Increased REM sleep associated with melatonin deficiency after pinealectomy: a case study

The objectives of the investigation were to assess hypersomnia, which progressively appeared in a young patient after a pinealectomy, chemotherapy, and radiotherapy for a typical germinoma, as well as the potential benefit of melatonin administration in the absence of its endogenous secretion. 24 h ambulatory polysomnography and the Multiple Sleep Latency Test (MSLT) were performed; in addition, daily plasma melatonin, cortisol, growth hormone, prolactin, and rectal temperature profiles were determined before and during melatonin treatment (one 2 mg capsule given nightly at 21:00 h for 4 weeks). MSLT showed abnormal sleep latency and two REM sleep onsets. Nighttime total sleep duration was lengthened, mainly as a consequence of an increased REM sleep duration. These parameters were slightly modified by melatonin replacement. Plasma melatonin levels, which were constantly nil in the basal condition, were increased to supraphysiological values with melatonin treatment. The plasma cortisol profile showed nycthemeral variation within the normal range, and the growth hormone profile showed supplementary diurnal peaks. Melatonin treatment did not modify the secretion of either hormone. The plasma prolactin profile did not display a physiological nocturnal increase in the basal condition; however, it did during melatonin treatment, with the rise coinciding with the nocturnal peak of melatonin concentration. A 24 h temperature rhythm of normal amplitude was persistent, though the mean level was decreased and the rhythm was dampened during melatonin treatment. The role of radiotherapy on the studied parameters cannot be excluded; the findings of this case study suggest that the observed hypersomnia is not the result of melatonin deficiency alone. Overall, melatonin treatment was well tolerated, but the benefit on the sleep abnormality, especially on daytime REM sleep, was minor, requiring the re-introduction of modafinil treatment.     

Effect of constant light on prolactin and corticosterone rhythms evaluated using a noninvasive urine sampling protocol in the rat.

Circadian prolactin and corticosterone rhythms are usually investigated in the rat by analysis of plasma hormone profiles. In order to develop a nonstressful methodology for long-term studies, we validated prolactin and corticosterone radioimmunoassays in rat urine samples. Among the criteria of validation, prolactin was identified in urine by Western blot whereas both prolactin and corticosterone levels were undetectable in the urine of hypophysectomized rats. The determination of prolactin and corticosterone levels on serial urine samples showed daily variations in male rats entrained by the light-dark cycle. The acrophases of the 24-hour prolactin and corticosterone profiles were located at 03:26 h and 23:32 h respectively, a delay of 3-4 hours compared with the values of the 24-hour plasma profiles reported in the literature. Corticosterone and prolactin rhythms were abolished or dramatically delayed after 3 weeks of constant illumination. As expected, constant light suppressed the rhythm of 6-sulfatoxymelatonin, the major hepatic metabolite of melatonin. The noninvasive and nonstressful methodology we developed could be of interest for studying the regulation of hormone rhythms and their mutual endocrine interactions in physiological conditions, especially their evolution in the aging process.     

Influence of N-phthaloyl gamma-aminobutyric acid on circadian rhythms of lipid peroxidation products and antioxidants

N-Phthaloyl GABA was administrated daily (50 mg/kg body weight-i.p) to Wistar rats for 21 days and circadian rhythms of thiobarbituric acid reactive substances (TBARS) and antioxidants such as reduced glutathione (GSH), catalase (CAT) and superoxide dismutase (SOD) were studied. N-Phthaloyl GABA was found to delay TBARS and to advance GSH, CAT and SOD acrophases. Amplitude and mesor values of these rhythms were found to be altered during N-Phthaloyl GABA treatment. Since GABA is hypothesized to be involved in conveying dark information to clock, exogenous administration of P-GABA might alter the photic information received by the clock. Our study shows that P-GABA administration alters the temporal patterns of lipid peroxidation and antioxidants in Wistar rats. But the exact mechanism remains to be explored and further research is needed.     

Melatonin entrains free-running blind people according to a physiological dose-response curve

The specific circadian role proposed for endogenous melatonin production was based on a study of sighted people who took low pharmacological doses (500 µg) of this chemical signal for the “biological night”: the magnitude and direction of the induced phase shifts were dependent on what time of day exogenous melatonin was administered and were described by a phase-response curve that turned out to be the opposite of that for light. We now report that lower (physiological) doses of up to 300 µg can entrain (synchronize) free-running circadian rhythms of 10 totally blind subjects that would otherwise drift later each day. The resulting log-linear dose-response curve in the physiological range adds support for a circadian function of endogenous melatonin in humans. Efficacy of exogenous doses in the physiological range are of clinical significance for totally blind people who will need to take melatonin daily over their entire lifetimes in order to remain entrained to the 24 h day. Left untreated, their free-running endocrine, metabolic, behavioral, and sleep/wake cycles can be almost as burdensome as not having vision.     

Low,but not high,doses of melatonin entrained a free-running blind person with a long circadian period

In a previous report, we were unable to entrain one out of seven totally blind people with free-running endogenous melatonin rhythms to 10 mg of exogenous melatonin. This person had the longest circadian period (24.9 h) of the group. We now find that this person can be entrained to 0.5 mg of melatonin, but not to 20 mg. These results are consistent with the idea that too much melatonin may spill over onto the wrong zone of the melatonin phase-response curve.     

Shifts of the hormonal rhythms of melatonin and cortisol after a 4 h bright-light pulse in different diurnal types

If applied during corresponding times of the individual melatonin profiles, bright light shifts the circadian phase equally, irrespective of diurnal type. We examined 32 young men: 10 morning types, 11 evening types, and 11 with no predisposition; 16 with high and 16 with low melatonin production. Each completed a 40 h session that included two consecutive nights during which the participants remained, apart from two short breaks during the second day, in bed under an illumination level of 30 lux. A 4 h bright light pulse was applied just after the expected individual melatonin onset the first night to cause a delay of the hormonal profile the second night. Salivary levels of melatonin and cortisol were determined hourly. Melatonin was delayed by 108 min, and cortisol offset and onset by 47 and 110 min, respectively. The cortisol quiescent period (start and end of the quiescent period being defined by the decrease below and the increase above 60% of the average cortisol production between 18:00 and 09:00 h) was prolonged. In contrast to the other subgroups, the delay of melatonin synthesis was about 0.5 h shorter in morning types, and their cortisol quiescent period was shortened. The present study leads to the hypothesis that, despite individually scheduled light exposure, morning types are potentially disadvantaged due to elevated cortisol levels, if persisting, in career night workers.     

Melatonin in the regulation of annual testicular events in carp Catla catla: evidence from the studies on the effects of exogenous melatonin, continuous light, and continuous darkness

The physiological significance of melatonin in the regulation of annual testicular events in a major carp Catla catla was evaluated through studies on the effects of graded dose (25, 50, or 100 µg/100 g body wt.) of melatonin exogenously administered for different durations (1, 15, or 30 days) and manipulation of the endogenous melatonin system by exposing the fish to constant darkness (DD) or constant light (LL) for 30 days. An identical experimental schedule was followed during the preparatory (February-March), pre-spawning (April-May), spawning (July-August), and post-spawning (September-October) phases of the annual cycle. Irrespective of the reproductive status of the carp, LL suppressed while DD increased the mid-day and mid-night values of melatonin compared to respective controls. Influences of exogenous melatonin varied in relation to the dose and duration of treatment and the reproductive status of the carp. However, testicular response to exogenous melatonin (at 100 µg, for 30 days) and DD in each reproductive phase was almost identical. Notably, precocious testicular maturation occurred in both DD and melatonin-injected fish during the preparatory phase and in LL carps during the pre-spawning phase. In contrast, testicular functions in both the melatonin-treated and DD fish were inhibited during the pre-spawning and spawning phases, while the testes did not respond to any treatment during the post-spawning phase. In conclusion, this study provided the first experimental evidence that melatonin plays a significant role in the regulation of annual testicular events in a sub-tropical surface-dwelling carp Catla catla, but the influence of this pineal hormone on the seasonal activity of testis varies in relation to the reproductive status of the concerned fish.     

Effects of time of l-ornithine administration on the diurnal rhythms of plasma growth hormone,melatonin, and corticosterone levels in mice

The synthesis and secretion of many hormones such as growth hormone (GH), melatonin, and corticosterone, exhibit temporal variations over each day and night. Oral administration of several nutritional factors, including l-ornithine, modulates these hormonal secretions and induces an acute increase in plasma GH levels. However, the impact of l-ornithine on the diurnal rhythms of hormone secretion remains unclear. In this study, we evaluated whether the diurnal rhythms of plasma GH, melatonin, and corticosterone secretion were altered by the daily administration of l-ornithine as well as the timing of the administration, in CBA/N mice. Our results showed that the plasma GH levels that peaked at light phase were amplified by l-ornithine (500?mg/kg) administered at Zeitgeber time (ZT) 22, but not at ZT10. Additionally, l-ornithine (1000?mg/kg) administered at ZT22 advanced the onset of the nocturnal rise of melatonin, which resulted in the elongation of the melatonin peak. On the other hand, l-ornithine (500 and 1000?mg/kg) administered at ZT10, but not at ZT22, suppressed the diurnal rhythm peaks of plasma corticosterone. The effects of l-ornithine on plasma GH rhythms lasted for at least 2 days after cessation of the daily administration. Running wheel activity during the active phase was slightly elevated by l-ornithine administration at ZT22, but the overall patterns were only slightly affected. l-Ornithine levels in the plasma and hypophysis after a single administration of l-ornithine at ZT22 were lower than those after administration at ZT10, suggesting that the metabolic rate of l-ornithine differs between day and night. In conclusion, our data suggest that a daily administration of l-ornithine regulates the diurnal rhythms of GH, melatonin, and corticosterone in a manner dependent on administration time, which might be related to the diurnal rhythms of l-ornithine metabolism.     

Antibody that blocks stimulation of cortisol secretion by adrenocorticotrophic hormone in Addison's disease

To investigate whether Addison''s disease may in some cases be due to the blocking of adrenocorticotrophic hormone''s action at the adrenal cortex by antibodies IgG isolated from a woman with Addison''s disease associated with the autoimmune polyglandular syndrome type I was studied. Its effects on guinea pig adrenal cells in vitro were investigated and compared with those of IgG from three normal subjects and IgG obtained commercially. IgG from the patient inhibited the stimulation of cortisol secretion by adrenocorticotrophic hormone by 77 (SD 2)% and 57 (12)% at concentrations of 0·5 and 0·05 g/l, respectively; IgG prepared five months after she had started treatment with replacement steroids inhibited cortisol secretion by 74 (1)% (0·5 g/l) and 51 (15)% (0·05 g/l). The other IgGs had no inhibitory effects. The IgG from the patient and that obtained commercially did not inhibit the stimulation of cortisol secretion by dibutyryl cyclic adenosine monophosphate or precursors of cortisol. None of the IgGs bound to adrenocorticotrophic hormone.These results suggest that the IgG from the patient acted against the receptor for adrenocorticotrophic hormone, and its presence may explain the patient''s raised concentrations of adrenocorticotrophic hormone, failure to respond to exogenous adrenocorticotrophic hormone, and normal basal cortisol concentrations. Addison''s disease may thus in some instances be a receptor antibody disease.     

Circadian rhythms of oviposition and feeding activity in Japanese quail: effects of cyclic administration of melatonin

The aim of these experiments was to test the effect of a cyclic administration of melatonin, by mimicking the daily rhythm of hormone levels, on the circadian organization of two distinct functions in quail: oviposition and feeding activity. Laying and feeding rhythms under photoperiodic conditions and constant darkness (DD) were investigated. Under DD, where the two rhythms were free running, a daily rhythm of melatonin was administered. In LD 14h:10h, two different individual profiles of laying were established, with stable females laying at the same time each day and delayed females laying progressively later each day. For feeding activity, all birds were clearly synchronized to the photoperiodic cycle. In DD, the laying birds showed a free-running rhythm of oviposition with a period longer than 24 h for both profiles but the delayed profile females had a longer period than stable profile females. In comparison, the free-running period of feeding rhythm of the same birds was shorter than 24 h. A cyclic administration of melatonin had no effect on laying rhythm, which continued to free-run in DD, whereas feeding activity was synchronized as soon as the first cycle of melatonin was administered. From these results, it seems that two different circadian systems drive each of the two types of behavior separately. Melatonin could be the main synchronizer for the temporal control of feeding behavior, but it does not play a part in the control of oviposition in Japanese quail.     

Comparative study of the activity/rest rhythms in young and old ringdove (Streptopelia risoria): correlation with serum levels of melatonin and serotonin

Aging is characterized by changes in the circadian rhythms of melatonin, serotonin, and sleep/wakefulness, alterations that affect sleep quality. The authors studied the circadian rhythms of serotonin and melatonin in young and old ringdoves (Streptopelia risoria) (2-3 and 10-12 yrs old, respectively), animals that are characterized by being monophasic and active by day, like humans. The aim was to correlate the indole rhythms with the animals' activity/rest periods. The animals were kept under a 12:12 h light/dark cycle, fed ad libitum, and housed in separate cages equipped for activity recording. Activity pulses were recorded with one actometer per animal (two perpendicular infrared transmitters) and were logged every 15 min by a computer program (DAS 16) throughout the experiment. Melatonin was measured by radioimmunoassay and serotonin by ELISA at intervals of 3 h (from 09:00 to 18:00 h) and 1 h (from 21:00 to 06:00 h), respectively. The results showed a reduction in nocturnal vs. diurnal activity of 89% and 61% in the young and old animals, respectively, with 100% considered to be the diurnal activity of each group. The amplitude of a cosine function fit to the melatonin concentrations of the old animals was half that of the young birds. The acrophase and nadir were at 02:00 and 14:00 h in the young and 01:00 and 13:00 h in the old animals, respectively. The amplitude of the corresponding cosine function fit to the serotonin concentrations in the old birds was one-third that of the young animals. The acrophase and nadir were at 15:00 and 03:00 h in the young and 16:00 and 04:00 h in the old animals, respectively. For both melatonin and serotonin, the concentrations in the young animals were significantly higher than in the old at most of the measurement times. There was a clear negative correlation between the circadian rhythms of activity and the serum melatonin levels in both young and old animals. The equivalent correlation for serotonin was positive, and stronger in the case of the young animals. The results suggest a possible relationship between the observed decline in the amplitude of the old animals' melatonin and serotonin rhythms and the lower percentage reduction in their nocturnal relative to diurnal activity pulses compared to the young animals. In conclusion, the circadian rhythms of melatonin and serotonin undergo alterations with age that could be involved in the changes in age-associated sleep.     

Acute psychological stress increases plasma levels of cortisol, prolactin and TSH.

The effects of acute stress during a parachute jump on hormonal responses were studied in 12 experienced and 11 inexperienced military parachutists. Each subject performed two jumps. Prior to and immediately after each jump blood samples were drawn and analysed for plasma levels of cortisol, prolactin, thyrotropin (TSH), somatotropin (STH), and luteinizing hormone (LH). While there was a significant increase in cortisol, prolactin and TSH levels after both jumps, no alterations could be observed in STH and LH levels. Stress-induced hormonal responses were not affected by jump experience. There was also no association between the endocrine variables and anxiety scores.     

Reproductive phase dependent circadian variations of plasma melatonin, testosterone, thyroxine and corticosterone in Indian palm squirrel, Funambulus pennanti

To explain the complex mechanism of environmental influence along with internal hormonal (factors) milieu on daily variations in the circulating levels of melatonin, testosterone, thyroxine and corticosterone were analyzed with the help of inferential statistics (Cosinor rhythmometry) in a seasonally breeding tropical rodent, F. pennanti during the reproductively active (RAP) and inactive phases (RIP). Plasma melatonin, thyroxine and corticosterone levels exhibited a significant circadian oscillation during both the active and inactive phases of the annual reproductive cycle. Melatonin showed higher amplitude during RIP in the circulating plasma. Testosterone presented a peak level during evening hours (16:00 - 18:00 h) during RAP only. The phase of thyroxine was noted ∼09:76 h and ∼10.35 h during active and inactive phases, respectively. Corticosterone showed a peak level at ∼12.00 h during both phases of the reproductive cycle. Further, in this tropical rodent, the minimum difference in photoperiod (∼3 - 4 hours) and maximum variation in temperature (max. 18°C - min. 10°C during RIP and max. 45°C - min. 32°C during RAP) and humidity (85% during RIP and 35% during RAP) regulated the diurnal rhythm of circulating melatonin circadian rhythm by ∼1 hour phase advance during RIP. In conclusion, the studied hormonal rhythms may be part of an integrative system to coordinate reproduction and physiological processes successfully with environmental factors.     

Chronobiotic effects of the melatonin agonist LY 156735 following a simulated 9h time shift: results of a placebo-controlled trial

Introduction: The melatonin agonist LY 156735 (LY) is a new investigational drug under development to treat circadian rhythm disorders. The present study assessed the efficacy of LY to alleviate the symptoms of shift lag and to enhance readaptation of desynchronized circadian rhythms to a new time zone.

Subjects and methods: Eight healthy male volunteers of age 25-35 yr participated in three identical trials of 13d duration in a temporal isolation unit separated by washout intervals. A high dose (HD) of 5 mg and a low dose (LD) of 0.5 mg of LY and placebo (PL) were administered double-blinded in a three-period cross-over design. Each trial consisted of an adaptation period, a pre-shift period for baseline measurements, a simulated 9h phase-advance shift, and a post-shift period for follow-up. The time shift was performed at 23:00h of day 6 by advancing the laboratory time to 08:00h of day 7. Double-blind study medication was administered at 14:30h on day 6, and at 22:30h on days 7-10. Subjective ratings of jet lag, alertness, tenseness, and daytime fatigue were assessed using visual analog scales (VAS) and standardized questionnaires. The objective markers of readaptation included core body temperature, wrist actigraphy, cortisol and electrolyte excretion, and a battery of computerized performance tests.

Results: HD but not LD enhanced the readaptation speed of all physiological rhythms investigated, as demonstrated by a significantly faster movement of acrophases towards the post-shift target time. HD (p=0.05) significantly blunted the post-shift deterioration of performance in those tests that were sensitive to shift lag. Parameters of subjective well-being were not significantly affected by either dose.

Conclusion: This pilot study demonstrates the chronobiotic efficacy of LY when taken at a dose of 5 mg/d.     

Disturbance of circadian rhythms in analgosedated intensive care unit patients with and without craniocerebral injury

Melatonin, cortisol, heart rate, blood pressure, spontaneous motor activity, and body temperature follow stable circadian rhythms in healthy individuals. These circadian rhythms may be influenced or impaired by the loss of external zeitgebers during analgosedation, critical illness, continuous therapeutic intervention in the intensive care unit (ICU), and cerebral injury. This prospective, observational, clinical study examined 24 critically ill analgo-sedated patients, 13 patients following surgery, trauma, or acute respiratory distress (ICU), and 11 patients with acute severe brain injury following trauma or cerebral hemorrhage (CCI). Blood samples for the determination of melatonin and cortisol were obtained from each patient at 2 h intervals for 24 h beginning at 18:00 h on day 1 and ending 16:00 h on day 2. Blood pressure, heart rate, body temperature, and spontaneous motor activity were monitored continuously. Level of sedation was assessed using the Ramsey Sedation Scale. The severity of illness was assessed using the APACHE-II-score. The time series data were analyzed by rhythm analysis with the Chronos-Fit program, using partial Fourier series with up to six harmonics. The 24 h profiles of all parameters from both groups of patients were greatly disturbed/abolished compared to the well-known rhythmic 24 h patterns in healthy controls. These rhythm disturbances were more pronounced in patients with brain injury. The results of this study provide evidence for a pronounced disturbance of the physiological temporal organization in ICU patients. The relative contribution of analgosedation and/or brain injury, however, is a point of future investigation.     

Aspartate modulates the circadian patterns of a few biochemical variables in Wistar rats

D-aspartate was used to demonstrate possible sources of excitatory input to the suprachiasmatic nucleus (SCN) in rats. Aspartate (50 mg/kg bodyweight) was orally administrated chronically for 60 days to Wistar rats and 24 h rhythmic patterns of glucose, cholesterol, total protein and aspartate transaminase (AST) were studied under light - dark (LD 12:12 h) cycle. Our results showed acrophase advances in glucose and delays in cholesterol and AST rhythms. Increased mesor and altered amplitude values were found in all rhythms; aspartate levels in the brain were found to be significantly increased in aspartate treated animals. We hypothesised that the altered biochemical rhythms in aspartate treated rats could be due to (1) modulation of neurotransmission in SCN, (2) behavioural rhythms and (3) feeding rhythms.     

Effects of granulocyte-macrophage colony stimulating factor on cortisol, growth hormone, prolactin and melatonin in cancer patients (short communication).

Several interleukins and interferons have been proven to induce endocrine effects. On the contrary, only few data are available about the possible hormonal activity of hemopoietic growth factors. This study was carried out to evaluate the endocrine influence of GM-CSF in humans. The study included nine head and neck cancer patients, evaluated in basal conditions and after an acute subcutaneous injection of GM-CSF at a dose of 3 mcg/kg b.w., by determining serum levels of cortisol, growth hormone (GH), prolactin (PRL) and melatonin. Both cortisol and GH significantly increased in response to GM-CSF, while PRL, and melatonin were not influenced. This preliminary study shows that hemopoietic growth factors, as well as interleukins, may also play endocrine effects in humans.     

Hormonal responses to analgesic nitrous oxide in man

Analgesic concentrations of nitrous oxide were administered to 6 healthy male subjects, and blood samples were assayed for prolactin, ACTH, follicle stimulating hormone, luteinising hormone, growth hormone, cortisol and thyroid hormones. Analgesic nitrous oxide (mean concentration = 48.8%) produced statistically significant elevation of prolactin and depression of cortisol whilst not producing statistically significant changes in the other hormones assayed. The increase in prolactin and decrease in cortisol levels are similar to the hormonal changes associated with administration of opioids in man. We have also confirmed the findings of other workers that cortisol levels may not always be correlated with ACTH levels.     

Marker rhythms of circadian system function: a study of patients with metastatic colorectal cancer and good performance status

Cancer patients may exhibit normal or altered circadian rhythms in tumor and healthy tissues. Four rhythms known to reflect circadian clock function were studied in 18 patients with metastatic colorectal cancer and good performance status. Rest-activity was monitored by wrist actigraphy for 72 h before treatment, and its circadian rhythm was estimated by an autocorrelation coefficient at 24h and a dichotomy index that compared the activity level when in and out of bed. Blood samples (9-11 time points, 3-6 h apart) were drawn on day 1 and day 4 of the first course of chronochemotherapy (5-fluorouracil: 800 mg/m2/day; folinic acid: 300 mg/m2/day; oxaliplatin: 25 mg/m2/day). Group 24h rhythms were validated statistically for plasma concentrations of melatonin, 6-alpha-sulfatoxymelatonin, and cortisol and for lymphocyte counts. Significant individual 24h rhythms were displayed in melatonin by 15 patients, cortisol by seven patients, lymphocytes by five patients, and prominent circadian rhythms in activity were displayed by 10 patients; only one patient exhibited significant rhythms in all the variables. The results suggest the rhythms of melatonin, cortisol, lymphocytes, and rest/activity reflect different components of the circadian system, which may be altered differently during cancer processes. Such 24h rhythm alterations appeared to be independent of conventional clinical factors.     

Melatonin administration to blind people: phase advances and entrainment.

The purpose of this study was to test the phase-shifting and entraining effects of melatonin in human subjects. Five totally blind men were found in a previous study to have free-running endogenous melatonin rhythms. Their rhythms were remarkably stable, so that any deviation from the predicted phase was readily detectable. After determination of their free-running period and phase, they were given exogenous melatonin (5 mg) at bedtime (2200 hr) for 3 weeks, in a double-blind, placebo-controlled trial. The effects on the endogenous melatonin rhythm were assessed at intervals ranging from several days to 2 weeks. Exogenous administration of melatonin phase-advanced their endogenous melatonin rhythms. In three of the subjects, cortisol was shown to be phase-shifted in tandem with the melatonin rhythm. A sixth subject [one of the coauthors (JS)] was previously found to have free-running cortisol and temperature rhythms and was plagued by recurrent insomnia and daytime sleepiness. He had tried unsuccessfully to entrain his rhythms for over 10 years. After he took melatonin (7 mg at 2100 hr), his insomnia and sleepiness resolved. Determination of his endogenous melatonin rhythm after about a year of treatment demonstrated endogenous rhythms that appeared normally entrained. The treatment of blind people with free-running rhythms has many advantages for demonstrating chronobiological effects of hormones or drugs.