A case of seasonal bipolar disorder exacerbated by Cushing's disease

Glucocorticoid dysregulations and their clinical correlates. From receptors to therapeutics

Clinicians have long known that a substantial proportion of patients treated with high-dose glucocorticoids experience a variety of serious side effects, including metabolic syndrome, bone loss, and mood shifts, such as depressive symptomatology, manic or hypomanic symptoms, and even suicide. The reason for individual variability in expression or severity of these side effects is not clear. However, recent emerging literature is beginning to shed light on possible mechanisms of these effects. As an introduction to this volume, this chapter will review the basic biology of glucocorticoid release and molecular mechanisms of glucocorticoid receptor function, and will discuss how dysregulation of glucocorticoid action at all levels could contribute to such side effects. At the molecular level, glucocorticoid receptor polymorphisms may be associated either with receptor hypofunction or hyperfunction and could thus contribute to differential individual sensitivity to the effects of glucocorticoid treatment. Numerous factors regulate hypothalamic-pituitary-adrenal (HPA) axis responsiveness, which could also contribute to individual differences in glucocorticoid side effects. One of these is sex hormone status and the influence of estrogen and progesterone on HPA axis function and mood. Another is immune system activity, in which immune molecules, such as interleukins and cytokines, activate the HPA axis and alter brain function, including memory, cognition, and mood. The effects of cytokines in inducing sickness behaviors, which overlap with depressive symptomatology, could also contribute to individual differences in such symptomatology. Taken together, this knowledge will have important relevance for identifying at-risk patients to avoid or minimize such side effects when they are treated with glucocorticoids. A framework for assessment of patients is proposed that incorporates functional, physiological, and molecular biomarkers to identify subgroups of patients at risk for depressive symptomatology associated with glucocorticoid treatment, and for prevention of side effects, which in many cases can be life-threatening.

Modulation of stress by imidazoline binding sites: implications for psychiatric disorders

In this review, we present evidence for the involvement of imidazoline binding sites (IBS) in modulating responses to stress, through central control of monoaminergic and hypothalamo-pituitary-adrenal (HPA) axis activity. Pharmacological and physiological evidence is presented for differential effects of different IBS subtypes on serotoninergic and catecholaminergic pathways involved in control of basal and stress-stimulated HPA axis activity. IBS ligands can modulate behavioural and neuroendocrine responses in animal models of stress, depression and anxiety, and a body of evidence exists for alterations in central IBS expression in psychiatric patients, which can be normalised partially or fully by treatment with antidepressants. Dysfunction in monoaminergic systems and the HPA axis under basal and stress-induced activation has been extensively reported in psychiatric illnesses. On the basis of the literature, we suggest a potential therapeutic role for selective IBS ligands in the treatment of depression and anxiety disorders.