Comparison of growth hormone stimulation induced by desimipramine, diazepam and metaclazepam in man

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.

Dependency of growth hormone (GH) stimulation following releasing hormones on the spontaneous 24-hour GH secretion in healthy male and female subjects

The purpose of this investigation was to evaluate whether in healthy subjects the GH response following stimulation with releasing hormones is dependent on the spontaneous GH secretion within 24 hr prior to the stimulation test. In 18 male and 9 female healthy subjects (21-59 years) GH was measured every 15 min over 26 hr. Twenty-four hours after the beginning of blood sampling, a GH stimulation test was performed by using a combined releasing hormone test. Sleep was recorded in three consecutive nights. A positive correlation was found between the AUCs of the 24-hr GH secretion and the AUCs of GH stimulation, which could not be explained by an age effect only. This study demonstrates that subjects with comparatively high amounts of GH secreted within 24 hr also show good GH secretory responses when immediately after the 24-hr sampling period a stimulation test is undertaken. Therefore, a low GH response to stimulation cannot be explained by feedback effects of high GH amounts secreted during the 24 hr before the test or by empty pituitary GH storages.

Neuroendocrine effects of diazepam in panic and generalized anxiety disorders

The adrenocorticotropic hormone (ACTH), cortisol, and growth hormone responses to four consecutive, logarithmically increasing doses of intravenous diazepam compared with placebo given at 15-min intervals were examined in patients with panic disorder (n = 13), generalized anxiety disorder (n = 8), and healthy controls (n = 13). Diazepam caused dose-dependent decreases in cortisol and increases in GH and dose-independent decreases in ACTH. There were no patient-control differences, possibly due to either the small sample size of the experimental paradigm, which tested subjects in an upright, sitting position in mildly arousing circumstances.

Growth hormone response to intravenous diazepam and placebo in 82 healthy men

Growth hormone (GH) response to placebo and two different doses of diazepam (0.12 mg/kg and 0.20 mg/kg) were evaluated in 82 healthy young men. Both diazepam doses had a significant effect on the growth hormone secretion, with peak values occurring between 30 and 60 min postinfusion, after which levels returned to baseline. There was also a small but significant change in this hormone over time after placebo, but this was reflected by a slow rise following the saline infusion. Individual GH responses to diazepam were variable and, when a cut-off point of 7.5 ng/ml GH increase before 90 min postdrug administration was used, 1% of the men demonstrated a response after placebo, 17% after low-dose diazepam, and 37% following high-dose diazepam. The clinical implications and limitations of these findings are discussed.

Intravenous diazepam fails to change growth hormone and cortisol secretion in humans

Some, but not all studies have reported that a single dose of benzodiazepine affects growth hormone (GH) and cortisol secretion in healthy volunteers. The majority of studies that found GH elevations after benzodiazepine administration did not use placebo trials. The present placebo-controlled investigation determined plasma GH and cortisol levels after intravenous administration of diazepam (0.15 mg/kg) to 10 healthy volunteers. Neither GH nor cortisol secretion changed significantly after diazepam infusion. The lack of placebo trials and the presence of elevated baseline GH values may have been responsible for peak GH elevations reported in previous studies.

Does alprazolam, in contrast to diazepam, activate alpha 2-adrenoceptors involved in the regulation of rat growth hormone secretion?

The conventional benzodiazepine diazepam and the novel triazolobenzodiazepine alprazolam were compared with respect to effects on growth hormone (GH) release in reserpine pretreated rats. The reserpine pretreatment was undertaken to eliminate brain monoaminergic influence on GH secretion, hence obtaining a low GH baseline from which a drug induced increase could be easily detected. Previous studies have indicated that activation of brain alpha 2-adrenoceptors is an indispensable prerequisite for GH release induced by other agents such as serotonin and opiate receptor agonists. In line with these findings, diazepam was found to induce GH release in reserpine pretreated rats only when the alpha 2-receptor agonist clonidine was simultaneously administered. In contrast, alprazolam caused a dose-dependent increase in plasma GH when given alone to reserpine pretreated rats. This effect of alprazolam was effectively antagonized by either of the two selective alpha 2-receptor antagonists yohimbine or idazoxane. The data indicate that alprazolam, but not diazepam, activates brain alpha 2-adrenoceptors involved in rat GH regulation. The possibility that an alpha 2-agonistic profile of alprazolam may contribute to the suggested effectiveness of the drug in the treatment of panic disorder is discussed.

Inhibitory effect of phentolamine on diazepam-induced growth hormone secretion and lack of effect of diazepam on prolactin secretion in man

Phentolamine, a postsynaptic noradrenergic (NA) receptor blocker, inhibits diazepam-induced growth hormone (GH) secretion in man. In order to study the effect of phentolamine on six healthy subjects with a diazepam (10 mg i.v.)-induced GH increase greater than 7.5 ng/ml, it was necessary to test 11 subjects. The six diazepam GH responders showed a significantly higher (p less than 0.01) GH stimulation after diazepam alone than after diazepam plus phentolamine (60 mg i.v.). The inhibitory effect of phentolamine suggests that NA alpha receptors are involved in the diazepam-induced GH increase. Prolactin secretion after administration of diazepam (10 mg i.v.) was only slightly elevated in comparison with placebo (i.v.), suggesting that diazepam does not have an agonistic effect on dopamine (DA) receptors.