Effect of chronic consumption of sodium valproate and melatonin on seizure activity in Krushinskii-Molodkina rats

Experiments on Krushinskii-Molodkina rats with hereditary predisposition to audiogenic seizures showed that chronic consumption of aqueous solution of melatonin (50 mg/liter) had no effect on the pattern of seizures induced by 20-fold acoustic stimulation. Sodium valproate (50 mg/liter) insignificantly decreased the seizure response. Combined treatment with sodium valproate and melatonin produced a potent anticonvulsant effect, i.e. increased the latency and decreased the severity of audiogenic seizures. However, myoclonus in animals receiving combined treatment with these drugs developed much more rapidly compared to rats receiving melatonin or sodium valproate monotherapy. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 142, No. 11, pp. 549–552, November, 2006     

Effect of melatonin and pinealectomy on avoidance and exploratory activity in the rat

Melatonin in a daily dose of 50 μg/rat facilitated the extinction of active avoidance reflex and decreased the intertrial activity during extinction. However, it had no effect on learning and intertrial activity during acquisition. Pinealectomy was ineffective on acquisition, extinction and intertrial activity. Melatonin (100 μg/rat) given in 2 consecutive days facilitated the passive avoidance behavior in water deprived animals in two different experimental situations. Fifty μg of melatonin or pinealectomy was without effect on passive avoidance behavior. Neither melatonin nor pinealectomy had any influence on water intake or on exploratory activity.     

Effects of melatonin on Leydig cells in pinealectomized rat: an immunohistochemical study

We have investigated immunohistochemically the effects of melatonin on Leydig cells in rat. Three groups of Wistar rats were used. Rats in group I and II were sham-pinealectomized (control) and pinealectomized, respectively, whereas rats in group III were pinealectomized and injected daily with melatonin for 2 months. At the end of the experiment, all animals were killed by decapitation and blood samples were obtained. Serum testosterone levels were determined with the use of a chemiluminescent enzyme immunoassay. Testicular tissue was collected and processed for semiquantitative evaluation of immunohistochemical testosterone staining. Intensity of immunostaining was determined on a scale between 0 (no staining) and 5 (heavy staining). In pinealectomized rats, serum testosterone levels were significantly increased as compared to sham-pinealectomized rats. Daily administration of melatonin after pinealectomy resulted in significant decreased serum testosterone levels as compared to levels in control and pinealectomized rats. Immunostaining of testosterone was moderate (3+) in sham-pinealectomized rats, heavy (5+) in pinealectomized rats and low (1+) in pinealectomized rats that were treated with melatonin, respectively. The results of our study indicate that pinealectomy induces increased testosterone secretion in Leydig cells and this increased secretion can be prevented by administration of melatonin.     

Changes in mitotic activity of the corneal epithelium of albino rats cooled at different times of day

The effect of moderate hypothermia on mitotic activity of the corneal epithelium of albino rats was studied. The animals were cooled to 28°C by a contact method for 1 h. Cooling was carried out in the early morning (6 a.m.), at noon, and in the evening (6 p.m.). The response of the epithelium to cooling was found to depend on the time of day. The most marked inhibition of mitotic activity (by 14 times) occurred in the afternoon, 3 h after cooling at noon. A tendency toward restoration of normal cell division was observed 6 and 12 h later. The number of mitoses was reduced 3 h after cooling in the evening, but no changes in mitotic activity were discovered 6 and 12 h later. No changes were found 3 and 6 h after cooling in the morning, but 12 h later cell division was inhibited.Central Scientific-Research Laboratory, Khabarovsk Medical Institute. Laboratory of Cytology, Institute of Human Morphology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 82, No. 11, pp. 1371–1373, November, 1976.     

Dynamics of brain electrical activity

Summary In addition to providing important theoretical insights into chaotic deterministic systems, dynamical systems theory has provided techniques for analyzing experimental data. These methods have been applied to a variety of physical and chemical systems. More recently, biological applications have become important. In this paper, we report applications of one of these techniques, estimation of a signal's correlation dimension, to the characterization of human electroencephalographic (EEG) signals and event-related brain potentials (ERPs). These calculations demonstrate that the magnitude of the technical difficulties encountered when attempting to estimate dimensions from noisy biological signals are substantial. However, these results also suggest that this procedure can provide a partial characterization of changes in cerebral electrical activity associated with changes in cognitive behavior that complements classical analytic procedures.Dedicated to the Memory of Hassler Whitney, 1907–1989.Acknowledgment: PER would like to acknowledge NIH Grant NS19716, a grant from the Whitaker Foundation and the hospitality of the Department of Mathematics and Kingswood College at the University of Western Australia. TRB would like to acknowledge NIH Grants AG04581 and MH40627 and a grant from the Allegheny-Singer Research Foundation. JMM wishes to thank INRIA, Paris. AMA would like to acknowledge support from the Bryn Mawr College Faculty Committee on Awards and Grants. The continuing support of the College Computer Center of the Medical College of Pennsylvania is gratefully acknowledged. During the course of this research we have benefited from advice and instruction from many colleagues including E. Donchin, G. Goldberg, and R. N. Harner. The technical assistance of Joseph Waldron is gratefully acknowledged. We wish to express our thanks to UniSys Corporation for the generous donation of computer equipment to this project.     

Three dimensional representation of brain electrical activity

Summary Brain topography mapping is a useful technique for the representation of electrical activity recorded on the scalp. It clarifies spatial and temporal relationships between different cortical areas. In this work we propose a system which includes several enhancements over those previously proposed, such as an optimised interpolation method and a three dimensional reconstruction of maps. This system is available in a personal computer environment. Results clearly show a superiority of the 3D representation over 2D maps obtained with different projections. The performance of this system in terms of speed and precision is comparable to that of dedicated image processing and image synthesis workstations proposed for brain mapping.Real data and 2D maps were provided by Dr. J.M. Badier of the Unité d'Epileptologie, Hopital Pont Chaillou, Rennes, France.     

Cross-interval histograms for analysis of brain electrical activity

A method for constructing cross-interval histograms for time-localized EEG fragments of particular types is described. The basic principles of the method are presented. Examples of cross-interval histograms constructed for EEG extrema and their derivatives are presented. Cross-interval histograms were shown to include peaks, troughs, and other features. Cross-interval histogram and cross-correlation histograms are compared. The method yields qualitatively new data on interactions between changes in biopotentials in different areas of the brain and allows rapid processes to be studied. __________ Translated from Zhurnal Vysshei Nervnoi Deyatel’nosti imeni I. P. Pavlova, Vol. 55, No. 5, pp. 707–716, September–October, 2005.     

Proliferative activity in some tissues of mice unilaterally nephrectomized at different times of day

Unilateral nephrectomy was performed on mice at different times during the morning and evening. Mitotic activity was investigated in the proximal portions of the convoluted tubules of the nephron of the remaining kidney and in the corneal epithelium 48 and 60 h after the operation. If the operation was performed in the morning the mitotic index (MI) was 4.3 times higher than the control and still remained high 60 h after the operation. If the operation was performed in the evening MI was 9.3 times higher than the control and fell after 60 h. It is concluded that the cells of the renal epithelium in animals nephrectomized in the evening divide more synchronously than in mice nephrectomized in the morning. Nephrectomy did not affect the level or rhythm of cellular proliferation in the corneal epithelium.Department of Biology and Laboratory of Chronobiology, Research Center, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR Yu. M. Lopukhin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 7, pp. 67–69, July, 1978.     

Effect ofsalmonella typhi Infection on the mitotic activity of esophageal epithelium in mice infected at different times of the day

After infection in the morning, the mitotic index at first rises and then drops, followed by normalization by the end of the experiment. Infection in the evening is at first attended by a rise of the mitotic index followed by its fall, after which the mitotic index again increases and then normalizes, by the end of the experiment being lower than in the control. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o 2, pp. 168–171, February, 1994     

Effect of melatonin on the relationship between lipid peroxidation and proteolytic activity in basal nuclei of rat brain during acute hypoxia

We studied the effect of melatonin on the relationship between LPO intensity and proteolytic activity in basal nuclei (caudate nucleus, globus pallidus, amygdaloid complex, and nucleus accumbens septi) of rat brain during acute hypobaric hypoxia. Acute hypoxia was accompanied by LPO activation and increase in proteolytic activity. It should be emphasized that the intensity of proteolysis was higher in structures responding by more pronounced LPO activation (nucleus accumbens septi and globus pallidus). Intraperitoneal injection of 1 mg/kg melatonin 30 min before acute hypoxia inhibited LPO and prevented the increase in proteolysis in basal nuclei of the brain. The effect of melatonin was most pronounced in basal nuclei highly sensitive to acute hypoxia. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 142, No. 7, pp. 94–96, July, 2006     

Day-time melatonin administration: Effects on core temperature and sleep onset latency

Significant hypothermic and hypnotic effects have been reported for melatonin at a wide range of doses. It has been suggested that this decrease in core temperature (Tc) following melatonin administration may mediate the observed increase in sleepiness. To test this, melatonin was administered to young adults during the day, and the concurrent effects on Tc and sleep onset latency (SOL) were recorded. Sixteen healthy males received either a 5 mg oral formulation of melatonin or placebo at 14.00 hours. Core temperature was recorded continuously. Sleep onset latency to stage 1 (SOL1) and stage 2 (SOL2) were recorded using an hourly multiple sleep latency test (MSLT). Compared with placebo, melatonin significantly decreased Tc 1.5 h after administration for 6 h. Between 15.00 and 18.00 hours, the drop in Tc was associated with a concurrent decrease in SOL1 and SOL2. Following administration mean SOL1 and SOL2 were reduced by 40 and 25%, respectively. In this study, daytime melatonin administration produced a significant decrease in Tc with a corresponding decrease in SOL. Taken together, these data are not inconsistent with the suggestion that melatonin may facilitate sleep onset via a hypothermic effect. In addition, this study provides support for the idea that melatonin may play a role in regulating circadian and/or age-related variations in sleep/wake propensity. From a practical perspective, exogenous melatonin may be useful in the treatment of sleep disorders associated with increased nocturnal Tc.     

Lipid peroxidation in the brain and liver of rats during acute stress and melatonin treatment

We studied the effects of acute stress and exogenous melatonin in various doses on the intensity of lipid peroxidation in emotiogenic structures of the brain and liver of rats with different activity in the open field. Stress had no effect on the content of malonic dialdehyde in the hypothalamus, sensorimotor cortex, and liver of active and passive rats receiving physiological saline. The influence of melatonin on malonic dialdehyde content depended on the dose of this substance. The amount of malonic dialdehyde in brain structures (active and passive rats) and liver (active rats) increased after administration of exogenous melatonin in doses of 0.5 and 2 mg/kg, but decreased after treatment with the hormone in a dose of 1 mg/kg. Melatonin in various doses decreased malonic dialdehyde content in the liver of passive rats. The effects of melatonin are partly related to modulation of lipid peroxidation in central and peripheral tissues of the organism. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 138, No. 7, pp. 19–23, July, 2004     

Depressant effect of androgens on the cat brain electrical activity and its antagonism by ruthenium red

Electroencephalographic synchronization and a fall in the multiunit activity was observed in the mesencephalic reticular formation, ventromedial hypothalamus and dorsal hippocampus following intravenous administration of some 5α and 5β-reduced testosterone derivatives. The most potent compounds were androsterone and androstanediol which have the 3α-hydroxy-5α ring A configuration. Steroids with 5β reduction, i.e. 5β-dihydrotestosterone, etiocholanolone and epi-etiocholanolone, at high doses produced the inhibitory effect. Testosterone and its closer 5α metabolites (5α-dihydrotestosterone and 5α-androstanedione) were ineffective. The depressive effect of androsterone on neurones was antagonized by the intraventricular injection of ruthenium red. On the other hand, the convulsant effect of ruthenium red was prevented or diminished by the action of androsterone.These findings support the hypothesis that testosterone metabolites reduced either at 5α or 5β position can act in the brain at a membrane level and raise the possibility that testosterone may be a prehormone in the regulation of excitability in some brain functions.     

Effect of excess and deficiency of thyroid hormones on blood melatonin level in mature male rats

Laboratory of Biochemistry of Endocrine Diseases, Khar'kov Research Institute of Endocrinology and Hormone Chemistry. (Presented by Academician of the Academy of Medical Sciences of the USSR L. T. Malaya.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 111, No. 6, pp. 590–591, June, 1991.     

褪黑素对小鼠胃癌细胞褪黑素膜受体MT1、MT2表达的影响

目的:探讨褪黑素对小鼠胃癌细胞褪黑素膜受体MT1、MT2表达的影响。方法:应用小鼠MFC前胃癌细胞建立荷胃癌小鼠模型,不同浓度褪黑素干预后,运用免疫组织化学、实时荧光定量PCR、免疫印迹定位定量检测MT1、MT2表达的变化。结果:移植瘤肿瘤细胞表达褪黑素膜受体MT1、MT2,褪黑素促进肿瘤组织膜受体MT1、MT2表达,并呈剂量依赖关系。结论:褪黑素上调褪黑素膜受体MT1、MT2的表达,说明褪黑素可能通过膜受体信号通路抑制胃癌生长。     

Effect of parlodel on brain electrical activity in experimental depressive syndrome in rats

In rats with experimental MPTP-induced depressive syndrome, chronic administration of parlodel prevented epileptiform activity, an increase in δ-band and a decrease in α-band spectral powers in the caudate-putamen structures, and an increase in δ-band spectral power in the hippocampus. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 129, No. 2, pp. 152–155, February, 2000