Growth hormone response to growth hormone releasing hormone in non-delusional and delusional depression and healthy controls

Longitudinal neuroendocrine changes assessed by dexamethasone/CRH and growth hormone releasing hormone tests in psychotic depression

Although psychotic depression has been reported to exhibit a greater degree of dysregulation of hypothalamic-pituitary-adrenocortical (HPA) function than non-psychotic depression, little is known concerning hypothalamic-pituitary-somatotropic (HPS) function in psychotic depression and how neuroendocrine function changes after treatment. To investigate the longitudinal changes in HPA and HPS system function in psychotic depression, we performed repeated dexamethasone/corticotropin releasing hormone (DEX/CRH) tests and growth hormone (GH) releasing hormone (GHRH) tests in inpatients with major depressive disorder. The psychotic depression group exhibited greater elevation of ACTH responses to the DEX/CRH test and stronger decreases in GH responses to the GHRH test than the non-psychotic depression group at admission. At discharge, the neuroendocrine responses to the DEX/CRH test of the psychotic depression group were still stronger than those of the non-psychotic depression group, though there were no significant differences in severity of depression between the groups. There were significant longitudinal changes in neuroendocrine responses to the DEX/CRH test between admission and discharge. The psychotic depression group exhibited increased GH responses to GHRH at discharge compared with those at admission, whereas no significant longitudinal change in GH response was found in the non-psychotic depression group. Consequently, there were no significant differences in GH responses to GHRH between the psychotic and non-psychotic depression groups at discharge. The results of GHRH test showed no significant relationships with severity of depression except psychotic features and the results of the DEX/CRH test. Our findings suggest that the HPS axis may be associated with psychotic features rather than general severity of depression. Further longitudinal studies are needed to clarify the role of HPS function in psychotic depression and whether sustained dysregulation of HPA function in psychotic depression is associated with a poor outcome after discharge.

Hormonal differences between psychotic and non-psychotic melancholic depression

BACKGROUND

The dexamethasone suppression test (DST) is the main hormonal disturbance in psychotic depression compared to non-psychotic depression. However, although there have been many studies of individual hormonal axes in depression, few multi-axial studies have been reported. This study aims to examine hormonal differences between these groups of patients through three functional hormonal tests: DST, thyroid stimulating hormone response to thyroid releasing hormone (TSH-TRF) and growth hormone response to growth hormone releasing factor (GH-GRF).

METHODS

Forty inpatients meeting DSM-III-R criteria for major depressive episode with melancholia (21 non-psychotic and 19 psychotic) were studied. Dexamethasone suppression test, TSH-TRF and GH-GRF tests were undertaken for all patients.

RESULTS

In the whole melancholic sample, 80.0% showed disturbances in at least one hormonal axis, 40.0% in two axes and 5.0% in all three axes. Basal and post-dexamethasone cortisol levels were significantly higher in psychotic than in non-psychotic patients. An association between post-dexamethasone cortisol and blunted GH-GRF response was demonstrated in those with psychotic depression. In the whole sample, GH blunting was found in 62.5% of patients, DST non-suppression in 37.5% and TSH blunting in 25.0% (no differences were found between psychotic and non-psychotic patients).

LIMITATIONS

Sample was restricted to melancholia and unknown factors may influence hormonal responses to stress.

CONCLUSIONS

Hormonal disturbances in depression are more evident when studying several axes, being the HPA and the GH axes the most prominents. Psychotic depression showed more HPA disturbance than non-psychotic depression. Influence of the HPA on the GH axis is discussed.

The combined T3/TRH test in depressed patients and healthy controls

It is well established that depressed patients show a blunted TSH response in the TRH-stimulation test. However, it has not been investigated so far whether pre-treatment with 3,5,3'-triiodothyronine (T3) is able to further suppress the TRH-induced TSH response in depressed patients or whether it may cause an escape-phenomenon with paradoxically enhanced TSH stimulation in a subsequent TRH test. In 20 drug-free depressed patients (eight men, 12 women) suffering from a major depressive episode according to DSM-IV criteria and in 20 age- and sex-matched healthy controls, the single TRH-stimulation test (administration of 200 microg TRH at 09:00 h) was carried out followed by a combined T3/TRH test (pre-treatment with 40 microg T3 at 23:00 h the night before; administration of 200 microg TRH at 09:00 h the next day). Compared to the controls, the depressed patients showed a significantly blunted TSH response in the single TRH test. However, the percentage suppression of TRH-induced TSH stimulation after pre-treatment with 40 microg T3 was comparable in the depressive patients (61.07%) and the healthy volunteers (64.20%). Prolactin secretion did not differ between patients and controls either in the single TRH test or in the combined T3/TRH test. Apparently, in contrast to the hypothalamo-pituitary-adrenocortical (HPA) system, no disturbance of feedback control in regulation of the hypothalamo-pituitary-thyroid (HPT) axis secretion can be demonstrated in depressed patients when using the combined T3/TRH test.

Insulin-like growth factor 1 and growth hormone binding protein in depression: a preliminary communication

This study was undertaken in order to advance our understanding of the distal growth hormone axis in depression. Insulin-like growth factor 1 (IGF-1) and growth hormone binding protein (GHBP) were measured in a group of 19 depressed women and a group of 16 healthy women. Using a generalized linear model, IGF-1 levels were negatively correlated with age (p = 0.0001), influenced by menstrual phase (p = 0.016), and significantly increased in the depressed group (p = 0.02). Using the same type of analysis, GHBP was significantly related to menstrual phase (p = 0.0001) and body mass index (p = 0.0001), but was not significantly different in patients and controls. IGF-1 and GHBP were positively correlated among healthy subjects (r = 0.46, p = 0.08), but not among depressed patients (r = -0.16, p = 0.51), although these correlation coefficients were not statistically significantly different from each other. These findings confirm the importance of several physiological factors in the regulation of IGF-1 and GHBP, and suggest that depression further influences this regulation.