Corticotropin-releasing factor and adrenal function in major depression

Antidepressant-like effect of resveratrol: involvement of antioxidant effect and peripheral regulation on HPA axis

This study focused on exploring the antidepressant potential of resveratrol (RES) and its possible mechanisms of action. Cell injury was induced by corticosterone (CORT) and detected through cell viability and contents of lactate dehydrogenase (LDH) and malonaldehyde (MDA). A rat model of depression was established through 3weeks of consecutive chronic unpredictable mild stress (CUMS), and both the depression-like behaviors and the activity of the hypothalamic-pituitary-adrenal (HPA) axis were tested. Apart from the inhibitory effect on MDA production in vitro and in vivo, the results showed that RES (10(-10)mol/L to 10(-5)mol/L) could significantly increase the cell viability and decrease the LDH activity and that RES (15mg/kg) treatment could alleviate the depression-like behavior of CUMS rats, as indicated by increased sucrose preference and decreased immobility in forced swimming test and tail suspension test. Rats that received RES treatment displayed a reduction of serum CORT, suggesting that RES affected the hyperactivity of the HPA axis in CUMS rats. However, RES did not affect the expression of corticotropin-releasing hormone (CRH) mRNA in the hypothalamus of CUMS rats. In summary, our results demonstrated that in addition to its widely known antioxidant properties, RES also has antidepressant-like effects, and suggested that the underlying mechanism might involve its peripheral effect on the regulation of the HPA axis.

Cortagine: behavioral and autonomic function of the selective CRF receptor subtype 1 agonist

Corticotropin-releasing factor (CRF) is a neuropeptide and mediating component of neuroendocrine, autonomic, and behavioral processes associated with the stress response. The two receptor subtypes identified in the mammalian brain, CRF receptor subtype 1 (CRF1) and CRF2, are suggested to differentially modulate these processes. Manipulation of these receptors with selective CRF compounds and transgenic models has revealed, in most studies, a clear potentiation of the stress response through central activation of CRF1. However, pharmacological activation of CRF restricted to CRF1 has been limited by the availability of selective peptidic compounds. Recently, a highly selective CRF1 agonist, cortagine, has been developed. It was synthesized from chimeric intermediate sequences of ovine CRF, sauvagine, and human/rat CRF into a highly soluble peptide with strong affinity for CRF1 (IC(50) < 5 nM) and a very low binding preference for CRF2 (IC(50) > 500 nM). Affinity for the CRF binding protein (IC(50) > 1,000 nM) can be abolished by the addition of a glutamate residue on position 21 of the cortagine peptide sequence. Cortagine has recently been tested in a variety of preclinical models of behavior including the elevated-plus-maze (EPM), forced swim test (FST), homecage, and rat exposure test (RET). Preliminary characterization in the EPM and FST suggested that this compound elicits anxiogenic and antidepressant-like effects, respectively. Additional testing in the homecage and RET, which targets various elements of behavior, directs to a more potent anxiogenic profile of cortagine. In this review, we discuss the behavioral findings and the tests used to measure these effects. Finally, we also discuss preliminary findings of autonomic activation obtained by central injection of cortagine that support CRF1 involvement in the modulation of heart rate and heart rate variability.

Corticotropin-releasing factor test in melancholic patients in depressed state versus recovery: a comparative study

PURPOSE

Basal adrenocorticotropin hormone (ACTH) and cortisol levels and their response to corticotropin-releasing factor (CRF) test were studied in melancholic depressive patients in depressed state and recovery, and compared with healthy controls.

METHODS

Fifty-four outpatients diagnosed with unipolar depressive disorder with melancholic features according to DSM-IV and 23 healthy controls were included in the study. The Structured Clinical Interview for DSM-IV (SCID-IV) was used for diagnosis. Twenty-nine patients were in recovery, while 25 were in depressed state at the moment of the administration of the CRF test.

FINDINGS

No differences were found between the recovered and depressed groups with respect to CRF test. Lower ACTH and higher cortisol levels with significant differences were shown in the neuroendocrine variables at 15, 30, and 60 min, and in peak response and increase, in the ACTH and cortisol response curves to CRF challenge between the groups of melancholic patients, both recovered and depressed, compared with the healthy control subjects. Moreover, recovered and depressed melancholic patients had a higher whole cortisol area under the curve with significant differences than the healthy control subjects.

CONCLUSIONS

The crossover clinical status at the moment of the CRF test doesn't differentiate changes in the HPA axis in melancholic patients, while we did find significant differences in the group of healthy controls in comparison with the groups of melancholic patients both in depressive state and recovery. This supports the hypothesis that hypothalamic pituitary adrenal (HPA) axis shows alterations that remain in depressive patients even after recovery.

Cushing’s disease and melancholia

Striking similarities exist in the endocrinology of Cushing's disease and melancholic depression.Laboratory abnormalities, which have been found in both, include raised urinary,plasma and salivary cortisol, non-suppression of cortisol in the dexamethasone suppression test and adrenocorticotrophin (ACTH) hypersecretion. The hypercortisolism can be so severe in melancholic depression that it is difficult to distinguish from Cushing's disease and has been described as a "pseudo-Cushing's" state. Cerebrospinal fluid corticotrophin-releasing hormone (CRH) levels have been found to be lower in patients with Cushing's disease than in depressed subjects. Dynamic endocrine tests may help to distinguish between the two disorders.An exaggerated response to synacthen has been found in both but a reduced ACTH response to CRH occurs in depression, unlike those with Cushing's disease who show ACTH hyper-responsiveness. Other tests, which may help to distinguish between the two disorders,include the dexamethasone-CRH test, the naloxone test, the insulin-induced hypoglycemia test and the desmopressin stimulation test. Similarities in psychiatric symptoms have been recognised for many years. More recently, the physical complications of melancholic depression have been noted. These include osteoporosis, an increased risk of death from cardiovascular disease, hypertension, a redistribution of fat to intra abdominal sites and insulin resistance. Cushing's disease shares these physical complications and we propose that the common underlying factor is excessive plasma glucocorticoids. The increasing recognition of the physical complications and the increased morbidity and mortality in those who suffer from depression underscores the necessity for early detection and treatment of this illness and screening for undetected physical complications.

Comparison between the suppressive effects of dexamethasone and loperamide on cortisol and ACTH secretion in some pathological conditions

Since in patients with Cushing's disease, unlike in normal subjects, tonic inhibitory opioid control of ACTH secretion does not operate, use of the opiate agonist loperamide (LOP) has recently been proposed in the diagnosis of hypercortisolemic states. We compared the sensitivity, specificity and diagnostic accuracy of the LOP test (16 mg orally) with corresponding results of the dexamethasone test (DXM, 1 mg orally overnight) in 23 normal subjects and in a total of 42 patients, affected by Cushing's disease (n = 8), incidentally discovered adrenal masses with impaired function of the hypothalamic-pituitary-adrenal (HPA) axis (n = 6), obesity (n = 21) and depression (n = 7). While in controls both DXM and LOP strongly suppressed plasma cortisol and ACTH, in Cushing's disease and in incidentalomas no patient showed a decrease in cortisol levels below 50 ng/ml or a reduction in plasma cortisol greater than 50% of basal values in response to LOP and DXM. In obese subjects both drugs significantly reduced plasma cortisol and ACTH without giving false positive results. In the depressed group only 3/7 patients showed a decrement in cortisol levels below 50 ng/ml after LOP in contrast to 6/7 after DXM. Thus, in patients with impairment of the HPA-axis, i.e. in Cushing's disease and in patients with adrenal incidentalomas and hormonal abnormalities, LOP and DXM test sensitivity was 100%. In controls and in obese patients specificity was 100% both with LOP and DXM, while in depressed patients it was 43% and 86% with LOP and DXM, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Stimulation of the pituitary-adrenal system with graded doses of CRH and low dose vasopressin infusion in depressed patients and healthy subjects: a pilot study

A corticotropin-releasing hormone (CRH) stimulation test with four cumulative doses of human CRH (0.01, 0.06, 0.2 and 1 microgram/kg body weight) and infusion of a low dose of [Arg8]-vasopressin (0.004 U/kg body weight/30 min) was performed in five depressed patients and six healthy subjects. Plasma samples for the measurement of cortisol, ACTH and beta-endorphin were taken at regular intervals and considered as measures of pituitary-adrenal function. A dose-response relationship between CRH and the hormones measured was found in patients and controls. Depressed patients already responded to the lowest dose of CRH with respect to cortisol release, whereas ACTH and beta-endorphin responded to the second and third doses, respectively. In control subjects the cortisol and ACTH response started after the third dose of CRH, whereas beta-endorphin responded significantly to the highest dose only. When both groups were compared, differences in response were found to the higher doses of CRH with respect to cortisol, ACTH and, less markedly, beta-endorphin and to the lowest dose of CRH with respect to cortisol. Although numbers are small, the data show 'blunting' of the ACTH response to the higher doses of CRH in patients with an enhanced cortisol response of the adrenals to lower and higher doses of CRH. There was no significant difference in response when CRH was used with vasopressin as compared to treatment with CRH alone. Thus, in this design vasopressin did not contribute significantly to CRH activity. The data suggest that pituitary cell sensitivity might be changed in depression as part of HPA dysfunction.

Adrenocorticotropin hormone, beta-endorphin and cortisol responses to oCRF in melancholic patients

Several authors have reported attenuated adrenocorticotropin hormone (ACTH) responses to corticotropin releasing factor (CRF) administration in melancholic patients as compared with healthy controls. In order to explore the integrity of the hypothalamic-pituitary-adrenal (HPA)-axis in melancholics, we examined the following parameters in 98 subjects: the ACTH; beta-endorphin; and cortisol responses to ovine CRF (oCRF) (100 micrograms/i.v.); and the postdexamethasone cortisol values. We found significant lower CRF-induced ACTH responses in melancholic patients as opposed to healthy controls and minor depressives, while major depressives occupied an intermediate position. The psychopathological correlates of the blunted CRF-induced ACTH responses were feelings of worthlessness, self-reproach, or excessive guilt. The CRF-stimulated beta-endorphin and cortisol response did not differ between the study samples. Higher baseline plasma cortisol was associated with attenuated CRF-induced ACTH responses, but these effects were not pertinent to melancholia. There were no relationships between the disordered oCRF test results, and postdexamethasone cortisol values, age, body size, sex and severity of illness. The diagnostic power of the oCRF and the dexamethasone suppression test for melancholia is enhanced when both test results are combined.

Effects of metyrapone and dexamethasone upon pro-gamma-MSH plasma levels in depressed patients and healthy controls

There is current controversy over the mechanisms underlying hypothalamic-pituitary-adrenal (HPA) axis hyperactivity in depression. Pro-gamma-melanocyte-stimulating hormone (MSH), a portion of the N-terminal region of pro-opiomelanocortin, has been shown to act synergistically with adrenocorticotropic hormone (ACTH) in stimulating corticosteroid secretion both in vitro and in vivo. Pro-gamma-MSH and ACTH plasma levels were measured in 30 drug-free male patients with a DSM-IIIR major depressive disorder and 21 healthy controls. The baseline levels were similar in the two groups. After single-dose metyrapone stimulation, both hormones increased, but pro-gamma-MSH was significantly higher in control subjects than in depressives. After overnight 1-mg dexamethasone, ACTH was significantly less suppressed in depressives than controls. These results suggest that HPA axis dysregulation in depression may involve peptides other than ACTH and be more complex than previously reported.