Endogenous and exogenous factors on sleep-wake cycle regulation

A number of theories have proposed the involvement of different brain structures and neurotransmitters in order to explain the regulation of the sleep wake cycle. However, there is no clear consensus as to the mechanisms through which the brain structures and their various neurotransmitters interact to produce theses phases. Perhaps the problem is related to the fact sleep is a very fragile state, easily modified or influenced by a variety of substances or experimental manipulations. In this paper, we describe the evidence of two different groups of factors that induce important changes on the sleep wake cycle. The endogenous factors: neurotransmitters; hormone; peptides; and some substances of lipidic nature and exogenous factors: stress, food intake, learning, sleep deprivation, sensorial stimulation, exercise and temperature on the regulation the sleep-wake cycle. Likewise, we propose a hypothesis which attempts to reconcile the fact that endogenous and exogenous factors have similar effects.

Transplant of cultured neuron-like differentiated chromaffin cells in a Parkinson's disease patient. A preliminary report

BACKGROUND

Treatment of Parkinson's Disease (PD) has been attempted by others by transplanting either the patient's own adrenal medullary tissue or fetal substantia nigra into caudate or putamen areas. However, the difficulties inherent in using the patient's own adrenal gland, or the difficulty in obtaining human fetal tissue, has generated the need to find alternative methods.

METHODS

We report here of an alternative to both procedures by using as transplant material cultured human adrenal chromaffin cells differentiated into neuron-like cells by extremely low frequency magnetic fields (ELF MF).

RESULTS

The results of this study show that human differentiated chromaffin cells can be grafted into the caudate nucleus of a PD patient, generating substantial clinical improvement, as measured by the Unified Rating Scale for PD, which correlated with glucose metabolism and D2 DA receptor increases as seen in a PET scan, while allowing a 70% decrease in L-Dopa medication.

DISCUSSION

This is the first preliminary report showing that transplants of cultured differentiated neuron-like cells can be successfully used to treat a PD patient.

Anandamide modulates sleep and memory in rats

In this study we have assessed the effect of the intracerebroventricular administration of anandamide (ANA) as well as its precursor metabolite arachidonic acid (AA), on the sleep-wakefulness cycle, memory formation, locomotor activity and pain perception. Our results have indicated that ANA strikingly increases slow-wave sleep (SWS)2 and rapid-eye movement (REM) sleep at the expense of wakefulness (W); while deteriorating memory consolidation. ANA also increases locomotor activity but does not modify pain perception threshold. In contrast, AA increases W and reduces SWS2, while deteriorating memory consolidation and increasing locomotor activity. AA has no effect on pain perception. These results suggest that the brain cannabinoid system participates in the modulation of the vigilance states and mnemonic processes. Additionally, they suggest that the effect on pain perception may be a peripheral rather than a central effect.

Manipulations during forced wakefulness have differential impact on sleep architecture, EEG power spectrum, and Fos induction

We propose a hypothesis suggesting that the most prominent experiences occurring during wakefulness activate specific clusters of neurons related to such experiences. These neurons could possibly then evoke the release of various types of sleep-inducing molecules, thereby causing different patterns of sleep architecture. In this study, we therefore sought to determine whether manipulations of behavior during wakefulness, such as forced wakefulness induced by gentle handling, forced wakefulness associated with a stressful condition such as immobilization, or forced wakefulness associated with excess intake of palatable food, could result in a variation of Fos immunoreactivity in selective brain structures and could also result in different sleep and EEG power density patterns. The results showed that the sleep-wake cycle of rats after all the experimental manipulations was different not only with respect to the control group but also among themselves. Additionally, power spectrum analysis showed an increase of 0.25-4.0 Hz in all experimental manipulations, whereas the 4.25-8.0 Hz increase occurred only in the situation of forced wakefulness plus stress. The Fos induction showed activation of cell clusters in cortical areas and telencephalic centers, in several hypothalamic nuclei, in monoaminergic cell groups, and in brain stem nuclei. The density of Fos-immunoreactive neurons varied in relation to the different paradigms of forced wakefulness. These results suggest that activation of cell clusters in the brain are related to the type of manipulation imposed on the rat during wakefulness and that such variation in cell activation prior to sleep may be associated with sleep architecture and EEG power.

Effects of nicotine and mecamylamine on rat dorsal raphe neurons

This study investigates the hypothesis that serotonin mediates certain nicotine effects, such as mood improvement and the suppression of the ponto-geniculo-occipital spikes of rapid eye movement sleep. The influence of nicotine (10-300 microM) on the firing rate of dorsal raphe neurons and on serotonin release was therefore, studied in rat midbrain slices. Nicotine increased the firing rate, 10-90%, in 67.5% recorded neurons and decreased it, 8-100%, in the remaining 32.5%. Serotonin release increased 2-7 times after nicotine administration, regardless of firing frequency, but the absolute value of serotonin release was 3 times higher during the decreases than during the increases in firing rate. Mecamylamine (1-20 microM) transiently stimulated the dorsal raphe neurons and competitively antagonized the nicotine-induced serotonin release. The results support the working hypothesis and additionally show that mecamylamine also stimulates dorsal raphe neurons.

Neuronal differentiation of chromaffin cells in vitro, induced by extremely low frequency magnetic fields or nerve growth factor: a histological and ultrastructural comparative study

The application of nerve growth factor (NGF) to primary adrenal medulla chromaffin cell cultures induces phenotypic changes characterized mainly by the presence of neurites. A similar effect has been seen when these cells are stimulated by extremely low frequency magnetic fields (ELFMF). In this study, newborn rat chromaffin cells were cultured and subjected to NGF or ELFMF in order to compare their histological and ultrastructural characteristics. Cells cultured in the presence of NGF developed cytoplasmic projections and their distal ends showed growth cones as well as filopodia. With scanning and transmission electron microscopy, an increased submembranous electron density was observed in the nuclei of cells as well as irregular, wavy neuritic projections with a moderate number of varicosities, as well as the prevalence of intermediate filaments among the cytoskeleton components. Cells stimulated with ELFMF presented straighter neuritic extensions with a greater number of varicosities. With the transmission electron microscope, numerous neurotubules were observed, both in the cell soma and in their neuritic extensions. In both groups, growth cones were clearly identified by their ultrastructural characteristics. The differences seen in the cytoskeleton of cells stimulated with NGF or ELFMF suggest differential stimulation mechanisms possibly determining the biochemical, electrophysiological, and morphological characteristics in both types of cell cultures.

Biochemical effects induced by REM sleep deprivation in naive and in D-amphetamine treated rats

The neurochemical dysfunction present in patients showing self-mutilating behavior (SMB) is not well understood. In animal models, rapid eye movement (REM) sleep deprivation enhances the SMB induced by the chronic administration of d-amphetamine. To understand the mechanism underlying these effects the levels of dopamine (DA), noradrenaline (NA) and serotonin (5-HT) were measured in REM sleep deprived only, and in REM sleep deprived and d-amphetamine treated rats. DA levels were elevated (31%) after REM sleep deprivation (48 h) in the neostriatum and the cerebral cortex (33%), while the levels of NA and 5-HT remained constant. A 6-day treatment with d-amphetamine (7.5 mg/kg; i.p.) failed to affect, in REM sleep deprived rats, DA, NA and 5-HT levels. It was also found that REM sleep deprivation had no effects on the d-amphetamine induced [3H]DA release from slices of the same regions. Our results suggests that dopaminergic mechanisms are involved in the effects of REM sleep deprivation on SMB.

The effects of sensory stimulation on REM sleep duration

Previous experiments have demonstrated that auditory (AS) and/or somatosensory (SS) stimulation can increase the duration of REM sleep periods in rats, cats and humans. The objectives of this study were to determine whether repeated AS stimulation causes habituation to the stimulus and whether any additive effects could be obtained with the simultaneous application of AS and SS. Three experimental procedures were used in this study. In experiment 1, animals were recorded for 4 consecutive days with AS, followed by a post-stimulus session. In experiment 2, they were recorded for 24 hours with AS applied at each REM period, followed by a subsequent 24-hours-post-stimulus recording. In experiment 3, animals underwent AS, SS stimulation, or simultaneous application of both in a random fashion at each REM period. The results of all experiments confirm previous findings showing that auditory or somatosensory stimuli significantly increase REM sleep period duration. In addition, AS--applied with different presentations during REM and throughout the sleep-wake cycle--are capable of increasing REM duration regardless of the manner in which they were presented. However, the effects of the stimuli were not additive. It is worth noting that although REM duration increased, REM period frequency decreased, resulting in no net change of total REM sleep through time. Furthermore, no changes were observed in other sleep-wake variables. These experiments clearly demonstrate that repeated auditory stimulation does not cause habituation, and there are no evident side effects on the sleep-wake cycle. These results confirm that the mechanisms involved in REM generation and maintenance can be modulated by sensory modalities.

The role of voltage-gated Ca2+ channels in neurite growth of cultured chromaffin cells induced by extremely low frequency (ELF) magnetic field stimulation

The ion Ca2+ has been shown to play an important role in a wide variety of cellular functions, one of them being related to cell differentiation in which nerve growth factor (NGF) is involved. Chromaffin cells obtained from adrenals of 2- to 3-day-old rats were cultured for 7 days. During this time, these cells were subjected to the application of either NGF or extremely low frequency magnetic fields (ELF MF). Since this induced cell differentiation toward neuronal-like cells, the mechanism by which this occurred was studied. When the L-Ca2+ channel blocker nifedipine was applied simultaneously with ELF MF, this differentiation did not take place, but it did when an N-Ca2+ channel blocker was used. In contrast, none of the Ca2+ channel blockers prevented differentiation in the presence of NGF. In addition, Bay K-8644, an L-Ca2+ channel agonist, increased both the percentage of differentiated cells and neurite length in the presence of ELF MF. This effect was much weaker in the presence of NGF. [3H]-noradrenaline release was reduced by nifedipine, suggesting an important role for L-Ca2+ channels in neurotransmitter release. Total high voltage Ca2+ currents were significantly increased in ELF MF-treated cells with NGF, but these currents in ELF MF-treated cells were more sensitive to nifedipine. Amperometric analysis of catecholamine release revealed that the KCl-induced activity of cells stimulated to differentiate by ELF MF is highly sensitive to L-type Ca2+ channel blockers. A possible mechanism to explain the way in which the application of magnetic fields can induce differentation of chromaffin cells into neuronal-like cells is proposed.

A novel effect of nicotine on mood and sleep in major depression

The role of repeated nicotine administration on sleep and major depression was studied. Six non-smoking normal volunteers (NV) and six non-smoking major depressed patients (MD) with a Hamilton Rating Scale for Depression > 18 served as subjects. All subjects underwent the following sleep procedures: acclimatization, control night, four nicotine nights (17.5 mg, transdermal patches) and one withdrawal night (WN). Nicotine increased REM sleep time in both groups and also on the WN. Hamilton scores showed an average reduction of 43.9% in the depressed patients. These findings suggest that nicotine receptor activation may be important in major depression and shows for the first time that nicotine patches may be useful in the treatment of depression.

Extremely low frequency magnetic fields promote neurite varicosity formation and cell excitability in cultured rat chromaffin cells

We report the use of an extremely low frequency magnetic field (ELF-MF, 60 Hz, 10 Grms) to stimulate cultured chromaffin cells to determine the possible changes that may occur in their electrical properties. The results showed that ELF-MF not only facilitated neurite outgrowth, but also formation of neurite varicosity with high concentration of catecholamines. This report also shows for the first time that a greater number of cultured chromaffin cells differentiated by ELF-MF have spontaneous extracellular electrical activity and that their firing frequency is higher than that seen in non-stimulated cells.

Effects of REM sleep deprivation on the d-amphetamine-induced self-mutilating behavior

It is well known that self-mutilating behavior (SMB) is developed in rats and humans during the daily treatment with d-amphetamine. Accordingly, in this work it was found that the daily treatment with 7.5 mg/kg d-amphetamine induced in rats a progressive appearance of SMB. Lower doses (5.0 mg/kg) were uneffective and higher doses (10 mg/kg) produced a pattern of SMB in which the mutilation induced at the beginning of the d-amphetamine administration disappears completely as the treatment progresses. Interestingly, it was also found that REM sleep deprivation (48 h) potentiated significantly the SMB induced by the daily administration of 7.5 mg/kg d-amphetamine, and to lesser extent, the SMB induced by the daily treatment with 10 mg/kg d-amphetamine. R(+)-SCH-23390 a D1 dopamine (DA) receptor antagonist blocked completely or abolished the SMB induced by 7.5 mg/kg d-amphetamine in REM sleep deprived rats while (+/-)-sulpiride a D2 DA receptor antagonist had only a partial blocking effect. Haloperidol a D1/D2 DA receptor antagonist behaved as a D1 antagonist. Our results indicate that REM sleep deprivation enhances the SMB induced by the daily administration of d-amphetamine and suggest the involvement of D1 DA receptors in the mechanism underlying the SMB. A role of REM sleep deprivation is also suggested in the appearance of self-mutilating episodes in d-amphetamine addicts.

Sleep changes after 4 consecutive days of venlafaxine administration in normal volunteers

BACKGROUND

The purpose was to examine the effect of the antidepressant drug venlafaxine on sleep architecture and periodic leg movements of sleep (PLMS) in normal volunteers.

METHOD

Eight normal volunteers were studied under laboratory sleep conditions as follows: 1 acclimatization night, 1 baseline night, and 4 consecutive nights of venlafaxine p.o. administration (75 mg during the first 2 nights and 150 mg the last 2 nights).

RESULTS

Venlafaxine increased both wake time and sleep stage I. Sleep stages II and III were reduced. REM sleep time was reduced after the first venlafaxine dose, and, by the fourth night, REM sleep was completely suppressed in all volunteers. Six of the eight volunteers showed PLMS at a frequency above 25 per hour.

CONCLUSION

Venlafaxine produces several sleep disturbances, which include abnormal leg movements.

Repeated REM sleep deprivation after chronic haloperidol administration in the rat

Repeated haloperidol administration produces up-regulation of dopamine (DA) receptors. REM sleep deprivation (REMSD) does also, but in addition, has been shown to produce REM sleep rebound. Should DA receptor up-regulation play a role in REM sleep rebound, haloperidol could conceivably have effects similar to those observed following REMSD. This is the central question investigated in this study. Male Wistar rats were prepared for sleep recordings. They were randomly assigned to the following groups: group 1, REMSD by small platforms (40 h REMSD + 8 h recording); group 2, was the large platform control group (40 h in large platforms + 8 h of recording); group 3, received 2-week daily administration of haloperidol (3 mg/kg, i.p.) plus REMSD (40 h REMSD + 8 h of recording); group 4, 2-week administration of haloperidol (3 mg/kg) without sleep manipulation and at the end 40 h were allowed to elapse, following which 8 h of sleep recordings was carried out. In each group the sleep manipulation and/or sleep recordings were repeated five consecutive times. Repeated REMSD produced increases of REM sleep time after each recovery in group 1. Large platforms did not produce increases of REM sleep during the recovery trials. The 2-week administration of haloperidol plus REMSD prevented REM sleep rebound (group 3). The 2-week administration of haloperidol without sleep manipulation (group 4) produced a REM sleep reduction. Dopamine modulation seems not to be important for REM sleep rebound. Hypersensitivity of DA receptors developed after REMSD may be an epiphenomenon associated with this sleep manipulation, but seems not to participate in REM sleep enhancement after REMSD.

Differential role of dopamine receptors on motor asymmetries of nigro-striatal lesioned animals that are REM sleep deprived

Recently, we have shown that rapid eye movement sleep deprivation (REM-SD) in animals with lesions of the nigro-striatal pathway facilitates turning behavior and such increase still occurred even in the presence of dopaminergic grafts. The objective of this work was to determine which DA receptors are preferentially involved. The results showed that the D2 receptor antagonist sulpiride decreases significantly turning behavior of lesioned animals, with no effect whatsoever of the D1 antagonist SCH 23390. When lesioned animals were REM sleep deprived, the D1 but not the D2 receptor antagonist prevented the increase of turning induced by REM-SD. This work suggests that the increase of post-synaptic supersensitivity induced by REM-SD in nigro-striatal lesioned animals is mediated by D1 receptors.

Transdermal nicotine on sleep and PGO spikes

There is conflicting evidence for the role of nicotine in sleep regulation. This study was undertaken to determine the effects of transdermal nicotine at doses of 17.5, 35 and 52.5 mg on sleep and PGO spike activity. Minor effects were observed on sleep with a general increase in waking. PGO spike activity was abolished by all patches. The results are discussed in terms of the mechanisms involved in the disappearance of PGO spikes as a result of nicotine.

Rapid eye movement (REM) sleep deprivation in 6-OHDA nigro-striatal lesioned rats with and without transplants of dissociated chromaffin cells

Since both REM sleep deprivation and unilateral 6-OHDA lesions induce supersensitivity of DA receptors, the purpose of this study was to determine whether the response of rats with such lesions would be modified by REM sleep deprivation. In addition, the effect of grafts of dissociated chromaffin cells was also tested. Rats with 6-OHDA lesions were subjected to 24 or 72 h of REM sleep deprivation and tested with various doses of apomorphine to determine turning behavior frequencies. At end of those experiments, the animals were transplanted with dissociated chromaffin cells and turning behavior was tested again. The results showed that REM sleep deprivation nearly doubled the turning behavior frequency, that chromaffin cell grafts decreased it, but that REM deprivation in grafted animals still seemed to produce an increase of post-synaptic supersensitivity independent of denervation. The results were discussed in terms of the possible relationship of sleep with Parkinson's disease through the DA system.

Temporal variations of adenosine metabolism in human blood

Eight diurnally active (06:00-23:00 h) subjects were adapted for 2 days to the room conditions where the experiments were performed. Blood sampling for adenosine metabolites and metabolizing enzymes was done hourly during the activity span and every 30 min during sleep. The results showed that adenosine and its catabolites (inosine, hypoxanthine, and uric acid), adenosine synthesizing (S-adenosylhomocysteine hydrolase and 5'-nucleotidase), degrading (adenosine deaminase) and nucleotide-forming (adenosine kinase) enzymes as well as adenine nucleotides (AMP, ADP, and ATP) undergo statistically significant fluctuations (ANOVA) during the 24 h. However, energy charge was invariable. Glucose and lactate chronograms were determined as metabolic indicators. The same data analyzed by the chi-square periodogram and Fourier series indicated ultradian oscillatory periods for all the metabolites and enzymatic activities determined, and 24-h oscillatory components for inosine, hypoxanthine, adenine nucleotides, glucose, and the activities of SAH-hydrolase, 5'-nucleotidase, and adenosine kinase. The single cosinor method showed significant oscillatory components exclusively for lactate. As a whole, these results suggest that adenosine metabolism may play a role as a biological oscillator coordinating and/or modulating the energy homeostasis and physiological status of erythrocytes in vivo and could be an important factor in the distribution of purine rings for the rest of the organism.

Brain distribution of vasoactive intestinal peptide receptors following REM sleep deprivation

Vasoactive intestinal peptide (VIP) has been shown to increase rapid eye movement (REM) sleep in normal and insomniac animals, while the administration of anti-VIP antibodies or an antagonist of VIP receptors decreases REM sleep. In addition, recently, it has been suggested that a VIP-like substance accumulates in the CSF during waking and that it may be involved in the production of the REM rebound normally seen following REM sleep deprivation. This evidence suggests that VIP may be important in modulating REM sleep in normal conditions and during REM sleep rebound. To determine whether VIP is involved in REM sleep homeostasis, VIP receptors of discrete brain areas was determined by autoradiography after 24 and 72 h of REM sleep deprivation (REM SD) by the water tank technique. Since this procedure has been suggested to produce some stress, an additional group adapted for 7 days to the sleep deprivation situation was tested. The results showed that REM SD produces an increase in the density of VIP receptors in several brainstem and forebrain structures at 24 h of REM SD and more so at 72 h of REM SD. Interestingly, results showed that habituation to the REM SD procedure decreases the density of VIP receptors in some areas of the brain of the REM sleep-deprived rats. The results are discussed in terms of the possibility that waking induces an increase of VIP receptors in several structures, which in turn are responsible for modulating REM sleep, but that stress contributes in part to VIP receptor changes.

Delay in manifestations of aging by grafting NGF cultured chromaffin cells in adulthood

Dopamine agonists or grafts compensate impaired motor functions in aged rats. However, there is no evidence showing whether grafting in adulthood retard aging manifestations. Motor performance of 13-month-old rats was tested on 2 meter-long wooden beams which had a 15 degree inclination and whose thickness varied from 3, 6, 12, 18, to 24 mm. Rats at 14 months were randomly assigned to 3 groups: sham graft (Group 1); intrastriatal graft of chromaffin cells cultured with NGF (Group 2); intrastriatal graft of chromaffin cells (Group 3). Motor performance was tested at monthly intervals up until rats were 26 months old. Two more groups were included: 26-month-old naive rats (Group 4); and 3- to 5-month-old naive rats (Group 5) both evaluated only once. At 26 months, the basal activity of ventral mesencephalic dopaminergic neurons was recorded. Results showed in Group 2 delay of motor detriments seen in aged rats, maintenance of basal firing rates of nigral cells compared to those of younger rats, and greater survival of substantia nigra cells. It is suggested that NGF cultured chromaffin cells produce a delay of motor detriments in aged rats, as a result of inducing survival and firing rates of nigral cells comparable to those seen in young rats.

Effects of transderman nicotine on mood and sleep in nonsmoking major depressed patients

The role of nicotine as an indirect cholinergic agent in sleep has been studied in normal subjects. There are no studies of its effects on sleep in depressed patients. Nicotine transdermal patches (17.5 mg), were studied in eight depressed patients (DSM-III-R) and eight normal volunteers. Subjects wore placebo and nicotine patches for 24 h. Depressed patients showed increased REM sleep without changes in other sleep variables. They also showed a short term improvement of mood. Normal volunteers had sleep fragmentation, and reduction of REM sleep time. No major side effects were reported in either group.

The function of sleep is to regulate brain excitability in order to satisfy the requirements imposed by waking

A hypothesis is proposed which suggests that the requirements imposed by waking on a day to day basis dictates the way organisms sleep. This generates 'somnoprints' which are characteristic patterns of sleep directly related to events of waking. REM sleep is suggested to be the phase which contends with waking requirements by manifesting levels of excitability which have the dual function of generating the phase and maintaining it for period durations which are determined by the functional requirements imposed by the moment. Since the brain cannot maintain long periods of excitation, it always alternates with SWS for homeostatic reasons. The hypothesis includes the justification for the diversity of chemical signals regulating sleep, by suggesting that waking activities generate different needs which in turn generate different chemical signals and activate different set of neuronal nets who increase their excitability levels to maintain sleep through varying pathways.

Brain distribution of c-fos expression as a result of prolonged rapid eye movement (REM) sleep period duration

Auditory stimulation (AS) or recovery from sleep deprivation (SD) has been shown to increase REM sleep periods in rats, cats and humans. This increment in REM has been credited to an amplified level of excitability in a widely distributed neuronal network throughout the brain. Fos-like immunostaining (FLI) has been useful in constructing maps of post-synaptic neuronal activity with single cell resolution, and has been proposed to be tightly related with progressing neuronal activation. This study utilized FLI as a marker to determine the number of neurons and structures which express c-fos in broadly distributed areas of the brain in animals with REM periods prolonged by either AS or SD. The results indicated that the brain stem and diencephalon present FLI increases in a variety of structures that possibly share various functional aspects of the REM sleep mechanism. These results are discussed in terms of the possibility that REM maintenance is related to an increase in the recruitment of REM-on neurons.