Uncompetitive stimulation of rat brain Na-K ATPase activity by rapid eye movement sleep deprivation

Rapid eye movement sleep deprivation is associated with an increase in Na-K ATPase activity. In order to understand the possible biochemical mechanism of this increase, the kinetics of Na-K ATPase was studied. Although the enzyme activity increased after the deprivation, the catalytic efficiency of the enzyme remained unaltered. The rapid eye movement sleep deprivation increased both the Vmax and the Km suggesting an uncompetitive stimulation of the enzyme. While increase in norepinephrine resulted in an increased Vmax, that of calcium increased the Km. Since an increase in norepinephrine has been suggested after deprivation, the increased Vmax is attributed to increased norepinephrine level following deprivation. However, since rapid eye movement sleep deprivation is reported to be associated with a decrease in calcium levels, the increase in Km following deprivation may be attributed to changes in factor(s) other than calcium.     

Tyrosine hydroxylase activity in rat brain following "REM" sleep deprivation

I n R ecent years biogenic amines have been implicated in the control mechanism for induction and maintenance of sleep processes (J ouvet , 1969). Investigators have looked for changes in the rate of synthesis of cerebral norepinephrine from [³H]tyrosine after REM sleep deprivation and reported increased rates of synthesis during REM sleep deprivation (M ark , H einer , M andel and G odin , 1969) and REM sleep rebound following 91 h of deprivation (P ujol , M ouret and G lowinski , 1968). Because tyrosine is thought to be the rate-limiting enzyme (U denfriend , 1966) in the synthetic pathways for norepinephrine and since the above-mentioned studies are suggestive of changes in the activity of the enzyme, we decided to measure tyrosine hydroxylase activity following REM sleep deprivation.     

Quantitative indices of lysozyme activity in staphylococci]

The lysozyme activity of 354 lysozyme-positive and 100 lysozyme-negative (by the results of qualitative test) staphylococcus strains were studied quantitatively. The method was based on titration of the lysozyme in the culture fluid of 48-hour broth cultures of the strains under study. The quantitative method proved to be more sensitive than the qualitative one, and permitted to reveal the lysozyme production in 71% of the strains which were formerly considered to be lysozyme-negative. There were distinct species differences between the lysozyme-positive staphylococci: the mean lysozyme level in the S. aureus was significantly greater then in the S. epidermis. There was no regular association between the lysozyme activity, staphylococcus origin, bacteriophage reference and the antibiotic resistance.     

Action of the delta-sleep peptide on monoamine oxidase and acetylcholinesterase activity in subcellular fractions from different rabbit brain formations in vivo

Administration of delta-sleep-inducing peptide (DSIP) in vivo in a dose of 30 microgram/kg bw brings about MAO-A (substrate-serotonin) activation in synaptosome subfractions and cellular mitochondria from the brain structures (motor cortex, nucleus caudatus, thalamus). Activity of MAO-B (substrate-p-nitrophenylethylamine) and acetylcholinesterase was inhibited negligibly and specifically in subcellular fractions of the test brain structures. The results suggest that DSIP effects the regulatory or modulation function in the synapse. As one of the elements of sleep mechanisms this peptide induces a number of processes, particularly in serotonin metabolism.     

A rapid intraoperative estimation of the proliferative activity in brain tumors.

A technique for staining the nucleolar organizer regions (NORs) in tumor cells applied to smears from brain tumor biopsy specimens is described. This technique provides a rapid intraoperative evaluation of the proliferative activity in cerebral neoplasms and is a valuable complement to hematoxylineosin stained smears, supporting the criteria of benignity or malignancy in these tumors.     

Effects of paradoxical sleep deprivation on the activity of opiate receptors isolated from synaptic membranes of the rat brain]

The specific binding of 3H-naloxone with opiate receptors isolated from brain synaptic membranes of control and paradoxical sleep deprived rats were studied. This extreme state was shown to reduce the naloxone-binding activity of synaptic membranes by 35% and isolated receptors by 25-28%. The values of Kd and Bmax were calculated for isolated opiate receptors at different stages of purification. Considerable decrease of 3H-naloxone binding sites density (2 times) in the isolated opiate receptors with simultaneous increase of their affinity (3-4,5 times) was found following 24 hours paradoxical sleep deprivation. These findings suggest development of fixed alterations in the structure and functions of integral receptor proteins under extreme influences.     

Muramyl dipeptide does not induce slow-wave sleep or fever in rats

The synthetic muramyl dipeptide, N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP), is reported to increase slow-wave sleep and body temperature in cats, rabbits, and squirrel monkeys. The present study examined the ability of MDP to induce sleep and fever in rats. MDP was administered IP at 50, 250 and 500 micrograms/kg. Sleep and body temperature were monitored for 12 hr. MDP failed to affect the duration of wakefulness, S1, S2, or total (S1 + S2) slow-wave sleep. There was also no change in the latency to the first episode of S2 sleep. In contrast, rapid-eye-movement (REM) sleep was significantly suppressed for the first 6 hr after 250 and 500 microgram/kg doses of MDP. There was, however, a rebound increase in REM sleep after the initial period of suppression which resulted in no overall change in the amount of REM sleep. Body temperature was unaffected by MDP. Thus, we conclude that MDP has neither sleep-promoting nor pyrogenic actions in the rat when administered systemically at doses reported to be effective in several other species.     

Phosphorylation processes mediate rapid changes of brain aromatase activity

The enzyme aromatase (also called estrogen synthase) that catalyzes the transformation of testosterone (T) into estradiol plays a key limiting role in the action of T on many aspects of reproduction. The distribution and regulation of aromatase in the quail brain has been studied by radioenzyme assays on microdissected brain areas, immunocytochemistry, RT-PCR and in situ hybridization. High levels of aromatase activity (AA) characterize the sexually dimorphic, steroid-sensitive medial preoptic nucleus (POM), a critical site of T action and aromatization for the activation of male sexual behavior. The boundaries of the POM are clearly outlined by a dense population of aromatase-containing cells as visualized by both immunocytochemistry and in situ hybridization histochemistry. Aromatase synthesis in the POM is controlled by T and its metabolite estradiol, but estradiol receptors alpha (ER) are not normally co-localized with aromatase in this brain area. Estradiol receptor beta (ERβ) has been recently cloned in quail and localized in POM but we do not yet know whether ERβ occurs in aromatase cells. It is therefore not known whether estrogens regulate aromatase synthesis directly or by affecting different inputs to aromatase cells as is the case with the gonadotropin releasing hormone neurons. The presence of aromatase in presynaptic boutons suggests that locally formed estrogens may exert part of their effects by non-genomic mechanisms at the membrane level. Rapid effects of estrogens in the brain that presumably take place at the neuronal membrane level have been described in other species. If fast transduction mechanisms for estrogen are available at the membrane level, this will not necessarily result in rapid changes in brain function if the availability of the ligand does not also change rapidly. We demonstrate here that AA in hypothalamic homogenates is rapidly down-regulated by exposure to conditions that enhance protein phosphorylation (addition of Ca²⁺, Mg²⁺, ATP). This inhibition is blocked by kinase inhibitors which supports the notion that phosphorylation processes are involved. A rapid (within minutes) and reversible regulation of AA is also observed in hypothalamic explants incubated in vitro and exposed to high Ca²⁺ levels (K⁺-induced depolarization, treatment by thapsigargin, by kainate, AMPA or NMDA). The local production and availability of estrogens in the brain can therefore be rapidly changed by Ca²⁺ based on variation in neurotransmitter activity. Locally-produced estrogens are as a consequence available for non-genomic regulation of neuronal physiology in a manner more akin to the action of a neuropeptide/neurotransmitter than previously thought.     

Reduction of rapid eye movement (REM) sleep by glucose alone or glucose and insulin in rats

Administration of a high dose of glucose (2.5 g/kg, i.p.) that is known to produce severe hyperglycemia in euglycemic rats suppressed rapid eye movement (REM) sleep time significantly during the first three hours of 8 hr total electroencephalogram (EEG) recording period. Co-administration of glucose (2.5 g/kg, i.p.) and a non-convulsive dose of insulin (1.0 I.U./kg, i.p.) produced a significant reduction in REM sleep time during 1st through 5th hour and an increase in slow-wave sleep (NREM) time in the 3rd and 4th hour of 8 hr total EEG recording period. However, awake, NREM and REM sleep time in the 8 hr total EEG recording period were unaffected by either glucose alone or glucose plus insulin treatments. These results strongly suggest that the insulin's effects on the sleep-awake cycle i.e. reduction in REM and a slight increase in NREM sleep times of rats is not due to indirect effects of insulin on the central nervous system via hypoglycemia as reported by us previously, but could possibly be due to its direct effects on brain chemistry of neurotransmitters such as serotonin, catecholamines and acetylcholine which are believed to modulate the sleep-awake cycle pattern in rats.     

Quantitative indices of the activity and the electrophoretic characteristics of staphylococcal catalase]

The average levels of activity of intracellular and extracellular catalase were determined. The activity of intracellular catalase was shown to be significantly higher than that of extracellular catalase, the average level of activity of extracellular catalase being higher in S. aureus than in S. epidermidis. In most of the strains one zone of extracellular catalase and two molecular forms of intracellular catalase were revealed by means of polyacrylamide gel electrophoresis.     

The thermal activity of the rabbit brain during the interaction of "animal hypnosis" and of the hunger dominant]

The character of interaction between two dominant foci (motivation hunger dominant and "animal hypnosis") which had been formed in the rabbit brain was ambiguous: the foci could either function simultaneously or compete. In the first case, summation food reactions were observed when the hunger dominant was tested during a hypnotic episode against the background of deep and continuous hypnotic state. Brain thermal activity was asymmetric the temperature being higher in the parieto-occipital areas of the left hemisphere. If the hypnosis inhibited the hunger dominant, summation reactions were absent and the brain temperature was higher in the parieto-occipital areas of the right hemisphere. In cases when despite the repeated immobilization sessions the hunger dominant prevented from induction of hypnosis, the left-hemisphere thermal dominance persisted against the background of general brain cooling.     

Some proteins not belonging to the clotting or to the kallikrein-kinin system altered by kallikrein

Plasma kallikrein activation occurs frequently during blood drawing and subsequent plasma handling. The purified enzyme was incubated with ceruloplasmin, inter-alpha-trypsin inhibitor and complement factor C4. Proteolysis caused by this enzyme was compared with the degradative effects of plasmin and thrombin. Among these proteins C4 proved to be most easily degraded; its cleavage products can interact with C4-binding protein.     

Decrease in the lower limit of the rat brain vital activity by the physiological method]

The brain temperature, at which the cessation of the lung respiration occurs in the cooled animals, can be named the lower temperature limit of the brain functional competence, since at this temperature the spontaneous respiration is not restored on its own, and without special artificial undertakings the animals perish. In this study upon the total cooling of the rat bodies their lung respiration stopped completely as the temperature of the medulla oblongata in the region of the respiratory center decreased to 18.18 +/- 0.17 degrees C. This occurred simultaneously with an abrupt decrease in the heart rate and in the arterial blood pressure (AP) to 42 +/- 1 mm Hg. Upon an isolated cooling of the rat head the heart rate and AP were maintained at a comparatively high level. Under such conditions the lung respiration did not stop even as the temperature of the medulla oblongata decreased to 17.23 +/- 0.25 degrees C. It retained rhythmicallity, a particular rate, and a comparatively high amplitude. It is suggested that an intensive blood supply of the cooled brain decreases the lower temperature limit of its vital activity.