal meal-related CCK secretion. Preliminary evidence shows robust meal-related CCK secretion in melancholic depression with anorexia. We have also begun to explore the dynamics of CCK secretion into cerebrospinal fluid (CSF) utilizing an indwelling lumbar catheter. From studies in humans, we note that this peptide is secreted into the CSF in large (ng/ml) quantities in an episodic fashion that may bear some relationship to food ingestion. Further study of this parameter in volunteers and patients is now underway.