Indeed, hypercortisolemia in depressed patients is associated with elevated CSF CRH levels (see above). The increased expression of CRH in the central amygdaloid
nucleus may be responsible for the increase in emotionality and anxiety, and the neurovegetative instability often associated with major depression.87,88 Moreover, the central amygdaloid nucleus exerts a stimulatory influence on the HPA axis, via its direct and indirect (via the BNST) connections to the PVN.73 It may be speculated that in depressed patients a positive feed-forward Inhibitors,research,lifescience,medical loop may have been established between the amygdala and the HPA axis. Given that the neural and humoral components of this loop have uncountable interactions with other – central and peripheral – systems, the consequences will be Inhibitors,research,lifescience,medical manifold, including HTS assay effects on mood, cognition, libido, the cardiovascular system, immune system, and metabolism (Figure 4). Figure 4. Shift in limbic afferent control of the hypothalamic-pituitary-adrenocortical (HPA) axis and its
consequences for affective Inhibitors,research,lifescience,medical states and physiological functioning. This figure presents a working hypothesis on limbic-HPA axis interactions in anxiety and … Above, we postulated that CRHR1 and CRHR2 play different roles in stress-evoked anxiety, in which both receptors operate, possibly in different regions of the brain (eg, central amygdaloid nucleus, BNST, intermediate LS), in the acute (anxiogenic) phase
of the stress response, and in which CRHR2 promotes anxiolysis during the stress recovery phase. We have also described a parallel mechanism for the role of these receptors in the stress-induced HPA response. As Inhibitors,research,lifescience,medical mentioned, there are strong indications for a CRH-evoked CRHR1-mediated hypersignaling in the brain of patients suffering from anxiety and depressive disorders. This condition is thought to be responsible for the increases in emotionality and HPA activity, Inhibitors,research,lifescience,medical and neurovegetative and sleep disturbances seen in these patients. Indeed, a preliminary exploratory clinical study in our clinical department at the Max Planck Institute of Psychiatry others in which depressed patients were treated with the nonpeptidergic CRHR1 antagonist R121919 showed that blocking CRHRl signaling in these patients had beneficial effects (Figure 5). Beside the effects on sleep architecture (see above),64 the treatment resulted in a substantial reduction in the depression (Figure 5) and anxiety scores.92 The current status of research promises that CRHRl antagonism represents a novel pharmacotherapeutic strategy to treat depression, pathological anxiety such as phobias, panic, and posttraumatic, stress disorder. This new development in the pharmacological treatment of major depressive and anxiety disorders is a significant step toward the formation of basic science-driven therapies.