HPA axis disturbance in obsessive-compulsive disorder

Acute clomipramine exposure elicits dose-dependent surfacing behavior in adult zebrafish (Danio rerio)

Chronic treatment with clomipramine, a tricyclic antidepressant drug, reduces symptoms of obsessive-compulsive disorder (OCD) and can influence the activity of the hypothalamic-pituitary-adrenal axis. However, little is known regarding the effects of acute clomipramine on the immediate expression of stress responses. Serotonergic drugs can elicit surfacing, a behavioral profile potentially related to toxicity in fish, although surfacing has not yet been observed after clomipramine exposure. The present study investigated the impact of acute exposure to clomipramine on basal and stress-induced behaviors in the novel tank test and cortisol levels in mixed-sex, wild-type, adult zebrafish (Danio rerio). The findings show clomipramine-exposed groups (regardless of stress exposure) spent much more time in the top of the novel tank and had significantly less overall motor activity in the behavioral task compared to the fish not exposed to the drug. Then, the dose-dependent effects of acute clomipramine on activity in the surface of the novel tank (top third of the top half) were investigated further. Clomipramine dose-dependently increased surface-dwelling and elicited a dose-dependent hypoactivity in overall motor behavior. There were no statistically significant differences in whole-body cortisol levels in either experiment. Like other serotonin-acting drugs, clomipramine strongly elicited surface-dwelling and depressed motor behavior in adult zebrafish. Additional testing is needed to elucidate whether surfacing represents a toxic state and how serotonin regulates surfacing.

Neurobiology of Obsessive-Compulsive Disorder from Genes to Circuits: Insights from Animal Models

Obsessive-compulsive disorder (OCD) is a chronic, severe psychiatric disorder that has been ranked by the World Health Organization as one of the leading causes of illness-related disability, and first-line interventions are limited in efficacy and have side-effect issues. However, the exact pathophysiology underlying this complex, heterogeneous disorder remains unknown. This scenario is now rapidly changing due to the advancement of powerful technologies that can be used to verify the function of the specific gene and dissect the neural circuits underlying the neurobiology of OCD in rodents. Genetic and circuit-specific manipulation in rodents has provided important insights into the neurobiology of OCD by identifying the molecular, cellular, and circuit events that induce OCD-like behaviors. This review will highlight recent progress specifically toward classic genetic animal models and advanced neural circuit findings, which provide theoretical evidence for targeted intervention on specific molecular, cellular, and neural circuit events.

Bioelectronic sensor mimicking the human neuroendocrine system for the detection of hypothalamic-pituitary-adrenal axis hormones in human blood

In the neuroendocrine system, corticotropin-releasing hormone (CRH) and adrenocorticotropic hormone (ACTH) play important roles in the regulation of the hypothalamic-pituitary-adrenal (HPA) system. Disorders of the HPA system lead to physiological problems, such as Addison's disease and Cushing's syndrome. Therefore, detection of CRH and ACTH is essential for diagnosing disorders related to the HPA system. Herein, receptors of the HPA axis were used to construct a bioelectronic sensor system for the detection of CRH and ACTH. The CRH receptor, corticotropin-releasing hormone receptor 1 (CRHR1), and the ACTH receptor, melanocortin 2 receptor (MC2R), were produced using an Escherichia coli expression system, and were reconstituted using nanodisc (ND) technology. The receptor-embedded NDs were immobilized on a floating electrode of a carbon nanotube field-effect transistor (CNT-FET). The constructed sensors sensitively detected CRH and ACTH to a concentration of 1 fM with high selectivity in real time. Furthermore, the reliable detection of CRH and ACTH in human plasma by the developed sensors demonstrated their potential in clinical and practical applications. These results indicate that CRHR1 and MC2R-based bioelectronic sensors can be applied for rapid and efficient detection of CRH and ACTH.

Behavioral and biological markers for predicting compulsive-like drinking in schedule-induced polydipsia

Schedule-induced polydipsia (SIP), characterized by the development of persistent and excessive drinking under intermittent food-reinforcement schedules, is an animal model of compulsive behavior that can differentiate two populations: high drinkers (HD) and low drinkers (LD). The aim of the present study was to identify behavioral and biological markers to predict the vulnerability to developing compulsive-like drinking in SIP. Adult male Wistar rats were first trained in a spatial-discrimination serial reversal-learning task and in a reinforcer devaluation task to measure behavioral flexibility and habit formation, respectively. Subsequently, the rats were tested using the SIP protocol and identified as HD or LD based on their drinking rates. The performance of HD and LD rats in the two previous tasks was then analyzed. Before and after SIP exposure, blood glucose and plasma corticosterone (CORT) levels were measured. Additionally, serum electrolyte levels, including sodium, potassium, and chloride, were analyzed after SIP. HD rats showed higher behavioral inflexibility by exhibiting increased perseverative responses in the reversal-learning task and insensitivity to reinforcer devaluation during extinction under selective satiation. After SIP exposure, HD rats exhibited increased basal plasma CORT levels, indicating that this vulnerable group might have a dysregulation of the HPA axis. Although HD and LD rats had blood glucose levels within normal range, the HD group showed lower levels. The HD group did not exhibit hyponatremia (i.e., reduced serum sodium levels) when compared to LD rats after 20 daily SIP sessions. The results of the present study demonstrated that HD rats exhibit behavioral inflexibility and greater habitual-like behavior before SIP. Moreover, these results highlight the importance of measuring different behavioral and biological markers for predicting the vulnerability to developing compulsivity, and for enhancing the understanding of the pathophysiology of compulsive spectrum disorders.

Are carriers of CYP21A2 mutations less vulnerable to psychological stress? A population-based national cohort study

BACKGROUND

Congenital adrenal hyperplasia (CAH) is one of the most common monogenic autosomal recessive disorders with an incidence of one in 15 000. About one in 70 individuals in the general population are carriers of a severe CYP21A2 mutation. It has been suggested that this confers a survival advantage, perhaps as a result of increased activity in the hypothalamic-pituitary-adrenal axis. We investigated vulnerability to psychological stress in obligate carriers.

METHOD

The Swedish CAH Registry encompasses more than 600 patients. Parents, that is obligate carriers of the CYP21A2 mutation, were identified through the Multigeneration Register. The diagnosis of the child was used as the psychological stressor. Psychiatric diagnoses before and after the birth of a child with CAH were compared to those of controls derived from (i) the general population, (ii) parents of children with hypospadias and (iii) parents of children with diabetes mellitus type 1 (T1DM).

RESULTS

Parents of children with CAH had less risk of being diagnosed with any psychiatric disorder (OR, 0·6), an affective disorder (OR, 0·5) or substance misuse (OR, 0·5) after the diagnosis of the child, compared to the general population. Their risk was also decreased compared to parents of a child with hypospadias (OR, 0·6, 0·4 and 0·2, respectively) and parents of a child with T1DM (OR 0·7, 0·6 and 0·2, respectively). The CYP21A2 carriers had a lower risk of developing mood and stress-related disorders after the diagnosis of the child.

CONCLUSION

Obligate CYP21A2 carriers had a reduced risk of a psychiatric diagnosis and were less vulnerable to a psychologically stressful situation, at least with respect to receiving a psychiatric diagnosis. This indicates a better ability to cope with psychological stress among heterozygous carriers of severe CYP21A2 mutations, which may contribute to the apparent survival advantage.

Hypothalamic-pituitary-adrenocortical axis: neuropsychiatric aspects

Evidence of aberrant hypothalamic-pituitary-adrenocortical (HPA) activity in many psychiatric disorders, although not universal, has sparked long-standing interest in HPA hormones as biomarkers of disease or treatment response. HPA activity may be chronically elevated in melancholic depression, panic disorder, obsessive-compulsive disorder, and schizophrenia. The HPA axis may be more reactive to stress in social anxiety disorder and autism spectrum disorders. In contrast, HPA activity is more likely to be low in PTSD and atypical depression. Antidepressants are widely considered to inhibit HPA activity, although inhibition is not unanimously reported in the literature. There is evidence, also uneven, that the mood stabilizers lithium and carbamazepine have the potential to augment HPA measures, while benzodiazepines, atypical antipsychotics, and to some extent, typical antipsychotics have the potential to inhibit HPA activity. Currently, the most reliable use of HPA measures in most disorders is to predict the likelihood of relapse, although changes in HPA activity have also been proposed to play a role in the clinical benefits of psychiatric treatments. Greater attention to patient heterogeneity and more consistent approaches to assessing treatment effects on HPA function may solidify the value of HPA measures in predicting treatment response or developing novel strategies to manage psychiatric disease.

Childhood stressful events, HPA axis and anxiety disorders

Anxiety disorders are among the most common of all mental disorders and their pathogenesis is a major topic in psychiatry, both for prevention and treatment. Early stressful life events and alterations of hypothalamic pituitary adrenal (HPA) axis function seem to have a significant role in the onset of anxiety. Existing data appear to support the mediating effect of the HPA axis between childhood traumata and posttraumatic stress disorder. Findings on the HPA axis activity at baseline and after stimuli in panic disordered patients are inconclusive, even if stressful life events may have a triggering function in the development of this disorder. Data on the relationship between stress, HPA axis functioning and obsessive-compulsive disorder (OCD) are scarce and discordant, but an increased activity of the HPA axis is reported in OCD patients. Moreover, normal basal cortisol levels and hyper-responsiveness of the adrenal cortex during a psychosocial stressor are observed in social phobics. Finally, abnormal HPA axis activity has also been observed in generalized anxiety disordered patients. While several hypothesis have attempted to explain these findings over time, currently the most widely accepted theory is that early stressful life events may provoke alterations of the stress response and thus of the HPA axis, that can endure during adulthood, predisposing individuals to develop psychopathology. All theories are reviewed and the authors conclude that childhood life events and HPA abnormalities may be specifically and transnosographically related to all anxiety disorders, as well as, more broadly, to all psychiatric disorders.

Schedule-induced polydipsia as a model of compulsive behavior: neuropharmacological and neuroendocrine bases

BACKGROUND

Schedule-induced polydipsia (SIP), characterized by the development of excessive drinking under intermittent food-reinforcement schedules, has been proposed as a successful model for obsessive-compulsive disorder (OCD), schizophrenia, and alcohol abuse.

OBJECTIVES

The purpose of this study was to review the main findings and current thinking regarding the use of SIP for compulsivity assessment and evaluate its contribution to improving our knowledge of the neurobehavioral mechanisms underlying the excessive behavior manifested in SIP relevant to compulsive behavior disorders.

METHODS

The literature reviews SIP procedure and surveys main findings about its neurobehavioral basis and pharmacology relevant to its possible status as a model for compulsive disorders. Specifically, we reviewed effects of antipsychotics and serotoninergic drugs used in the treatment of OCD and schizophrenia. We also considered individual differences in SIP and its relevance as a possible compulsivity endophenotype.

CONCLUSIONS

SIP represents an animal model of non-regulatory and excessive drinking that may be valid for studying the psychopharmacology of the compulsive phenotype and modeling different psychopathologies from compulsivity spectrum disorders.

Smaller pituitary volume in adult patients with obsessive-compulsive disorder

AIMS

Another structure in the obsessive-compulsive disorder (OCD) circuit may be the pituitary gland because of the fact that limbic-hypothalamic-pituitary-adrenal (LHPA) axis abnormality has been reported in patients with OCD. There has been only one prior study, however, concerning pituitary volumetry, in which the sample was a pediatric group. The purpose of the present study was therefore to investigate this in an adult OCD patient group using magnetic resonance imaging (MRI).

METHODS

Pituitary volume was measured in 23 OCD patients and the same number of healthy control subjects. Volumetric measurements were made on T1-weighted coronal MRI, with 2.40-mm-thick slices, at 1.5 T, and were done blindly.

RESULTS

A statistically significantly smaller pituitary volume was found in OCD patients compared to healthy controls (age and intracranial volume as covariates). With regard to gender and diagnosis, there was a significant difference in pituitary gland volume (F = 4.18, P < 0.05). In addition, post-hoc analysis indicated near-significant difference in men with OCD as compared with women with OCD (P = 0.07) and significant difference between control men and control women (F = 10.96, P < 0.001).

CONCLUSIONS

Taking into consideration that the prior study found decreases in pituitary volume in pediatric patients with OCD as compared with healthy control subjects, future large MRI studies should investigate pituitary size longitudinally, with a careful characterization of hypothalamo-pituitary-adrenal (HPA) function in conjunction with anatomic MRI evaluation.

Increased nocturnal secretion of ACTH and cortisol in obsessive compulsive disorder

Information on the function of the hypothalamic-pituitary-adrenal (HPA) axis, the main mammalian system of stress response, in obsessive compulsive disorder (OCD) is inconsistent. In this study, nine inpatients with a DSM-IV diagnosis of OCD without comorbid major depression (Yale-Brown Obsessive Compulsive Scale [Y-BOCS] score >15; HAMD-21 total score 16) and nine healthy matched controls were included. Blood of patients (seven males; 31.8 +/- 9.3 years, Y-BOCS: 27.3 +/- 4.3, HAMD-21: 13.3 +/-1.9) and controls (seven males, 31.6 +/- 9.1 years) was drawn every 20 min between 23:00 and 7:00 h during sleep using a long catheter for later ACTH and cortisol analysis. Secretion patterns of cortisol and ACTH were similar in both groups, in OCD, however, at a higher level. Area under the curve plasma concentrations of both ACTH (p<0.05) and cortisol (p<0.005) were significantly greater in patients with OCD (ACTH: 674.3 +/- 57.4; cortisol: 2148.4 +/-271.7) than in controls (ACTH: 460.2 +/- 61.0; cortisol: 1191.2 +/- 124.1). In conclusion, our findings suggest that the activity of the HPA axis in patients with OCD is increased compared to healthy controls.

Forebrain glucocorticoid receptors modulate anxiety-associated locomotor activation and adrenal responsiveness

Stress potently modulates anxiety- and depression-related behaviors. In response to stressors, the hypothalamic-pituitary-adrenal (HPA) axis is activated, resulting in the release of glucocorticoids from the adrenal cortex. These hormones act peripherally to restore homeostasis but also feed back to the CNS to control the intensity and duration of the stress response. Glucocorticoids act in limbic areas of the CNS to mediate the psychological and behavioral effects of stress. In this study, we investigate the effect of forebrain-specific disruption of the glucocorticoid receptor (GR) on stress- and anxiety-related behaviors. We demonstrate that mice with disruption of forebrain GR show alterations in stress-induced locomotor activation in a number of anxiety-related behavioral paradigms. These changes are associated with alterations in stress-induced HPA axis activation and, importantly, are not attenuated by chronic treatment with the tricyclic antidepressant imipramine. These data demonstrate the importance of forebrain GR in regulation of physiological and behavioral stress reactivity and suggest that distinct pathways regulate despair- and anxiety-related behaviors.

Decreased TNF-alpha and NK activity in obsessive-compulsive disorder

BACKGROUND

Accumulating evidence points towards the involvement of autoimmune mechanisms in the pathophysiology of some subgroups of obsessive-compulsive disorder (OCD). This study was carried out to investigate whether obsessive-compulsive disorder is associated with altered activity of the immune system, and whether these changes are related to particular clinical characteristics.

METHODS

Ex vivo production of TNF-alpha, IL-4, IL-6, IL-10, and IFN-gamma in whole blood cultures, and NK-cell activity and peripheral blood NK cell-, monocytes-, T-cell-, and B-cell- percentages were measured in 50 medication-free outpatients with OCD and 25 controls.

RESULTS

In OCD patients, we found a significant decrease in production of TNF-alpha (p < 0.0001) and NK-activity (p = 0.002) in comparison with controls. No significant differences were observed in the other immune variables. Patients with first-degree relatives with OCD had significant lower NK-activity than patients who had no relatives with OCD (p = 0.02), and patients with a childhood onset of OCD had significantly lower number of NK-cells than patients with a late onset (p= 0.003).

CONCLUSIONS

Changes in TNF-alpha and NK activity suggest a potential role of altered immune function in the pathophysiology of obsessive-compulsive disorder.

Serotonin and the neuroendocrine regulation of the hypothalamic--pituitary-adrenal axis in health and disease

Serotonin (5-hydroxytryptamine, 5-HT)-containing neurons in the midbrain directly innervate corticotropin-releasing hormone (CRH)-containing cells located in paraventricular nucleus of the hypothalamus. Serotonergic inputs into the paraventricular nucleus mediate the release of CRH, leading to the release of adrenocorticotropin, which triggers glucocorticoid secretion from the adrenal cortex. 5-HT1A and 5-HT2A receptors are the main receptors mediating the serotonergic stimulation of the hypothalamic-pituitary-adrenal axis. In turn, both CRH and glucocorticoids have multiple and complex effects on the serotonergic neurons. Therefore, these two systems are interwoven and communicate closely. The intimate relationship between serotonin and the hypothalamic-pituitary-adrenal axis is of great importance in normal physiology such as circadian rhythm and stress, as well as pathophysiological disorders such as depression, anxiety, eating disorders, and chronic fatigue.

Dopamine function in obsessive compulsive disorder: cortisol response to acute apomorphine stimulation

Central dopaminergic dysfunction has been suggested to be involved in the pathogenesis of obsessive compulsive disorder (OCD). In 15 patients with OCD and in 15 age-sex matched controls we evaluated the dopamine (DA) function by measuring the cortisol (CORT) responses to stimulation with the DA agonist apomorphine (APO). The CORT response to acute saline administration was also measured, to exclude the existence of a pathology of the circadian secretion of the hormone which could obscure the significance of the CORT response to APO stimulation. Basal levels of CORT were the same in patients and controls, but the values after saline administration were significantly higher in patients than in controls. APO stimulation-induced CORT rises were significantly higher in patients than in controls, but when the data after APO were corrected for those after saline, there were no significant difference between the two groups of subjects. Our data suggest that there are no alterations of the central dopaminergic function connected with the regulation of the hypothalamo-pituitary-adrenal axis in OCD.

Normal urinary free cortisol and postdexamethasone cortisol in social phobia: comparison to normal volunteers

In primates, social stress is associated with activation of the hypothalamic-pituitary-adrenal (HPA) axis. Social phobia is a common, often disabling, form of pathological anxiety characterized by marked distress in situations involving possible scrutiny or evaluation. Little is known about HPA function in patients with social phobia. We examined 24-hour excretion of urinary free cortisol (UFC) in 54 patients with social phobia and post-dexamethasone cortisol levels in 64 patients with social phobia and found no evidence of HPA-axis overactivity compared to normal controls, despite pathological levels of anxiety.

Urinary free cortisol levels in obsessive-compulsive disorder

Seventeen obsessive-compulsive disorder (OCD) patients and 25 normal control subjects submitted 24-hour urine samples for measurement of urinary free cortisol (UFC). Thirteen of the 17 OCD patients submitted a second 24-hour urine collection after a 10-week trial of either clomipramine (n = 6) or placebo (n = 7). At baseline, the OCD patients had significantly higher UFC levels than the control group. After 10 weeks of clomipramine or placebo, however, the UFC levels for both OCD groups decreased and were comparable with those of the control group. Obsessive-compulsive symptomatology, as assessed by the Yale-Brown and the NIMH Global Obsessive-Compulsive Scales, improved in the clomipramine group but did not improve in the placebo group. There was a relationship between UFC levels and depressive symptoms.