Tricyclic wash-out and growth hormone response to clonidine

Dopaminergic, Noradrenergic, Adrenal, and Thyroid Abnormalities in Psychotic and Affective Disorders

BACKGROUND

This study aimed to assess hypothalamic-pituitary dopaminergic (DA), noradrenergic (NA), thyroid (HPT), and adrenal (HPA) activity in schizophrenia, in schizoaffective disorder, and in bipolar disorder.

METHOD

We investigated a combined approach of hormone responses to (1) apomorphine (APO), a short-acting DA receptor agonist which decreases prolactin secretion (PRL), and stimulates secretion of growth hormone (GH), adrenocorticotropin (ACTH), and cortisol; (2) clonidine (CLO), an alpha 2-adrenoceptor agonist which stimulates GH secretion; (3) 8 AM and 11 PM protirelin (TRH) which stimulates thyrotropin (TSH) secretion; and (4) dexamethasone which suppresses cortisol secretion, in 13 hospitalized healthy male controls and 39 untreated male inpatients: 13 with DSM-IV paranoid schizophrenia, 13 with DSM-IV schizoaffective disorder (bipolar subtype, depressed at the time of the study), and 13 with DSM-IV bipolar disorder (depressed).

RESULTS

Compared to controls, paranoid schizophrenic patients showed (1) lower APO-induced ACTH and cortisol stimulation, and (2) higher post-dexamethasone cortisol values. Compared to controls, schizoaffective and bipolar patients showed (1) lower ΔΔTSH values (i.e., difference between 11 PM and 8 AM TRH-TSH responses), (2) lower APO-induced PRL suppression, (3) lower CLO-induced GH stimulation, and (4) higher post-dexamethasone cortisol values.

CONCLUSIONS

Although results must be interpreted with caution because of the small sample, this preliminary study suggests that depressed bipolar and schizoaffective patients share common biological dysregulations, distinct from that of paranoid schizophrenic patients. From a pathophysiological viewpoint, paranoid schizophrenic patients can be characterized by hyposensitivity of the hypothalamic DA receptors (possibly resulting from an increase in presynaptic DA release) associated with increased HPA axis activity, while depressed bipolar and schizoaffective patients can be characterized by hyposensitivity of the pituitary TRH and DA-D₂ receptors (possibly linked to the activation of the hypothalamic TRH and tuberoinfundibular DA neurons, respectively), together with subsensitive postsynaptic α₂-adrenoreceptors at the hypothalamic level (possibly secondary to an erratic release of NA) and increased HPA axis activity.

The effect of antidepressant treatment on alpha2 adrenoceptor function in DSM 111 major depression

Twenty-one drug free patients fulfilling the DSM-111-R criteria for major depressive disorder were administered an alpha2 adrenoceptor challenge test. They were then treated with an antidepressant or ECT. Six weeks later, alpha2 function was again tested and found to be universally downregulated in treatment responders. Those who failed to respond to treatment (33%) had evidence of continuing alpha2 adrenoceptor activity. These results suggest central noradrenergic overactivity as a possible mechanism for depression, which runs counter to the classic catecholamine hypothesis.

What future for neuroendocrinology in psychiatry?

In psychiatry, neuroendocrine techniques were initially considered a potential "window into the brain" by indirectly marking central nervous system limbic dysfunction. At present this conception has evolved, owing to significant progress over the last decades demonstrating direct involvement of neuropeptides and neurohormones in psychiatric diseases. In a synchronic perspective, neuroendocrine investigations evaluate a functional status at a given moment in the evolution of the disease, which results from both etiopathogenic processes and compensatory homeostatic mechanisms. These vital physiological changes appear to be potential targets for novel hormonally based pharmacotherapies. However, in the past few years, the interest for the study of neuroendocrine dysregulations in psychiatric patients has declined. In order to better understand this relative disinterest, this article will attempt to shed light on strengths and limitations of the neuroendocrine approaches in psychiatry. It is necessary to bear in mind that the usefulness of these techniques in the clinical, pathophysiological and therapeutic fields depends largely on the selectivity of stimuli and the appropriateness of the methodologies used. Owing to the complexity of the clinical phenomena, multifactorial approaches (combining several neuroendocrine challenge tests to imaging, immunological, neurophysiological, neurochemical and/or genetic techniques) are to be privileged in psychiatric investigations. Despite the inherent limitations of these approaches, due to their technical and ethical constraints, the neuroendocrine strategy can inform modern clinical practice and lead to new breakthroughs in future science and practice.

Twenty-four hour growth hormone secretion in patients with panic disorder

BACKGROUND

Patients with panic disorder have blunted growth hormone (GH) responses to clonidine, suggesting subsensitivity of post-synaptic alpha(2)-adrenoreceptors, presumably in response to excessive central noradrenergic outflow. However, basal levels of GH release over a full circadian cycle have not been examined in panic. Reduced basal GH release would suggest an overall hypo-active GH system rather than a specific alpha-adrenergic abnormality.

METHODS

To determine whether panic patients show reduced basal GH secretion, 20 patients and 12 healthy controls were studied. Blood samples were drawn every 15 min for 24 h and plasma was assayed for GH. Patients were restudied during successful treatment with alprazolam. Groups were compared on overnight and daytime GH secretion and circadian patterns of release.

RESULTS

Patients showed normal levels on all measures of GH release. Treatment may have reduced nocturnal GH release slightly, but treated patients still did not differ from controls. The normal predominance of sleep over waking GH secretion was seen in both groups.

CONCLUSIONS

Panic patients, in contrast to depressed patients, have normal somatotrophic axis activity when measured in a resting state over a full circadian cycle. GH dysregulation may only be evident in these patients in activation paradigms and has been most consistently demonstrated by challenges with the alpha(2)-noradrenergic agonist, clonidine.

Anxious and depressive disorders and their comorbidity: effect on central nervous system noradrenergic function

BACKGROUND

Although comorbidity of anxiety with depression is common, investigations of physiologic abnormalities related specifically to comorbidity are rare. This study examined relationships of DSM-IV-defined depression, anxiety, and their comorbidity to noradrenergic function measured by blunting of the growth hormone (GH) response to the alpha2 adrenoreceptor agonist (and imidazoline receptor agent) clonidine and by blood pressure and symptom responses.

METHODS

Fifteen subjects with pure social anxiety or panic disorder, 15 with pure major depression, and 18 with both depression and anxiety were compared with healthy control subjects matched for age and gender. Other factors known to affect GH (weight, menstrual status, prior antidepressant, or other drug exposure) were controlled.

RESULTS

Anxiety produced GH blunting, but depression was associated with normal GH responses. The comorbid state did not affect results beyond the impact of anxiety. Preclonidine stress-related GH elevations were observed, to the greatest degree in anxious subjects. Relevant symptom, but not blood pressure, changes were significantly associated with blunting.

CONCLUSIONS

With use of pure depression and anxiety groups and careful control of other factors known to affect GH, these results demonstrate central nervous system noradrenergic dysfunction in anxiety disorders. In contrast to less rigorously controlled studies, noradrenergic function in depression was normal.

Menstrual cycle effects on hypothalamic dopamine receptor function in women with a history of puerperal bipolar disorder

Neuroendocrine challenge tests of hypothalamic dopamine receptor function in the early postpartum period suggest that the sensitivity of these receptors is increased in women with a history of bipolar disorder after childbirth. We tested the hypothesis that, in women predisposed to bipolar disorder in the puerperium, hypothalamic dopamine receptor function is more sensitive to changes in circulating ovarian hormone concentrations than in women without such histories. Eight fully recovered and drug-free women who had had at least one episode of bipolar illness following childbirth were compared with nine normal controls. Growth hormone (GH) responses to apomorphine (APO 0.005 mg s.c.) were measured in the early follicular phase, when plasma concentrations of ovarian hormones are low, and in the mid-luteal phase, when they are relatively high. The recovered bipolar subjects and the controls did not differ from each other in their follicular and midluteal oestrogen and progesterone concentrations. In the midluteal phase, both groups had increased oestrogen and progesterone levels. The recovered bipolar subjects did not differ from controls in baseline concentrations of GH in either of the menstrual phases. The APO-GH responses of the two groups did not differ in the follicular phase, but in the midluteal phase, when female sex steroids are relatively increased, the recovered group had significantly enhanced APO-GH responses [MANOVA for repeated measures: (i) area under the curve, group by phase effect: p < 0.04; (ii) GH peak rise after APO, group by phase effect: p < 0.056] and the responses were not related to concurrent measures of mood. The results of this small study of women predisposed to bipolar disorder in the puerperium shows an increased dopaminergic receptor sensitivity in the luteal phase of the menstrual cycle. It suggests that their dopaminergic systems have increased sensitivity to changes in circulating female sex steroids. This may be aetiologically relevant to the pathogenesis of puerperal bipolar disorder.

Mirtazapine, but not fluvoxamine, normalizes the blunted REM sleep response to clonidine in depressed patients: implications for subsensitivity of alpha(2)-adrenergic receptors in depression

To determine whether alpha(2)-adrenergic receptor (alpha2AR) subsensitivity is a state or a trait marker of depression, we consecutively challenged 32 drug-free depressed patients with a clonidine REM suppression test (CREST). We then treated the patients with fluvoxamine, a selective serotonin reuptake inhibitor, or mirtazapine, a selective alpha(2)-adrenergic receptor antagonist. The first 10 patients from each treatment group who recovered were given a second challenge test. The CREST values of the two treatment groups at each time point were compared, and also compared with the CREST values of a group of 10 normal subjects. Before treatment, the REM sleep response to clonidine in the two groups of patients was significantly blunted compared with the REM sleep response in the healthy subjects. After treatment, there was still an abnormal REM sleep response to clonidine in the fluvoxamine-treated patients, despite clinical recovery, but there was a normalized REM sleep response in the mirtazapine-treated patients. These results are compatible with the hypothesis that alpha2AR subsensitivity is a trait marker of depression and suggest that the effects of these two antidepressants on alpha2AR sensitivity may not be linked to the alleviation of depression.

Reduced dopamine function in depressed patients is related to suicidal behavior but not its lethality

Several lines of evidence suggest a role for dopamine in the control of suicidal behaviour. Previously, we suggested an involvement of D2-dopaminergic function in the biology of suicide by demonstrating a smaller growth hormone (GH) response to apomorphine, a dopaminergic agonist, in depressed patients who later died by suicide. The purpose of the present study was to assess GH response to apomorphine in major depressed in-patients with a history of highly lethal suicide attempt compared to depressed patients with a low lethal lifetime suicide attempt history and non-attempters. The study was performed in a sample of 26 male depressed in-patients with a history of suicide attempt compared to 26 male depressed non-attempters. We observed a significant difference between suicide attempters and non-attempters (for GH peak, 6.3+/-5.1 ng/ml vs 15.8+/-14.2 ng/ml, F=10.3, df=1, 50, P=0.002). Moreover, GH peak responses to apomorphine did not differ between depressed patients with a high lethal lifetime suicide attempt history and patients who made low lethal lifetime suicide attempt. In conclusion, the results of the present study support a role for dopamine in the biology of suicidal behaviour. More specifically, an impaired GH response to apomorphine could be a marker of suicide risk.

Noradrenergic receptor sensitivity in obsessive-compulsive disorders: I. Growth hormone response to clonidine stimulation

In 15 patients with obsessive-compulsive disorder (OCD) and in 15 healthy controls postsynaptic alpha-2-adrenoceptor sensitivity was examined by measuring the growth hormone (GH) response to growth hormone-releasing hormone (GHRH) and to clonidine stimulation. Basal values of GH and somatomedin-C (SMD-C) and mean GH responses to GHRH were the same in patients and controls, thus suggesting that a peripheral pathology of the somatotropic axis should not be present. GH responses to clonidine stimulation were blunted in patients suggesting that post-synaptic alpha-2-adrenoceptors are subsensitive, possibly due to higher than normal noradrenergic secretion.

Efficacy of the 'clonidine REM suppression test (CREST)' to separate patients with major depression from controls; a comparison with three currently proposed biological markers of depression

We have shown that clonidine, infused i.v. during the second non-REM period, was significantly less REM sleep suppressant in depressed patients than in control subjects. We have named this procedure the 'clonidine REM suppression test (CREST)'. In this report, we compare in the same sample (15 patients with primary major affective illness, 10 normal controls, 15 patients with minor depression and 15 patients with generalized anxiety) the efficacy of the CREST to separate the major depressed patients from the control subjects with the efficacy of three currently proposed biological markers of depression, i.e., the latency of REM sleep, the dexamethasone suppression test and the clonidine growth hormone stimulation test. We found that the CREST had the highest efficacy and suggest that further studies with independent and larger samples of patients and controls are needed to confirm those preliminary results and establish if the CREST could provide a new biological marker of major affective disorders.

Growth hormone response to apomorphine in panic disorder: comparison with major depression and normal controls

Several lines of evidence suggest that dopamine might be involved in anxiety states. In the present study we assessed the growth hormone (GH) response to 0.5 mg apomorphine (a dopaminergic agonist) in 10 male drug-free inpatients meeting Research Diagnostic Criteria for panic disorder who were compared with 10 male major depressive inpatients and 10 male normal controls. The three groups differed significantly in the GH peak response (mean +/- SD): 27.8 +/- 12.5 ng/ml in panics, 5.4 +/- 4.0 ng/ml in major depressives, and 25.8 +/- 11.3 ng/ml in normal controls (F(2,27) = 15.3; P = 0.00003). Although there were significant differences between panics and major depressives (P = 0.00004), and between major depressives and controls (P = 0.00004), panics did not significantly differ from controls. These results do not support the hypothesis of an overlap between panic and affective disorders, and suggest that the hypothalamo-GH-somatomedin axis could be intact in panic disorder.

Alpha 2-adrenergic receptor sensitivity in panic disorder: I. GH response to GHRH and clonidine stimulation in panic disorder

Baseline levels of GH and somatomedin C (SmC) and GH responses to GHRH (1 microgram/kg b.w.) and to clonidine (150 micrograms) were measured in 10 outpatients with panic disorder before and after 30 days of 2-2.5 mg of alprazolam therapy, and in 10 psychophysically healthy controls. Basal levels of GH were normal in the patients and those of SmC significantly elevated, both before and after therapy. Basal GH responses to GHRH stimulation were normal and did not change change after alprazolam treatment. Basal GH responses to clonidine stimulation were blunted in the patients and improved after therapy, in parallel with an amelioration of the psychopathology. Our data suggest that adrenoceptor sensitivity, investigated by the clonidine test, is reduced in panic disorder.

A review of GHRH stimulation test in psychiatry

We critically reviewed controlled investigations of the growth hormone releasing hormone (GHRH) stimulation test in depression, anorexia nervosa, bulimia, panic disorder, schizophrenia, and Alzheimer's disease. Comparisons of GH responsiveness between patients and controls within each diagnostic category were equivocal and in some cases contradictory. Factors that may contribute substantially to the inconsistent findings within diagnostic categories include (1) the variability of GHRH-simulated GH among control groups; (2) the lack of uniformity in test procedures and outcome measures; and (3) the age and gender of subjects. In addition, the individual reproducibility of the GHRH stimulation test has not been adequately investigated and until the test's stability within subjects can be determined, the validity of interpretations resulting from the GHRH simulation test are in question.

Relationship between alpha 2-adrenergic function and suicidal behavior in depressed patients

The current main neurochemical theories of the biological correlates of suicidal behavior involve serotonergic and, to a lesser extent, dopaminergic systems. Few data are available about the possible implication of the noradrenergic function. In the present study, we assessed the growth hormone response to clonidine, a selective alpha 2-adrenergic agonist, in 15 DSM-III-R major depressive inpatients with a history of suicide attempts, compared with 15 age- and gender-matched major depressive inpatients without a history of suicidal behavior. Mean (+/- SD) growth hormone peak responses to clonidine were significantly lower in the group of suicide attempters than in the control group: 2.93 +/- 3.01 ng/ml vs. 8.28 +/- 8.15 ng/ml. Therefore, these results suggest that a blunted growth hormone response to clonidine could be a biological correlate of suicidal behavior.

Blunted growth hormone response to clonidine in Gilles de la Tourette syndrome

Noradrenergic mechanisms have been involved in the pathogenesis of Gilles de la Tourette Syndrome (GTS). Since the central alpha 2 adrenergic agonist clonidine is widely used as a therapeutic agent in GTS, the present study aimed at assessing whether GH release after clonidine, representing central alpha 2-adrenergic receptor sensitivity, was altered in GTS. After administration of 2 micrograms/kg body weight clonidine, the GH response was examined in nine drug-free, alcohol-abstinent GTS patients (eight men, one woman) and in nine age- and sex-matched abstinent healthy controls. A blunted response of GH release (< 5 ng/ml) was observed in seven patients and the area under the curve (AUC) of the GH-release was significantly reduced (p < .01) compared to controls. This finding indicates an involvement of the noradrenergic system in GTS.

The stability of plasma growth hormone and MHPG responses to repeated clonidine challenge in normal males

Clonidine is a centrally acting alpha 2-adrenergic agonist used in many psychiatric studies to assess adrenergic functioning. The short- and long-term stability of plasma growth hormone (GH) and plasma 3-methoxy-4-hydroxy phenylglycol (MHPG) responses to clonidine (2 micrograms/kg IV) over a 60-min period were assessed in subsets of 13 male normal controls on 2 consecutive days (Study A; n = 11) and on 2 days separated by several months (Study B; n = 11). In Study A, no significant differences between consecutive days were found in either baseline plasma GH or MHPG or their responses to clonidine. The 60 minute plasma GH responses between consecutive days were highly correlated (r = 0.75, n = II, p < .001), while the 60 min plasma MHPG responses were not. In Study B, no significant differences in baseline plasma GH or MHPG, or their responses to clonidine challenge, were found between the 2 test days. However, neither the plasma GH responses nor the plasma MHPG responses to clonidine at 60 min correlated significantly between the 2 study days separated by several months. Both in Study-A and in Study B, 8 of 11 subjects had a stable GH response to clonidine across both study days when defined dichotomously (blunted < 4 ng/ml; otherwise, not blunted). These results suggest that the plasma GH response and plasma MHPG response to clonidine are unaffected by repeat clonidine challenge separated by 24 h, and that the plasma GH response to clonidine may be more stable over time than the plasma MHPG response to clonidine.

Growth hormone and physiological responses to clonidine in depression

Clonidine (1.3 micrograms/kg) was administered to 62 control and 55 depressed patients free of psychoactive drugs for at least 7 days and fasted overnight. Growth hormone (GH), pulse, blood pressure and sedation were measured every 15 min for 1 h before and 2 h after clonidine infusion. GH response did not differ significantly between control and depressed subjects overall or when divided by sex. The systolic hypotensive and sedative responses were blunted in depressed subjects compared with controls; these effects appeared to be secondary to residual antidepressant drugs since the differences were only significant for those depressed subjects with short drug-free intervals. No differences between depressed subjects and controls were seen in diastolic hypotensive or bradycardic responses and no differences in GH, cardiovascular or sedative responses were found between endogenous and non-endogenous depressed subjects.

Guanfacine as an alpha-2-agonist inducer of growth hormone secretion--a comparison with clonidine

Doses of 0.5 mg and 1.0 mg of the alpha-2-adrenoceptor agonist guanfacine (GUA) and NaCl were administered intravenously (IV) in a randomized order to 18 healthy male subjects. GUA induced growth hormone (GH) secretion in a dose-dependent manner without affecting blood pressure or heart rate or inducing sedation. The effects of GUA 1.5 mg i.v. was compared with those of another alpha-2-adrenoceptor agonist, clonidine (CLON) 150 micrograms i.v. in six other male volunteers. Both alpha-2-agonists increased GH to similar levels. CLON reduced both systolic and diastolic blood pressure levels, whereas GUA reduced only systolic levels. Sedation was significantly more pronounced after CLON. The results suggest that the GUA/GH-test (1.5 mg GUA i.v.) may be an alternative to the CLON/GH-test in neuroendocrine assessment of alpha-2-adrenoceptor sensitivity.

Dopaminergic function in panic disorder: comparison with major and minor depression

Several lines of evidence suggest that dopamine might be involved in anxiety states. In this study, we assessed the growth hormone (GH) response to apomorphine (a dopaminergic agonist) 0.5 mg SC in nine drug-free inpatients meeting Research Diagnostic Criteria (RDC) for panic disorder who were age-matched and gender-matched with nine major depressive, and nine minor depressive inpatients. The three groups differed significantly in their mean GH peak response: 5.29 +/- 2.75 ng/ml in major depressives, 26.27 +/- 12.71 ng/ml in minor depressives, and 37.28 +/- 10.58 ng/ml in panics, with a significantly higher response in panic than in either minor or major depressive patients. These results support dopaminergic overactivity in panic disorder as compared with major and minor depression.

Growth hormone response to clonidine in male patients with panic disorder untreated by antidepressants

We report a non-significantly higher growth hormone (GH) response to intravenous clonidine administration (150 micrograms) in 10 male patients with panic disorder who had never received antidepressant therapy than in 10 matched controls. These results are consistent with data suggesting a normal or increased adrenergic receptor sensitivity in panic disorder patients.

Suicidal behavior and growth hormone response to apomorphine test

Several cerebrospinal fluid (CSF) studies have provided support for a possible role for the dopaminergic system as a biological correlate of suicidal behavior. Indeed, low CSF levels of the dopamine metabolite homovanillic acid (HVA) have been described in depressed patients with a history of suicide attempts. In this study, we assessed the dopamine receptor sensitivity in relationship to suicidal behavior by measuring growth hormone (GH) response to apomorphine 0.5 mg subcutaneously (sc) in 15 DSM-III-R (APA 1987) major depressive inpatients with a history of suicide attempts, compared to age-matched and gender-matched major depressive inpatients without a history of suicide. Patients with a history of suicidal behavior exhibited a significantly lower GH response to apomorphine than patients who never attempted suicide (t = 3.60, df = 1.28, p = 0.0012). Therefore, these results suggest that a blunted GH response to apomorphine could represent a biological marker of suicidal behavior.

Neuroendocrine evidence for decreased function of alpha 2-adrenergic receptor after electroconvulsive therapy

Growth hormone (GH) and hypotensive responses to clonidine (150 micrograms, i.v.) were investigated before and after electroconvulsive therapy (ECT) in 16 depressed patients. Because of high baseline serum GH concentrations, results from only 10 patients could be evaluated. The level of GH secretion induced by clonidine was significantly reduced after ECT, but the hypotensive responses to clonidine remained unchanged. The results indicate downward regulation of the sensitivity of alpha 2-adrenergic receptors in the hypothalamus after ECT.

Hormonal responses to clonidine and urinary MHPG in delusional and nondelusional melancholic patients: a placebo-controlled study

The growth hormone (GH) and cortisol responses to intravenous clonidine (0.15 mg) treatment of 25 melancholic patients, 12 with and 13 without delusions, were studied with placebo control. The baseline concentrations of the main noradrenaline metabolite, 3-methoxy-4-hydroxyphenylglycol (MHPG) were also estimated in urine. Cortisol plasma levels decreased significantly and equally after both placebo and clonidine. Baseline cortisol levels correlated positively with urinary MHPG. Clonidine did not increase GH levels significantly over time compared with placebo. Delusional melancholic patients tended to have smaller GH responses to clonidine than nondelusionals (F = 2.18, P = 0.06). There were no differences in GH response to clonidine between high and low MHPG excretors.