HPA hyperactivity with increased plasma cortisol affects dexamethasone metabolism and DST outcome

Drug development and potential targets for Cushing's syndrome

Cushing's syndrome (CS) is a complex disorder characterized by the excessive secretion of cortisol, with Cushing's disease (CD), particularly associated with pituitary tumors, exhibiting heightened morbidity and mortality. Although transsphenoidal pituitary surgery (TSS) stands as the primary treatment for CD, there is a crucial need to optimize patient prognosis. Current medical therapy serves as an adjunctive measure due to its unsatisfactory efficacy and unpredictable side effects. In this comprehensive review, we delve into recent advances in understanding the pathogenesis of CS and explore therapeutic options by conducting a critical analysis of potential drug targets and candidates. Additionally, we provide an overview of the design strategy employed in previously reported candidates, along with a summary of structure-activity relationship (SAR) analyses and their biological efficacy. This review aims to contribute valuable insights to the evolving landscape of CS research, shedding light on potential avenues for therapeutic development.

Role of glucocorticoid- and monoamine-metabolizing enzymes in stress-related psychopathological processes

Glucocorticoid signaling is fundamental in healthy stress coping and in the pathophysiology of stress-related diseases, such as post-traumatic stress disorder (PTSD). Glucocorticoids are metabolized by cytochrome P450 (CYP) as well as 11-β-hydroxysteroid dehydrogenase type 1 (11βHSD1) and 2 (11βHSD2). Acute stress-induced increase in glucocorticoid concentrations stimulates the expression of several CYP sub-types. CYP is primarily responsible for glucocorticoid metabolism and its increased activity can result in decreased circulating glucocorticoids in response to repeated stress stimuli. In addition, repeated stress-induced glucocorticoid release can promote 11βHSD1 activation and 11βHSD2 inhibition, and the 11βHSD2 suppression can lead to apparent mineralocorticoid excess. The activation of CYP and 11βHSD1 and the suppression of 11βHSD2 may at least partly contribute to development of the blunted glucocorticoid response to stressors characteristic in high trait anxiety, PTSD, and other stress-related disorders. Glucocorticoids and glucocorticoid-metabolizing enzymes interact closely with other biomolecules such as inflammatory cytokines, monoamines, and some monoamine-metabolizing enzymes, namely the monoamine oxidase type A (MAO-A) and B (MAO-B). Glucocorticoids boost MAO activity and this decreases monoamine levels and induces oxidative tissue damage which then activates inflammatory cytokines. The inflammatory cytokines suppress CYP expression and activity. This dynamic cross-talk between glucocorticoids, monoamines, and their metabolizing enzymes could be a critical factor in the pathophysiology of stress-related disorders.Lay summaryGlucocorticoids, which are produced and released under the control by brain regulatory centers, are fundamental in the stress response. This review emphasizes the importance of glucocorticoid metabolism and particularly the interaction between the brain and the liver as the major metabolic organ in the body. The activity of enzymes involved in glucocorticoid metabolism is proposed to play not only an important role in positive, healthy glucocorticoid effects, but also to contribute to the development and course of stress-related diseases.

Relative hypocortisolism is associated with obesity and the metabolic syndrome in recurrent affective disorders

BACKGROUND

Cardiovascular disease (CVD) is one of the main causes of excess deaths in affective disorders. Affective disorders are associated with increased frequencies of CVD risk-factors such as obesity, dyslipidemia, and metabolic syndrome. Stress-induced chronic cortisol excess has been suggested to promote obesity and metabolic syndrome. Chronic stress with frequent or persisting hypothalamic-pituitary-adrenal-axis (HPA-axis) hyperactivity may, over time, lead to a state of low HPA-axis activity, also denoted hypocortisolism. A low-dose weight-adjusted dexamethasone-suppression-test (DST) is considered to be a sensitive measure of hypocortisolism.

METHODS

245 patients with recurrent depression or bipolar disorder and 258 controls participated in a low-dose DST and were also examined with regard to metabolic status.

RESULTS

Patients with hypocortisolism (low post-DST cortisol) compared with patients without hypocortisolism (normal or high post-DST cortisol) exhibited increased odds ratios (OR) for obesity (OR=4.0), overweight (OR=4.0), large waist (OR=2.7), high LDL (OR=4.2), low HDL (OR=2.4), high LDL/HDL ratio (OR=3.3), high TC/HDL ratio (OR=3.4) and metabolic syndrome (OR=2.0). A similar pattern but less pronounced was also found in the control sample.

LIMITATIONS

The cross sectional study design and absence of analyses addressing lifestyle factors.

CONCLUSIONS

Our findings suggest that a substantial portion of the metabolic disorders and cardiovascular risk factors seen in recurrent affective disorders are found among individuals exhibiting hypocortisolism. This might indicate that long-term stress is a central contributor to metabolic abnormalities and CVD mortality in recurrent affective disorders.

Basal hypothalamic pituitary adrenal axis activity and hippocampal volumes: the SMART-Medea study

BACKGROUND

It has frequently been hypothesized that high levels of glucocorticoids have deleterious effects on the hippocampus and increase risk for cognitive decline and dementia, but no large-scale studies in humans have examined the direct relation between hippocampal volumes and hypothalamic-pituitary-adrenal axis activity.

METHODS

Cross-sectional analyses within the Second Manifestations of ARTerial disease-Magnetic Resonance (SMART)-Medea study, an ancillary study to the SMART-MR study on brain changes on magnetic resonance imaging (MRI) among patients with arterial disease. In 575 patients (mean age 62 +/- 9 years), diurnal cortisol rhythm was assessed with six saliva samples, collected at awakening; at 30, 45, and 60 min thereafter; and at 10 pm and 11 pm. A low dose of dexamethasone (.5 mg) was administered at 11 pm, and saliva was sampled the next morning at awakening. Volumetric measurements of the hippocampus were performed on a three-dimensional fast field echo T1-weighted scan with isotropic voxels.

RESULTS

Mean total relative hippocampal volume was 6.0 +/- .7 mL. Linear regression analyses, adjusted for age, sex, vascular risk factors, and global brain atrophy showed that participants with higher evening levels and higher awakening levels after dexamethasone had smaller hippocampal volumes [B per SD (4.2) increase = -.09 mL; 95% confidence interval -.15 to -.03 mL and B per SD (2.5) increase = -.07 mL; 95% confidence interval -.13 to -.01 mL, respectively]. The awakening response was not significantly associated with hippocampal volumes.

CONCLUSIONS

In this population, higher evening cortisol levels and reduced suppression after dexamethasone were associated with smaller hippocampal volumes, independent of total brain volume. The cortisol response after awakening was not associated with hippocampal volume.

The low-dose dexamethasone suppression test in fibromyalgia

OBJECTIVE

Fibromyalgia syndrome (FMS) has been associated with decreased cortisol secretion. Patients with posttraumatic stress disorder (PTSD) exhibit similar hypocortisolism in the context of increased negative feedback sensitivity of the hypothalamic-pituitary-adrenal (HPA) axis. Because trauma and PTSD have been associated with fibromyalgia, we evaluated whether patients with fibromyalgia demonstrate increased HPA feedback sensitivity.

METHOD

Baseline blood samples were obtained at 0800 h, and 0.5 mg of dexamethasone was administered to 15 female patients with FMS and 20 normal controls at 2300 h. Adrenocorticotropin (ACTH), cortisol, and dexamethasone levels were measured at 0800 h after dexamethasone intake.

RESULTS

There were no group differences in mean ACTH or cortisol levels or in ACTH/cortisol ratio at baseline. After dexamethasone intake, patients with FMS exhibited more pronounced suppression of cortisol but not of ACTH, as well as increased ACTH/cortisol ratios compared with controls. Percent cortisol suppression was associated with pain and fatigue, while ACTH/cortisol ratio and dexamethasone availability were associated with stress and anxiety measures.

CONCLUSION

Our results suggest increased sensitivity to glucocorticoid feedback, manifested at the adrenal level, in FMS.

MDR1 Gene Polymorphism in Japanese Patients with Schizophrenia and Mood Disorders Including Depression

P-Glycoprotein (ABCB1-type P-gp), a membrane protein encoded by the multi drug resistant gene (MDR1), expressing on the blood brain barrier protects the brain from many drugs including dexamethasone. Psychiatric disorders, schizophrenia and depression, have known to have abnormal hypothalamus-pituitary-adrenal (HPA) activity, which is assessed by non-suppression of cortisol in dexamethasone suppression test. The poor response to dexamethasone in these patients' population suggested the impaired activity on dexamethasone penetration into the brain via P-gp, which was associated with MDR1 polymorphisms. We, therefore, examined five SNPs of the MDR1 gene, -1517 T>C (promoter), -41 A>G (intron -1), -129 T>C (exon 1b), 2677 G>A,T (exon 21) and 3435 C>T (exon 26), in Japanese patients with schizophrenia (n=121) and mood disorders (n=62), and compared with the control subjects (n=160). The frequency of MDR1 mutant alleles at -1517, -41 and -129 in patients with mood disorders was significantly lower (2.4, 5.6, 2.4%, respectively) than those of controls (7.8, 13.7, 7.8%, respectively) (p<0.05). The frequencies of MDR1 2677 G/A and A/A genotype in mood disorders was significantly higher (17.7, 6.5%, respectively) than controls (11.2, 0%, respectively) (p<0.05). The 2677A allele frequency in mood disorders (20.2%) was significant higher than controls (10.9%) (p<0.05). Haplotype of 129-2677-3435 (T-A-C) in mood disorders was significantly higher (14.4%) than controls (8.0%) (p<0.05). There was no significant difference in allele and genotype frequencies between the patients with schizophrenia and controls. These findings suggested that predispose to mood disorders, not schizophrenia, was associated with possible alteration of P-gp activities corresponding MDR1 polymorphism at least partly.

Hypothalamic-pituitary-adrenal axis activity and sleep in posttraumatic stress disorder

Alterations of the hypothalamic-pituitary-adrenal (HPA) axis and sleep disturbances have been described separately in post-traumatic stress disorder (PTSD). It is not known if HPA alterations and sleep disturbances are associated in PTSD. This study examined sleep and HPA activity in 20 male medication-free subjects with PTSD and 16 matched healthy controls. Two nights of polysomnography were obtained and 24-h urinary cortisol was collected during day 2. Subjects self-administered a low-dose (0.5 mg) salivary dexamethasone test at home. Compared with controls, PTSD subjects had higher 24-h urinary microg cortisol/g creatinine (mean+/-SD 40+/-17 vs 28+/-12, p=0.03) but not significantly higher 24-h urinary cortisol (mean+/-SD 52+/-15 microg/day vs 43+/-23, p=0.19). PTSD subjects showed a trend towards less cortisol suppression after dexamethasone (73%+/-18 vs 83%+/-10, p=0.06). In the combined sample, delta sleep was significantly and negatively correlated with 24-h urinary cortisol (r=-0.36, p=0.04), and with 24-h urinary cortisol/g creatinine on a trend level (r=-0.34, p=0.06). Our results suggest that increased cortisol is negatively associated with delta sleep. This may contribute to sleep abnormalities in conditions associated with elevated cortisol, possibly including PTSD. Future studies should explore the temporal relationship between HPA activity, sleep disturbances, and psychopathology after a traumatic event.

Hypothalamic-pituitary-adrenal axis function in patients with bipolar disorder

BACKGROUND

Hypothalamic-pituitary-adrenal (HPA) axis function, as variously measured by the responses to the combined dexamethasone/corticotrophin-releasing hormone (dex/CRH) test, the dexamethasone suppression test (DST) and basal cortisol levels, has been reported to be abnormal in bipolar disorder.

AIMS

To test the hypothesis that HPA axis dysfunction persists in patients in remission from bipolar disorder.

METHOD

Salivary cortisol levels and the plasma cortisol response to the DST and dex/CRH test were examined in 53 patients with bipolar disorder, 27 of whom fulfilled stringent criteria for remission, and in 28 healthy controls. Serum dexamethasone levels were measured.

RESULTS

Patients with bipolar disorder demonstrated an enhanced cortisol response to the dex/CRH test compared with controls (P=0.001). This response did not differ significantly between remitted and non-remitted patients. These findings were present after the potentially confounding effects of dexamethasone levels were accounted for.

CONCLUSIONS

The dex/CRH test is abnormal in both remitted and non-remitted patients with bipolar disorder. This measure of HPA axis dysfunction is a potential trait marker in bipolar disorder and thus possibly indicative of the core pathophysiological process in this illness.

Salivary cortisol responses to dexamethasone in adolescents with posttraumatic stress disorder

OBJECTIVE

Previous studies of adults with posttraumatic stress disorder (PTSD) have found various abnormalities in the regulation of the hypothalamic-pituitary-adrenal axis, including enhanced suppression of cortisol following low-dose dexamethasone. The purpose of the present study was to investigate salivary cortisol responses to low-dose dexamethasone in adolescents with PTSD.

METHOD

Forty-eight adolescents (20 with current PTSD, 9 trauma controls without PTSD, and 19 healthy nontraumatized controls) were enrolled in the study. On day 1, baseline saliva samples were obtained at 8 a.m. and 0.5 mg of dexamethasone was administered at 11 p.m. Cortisol and dexamethasone levels were assessed at 8 a.m. the following day.

RESULTS

Adolescents with current PTSD showed no difference in the suppression of salivary cortisol in response to low-dose (0.5 mg) dexamethasone compared to trauma controls without PTSD and nontraumatized controls. More severely affected PTSD subjects with co-occurring major depression showed higher pre- and post-dexamethasone salivary cortisol levels compared to controls.

CONCLUSIONS

The present study did not find evidence for enhanced suppression of salivary cortisol at 8 a.m. following low-dose dexamethasone in multiply traumatized adolescents with PTSD. This result differs from findings in adults with PTSD. Further investigations of hypothalamic-pituitary-adrenal axis abnormalities in traumatized children and adolescents are needed.