A reexamination of the relationship between growth hormone secretion and slow wave sleep using delta wave analysis

Post-stress glucose consumption facilitates hormesis and resilience to severe stress

Oral ingestion of a glucose solution following severe stress is a simple and effective way of preventing several of the negative sequelae of stress in rats. Similar resilience is obtained through hormetic training - pre-exposure to mild-to-moderate stress prior to severe stress. Here, we examined whether hormetic training is facilitated when a glucose solution is available following each hormetic training session. In Experiment 1, all rats were pre-exposed to a 30 min hormetic session of 25 inescapable tailshocks on each of 3 days. The schedule or hormesis differed between groups. The hormetic sessions occurred on either 3 consecutive days or with an interpolated day of rest between each hormetic session. Furthermore, in each of these conditions, one group had access to water and one group had access to a 40% glucose solution immediately after each hormetic session to complete a 2x2 factorial design. All groups were exposed to 100 inescapable tailshocks on the day following the end of hormetic training. Shuttle-escape testing occurred 24 h later. In Experiment 2, rats received two consecutive days of 100 inescapable tailshocks. Water or glucose was available following each session. Testing occurred 24 h after the second shock exposure. Experiment 1 replicated previous findings that rats exposed to hormetic training with interpolated rest did not show exaggerated fear responding or shuttle-escape deficits that normally result from 100 inescapable tailshocks, but training was ineffective if no rest was given between stress sessions. However, all post-stress glucose groups showed an elimination of helpless behavior. In Experiment 2, it was revealed that even 100 tailshocks can be made hormetic by post-stress glucose consumption.

Improved Sleep Quality is Associated with Reductions in Depression and PTSD Arousal Symptoms and Increases in IGF-1 Concentrations

STUDY OBJECTIVES

One-third of deployed military personnel will be diagnosed with insomnia, placing them at high risk for comorbid depression, posttraumatic stress disorder (PTSD), and medical conditions. The disruption of trophic factors has been implicated in these comorbid conditions, which can impede postdeployment recovery. This study determined if improved sleep quality is associated with (1) reductions in depression and posttraumatic symptoms, as well as enrichments in health-related quality of life (HRQOL), and (2) changes in plasma concentrations of brain derived neurotrophic factor (BDNF) and insulin-like growth factor-1 (IGF-1).

METHODS

Forty-four military personnel diagnosed with insomnia underwent clinical evaluations and blood draws at pretreatment and at posttreatment following cognitive behavioral therapy for insomnia and automatic positive airway pressure treatment. Participants were classified as sleep improved (n = 28) or sleep declined (n = 16) based on their change in pretreatment to posttreatment Pittsburgh Sleep Quality Index (PSQI) score. Both groups were compared on outcomes of depression, PTSD, HRQOL, BDNF, and IGF-1.

RESULTS

Paired t-tests of the sleep improved group revealed significant declines in depression (p = 0.005) and posttraumatic arousal (p = 0.006) symptoms, and a significant increase in concentrations of IGF-1 (p = 0.009). The sleep declined group had no relevant change in psychiatric symptoms or trophic factors, and had further declines on five of eight dimensions of HRQOL. Between-group change score differences were significant at p < 0.05.

CONCLUSIONS

These findings suggest that interventions, which successfully improve sleep quality, are an effective means to reduce the depression and posttraumatic arousal symptoms common to military personnel, as well as increase protective trophic factors implicated in these conditions.

Circadian system, sleep and endocrinology

Levels of numerous hormones vary across the day and night. Such fluctuations are not only attributable to changes in sleep/wakefulness and other behaviors but also to a circadian timing system governed by the suprachiasmatic nucleus of the hypothalamus. Sleep has a strong effect on levels of some hormones such as growth hormone but little effect on others which are more strongly regulated by the circadian timing system (e.g., melatonin). Whereas the exact mechanisms through which sleep affects circulating hormonal levels are poorly understood, more is known about how the circadian timing system influences the secretion of hormones. The suprachiasmatic nucleus exerts its influence on hormones via neuronal and humoral signals but it is now also apparent that peripheral tissues contain circadian clock proteins, similar to those in the suprachiasmatic nucleus, that are also involved in hormone regulation. Under normal circumstances, behaviors and the circadian timing system are synchronized with an optimal phase relationship and consequently hormonal systems are exquisitely regulated. However, many individuals (e.g., shift-workers) frequently and/or chronically undergo circadian misalignment by desynchronizing their sleep/wake and fasting/feeding cycle from the circadian timing system. Recent experiments indicate that circadian misalignment has an adverse effect on metabolic and hormonal factors such as circulating glucose and insulin. Further research is needed to determine the underlying mechanisms that cause the negative effects induced by circadian misalignment. Such research could aid the development of novel countermeasures for circadian misalignment.

The temporal relationship between growth hormone and slow wave sleep is weaker after menopause

OBJECTIVE

To study the temporal association between growth hormone (GH) and slow wave sleep (SWS) in middle-aged women.

METHODS

Seventeen premenopausal and 18 postmenopausal women were studied using all-night polygraphic sleep recordings and blood sampling at 20-min intervals. The postmenopausal women were re-studied after six months on hormone therapy (HT) according to a randomized, double-blind, placebo-controlled protocol.

RESULTS

The total sleep time (premenopausal 361.9±81.5 min, postmenopausal 358±67.7 min) and the percentages of the sleep stages did not differ between pre- and postmenopausal women. In postmenopausal women the first GH peak after sleep onset occurred later and with a more variable time interval compared to premenopausal women. The percentage of SWS was highest 40-20 min prior to the first GH peak after sleep onset in both groups with a higher SWS proportion in premenopausal women (p=0.048), although the total SWS percent for night did not differ. HT did not affect the distribution of SWS in postmenopausal women.

CONCLUSIONS

The temporal relationship between GH and SWS in premenopausal women is less robust after menopause and is not improved with HT.

The effect of adenotonsillectomy on children suffering from obstructive sleep apnea syndrome (OSAS): the Negev perspective

OBJECTIVE

To present the Negev perspective in recent decades as to the effect of adenotonsillectomy regarding clinical and polysomnographic features, cardiopulmonary morbidity, growth, neurocognitive function, health care services utilization, and enuresis by reviewing current related literature.

METHODS

All relevant published data by the Soroka University Medical Center and related community medical services were reviewed and compared to MEDLINE linked literature regarding aspects of childhood obstructive sleep apnea published through November 2005.

RESULTS

Published data support a significant effect of adenotonsillectomy on the associated co morbidities: adenotonsillectomy resulted in the reduction of pulmonary hypertension, improved growth as a result of an increase in growth hormone secretion, improvement of neurocognitive function to the normal range, reduction in nocturnal enuresis, as well as reducing general morbidities, as reflected by the reduction in health care utilization. However, there are still uncertainties relating to major aspects. There is no specific definition for OSAS grading, or for generating a guideline for surgical treatment and refinement of the indications of T&A.

CONCLUSIONS

Adenotonsillectomy has a beneficial effect on children with OSAS, however, further research is required before recommendations for the treatment of OSAS in children can be formulated.

Endocrine effects of nasal continuous positive airway pressure in male patients with obstructive sleep apnoea

OBJECTIVE

Obstructive sleep apnoea (OSA) is a relatively common condition producing disabling somnolence and profound physiological responses to hypoxaemic episodes during sleep, including significant oscillations in blood pressure. This study aimed to provide controlled data on the interaction between OSA and endocrine axes to establish whether overrepresentation of pathology such as hypertension and hypogonadism in OSA subjects might have an endocrine basis.

DESIGN, SETTING AND SUBJECTS

Parallel randomized sham placebo controlled 1-month trial of nasal continuous positive airway pressure (nCPAP) in 101 male subjects with OSA presenting to a respiratory sleep clinic.

METHODS

Analysis of gonadotrophins, testosterone, sex hormone binding protein (SHBG), prolactin, cortisol, thyroid stimulating hormone (TSH), free thyroxine (free T4), insulin-like growth factor-1 (IGF-1), renin and aldosterone were performed at baseline and after 1 month's active or placebo nCPAP intervention. Quality of life questionnaire scoring was also recorded over the same time period.

RESULTS

Testosterone and SHBG showed significant negative correlations with baseline OSA severity. Active treatment of OSA produced SHBG elevation and TSH reduction (P< or =0.03). Both groups showed an increase in aldosterone (P<0.001) and IGF-1 (P< or =0.03), associated with a large improvement in subjective quality of life scoring.

CONCLUSIONS

These findings demonstrate significant changes in endocrine axes not previously reported in a placebo-controlled trial. OSA is a recognized reversible cause of testosterone reduction; SHBG suppression correlating to baseline OSA severity supports a diagnosis of secondary hypogonadism. Significant rises in aldosterone and IGF-1 on treatment coincide with increased physical activity and an improved quality of life score.

The effects of tonsillectomy and adenoidectomy on serum IGF-I and IGFBP3 levels in children

OBJECTIVE

Obstructive adenoid and tonsillar hyperplasia may present with retardation of growth. Interruption of growth hormone-insulin-like growth factor I axis resulting from abnormal nocturnal growth hormone secretion is among the postulated causes. Growth hormone (GH) mediates its anabolic effects on tissues through insulin-like growth factor I (IGF-I). Most of the circulating IGF-I is bound to insulin-like growth factor binding protein 3 (IGFBP3). The objective of this study is to determine blood serum levels of IGF-I and IGFBP3 in patients with adenoid and tonsillar hypertrophy. Furthermore, we want to investigate the effect of tonsillectomy and adenoidectomy (T&A) on these levels.

STUDY DESIGN

The blood serum levels of IGF-I and its binding protein IGFBP3 were examined in 41 randomly selected children with a diagnosis of upper airway obstruction resulting from hypertrophic tonsils and adenoids.

METHODS

Blood samples were taken preoperatively and repeated at 3 to 6 months (mean, 4.3 mo) following T&A operation. Coated-tube immunoradiometric assay (IRMA) method was used to analyze IGF-I and IGFBP3 levels.

RESULTS

Thirty-two of 41 children were eligible for the analysis. When the preoperative and postoperative results were compared, it was found that there was a statistically significant increase in serum IGF-I and IGFBP3 levels in these 32 children (P <.001). In 7 of the 32 patients, the preoperative serum IGF-I levels were below normal. Postoperatively these levels increased within normal range. This was also statistically significant (P = .016).

CONCLUSION

These findings revealed that obstructive adenoid and tonsillar hypertrophy may cause decreased serum IGF-I levels by affecting the GH-IGF-I axis, and T&A is an effective therapeutic measure in these patients.

Hormonal responses to exercise after partial sleep deprivation and after a hypnotic drug-induced sleep

The aim of this study was to determine the hormonal responses, which are dependent on the sleep wake cycle, to strenuous physical exercise. Exercise was performed after different nocturnal regimens: (i) a baseline night preceded by a habituation night; (ii) two nights of partial sleep deprivation caused by a delayed bedtime or by an early awakening; and (iii) two nights of sleep after administration of either a hypnotic compound (10 mg zolpidem) or a placebo. Eight well-trained male endurance athletes with a maximal oxygen uptake of 63.5 +/- 3.8 ml x kg(-1) x min(-1) (mean value +/- s(x)) were selected on the basis of their sleeping habits and their physical training. Polygraphic recordings of EEG showed that both nights with partial sleep loss led to a decrease (P< 0.01) in stage 2 and rapid eye movement sleep. A delayed bedtime also led to a decrease (P < 0.05) in stage 1 sleep. Zolpidem had no effect on the different stages of sleep. During the afternoon after an experimental night, exercise was performed on a cycle ergometer. After a 10-min warm-up, the participants performed 30 min steady-state cycling at 75% VO(2-max) followed by a progressively increased workload until exhaustion. The recovery period lasted 30 min. Plasma growth hormone, prolactin, cortisol, catecholamine and lactate concentrations were measured at rest, during exercise and after recovery. The concentration of plasma growth hormone and catecholamine were not affected by partial sleep deprivation, whereas that of plasma prolactin was higher (P < 0.05) during the trial after an early awakening. Plasma cortisol was lower (P < 0.05) during recovery after both sleep deprivation conditions. Blood lactate was higher (P < 0.05) during submaximal exercise performed after both a delayed bedtime and an early awakening. Zolpidem-induced sleep did not affect the hormonal and metabolic responses to subsequent exercise. Our results demonstrate only minor alterations in the hormonal responses to exercise after partial sleep deprivation.

The effect of melatonin administration on pituitary hormone secretion in man

OBJECTIVE

Evidence is accumulating that the nocturnal increase in melatonin may influence pituitary hormone secretion. The aim of this study was to determine the effect of exogenous melatonin, in concencetrations spanning the physiological range, on the release of pituitary hormones in man during daylight hours.

DESIGN

A double blind, randomized, crossover study.

SUBJECTS

Eight healthy male volunteers with a mean age of 21 +/- 0.5 years were studied on four occasions, observations being made after the adminstration of melatonin in doses of 0.05, 0.5 or 5.0 mg or placebo. They refrained from taking heavy exercise, alcohol and from smoking for 24 h prior to the study.

MEASUREMENTS

Serum cortisol, growth hormone, prolactin and plasma oxytocin, vasopressin, sodium, osmolality and packed cell volume were measured in samples taken at 30 minutes intervals for 150 minutes after the administration of melatonin.

RESULTS

Melatonin produced dose-dependent changes in circulating concentrations of oxytocin and vasopressin, the 0.5 mg dose being stimulatory, while 5.0 mg was inhibitory. These two doses stimulated growth hormone release, while there was no significant effect on prolactin or cortisol release.

CONCLUSIONS

These results confirm that the nocturnal increase in melatonin could contribute to the patterns of oxytocin, vasopressin and growth hormone release seen over 24 h.

The effect of adenotonsillectomy on serum insulin-like growth factor-I and growth in children with obstructive sleep apnea syndrome

OBJECTIVE

Obstructive sleep apnea syndrome (OSAS) in children is frequently associated with growth interruption. The objective of this study was to evaluate the effect of OSAS and adenotonsillectomy on the insulin-like growth factor-I (IGF-I) axis in children.

STUDY DESIGN

Thirteen prepubertal children (mean age, 6.0 +/- 2.8 years) were studied before and after adenotonsillectomy (T&A). Weight, height, overnight polysomnography, and IGF-I and IGF-binding protein-3 levels were evaluated before and 3 to 12 months after T&A. The children's weights and heights were monitored for 18 months.

RESULTS

The respiratory disturbance index improved from 7.8 +/- 9.1 events/h to 1.0 +/- 2.1 events/h after T&A (P <.02). Slow-wave sleep increased from 29.1% +/- 7.2% to 34.6% +/- 9.8% after T&A (P <.02). The weight standard deviation score increased from 0.86 +/- 1 to 1. 24 +/- 0.9, 18 months after T&A (P <.01). Serum IGF-I levels increased from 146.3 +/- 76.2 ng/mL before T&A to 210.3 +/- 112.5 ng/mL after surgery (P <.01), but IGF-binding protein-3 levels did not change significantly.

CONCLUSION

The respiratory improvement after T&A in children with OSAS is associated with a significant increase in serum IGF-I levels and weight. We conclude that the IGF-I axis is affected in children with OSAS.

Neuroendocrine control of growth hormone secretion

The secretion of growth hormone (GH) is regulated through a complex neuroendocrine control system, especially by the functional interplay of two hypothalamic hypophysiotropic hormones, GH-releasing hormone (GHRH) and somatostatin (SS), exerting stimulatory and inhibitory influences, respectively, on the somatotrope. The two hypothalamic neurohormones are subject to modulation by a host of neurotransmitters, especially the noradrenergic and cholinergic ones and other hypothalamic neuropeptides, and are the final mediators of metabolic, endocrine, neural, and immune influences for the secretion of GH. Since the identification of the GHRH peptide, recombinant DNA procedures have been used to characterize the corresponding cDNA and to clone GHRH receptor isoforms in rodent and human pituitaries. Parallel to research into the effects of SS and its analogs on endocrine and exocrine secretions, investigations into their mechanism of action have led to the discovery of five separate SS receptor genes encoding a family of G protein-coupled SS receptors, which are widely expressed in the pituitary, brain, and the periphery, and to the synthesis of analogs with subtype specificity. Better understanding of the function of GHRH, SS, and their receptors and, hence, of neural regulation of GH secretion in health and disease has been achieved with the discovery of a new class of fairly specific, orally active, small peptides and their congeners, the GH-releasing peptides, acting on specific, ubiquitous seven-transmembrane domain receptors, whose natural ligands are not yet known.

Growth hormone secretion during sleep in male depressed patients

1. Growth hormone (GH) secretion during sleep was studied in ten male patients with major depression according to DSM III and eight normal controls. 2. Samples were collected through a continuous blood withdrawal pump while sleep was recorded in the laboratory. 3. The results showed a marked decrease in the GH secretion mainly during the first three hours of sleep in depressed patients as compared to normal controls. DST and TRH tests were also administered to the same patients but no correlation was observed between a positive test and a blunted GH secretion, suggesting that the various neuroendocrinological disturbances do not coexist in all depressed patients. 4. This disturbance in GH secretion during sleep, along with reduced slow wave sleep (SWS), gives support to the theory that GHRH is the common stimulus of SWS and GH release and that the ratio of GHRH and its counterpart CRH plays a major role in the pathophysiology of disturbed endocrine activity during sleep in depression.

Simultaneous stimulation of slow-wave sleep and growth hormone secretion by gamma-hydroxybutyrate in normal young Men

The aim of this study was to investigate, in normal young men, whether gamma-hydroxybutyrate (GHB), a reliable stimulant of slow-wave (SW) sleep in normal subjects, would simultaneously enhance sleep related growth hormone (GH) secretion. Eight healthy young men participated each in four experiments involving bedtime oral administration of placebo, 2.5, 3.0, and 3.5 g of GHB. Polygraphic sleep recordings were performed every night, and blood samples were obtained at 15-min intervals from 2000 to 0800. GHB effects were mainly observed during the first 2 h after sleep onset. There was a doubling of GH secretion, resulting from an increase of the amplitude and the duration of the first GH pulse after sleep onset. This stimulation of GH secretion was significantly correlated to a simultaneous increase in the amount of sleep stage IV. Abrupt but transient elevations of prolactin and cortisol were also observed, but did not appear to be associated with the concomitant stimulation of SW sleep. Thyrotropin and melatonin profiles were not altered by GHB administration. These data suggest that pharmacological agents that reliably stimulate SW sleep, such as GHB, may represent a novel class of powerful GH secretagogues.

Behavioural rhythmicity in transgenic growth hormone mice: trade-offs, energetics, and sleep–wake cycles

Transgenic mice with extra rat growth hormone (GH) genes (TRrGH mice) are behaviourally lethargic and sleep 3.4 h/d longer than normal on standard diets. We tested the hypothesis that the doubling of the growth rate of TRrGH mice reduced the energy available for behaviour. Provision of sucrose supplements ad libitum normalized the durations of activity and sleep. Our results support a new allocative theory suggesting that sleep serves as an umbrella function for a suite of synergistic anabolic functions (e.g., growth, immunity, repair). Relegating these to the period of sleep in a secure nest allows full dedication of waking resources to niche interfacing (resource acquisition, risk avoidance and environmental stress resistance). Energy stress in TRrGH mice may arise via specific diversion of energy from waking functions via GH-induced insulin resistance. GH is normally secreted during sleep, but any causal relationship remains unresolved. We examined the circadian and ultradian behaviour of TRrGH mice to determine how a chronically elevated GH level impacts sleep. Remarkably, even the major hormonal distortion in TRrGH mice had little impact on the timing of ultradian or circadian rhythms. Increased sleeping of TRrGH mice on normal diets was due to an increased likelihood and duration of sleep at permitted times. GH did, however, appear to increase the depth of sleep.

Growth hormone secretion in night workers

We previously reported that, in night workers, cortisol and TSH rhythms, known to have a high endogenous component, adapted only partially to the nocturnal schedule. The aim of the present study was to investigate the degree of adaptation of the growth hormone (GH) rhythm, considered to be mainly sleep-dependent, but for which a weak circadian drive has also been suggested. Eleven night workers were studied during their usual sleep-wake cycle, and two groups of 11 normally day-active subjects, sleeping once during the night and once after an 8-h sleep delay, were used as control groups. GH secretory rates were calculated by deconvolution of the plasma concentrations analyzed at 10-min intervals. The total amount of GH secreted during the 24 h did not differ between the three groups and the main secretory episode occurred, in most cases, during the first half of the sleep period. In night sleepers and night workers the enhanced amount of GH secreted at that time was followed by a significantly lower amount secreted during the second part of the sleep period (p < 0.001 and p < 0.05, respectively). For night sleepers, an enhanced GH pulse frequency was found at the beginning of sleep, whereas for night workers and day sleepers the pulses were distributed more randomly throughout the nychthemeron. After an abrupt sleep shift, all the subjects displayed a GH pulse at the usual time of early sleep, but such a pulse was present in only 8 of 11 night workers. Thus the amount of GH secreted between 23:00 h and 03:00 h in day sleepers did not differ significantly from that observed in night sleepers, whereas it differed for night workers. These results confirm the considerable influence of sleep in driving the GH rhythm and the existence of a circadian influence revealed by an acute shift in the sleep period. They also provide evidence of an incomplete adjustment of GH rhythms in night workers.

Growth hormone secretion timing in depression: clinical outcome comparisons

Growth hormone (GH) secretion in the 100 minutes preceding sleep onset (preSO), as well as in the first half of the night (1st HN), was examined for a group of 13 healthy women and 43 women with recurrent depression who participated in a 3-year maintenance therapy study. GH studies were obtained at several points during treatment and every 3 months during maintenance, during which patients were randomly assigned to active drug or drug-free maintenance treatment cells for 3 years, or until recurrence of depression. Depressed patients were divided into subgroups according to their maintenance treatment assignment (active drug or drug free) and treatment outcome (completing in remission or having a recurrence). Imipramine caused an increase in the GH ratio in all subgroups. Protocol completers had a significantly larger imipramine-induced increase in the GH ratio than did recurrers. The difference in time of GH secretion relative to sleep onset was found to correlate with treatment outcome and was independent of medication status during maintenance.

The 24-hour rhythms in plasma growth hormone, prolactin and thyroid stimulating hormone: effect of sleep deprivation

Twenty-four hour secretory rhythms of growth hormone (GH), prolactin (PRL) and thyroid stimulating hormone (TSH) were investigated in 9 normal adult men by means of serial blood sampling at 30 min intervals. The profiles of pituitary hormones were compared in 6 subjects between in normal nocturnal sleep condition and in delayed sleep condition. Plasma GH was measured with use of highly sensitive enzyme immunoassay (EIA) recently developed. Plasma TSH was also evaluated by highly sensitive time-resolved fluorometric immunoassay (TR-FIA). Time series analysis of plasma GH and PRL was performed by auto- and cross- correlation and spectral analysis. The detection limit of EIA for GH was 0.3 pg/ml and all plasma GH levels were within the detectable range of this EIA. Cross-correlation and spectral analysis suggested the presence of approximately 2-3 h rhythmicity of plasma GH. Plasma PRL appeared to have some 24-hour rhythmicity besides its sleep-dependent component. Sleep deprivation caused marked elevation of plasma TSH during night time. It is suggested that there appears two mechanisms regulating GH secretion: one has a sleep-independent and ultradian rhythm and another has a sleep-dependent rhythm.

Effects of pulsatile cortisol infusion on sleep-EEG and nocturnal growth hormone release in healthy men

This study investigates the short-term effects of pulsatile cortisol administrations upon sleep electroencephalogram (EEG) and spontaneous release of growth hormone (GH) in humans. Ten young healthy male volunteers received intravenous injections of either placebo or cortisol every 60 min between 17.00 hours and 06.00 hours (1 mg kg-1 BW with a loading dose of 20% starting at 17.00 hours, followed by a dose of 6% every hour until 06.00 hours). The amount of rapid eye-movement (REM) sleep was significantly reduced (placebo: 19.9 +/- 1.8; cortisol: 12.2 +/- 1.5%; P < 0.05), whereas the time spent in slow-wave sleep (SWS) was significantly increased (placebo: 9.4 +/- 1.6; cortisol: 13.9 +/- 1.9%; P < 0.05). The SWS-promoting effect was most prominent during the first hours of sleep, but tended to persist also during the second half of the night. The pulsatile cortisol administration augmented the total amount of plasma GH concentrations (mean area under the time course curve, AUC, placebo: 3.2 +/- 0.5; cortisol: 4.4 +/- 0.6 [ng x 1000 x ml min-1]; P < 0.05) due to an increase of GH release before sleep onset, and during the second half of the night, while the GH surge at sleep onset remained unchanged. Our data are in accordance with the hypotheses that cortisol-induced changes of both sleep-EEG and GH secretion involve a common mechanism that includes activation of the hypothalamic-somatotrophic (growth hormone releasing hormone-growth hormone) system.

Sleep-related growth hormone secretion is persistently suppressed in women with recurrent depression: a preliminary longitudinal analysis

Growth hormone secretion was monitored during sleep in a group of 43 women with recurrent major depression who were participating in a 3-year maintenance therapy program. Patients were studied before acute treatment, after complete remission, and at 3-month intervals during maintenance treatment and the data generated were compared to those obtained in a control group of 14 age-matched healthy women studied once under identical conditions. When compared to the control group, the depressed patients secreted significantly less growth hormone before treatment. This reduction in growth hormone secretion, which was confined to the first half of the sleep period, persisted across the length of the maintenance study regardless of whether the subjects completed three years of therapy or experienced a recurrence.

Symposium: Normal and abnormal rem sleep regulation: Episodic hormone release in relation to REM sleep

Similar periodicities of about 90-100 min characterize both hormone pulsatility and NREM-REM sleep cycles suggesting that both processes could be temporally linked. From the current knowledge of the literature, it appears that, in spite of the diversity of the relationship between hormones and the sleep/wake cycle, systematic relationships exist between hormone pulses and the NREM-REM sleep cycles. Early studies have demonstrated the temporal association between GH and SWS episodes occurring soon after sleep onset. Renin, a key enzyme of the renin-angiotensin system, displays nocturnal oscillations that are associated strongly with the NREM-REM sleep cycles, and represents the first identified biological marker of sleep stage alternation. SWS invariably occurs in the descending phases of TSH and cortisol pulses which suggests that some specific mechanisms of this sleep stage could modulate their levels or, conversely, that increased TSH and cortisol secretion prevents the occurrence of deep sleep. Apart from the period of sleep onset associated with reduced prolactin secretion, no systematic relationship has been found between REM sleep and hormone release. These results highlight the complexity of hormone and sleep interactions and provide a basis for further research into their functional significance.

Influence of partial sleep deprivation on the secretion of thyrotropin, thyroid hormones, growth hormone, prolactin, luteinizing hormone, follicle stimulating hormone, and estradiol in healthy young women

The influence of partial sleep deprivation during the second half of the night on the secretion of thyroid stimulating hormone (TSH), thyroxin (T4), free T4 (fT4), triiodothyronine (T3), prolactin (PRL), growth hormone (GH), luteinizing hormone (LH), follicle stimulating hormone (FSH), and estradiol (E2) was investigated in 10 healthy young women. Blood samples were drawn at hourly intervals over a 64-hour period (i.e., 3 consecutive days and nights). During night 2, all subjects were awakened at 1:30 a.m. During partial sleep deprivation, TSH concentrations increased significantly and remained elevated throughout the following day. Levels of T4, fT4, and T3 were enhanced during the partial sleep deprivation hours only, and changes in these hormones seemed to be independent of TSH. PRL levels decreased, LH and E2 concentrations increased, and GH and FSH secretion remained unchanged during partial sleep deprivation. This pattern of change of different endocrine axes during partial sleep deprivation resembles those seen after total sleep deprivation, suggesting that similar neurochemical changes are induced by both forms of antidepressant therapy. The late evening GH peak occurred almost exclusively before the onset of sleep. Partial sleep deprivation did not influence the chronobiological profiles of any of the hormones investigated. The chemical changes underlying these alterations are speculated to involve enhancement of central norepinephrine and dopamine activity with a concomitant increase in the activity of the sympathetic nervous system.

Profiles of spontaneous 24-hour and stimulated growth hormone secretion in male patients with endogenous depression

Abnormalities of both the spontaneous and the stimulated release of growth hormone (GH) have been described in patients with endogenous depression. In this study, six unmedicated male patients with endogenous depression (ICD 296.1/3) were compared with six age-matched healthy men. Levels of GH were determined at 15-minute intervals over 26 hours. A combined releasing hormone test was performed during the last 2 hours of blood sampling. The 24-hour profile of GH secretion was significantly lower in the depressed patients than in the healthy control subjects due to a significantly diminished sleep-related GH secretion. GH stimulation following releasing hormones was lower in the depressed patients than in healthy subjects. Hypersecretion of GH before the stimulation test might therefore not explain the blunted GH response to stimulation that has been observed in depressive patients.

Human slow wave sleep: a review and appraisal of recent findings, with implications for sleep functions, and psychiatric illness

Recent findings concerning human slow wave sleep (hSWS-stages 3 + 4; delta EEG activity) are critically reviewed. Areas covered include the significance of the first hSWS cycle; hSWS in extended sleep; relationship between hSWS, prior wakefulness and sleep loss; hSWS influence on sleep length; problems with hSWS deprivation; influence of the circadian rhythm; individual differences in hSWS, especially, age, gender and constitutional variables such as physical fitness and body composition. Transient increases in hSWS can be produced by increasing both the quality and quantity of prior wakefulness, with an underlying mechanism perhaps relating to the waking level of brain metabolism. Whilst there may also be thermoregulatory influences on hSWS, hypotheses that energy conservation and brain cooling are major roles for hSWS are debatable. hSWS seems to offer some form of cerebral recovery, with the prefrontal cortex being particularly implicated. The hSWS characteristics of certain forms of major psychiatric disorders may well endorse this prefrontal link.

The effect of SRIF on the EEG sleep of normal men

The aim of this investigation was to evaluate EEG sleep, especially measures of delta-wave sleep, during and after the administration of somatostatin (SRIF). Eleven normal men, ages 22-37 yr, were administered saline or SRIF (0.1 microgram/kg/min IV) over 160 min at bedtime. SRIF delayed sleep-related growth hormone (GH) secretion without altering the amount of GH available during the entire night of sleep. No changes in delta-wave sleep occurred during either the first 100 min of sleep or the remainder of the night. Furthermore, all major EEG sleep variables were not significantly different between the saline and SRIF infusion night. It would not appear that the peripheral administration of this dose of SRIF or the subsequent delay of GH release has quantitative effects on EEG measures of all-night sleep.

Acute effect of intravenous clomipramine upon sleep-related hormone secretion in depressed outpatients and healthy control subjects

Tricyclic antidepressants have been used frequently as pharmacological probes in neuroendocrine studies even though they appear to lack neurochemical specificity. Despite this, the hormonal responses to these drugs have been used to provide evidence that depressed patients have alterations in both noradrenergic and serotonergic tone within the central nervous system. Most studies have been conducted in the morning, which is not a time of high physiological neuroendocrine secretory activity. The present study has used the relatively specific serotonergic probe intravenous clomipramine given to depressed patients and healthy subjects immediately before sleep onset, which is a time of increased neuroendocrine activity. Under these conditions, 12.5 mg clomipramine stimulates the secretion of both cortisol and prolactin, but unlike studies conducted in the morning, clomipramine suppresses the secretion of growth hormone in both groups. These data suggest that serotonergic mechanisms are involved in the regulation of the secretion of these three hormones at the time of sleep onset.