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Letter 2001; 22(5): 330-331 PubMed PMID: 11600874 Citation  Keywords:  Adolescent, Adult, Animals, Child, Child, Preschool, Cytokines:secretion, Epilepsy:physiopathology, Female, Humans, Infant, Interleukin-1:secretion, Male, Tumor Necrosis Factor-alpha:secretion,.   

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Journal Article 2001; 22(3): 181-185 PubMed PMID: 11449196 Citation  Keywords:  Acetylglucosaminidase:metabolism, Animals, Antigens, CD13:metabolism, Cathepsin D:metabolism, Cathepsin L, Cathepsins:metabolism, Cysteine Endopeptidases, Female, Glucuronidase:metabolism, Kidney:enzymology, Kinetics, Lipase:metabolism, Liver:enzymology, .   

OBJECTIVES: Changes in the activity of beta-glucuronidase, N-acetyl-beta-glucosaminidase, cathepsin D and L, alanine aminopeptidase and lysosomal acid lipase in lysosomal fractions of the liver and kidneys of mice, which were administered 20 mg/kg b.w. of exogenous melatonin (N-acetyl-5-methoxytryptamine) for 7 and 14 days were investigated.

METHODS: The slices of the liver and kidney were homogenized in 0.1M phosphate buffer, pH 7.0. Homogenates were subjected to differentiated centrifuging and determination of studied enzymes.

RESULTS: Melatonin caused lowering of the activity of all the investigated lysosomal enzymes in the liver and kidney.

CONCLUSION: Administration of melatonin was caused the lowering of the activity of the investigated lysosomal enzymes in comparison with values in control groups....

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Journal Article 2001; 22(3): 208-214 PubMed PMID: 11449193 Citation  Keywords:  Animals, Corticosterone:blood, Cytokines:blood, Hormones:blood, Inflammation:blood, Interleukin-10:blood, Interleukin-6:blood, Kinetics, Leptin:administration & dosage, Lipopolysaccharides:administration & dosage, Luteinizing Hormone:blood, Male, Prolacti.   

OBJECTIVES: In many studies it has been reported, that leptin may play an important role not only in the regulation of food intake and body weight but can modify immune response. The aim of our study was to estimate the effects of the administration of exogenous leptin on serum concentration of proinflammatory cytokines (interleukin 6-IL 6 and tumor necrosis factor alpha-TNF alpha) and anti-inflammatory cytokine (interleukin 10 - IL 10) during LPS induced acute inflammation. We also estimated leptin's influence on pituitary, thyroid, adrenal and gonadal hormones in response to lipopolysaccharide (LPS) induced acute inflammation.

METHODS: Male rats Wistar-Kyoto were divided into four groups, which received respectively: placebo (0.9% NaCl), LPS, leptin and leptin with LPS. The TNF alpha and IL 6 serum concentrations were measured after 2 hours and IL 10 after 4 hours. The pituitary, thyroid, adrenal and gonadal hormones serum concentrations were measured after 2 and 4 hours. Cytokine concentrations were estimated using ELISA tests and hormones concentrations using RIA tests.

RESULTS: Leptin did not have an effect on both cytokine responses (proinflammatory and anti-inflammatory) in the time of LPS-induced acute inflammation. Leptin enhanced LPS-induced increasing of corticosterone secretion after 2 hours and decreased LPS-induced inhibition of testosterone secretion after 4 hours.

CONCLUSIONS: Leptin can modulate hormone response during LPS-induced acute inflammation....

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Journal Article 2001; 22(3): 199-207 PubMed PMID: 11449192 Citation  Keywords:  Animals, Apamin:pharmacology, Calcium:pharmacology, Cyclooxygenase Inhibitors:pharmacology, Dinoprost:pharmacology, Female, In Vitro Techniques, Indomethacin:pharmacology, Melatonin:pharmacology, Oxytocin:pharmacology, Potassium Channels:drug effects, Pot.   

OBJECTIVE: The aim of this study was to investigate the effects of melatonin on spontaneous and oxytocin-induced contractility of pregnant and non-pregnant rat myometrium in vitro.

DESIGN: Myometrial strips were removed from virgin or late pregnant (21 days gestation) Wistar rats following decapitation and placed in an organ bath containing Krebs' solution at 37 degrees C and pH 7.4, constantly bubbled with 95% oxygen-5% carbon dioxide and isometric contractions were recorded. Effects of cumulative concentrations of melatonin (0.1 to 10 microM) on spontaneous and oxytocin-induced contractions were studied. Possible involvement of Ca(2+)-activated K (+) channels in inhibitory actions of melatonin was investigated by using apamin (100 nM).

RESULTS: Melatonin inhibited spontaneous and oxytocin-induced contractions of myometrium from both virgin and late pregnant rats in a dose-dependent manner. After inhibition of oxytocin-induced contractions by melatonin, application of prostaglandin F (2alpha) (1 microM) but not high KCl (30 mM) containing solution initiated contractile activity. Inhibitory response induced by melatonin (13 microM) was not affected by apamin (100 nM).

CONCLUSIONS: Data from this study demonstrates that melatonin inhibits spontaneous and oxytocin-induced contractions of myometrium from pregnant and non-pregnant rats. Although the exact mechanism is not clear, melatonin-induced inhibition of myometrial contractions may results from its interactions with Ca(2+) channels....

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Journal Article 2001; 22(3): 187-191 PubMed PMID: 11449191 Citation  Keywords:  Animals, Cell Division, Ganglionectomy, Ileum:cytology, Intestine, Small:cytology, Jejunum:cytology, Male, Melatonin:biosynthesis, Mitosis, Pineal Gland:innervation, Rats, Rats, Sprague-Dawley, Superior Cervical Ganglion:physiology, Sympathetic Nervous Sy.   

OBJECTIVES: To observe the effect of changes in the pineal sympathetic innervation on the crypt cell proliferation rate in the rat small intestine, and compare these with the effect of pinealectomy to determine the role of the sympathetic innervation in the effect of pinealectomy.

METHODS: The effect of bilateral ablation of the superior cervical ganglion, and that of pinealectomy on the crypt cell proliferation rate in the rat small intestine was determined, using a stathmokinetic technique.

RESULTS: Pinealectomy was associated with a considerably increased crypt cell proliferation rate, whereas superior cervical ganglionectomy was associated with a slightly decreased rate.

CONCLUSIONS: It appears likely that changes in pineal melatonin production cannot be correlated directly with the effects of pinealectomy on the crypts, although melatonin production was not measured in this case. The role of loss of the non-adrenergic innervation of the pineal in the effect of pinealectomy needs to be examined. There is also other experimental evidence that melatonin-free extracts of the pineal, containing as yet unidentified substances, can influence mitotic activity in some tissues, so the possible role of these substances in the effects of pinealectomy should also be considered. Furthermore, the superior cervical ganglion itself has an extra-pineal role. Changes in pineal sympathetic innervation are not significant in the hyperproliferative effects of pinealectomy on the intestinal crypts....

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Journal Article 2001; 22(2): 101-108 PubMed PMID: 11335886 Citation  Keywords:  1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine:pharmacology, Animals, Apoptosis:drug effects, Brain:cytology, Cell Count, Corpus Striatum:cytology, DNA Fragmentation, Dopamine Agents:pharmacology, Male, Melatonin:pharmacology, Mesencephalon:cytology, Mice, .   

OBJECTIVES: 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a neurotoxin that induces a Parkinsonian-type syndrome in animals which is similar to Parkinson's disease in humans. MPTP toxicity partially depends on the production of free radicals which in turn play a key role in the apoptotic death of neurons. In the present study melatonin, a potent free radical scavenger with antiapoptotic properties, was given to determine whether it would reduce oxidative stress in mice treated with MPTP.

MATERIALS AND METHODS: Male mice were given MPTP with or without melatonin and the brain was studied either 6h, 24h, 7 days or 15 days after the last MPTP injection.

RESULTS: The results show that melatonin counteracted in vivo MPTP-induced apoptosis in midbrain neurons at 6 and 24 h after MPTP treatment, and partially prevented apoptosis at 7 and 15 days after MPTP administration. MPTP treatment also produced time-dependent cell damage, whereas melatonin reduced the percentage of damaged cells at all time points, the effect being most evident at 15 days after treatment. Moreover, melatonin counteracted MPTP-dependent DNA fragmentation in the midbrain and striatum at 7 and 15 days after drug administration.

CONCLUSION: These results support a role for melatonin in protecting neurons against MPTP toxicity in vivo, and suggest that its antiapoptotic action is one of the mechanisms by which melatonin protects neuronal cells from neurotoxic insults....

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Journal Article 2001; 22(2): 81-86 PubMed PMID: 11335883 Citation  Keywords:  Animals, Basement Membrane:pathology, Blood Platelets:pathology, Brain Ischemia:chemically induced, Capillaries:ultrastructure, Cerebral Cortex:blood supply, Endothelium, Vascular:ultrastructure, Erythrocytes:pathology, Extracellular Matrix:ultrastructure.   

OBJECTIVES: In our investigations we have reported that photochemical reaction leading to brain ischemia can also be precipitated with visible light from a non-coherent light source. It was revealed that focal cerebral ischemia after photochemical reaction cause the alterations in the capillaries ultrastructure and perivascular spaces of the barrier-competent regions of the brain. The purpose of this study is to first characterize the ultrastructural morphological consequences of photochemically induced ischemia in the cerebral cortex on the capillaries of neurohypophysis as the barrier-free region of the brain.

METHOD: We used a model of ischemic brain damage due to obliteration of microvessels following the photochemical reaction. Rats were treated with an intravenous injection of rose bengal and irradiated from a halogen lamp source through an intact cranium to precipitate microvascular damage. Material for electron microscopic studies were sampled from the neurohypophysis 1 and 4 days after irradiation (4 animals in each group) in experimental group and 1 and 4 days after a rose bengal injection in control group.

RESULTS: Investigations in transmission electron microscopy revealed platelet aggregation on the endothelium preceded by its early ultrastructural damage. In the capillaries of the neurohypophysis, one and four days after irradiation, numerous microthrombi adhering to the damaged endothelium were present. The capillary vessels contained a continuous, rather than a fenestrated endothelium. The basement membrane was thickened, blurred and locally multiplicated.

CONCLUSION: Our results show that experimentally-induced thrombosis of cortical microvessels leads to alterations in the capillaries of neurohypophysis....

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Journal Article 2001; 22(1): 33-37 PubMed PMID: 11335877 Citation  Keywords:  Adolescent, Adult, Animals, Chick Embryo, Complement System Proteins:metabolism, Embryo, Mammalian:abnormalities, Factor Analysis, Statistical, Female, Gestational Age, Humans, Maternal-Fetal Exchange, Models, Biological, Pregnancy:blood, Progesterone:blo.   

OBJECTIVE: In this paper the relation between progesterone levels and embryotoxic effect of serum complement was studied.

DESIGN: The aim of this study was to validate hypothesis that progesterone is strong inhibitor of complement embryotoxic action.

SETTING: We used chick embryo like an experimental model for evidence of our hypothesis. We treated chick embryos by sera acquired from healthy pregnant woman with physiologically elevated levels of progesterone and normal complement activity. We investigated embryotoxicity of these sera.

RESULT: We noticed a significant decrease of sera embryotoxicity inversely related to serum levels of progesterone. The main finding: The embryotoxicity of sera is reversally dependent on progesterone level.

CONCLUSIONS: These findings bring a new knowledge to the role of progesterone and complement system mainly in initial stages of pregnancy and in some cases of spontaneous abortions....

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