A benzodiazepine receptor antagonist decreases sleep and reverses the hypnotic actions of flurazepam.

The benzodiazepine receptor antagonist 3-hydroxymethyl-beta-carboline, which blocks several of the pharmacological actions of benzodiazepines, induces a dose-dependent increase in sleep latency in the rat. Furthermore, at a low dose that by itself does not affect sleep, 3-hydroxymethyl-beta-carboline blocks sleep induction by a large dose of flurazepam. The benzodiazepine receptor may play a role in both the physiological regulation and pharmacological induction of sleep.

Suppression of sleep-related prolactin secretion and enhancement of sleep-related growth hormone secretion.

Methysergide, a clinically-used blocker of serotonin receptors, was administered to 10 normal young men at a dose of 2 mg every 6 h for 48 h. After drug treatment, serum levels of growth hormone during sleep were 41.9% higher than placebo values (less than 0.001). In contrast, drug treatment was associated with a 36.4% decrease in stimulated growth hormone secretion during insulin tolerance testing (P less than 0.01). These opposite effects of methysergide suggest that different mechanisms are responsible for sleep-related and insulin-induced growth hormone secretion. Accordingly, data obtained with pharmacologic stimuli may lead to erroneous inferences regarding physiologic growth hormone control mechanisms. Administration of methysergide profoundly suppressed sleep-related prolactin secretion; overall nocturnal mean prolactin fell by 70.3% from 4.30+/-0.19 to 1.28+/-0.06 ng/ml (P less than 0.0001). It appears that serotonin may be significant modulating neurotransmitter for the control of growth hormone secretion, limiting sleep-related release, and enhancing insulin-induced release. It seems likely from these data that the role of serotonin in the control of prolactin secretion is relatively more important, since serotonin receptor blockade dramatically reduced sleep-related prolactin secretion.

Methoscopolamine inhibition of sleep-related growth hormone secretion. Evidence for a cholinergic secretory mechanism.

We have examined the effects of cholinergic blockade with 0.5 mg methscopolamine bromide, intramuscularly, on sleep-related and insulin-induced growth hormone (GH) secretion. 17 normal young men were studied; 8 had sleep studies, and 12 (including 3 who also had sleep studies) had insulin tolerance tests (ITT) with 0.1 U/kg of regular insulin. After an adjustment night in the sleep laboratory, saline control night and methscopolamine night studies were done in random sequence; study procedures included electroencephalographic, electromyographic, and electrooculographic recordings, and blood sampling every 20 min for hormone radioimmunoassays. Prolactin levels were also measured during sleep. For methscopolamine night studies, the mean overall control GH level of 2.89+/-0.44 ng/ml and the mean peak control GH level of 11.09+/-3.11 ng/ml were dramatically reduced to 0.75+/-0.01 and 1.04+/-0.25 ng/ml, respectively (P<0.0001 and <0.001). Despite virtual absence of GH secretion during the night in every study subject, no measured sleep characteristic was affected by methscopolamine, including total slow-wave sleep (12.1+/-2.6% control vs. 10.3+/-2.5% drug, P>0.2). Sleep prolactin levels were not changed by methscopolamine. In contrast to the abolition of sleep-related GH secretion, administration of methscopolamine had only a marginal effect on the GH response to insulin hypoglycemia. None of nine time points differed significantly, as was also the case with peak levels, mean increments, and areas under the curves (P>0.2). Analysis of variance did, however, indicate that the lower GH concentrations achieved during ITT after methscopolamine (average 31.7% below control) were significantly different than control concentrations. We conclude that the burst of GH secretion which normally occurs after sleep onset is primed by a cholinergic mechanism which does not influence slow-wave sleep. Cholinergic mechanisms do not appear to play an important role in sleep-related prolactin secretion. The contrast between the complete suppression of sleep-related GH release and the relatively small inhibitory effect on ITT-induced GH secretion suggests that the neurotransmitter mechanisms, and presumably the pathways, which subserve sleep-related GH secretion in man may be different from those which mediate the GH response to pharmacologic stimuli such as insulin.

The sleep of patients with obsessive-compulsive disorder.

Fourteen patients with obsessive-compulsive disorder (OCD) were studied with all-night sleep EEG recordings. Nine of these patients reported abnormal sleep patterns before the polygraphic study. Analysis of the sleep records disclosed significantly decreased total sleep time with more awakenings, less stage 4 sleep, decreased rapid-eye-movement (REM) efficiency, and shortened REM latency compared with those of a group of age- and sex-matched normal subjects. These abnormalities generally resembled those of an age-matched group of depressed patients, although significant differences remained. These findings suggest that such sleep abnormalities as shortened REM latency may not be entirely specific for primary affective illness. They also point to a possible biological link between OCD and affective illness.

Efficacy of melatonin as a hypnotic agent.

The seemingly contradictory literature on the use of melatonin in insomnia is best understood by considering issues of time of administration (day or night), dose range (physiological or pharmacological), subject selection (normals or insomniacs), choice of dependent variable (self-report or electroencephalogram), and comprehensiveness of the reported variables (sleep onset or sleep maintenance). Available data on nighttime administration to normals and insomniacs are reviewed. It is concluded that there is not yet a convincing body of evidence, using generally accepted measures, that melatonin administration improves sleep in insomniacs with noncircadian sleep disturbance.

Negative feedback suppression of sleep-related growth hormone secretion.

Previous studies have demonstrated that injections of growth hormone (GH) can blunt subsequent GH secretory responses to daytime pharmacological stimulation. The current study was undertaken to determine whether GH administration to normal subjects would suppress sleep-related secretion. GH (2 U im) was given nine times over 5 days to each of six subjects, and sleep studies with blood sampling were performed 6 h after the last injection. Secretion during the first 2 h of sleep was decreased by 62.4%, indicating that sleep-related GH secretion may be responsive to a negative-feedback mechanism.

Failure of nocturnal prolactin suppression by methysergide to entrain changes in testosterone in normal men.

In order to investigate further the postulated relationship between the secretion of PRL and testosterone, 10 normal young men were studied during polygraphically recorded sleep. Concentrations of LH and testosterone were measured in plasma every 20 min, and the results were analyzed in relation to sleep parameters and previously reported (J Clin Invest 56: 690, 1975) concentrations of PRL. All subjects were studied on a control night after placebo administration and on an experimental night after ingestion of the serotonin receptor blocker, methysergide. Analysis of variance revealed that concentrations of testosterone rose gradually during sleep on both nights, as has been noted in previous studies. Highest LH values occurred during stage 1 sleep, but were only 25% higher than the lowest values, which were seen in stage 4. As shown previously, PRL concentrations were markedly suppressed by methysergide treatment. However, no significant change in testosterone values were observed on the methysergide nights as compared to the control nights. When the data were analyzed by a correlational approach, again, no significant relation between concentrations of PRL and testosterone was found. Although these data do not support the concept that PRL-stimulated testosterone secretion occurs during the night in normal men, this study does not rule out the possibility that such a mechanism may be operative during daytime hours, or under conditions of PRL stimulation rather than PRL suppression.

Piperidine enhances sleep-related and insulin-induced growth hormone secretion: further evidence for a cholinergic secretory mechanism.

Piperidine, a nicotinic cholinergic receptor stimulator, was used in paired design studies of sleep-related and insulin-induced GH and PRL secretion. For the sleep studies, 100 mg piperidine or an equal volume of saline were infused for 30 min starting at sleep onset in eight normal volunteers. The same dose of piperidine was infused for 30 min (beginning 15 min before insulin injection) in an additional eight volunteers undergoing insulin tolerance tests. After piperidine administration, there was a significant (P less than 0.01) enhancement of sleep-related GH secretion, abut no change in PRL. GH concentrations during the first 2 h of sleep were 7.2 +/- 1.2 ng/ml after saline and 15.2 +/-2.9 ng/ml after piperidine (P less than 0.01). No alteration in any measured sleep parameter was noted with the drug. Piperidine did not affect the daytime insulin-induced secretion of either GH or PRL, as assessed by an analysis of variance. However, paired analysis of increments and areas under the response curves indicated a statistically significant effect for GH but not PRL. The maximum GH increment with piperidine was 48.0 +/- 4.3 ng/ml, compared to 36.8 +/- 3.6 ng/ml with saline (P less than 0.01). Piperidine given alone did not influence daytime concentrations of GH. These data are consistent with the view proposed by us, on the bass of methoscopolamine inhibition of nocturnal GH secretion, that cholinergic pathways play a facilitatory role in sleep-related and insulin-induced GH secretion. Thus, cholinergic mechanisms stimulate GH secretion. Nicotinic as well as muscarinic pathways appear to be involved, although the quantitative nicotinic contribution seems to be smaller than the associated with muscarinic sites.

Serotonin inhibition and sleep.

Methysergide a clinically used blocker of serotonin receptors, was given for 48 hr to 11 normal adults, at a dose of 8 mg per 24 hr. Total REM sleep time was decreased, although total sleep time was unchanged. Stage 4 decreased and stage 3 increased, while total slow wave sleep remained constant. There was a tendency toward a decrease in the number of intact sleep cycles. The relationship of these data to published reports on p-chlorophenylalanine is discussed.

The effect of growth hormone administration on human sleep: a dose-response study.

Human growth hormone and saline were administered for one night each to normal volunteers in a cross-over study. A dose of 2 units im given 15 min before bedtime had no effect on sleep EEG parameters. In contrast, 5 units resulted in a 19% decrease in slow-wave sleep (p < 0.01) and a 13% increase in REM sleep (p < 0.05). Neither doe, when given during daytime, affected tests of affect or serial learning.

Sleep in Gilles de la Tourette syndrome.

The sleep of six Tourette patients (drug-free and while taking haloperidol was compared with that of nine normal volunteers. The untreated patients had 30% less delta sleep, which returned to values indistinguishable from those of volunteers when they received haloperidol.

Age-dependent changes in recovery sleep after 48 hours of sleep deprivation in rats.

To characterize possible changes in homeostatic regulation of sleep with aging, we have examined sleep stages during recovery sleep after 48 h of sleep deprivation in young (3 months), middle aged (12 months), and old (24 months) rats. It was found that young and middle aged, in contrast to old rats, had large (21-24%) increases in total sleep time during recovery sleep; the old rats experienced a quantitatively small (8%) but significant rise in total sleep. NREM sleep increased significantly during the recovery period in young and middle aged, but not older rats. High voltage NREM sleep (HS2) declined by 30% during recovery in the young animals, but remained unchanged compared to baseline in the middle aged and old animals. The young and middle aged rats had increases in REM sleep during recovery compared to their baseline by 96% and 93%, respectively, which was significantly greater than a 65% increase during recovery in the old rats. Increases in total sleep and REM sleep during recovery were largely confined to the first 6 h in young and middle aged rats, but maxima for the old rats occurred in the second 6 h.

EEG delta power during sleep in young and old rats.

Delta EEG power density, which has been viewed as a measure of intensity of NREM sleep, declines across the lifetime in humans, cats, and hamsters, but data in rats have been unclear. It is also uncertain whether older rats differ from younger animals in the degree of change in delta power during recovery sleep following short-term sleep deprivation. We have examined delta power density in NREM sleep under baseline conditions and following 48 h of sleep deprivation in young (3 months), middle-aged (12 months), and older (24 months) rats. The presence or absence of age effects was highly dependent on the method of normalizing the data. When expressed as a fraction of total NREM EEG power, there was no age effect on baseline delta power density, or on the change from baseline to recovery conditions. When expressed as a multiple of delta power in REM under the same condition, the younger rats had higher delta power density than the middle-aged and older rats. For all the ages combined, there was an increase in delta power density in the recovery condition. When examined by age, the younger rats (which started from a higher level of delta power density than the other groups) did not have an increase in delta during recovery; the middle-aged rats tended to, and the older rats (which started from lower baseline levels) significantly increased delta power density in the recovery condition. This suggests that the lower delta power seen during baseline in older rats is not due to decreased ability to generate delta activity.

Disturbances of sleep and cognitive functioning in patients with dementia.

The relationship of sleep, circadian rhythms, and cognitive impairment in dementia patients is briefly reviewed. All-night sleep EEG data were collected in relatively young and relatively unimpaired patients with presumptive Alzheimer's disease and eight age-matched controls. Delta sleep time and Delta sleep % (Stages 3 and 4)--but not REM sleep measures--were significantly reduced in the patients. Implications of these findings are discussed.

Antidepressant effects of light in seasonal affective disorder.

The authors treated winter depression in 13 patients with typical seasonal affective disorder by extending the length of winter days with bright and dim light in the morning and evening in a balanced-order crossover study. Bright light had a marked antidepressant effect, whereas the dim light did not. This response could not be attributed to sleep deprivation. Subsequent pilot studies indicated that bright evening light alone is probably also effective. Several patients were able to maintain the antidepressant response throughout the winter months by continuing daily light treatments.

Nifedipine blocks effects of triazolam injected into the dorsal raphe nucleus on sleep.

In previous studies, the author has reported both in vitro and in vivo sleep studies in which there were complex interactions between benzodiazepine hypnotics and the dihydropyridine calcium channel blocker nifedipine. The author has also reported that microinjections of triazolam into the dorsal raphe nucleus of the rat result in enhancement of wakefulness. In the present study, nifedipine and triazolam were coadministered into this site. As previously was observed, triazolam produced a dose-dependent increase in sleep latency and a decrease in total sleep, primarily by reducing non-rapid-eye-movement sleep. Nifedipine had no effect on sleep when given by itself but prevented the alterations in sleep by triazolam. These various sleep effects were not associated with alterations in core temperature. These data are consistent with the view that aspect of the sleep-altering activity of triazolam involves interaction with voltage-dependent calcium channel activity.

Effects of triazolam and nifedipine injections into the medial preoptic area on sleep.

We have reported previously that microinjections of the benzodiazepine (BZ) hypnotic triazolam into the medial preoptic area (MPA) of the hypothalamus increase sleep in the rat. As a follow up to previous work, which has indicated that the dihydropyridine calcium channel blocker, nifedipine, prevents sleep induction by an intraperitoneally administered BZ, we have now coinjected nifedipine and triazolam into the MPA. It was found that nifedipine alone had no significant effects on sleep and prevented sleep induction by triazolam. There were no drug-specific effects on core temperature in any treatment condition. These data suggest that dihydropyridine-sensitive sites may be involved in the mechanism of sleep induction by BZs.

The hypnotic actions of the fatty acid amide, oleamide.

Oleamide is an endogenous fatty acid amide which can be synthesized de novo in the mammalian nervous system, and has been detected in human plasma. It accumulates in the CSF of rats after six hours of sleep deprivation and induces sleep in naive rats and mice. Inhibition of the primary catabolic enzyme of oleamide (fatty acid amide hydrolase) by trifluoromethyl-octadecenone reduces sleep latency and increases total sleep time when given centrally to rats and peripherally to mice. While the mechanism of action of oleamide is unclear, it has been demonstrated to increase the amplitude of currents gated by 5-HT2a, 5HT2c and GABAa receptors. Moreover, the action of oleamide most relevant to sleep induction involves, in part, cannabinergic pathways, as evidenced by the ability of the cannabinoid antagonist SR 141716 to inhibit the hypnotic actions of OA. Nonetheless, enhancement of cannabinergic function may not be the only mechanism by which OA alters sleep, as it can act synergistically with subthreshold doses of triazolam (0.125 microg) to reduce sleep latency. These findings raise the possibility that OA may be representative of a group of compounds which might be developed into clinically-used hypnotics, and are discussed in the context of fatty acid derivatives as modulators of neuronal function.

Arousal induced by injection of triazolam into the dorsal raphe nucleus of rats.

In order to explore the possible sites at which benzodiazepines alter sleep, we have performed sleep studies following administration of 0.5 microgram of triazolam into the dorsal raphe nucleus of rats. Triazolam significantly increased sleep latency and decreased non-rapid eye movement (REM) sleep, with an effect greatest in the first 2 hours after injection. Total REM sleep time was not significantly affected, although there was a modest trend toward reduction in the first 2 hours. In contrast to the decreased sleep resulting from injection into the dorsal raphe nucleus, triazolam did not significantly alter sleep in animals in whom it was injected into surrounding areas. Similarly, the low dose employed in this study did not significantly affect sleep when injected into the lateral ventricle. These data are reminiscent of studies showing transient decreases in sleep following lesions of the dorsal raphe nucleus.

Enhancement of sleep by microinjection of triazolam into the medial preoptic area.

A growing literature suggests that the basal forebrain may contain structures involved in the regulation of sleep. As part of a series of studies designed to locate the site(s) of hypnotic action of benzodiazepines, we have injected triazolam into the medial preoptic area (MPA) of the hypothalamus of rats. Total sleep time was increased, due primarily to an increase in non-rapid eye movement (non-REM) sleep and a trend toward a decrease in intermittent waking time. A previous study from this laboratory reported that injections into the raphe nucleus decreased sleep, whereas injections at adjacent sites were without effect. These studies indicate the selectivity with which different brain regions respond to triazolam in terms of actions on sleep.