Hypocretin release in normal and narcoleptic dogs after food and sleep deprivation,eating, and movement

Hypocretins (orexins) are recently discovered hypothalamic neuropeptides that have been implicated in the etiology of narcolepsy. The normal behavioral functions of these peptides are unclear, although a role in feeding has been suggested. We measured hypocretin-1 (Hcrt-1) in the cerebrospinal fluid of dogs during a variety of behaviors. We found that 48 h without food (24 h beyond normal 24-h fasting period) produced no significant change in Hcrt-1 levels nor did feeding after the deprivation. In contrast, 24 h of sleep deprivation produced on average a 70% increase in Hcrt-1 level compared with baseline levels. The amount of increase was correlated with the level of motor activity during the sleep-deprivation procedure. A 2-h period of exercise in the same dogs produced a 57% increase in Hcrt-1 levels relative to quiet waking levels, with the magnitude of the increase being highly correlated with the level of motor activity. The strong correlation between motor activity and Hcrt-1 release may explain some of the previously reported behavioral, physiological, and pathological phenomena ascribed to the Hcrt system.     

Orexin/hypocretin neurons: chemical phenotype and possible interactions with melanin-concentrating hormone neurons

We showed earlier that a specific neuron population of the rat lateral hypothalamus, differing from the codistributed melanin-concentrating hormone (MCH) neurons, express both dynorphin (DYN) and secretogranin II (SgII) genes. We demonstrated later that this population corresponds in fact to the newly identified orexin/hypocretin (OX/Hcrt) neurons. In the present study, by revisiting the chemical phenotype of these neurons, we confirm that all of them contain DYN B- and SgII-immunoreactive materials. The roles played by these peptide/protein in OX/Hcrt neurons are still unclear.Double immunocytochemical stainings highlight putative somasomatic, axosomatic and axodendritic contacts between OX/Hcrt and MCH neurons. Adding OX/Hcrt to the culture medium of hypothalamic slices from 8-day-old rats results either in a significant increase of MCH mRNA after 24 h survival or a strong fall after 10 days culture. These results taken together suggest that OX/Hcrt can directly and/or indirectly affect MCH expression, and that both OX/Hcrt and MCH neuron populations interact to respond in a coordinated manner to central and peripheral signals.     

The effect of coupled cardiovascular and respiratory afferent signals on the central processes of human information processing

On the basis of contemporary knowledge on close functional connections between respiratory and cardiovascular afferents a computerized experimental device was developed by means of which central information processing can be studied in dependence on respiration phase and the level of baroreceptor activity. In all the examined parameters (time of motor reaction of two hands, latency of eye-lid reflex) the greatest changes were observed at maximum baroreceptor activity. These changes were clearly distinguished by direction during the phases of inhalation and exhalation. Such effect is probably based on the fact that the influence of cardiovascular afferents on the level of central activity is modulated in respiration rhythm through the mechanism of breath "gating" of postsynaptic STN structures.     

Energy metabolism of Plantago lanceolata, as affected by change in root temperature

The long and short term metabolic effects of a shift in root temperature was investigated in Plantago lanceolata L. with special reference to the role of the cyanide resistant alternative pathway in root respiration. After a 10-day period of growth at a 13°C root temperature, a decrease in root as well as shoot growth was observed, compared to control plants grown continuously at 21°C. Apart from an increase in shoot soluble and insoluble sugar level, no changes in metabolism were found, neither in root respiration, shoot photosynthesis, nor in root sugar and plant protein level.
Decreasing the root temperature from 21 to 13°C gave several clear short term changes in metabolism. Within one hour a decrease in cytochrome chain activity of the roots was found together with an increase in activity of the alternative chain. After 24 h a recovery to the initial level of both chains was observed. An increase in root temperature from 13 to 21°C gave an immediate increase in activity of both respiratory chains that was still present 24 h after the switch.
It is concluded that the activity of the alternative respiratory pathway in the root is strongly affected by a sudden temperature change in the root environment. This pathway acts in a way which is described by 'the energy overflow model'. The presence of the alternative electron transport pathway should be taken into account in determinations of the respiratory Q₁₀. Moreover, the length of time between the temperature change and respiration measurements is an important factor.     

Reduced number of hypocretin neurons in human narcolepsy

Murine and canine narcolepsy can be caused by mutations of the hypocretin (Hcrt) (orexin) precursor or Hcrt receptor genes. In contrast to these animal models, most human narcolepsy is not familial, is discordant in identical twins, and has not been linked to mutations of the Hcrt system. Thus, the cause of human narcolepsy remains unknown. Here we show that human narcoleptics have an 85%-95% reduction in the number of Hcrt neurons. Melanin-concentrating hormone (MCH) neurons, which are intermixed with Hcrt cells in the normal brain, are not reduced in number, indicating that cell loss is relatively specific for Hcrt neurons. The presence of gliosis in the hypocretin cell region is consistent with a degenerative process being the cause of the Hcrt cell loss in narcolepsy.     

Raised Nitrate Concentration and Low SOD Activity in the CSF of Sporadic ALS Patients

To determine whether or not the occurrence of sporadic amyotrophic lateral sclerosis (sALS) is associated with both excess nitric oxide (NO) metabolites and decreased protective superoxide dismutase (SOD) activity in the cerebrospinal fluid (CSF), we measured nitrate concentration and SOD activity in the CSF of sALS patients and in age- and gender-matched controls. We found stable NO metabolite levels to be significantly higher and SOD activity lower in the CSF of sALS patients. In addition, SOD showed a negative correlation with motor neuron axonal damage expressed as the amplitude of motor action potentials in upper limbs. Our results provide new evidence in vivo suggesting that NO products and SOD activity play a role in oxidant/antioxidant imbalance in sporadic ALS.     

Hepatoma-derived growth factor, a new trophic factor for motor neurons, is up-regulated in the spinal cord of PQBP-1 transgenic mice before onset of degeneration

Hepatoma-derived growth factor (HDGF) is a nuclear protein homologous to the high-mobility group B1 family of proteins. It is known to be released from cells and to act as a trophic factor for dividing cells. In this study HDGF was increased in spinal motor neurons of a mouse model of motor neuron degeneration, polyglutamine-tract-binding protein-1 (PQBP-1) transgenic mice, before onset of degeneration. HDGF promoted neurite extension and survival of spinal motor neurons in primary culture. HDGF repressed cell death of motor neurons after facial nerve section in newborn rats in vivo. We also found a significant increase in p53 in spinal motor neurons of the transgenic mice. p53 bound to a sequence in the upstream of the HDGF gene in a gel mobility shift assay, and promoted gene expression through the cis-element in chloramphenicol acetyl transfer (CAT) assay. Finally, we found that HDGF was increased in CSF of PQBP-1 transgenic mice. Collectively, our results show that HDGF is a novel trophic factor for motor neurons and suggest that it might play a protective role against motor neuron degeneration in PQBP-1 transgenic mice.     

Modulation of respiratory motor output by cerebellar deep nuclei in the rat.

The present study was undertaken to determine what roles the various cerebellar deep nuclei (CDN) play in modulation of respiration, especially during chemical challenges. Experiments were carried out in 12 anesthetized, tracheotomized, paralyzed, and ventilated rats. The integrated phrenic nerve activity (integralPN) was recorded as an index of respiratory motor output. A stimulating electrode was sequentially placed into the fastigial nucleus (FN), the interposed nucleus, and the lateral nucleus. Only stimulation of the FN significantly altered respiration, primarily via increasing respiratory frequency associated with a pressor response. The evoked respiratory responses persisted after blocking the pressor response via pretreatment with phenoxybenzamine or use of transient stimulation (<2 s) but were abolished by microinjection of kainic acid into the FN. To test the involvement of FN neurons in respiratory chemoreflexes, ventilation with hypercapnic gases mixture and intravenous injection of sodium cyanide were applied before and after CDN lesions induced by kainic acid. CDN lesions did not significantly alter eupneic breathing, but FN lesions attenuated the respiratory response to hypercapnia and sodium cyanide. We conclude that, with respect to the CDN in the rat, FN neurons uniquely modulate respiration independent of cardiovascular effects and facilitate respiratory responses mediated by activation of CO(2) and O(2) receptors.     

Increase of the IL-1 beta and IL-6 levels in CSF in patients with vasospasm following aneurysmal SAH

Cytokines play a key role in mutual influence of the immunological, endocrine and CNS systems. It has been proven that proinflammatory ILs may intensify the cascade of biochemical changes in ischemic brain damage. Vasospasm, which may accompany SAH and often coexists with symptoms of DINDs, is the cause of ischemic changes in the brain. It is thought that immunological mechanisms may be one of the causes of degenerative-productive changes in vessel walls, in delayed vasospasm following SAH, which lead to substantial vasospasm and in consequence too cerebral ischemia. In the randomly selected group of patients, who underwent surgical treatment after aneurysmal SAH, we determined the concentration of IL-1 beta and IL-6 in CSF in the periods between Days 0 to 3; 4 to 7; and 8 to 15 after the occurrence of SAH. The presence and dynamics of development of vasospasm were assessed on the basis of increasing DINDs as well as CT and cerebral angiography. We examined the concentrations of ILs in CSF using radioimmunological methods, applying commercially available tests for their assessment. We found that in the period between 8 and 15 days after SAH, in increasing delayed vasospasm and DINDs, here is a statistically significant increase concentration of IL-1 beta in CSF (105.4 +/- 46.9 pg x ml-1; p<0.005), and no significant changes in patients without vasospasm and neurological deficits. On the other hand, we noted a statistically significant increase concentration of IL-6 in CSF (4802 +/- 1170 ng x ml-1; p<0.05) only in the acute phase after SAH (Days 0-3) in patients in poor clinical condition, in whom delayed vasospasm and cerebral ischemia developed later. This increase of ILs level in CSF is probably related to the intensity of the SAH, and secondarily aggravates the vasospasm and ischemic changes in the brain.     

Cardiovascular responses to dreamed physical exercise during REM lucid dreaming.

Previous studies have demonstrated intriguing psychophysiological correspondences when lucid dreamers carried out specific tasks during lucid dreams (e.g., eye movements and EMG activities). But only a few studies have investigated cardiovascular changes during dreamed physical activities. This study tests the hypothesis that physical activity (performing squats) carried out in a lucid dream increases cardiovascular parameters in the sleeping body. Therefore, 5 proficient lucid dreamers experienced with the eye-signaling method during lucidity spent 2 to 4 nonconsecutive nights in a sleep laboratory. Instructed to carry out specific tasks (counting and performing squats) while lucid dreaming, the participants reported becoming lucid and signaling in 11 REM periods recorded. Fourteen complete lucid dream tasks were verified by eye signaling. The results showed a statistically significant increase of heart rate between the preexercise and exercise periods and the postexercise period. The results for respiration rate were less clear. Even though respiration rate during the exercise period was higher than during the pre- and postexercise period, statistical significance was only found for the second comparison. Overall, the results support the hypothesis that lucidly dreamed motor action causes increases at the level of peripheral effectors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transgenic SOD1 G93A mice develop reduced GLT-1 in spinal cord without alterations in cerebrospinal fluid glutamate levels

Glutamate-induced excitotoxicity is suggested to play a central role in the development of amyotrophic lateral sclerosis (ALS), although it is still unclear whether it represents a primary cause in the cascade leading to motor neurone death. We used western blotting, immunocytochemistry and in situ hybridization to examine the expression of GLT-1 in transgenic mice carrying a mutated (G93A) human copper-zinc superoxide dismutase (TgSOD1 G93A), which closely mimic the features of ALS. We observed a progressive decrease in the immunoreactivity of the glial glutamate transporter (GLT-1) in the ventral, but not in the dorsal, horn of lumbar spinal cord. This effect was specifically found in 14- and 18-week-old mice that had motor function impairment, motor neurone loss and reactive astrocytosis. No changes in GLT-1 were observed at 8 weeks of age, before the appearance of clinical symptoms. Decreases in GLT-1 were accompanied by increased glial fibrillary acidic protein (GFAP) levels and no change in the levels of GLAST, another glial glutamate transporter. The glutamate concentration in the cerebrospinal fluid (CSF) of TgSOD1 G93A mice was not modified at any of the time points examined, compared with age-matched controls. These findings indicate that the loss of GLT-1 protein in ALS mice selectively occurs in the areas affected by neurodegeneration and reactive astrocytosis and it is not associated with increases of glutamate levels in CSF. The lack of changes in GLT-1 at the presymptomatic stage suggests that glial glutamate transporter reduction is not a primary event leading to motor neurone loss.     

Changes in the relationship between cerebrospinal fluid and blood composition produced by ACTH treatment in conscious sheep

It has been proposed that an increase in CSF osmolality could be involved in the genesis of hypertension by activation of central nervous system receptors involved in cardiovascular regulation. ACTH induced hypertension in the sheep is an adrenally dependent model of steroid induced hypertension. This study reports the effect of ACTH administration (20 g/kg/day) for 5 days on the composition of cerebrospinal fluid (CSF) and blood (plasma) in conscious sheep. ACTH increased CSF and plasma osmolality within 24 h associated with parallel increases in both blood and CSF glucose concentrations and plasma and CSF sodium concentration. Plasma potassium fell within 24 h, but CSF potassium did not change over the 5 days of ACTH treatment. Neither calcium nor magnesium changed in either plasma or CSF. CSF phosphate increased and plasma phosphate decreased. CSF and plasma bicarbonate were elevated with ACTH. Plasma chloride decreased after 5 days of ACTH treatment but was not associated with a change in CSF. The relevance of the measured changes in CSF osmolality and composition to the mechanisms involved in the production of ACTH-induced hypertension will be subject of further experimentation.     

Heat-shock protein 90 complexes in resting and thrombin-activated platelets

The orexins are peptides which were recently isolated from the rat hypothlamus. They play a role in energy homeostasis and regulation of feeding as well as in other functions such as the sleep-wake cycle. The involvement of glucocorticoids in stress processes as well as in body weight regulation is well known. In the present paper, we investigated the role of glucocorticoids on hypocretin (Hcrt)/orexin (OX) pathway in Sprague-Dawley rats. We confirmed by in situ hybridization that prepro-Hcrt/OX mRNA expression is restricted to the lateral hypothalamus area with extension to the perifornical nucleus and the posterior hypothalamic area. Lateral hypothalamic prepro-Hcrt/OX mRNA expression was decreased by 50% after adrenalectomy (99.8+/-5.0 vs 49.2+/-4.4 nCi/g, p<0.01). Peripheral glucocorticoid treatment (dexamethasone) restored its expression to normal levels (105.4+/-6.1 nCi/g). The present data provide direct evidence that Hcrt/OX expression in the lateral hypothalamus is modulated by the glucocorticoids status. As the Hcrt/Ox system is closely interactive with the corticotropin-releasing hormone and neuropeptide Y systems, we propose that hypocretin/orexins peptides constitute a very sensitive key relay for mediating both stress and feeding behavior.     

Molecular isoform distribution and glycosylation of acetylcholinesterase are altered in brain and cerebrospinal fluid of patients with Alzheimer's disease

The glycosylation of acetylcholinesterase (AChE) in CSF was analyzed by lectin binding. AChE from Alzheimer's disease (AD) patients was found to bind differently to two lectins, concanavalin A and wheat germ agglutinin, than AChE from controls. As multiple isoforms of AChE are present in both CSF and brain, we examined whether the abnormal glycosylation of AD AChE was due to changes in a specific molecular isoform. Globular amphiphilic dimeric (G2a) and monomeric (G1a) isoforms of AChE were found to be differentially glycosylated in AD CSF. Glycosylation of AChE was also altered in AD frontal cortex but not in cerebellum and was also associated with an increase in the proportion of light (G2 and G1) isoforms. This study demonstrates that the glycosylation of AChE is altered in the AD brain and that changes in AChE glycosylation in AD CSF may reflect changes in the distribution of brain isoforms. The study also suggests that glycosylation of AChE may be a useful diagnostic marker for AD.     

Male human motor cortex stimulus-response characteristics are not altered by aging

Evidence suggests that there are aging-related changes in corticospinal stimulus-response curve characteristics in later life. However, there is also limited evidence that these changes may only be evident in postmenopausal women and not in men. This study compared corticospinal stimulus-response curves from a group of young men [19.8 ± 1.6 yr (range 17-23 yr)] and a group of old men [n = 18, aged 64.1 ± 5.0 yr (range 55-73 yr)]. Transcranial magnetic stimulation (TMS) over the contralateral motor cortex was used to evoke motor potentials at a range of stimulus intensities in the first dorsal interosseous muscle of each hand separately. There was no effect of age group or hemisphere (i.e., left vs. right motor cortex) on motor evoked potential (MEP) amplitude or any other stimulus-response characteristic. MEP variability was strongly modulated by resting motor threshold but not by age. M-wave (but not F-wave) amplitude was reduced in old men, but expressing MEP amplitude as a ratio of M-wave amplitude did not reveal any age-related differences in cortically evoked stimulus-response characteristics. We conclude that male corticospinal stimulus-response characteristics are not altered by advancing age and that previously reported age-related changes in motor cortical excitability assessed with TMS are likely due to changes inherent in the female participants only. Future studies are warranted to fully elucidate the relationship between, and functional significance of, changes in circulating neuroactive sex hormones and motor function in later life.     

Pigment epithelium-derived factor is elevated in CSF of patients with amyotrophic lateral sclerosis

Pigment epithelium-derived factor (PEDF), a recently defined retinal trophic factor and anti-angiogenic factor for the eye, is also present in the CNS and is a motor neuron protectant. We asked whether PEDF levels in CSF are altered in patients with amyotrophic lateral sclerosis (ALS). Pigment epithelium-derived factor protein was detected by quantitative western blot analysis with a PEDF-specific antiserum. Levels of PEDF in CSF, expressed as a ratio to total CSF protein, were significantly elevated 3.4-fold in 15 patients with ALS compared with neurologic disease controls (p < 0.0003). This increase does not seem likely to reflect up-regulation of PEDF synthesis in muscle in response to denervation, as CSF PEDF was not elevated in severe denervating diseases other than ALS. Nor does the increase represent some non-specific release in neurodegeneration, as CSF PEDF was not elevated in other neurodegenerative diseases. While the mechanism of this presumably reactive increase is not known, the distinctive, surprisingly elevated level of PEDF in the CSF may be an autoprotective reaction in ALS.     

G(olf) protein levels in rat striatum are increased by chronic antidepressant administration and decreased by olfactory bulbectomy

There are many studies of the mechanisms of antidepressants; however, most of these studies were conducted on the hippocampus or frontal cortex. In the present study, we hypothesized that the nucleus accumbens and caudate/putamen might be major targets for antidepressant effects. Thus, we focused on G(olf) protein, a stimulant alpha-subunit of G protein that is coupled with the dopamine D1 receptor and specifically expressed in the striatum (nucleus accumbens, caudate/putamen and olfactory tubercle) in the rat brain. We examined the effects of chronic administration of imipramine, fluvoxamine, maprotiline and, as a negative control, cocaine on the level of G(olf) protein in the rat striatum. We also examined the effect of olfactory bulbectomy. Chronic imipramine treatment (10 mg/kg for 2 or 4 weeks) significantly increased the level of G(olf) in the striatum (by 17% or 18%, respectively), although this increase was not apparent after only 1 week of treatment. The time course of these changes corresponded well to that of the clinical efficacy of imipramine. Chronic fluvoxamine and maprotiline treatment (20 mg/kg for 2 weeks) also significantly increased the level of G(olf) (by 9% and 25%, respectively), but cocaine did not alter it significantly. Bulbectomy decreased the G(olf) protein level by 9%. The increases in G(olf) protein after chronic administration of these three different classes of antidepressants and the decrease after bulbectomy suggest that G(olf) protein may play an important role in the antidepressant effect.     

Internal aeration and respiration of submerged tomato hypocotyls are enhanced by ethylene-mediated aerenchyma formation and hypertrophy

With the impending threat that climate change is imposing on all terrestrial ecosystems, the ability of plants to adjust to changing environments is, more than ever, a very desirable trait. Tomato (Solanum lycopersicum L.) plants display a number of responses that allow them to survive under different abiotic stresses such as flooding. We focused on understanding the mechanism that facilitates oxygen diffusion to submerged tissues and the impact it has on sustaining respiration levels. We observed that, as flooding stress progresses, stems increase their diameter and internal porosity. Ethylene triggers stem hypertrophy by inducing cell wall loosening genes, and aerenchyma formation seems to involve programmed cell death mediated by hydrogen peroxide. We finally assessed whether these changes in stem morphology and anatomy are indeed effective to restore oxygen levels in submerged organs. We found that aerenchyma formation and hypertrophy not only increase oxygen diffusion toward the base of the plant, but also result in an augmented respiration rate. We consider that this response is crucial to maintain adventitious root development under such conditions and, therefore, making it possible for the plant to survive when the original roots die.     

Plasma concentrations of 5-HT, 5-HIAA,norepinephrine, epinephrine and dopamine in ecstasy users

Recreational use of the synthetic methamphetamine derivative MDMA (3,4-methylenedioxymethamphetamine), the main constituent of the illegal drug "ecstasy", has increased dramatically in recent years. The reasons for ecstasy-associated cardiovascular complications like tachycardia, arrhythmias and hypertensive crises and psychiatric symptoms like psychotic episodes are not well understood. We have measured the plasma concentrations of 5-HIAA, 5-HT, norepinephrine, epinephrine and dopamine in 159 ecstasy users and controls. Ecstasy users showed elevated resting sympathetic activity, reflected in increased norepinephrine, epinephrine and dopamine levels. The levels of these catecholamines correlated positively with the cumulative dose and also with consumption during the last 30 days and 12 months. Although it is known that significant changes in 5-HT and 5-HIAA appear in the cerebrospinal fluid in ecstasy users, we could not detect alterations in serotonergic neurotransmitters in plasma in this large sample of subjects. Thus, in the drug-free interval, ecstasy users show lowered central serotonergic activity (lowered 5-HT and 5-HIAA concentrations in CSF) along with unchanged central noradrenergic and dopaminergic activity (HVA and MHPG unchanged in CSF) and elevated peripheral noradrenergic, dopaminergic and adrenergic activity along with unchanged peripheral serotonergic activity (plasma levels). We conclude, that the data presented here could argue for a noradrenergic hyperreactivity in the drug-free interval in ecstasy users resulting from previous ecstasy consumption. Also for an association with psychotic episodes and cardiovascular complications like tachycardia, arrhythmias.     

Antioxidants and mitochondrial respiration in lung, diaphragm, and locomotor muscles: effect of exercise.

Previous studies have shown that exhaustive exercise may increase reactive oxygen species (ROS) generation in oxidative muscles that may in turn impair mitochondrial respiration. Locomotor muscles have been extensively examined, but there is few report about diaphragm or lung. The later is a privileged site for oxygen transit. To compare the antioxidant defense system and mitochondrial function in lung, diaphragm and locomotor muscles after exercise, 24 young adult male rats were randomly assigned to a control (C) or exercise (E) group. E group rats performed an exhaustive running test on a motorized treadmill at 80-85% VO2max Mean exercise duration was 66+/-2.7 min. Lung, costal diaphragm, mixed gastrocnemius, and oxidative muscles (red gastrocnemius and soleus: RG/SOL homogenate) were sampled. Mitochondrial respiration was assessed in tissue homogenates by respiratory control index (RCI: rate of uncoupled respiration/rate of basal respiration) measurement. Lipid peroxidation was evaluated by malondialdehyde concentration (MDA) and we determined the activity of two antioxidant enzymes: superoxide dismutase (SOD) and glutathione peroxidase (GPX). We found elevated basal (C group data) SOD and GPX activities in both lung and diaphragm compared to locomotor muscles (p<.001). Exercise led to a rise in GPX activity in red locomotor muscles homogenate (GR/SOL; C = 10.3+/-0.29 and E = 14.4+/-1.51 micromol x min(-1) x gww(-1); p<.05), whereas there was no significant change in lung and diaphragm. MDA concentration and mitochondrial RCI values were not significantly changed after exercise. We conclude that lung and diaphragm had higher antioxidant protection than locomotor muscles. The exercise test did not lead to significant oxidative stress or alteration in mitochondrial respiration, suggesting that antioxidant function was adequate in both lung and diaphragm in the experimental condition.