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Journal Article 2001; 22(2): 129-136 PubMed PMID: 11335889 Citation  Keywords:  Alkaline Phosphatase:blood, Animals, Biomarkers:analysis, Bone and Bones:metabolism, Calcium:urine, Circadian Rhythm, Collagen:blood, Collagen Type I, Disease Models, Animal, Female, Humans, Hydroxyproline:urine, Melatonin:blood, Osteoporosis, Postmenopau.   

BACKGROUND: Lately, there have been suggestions that bone mass changes occurring in postmenopausal women may remain related to melatonin.r />r /> OBJECTIVE: To assess the relationship between the dynamic pattern of nighttime levels of melatonin and chosen biochemical markers of bone metabolism in ovariectomized rats--a model of postmenopausal osteoporosis.r />r /> METHODS: Mature Wistar female rats were either ovariectomozed or underwent a sham operation. Following this they were killed at 02:00AM at weekly intervals for 8 weeks after surgery. Serum levels of MEL at death related to the chosen biochemical markers of bone formation (alkaline phosphatase--ALP; carboxyterminal propeptide of type I procollagen--PICP, both in serum) and resorption (cross-linked carboxyterminal telopeptide of type I collagen--ICTP in serum; hydroxyproline--HYP and total calcium--Ca, both excreted in urine).r />r /> RESULTS: In all ovariectomized rats changes of examined indices of bone tissue metabolism were found to be dynamic and statistically significant relative to the control group; however the changes were more pronounced regarding resorption markers. Following ovariectomy, the increase in ALP and PICP values was found to begin at the 4th and the 1st week, while that in ICTP, HYP and Ca at the 2nd, the 1st and the 1st week, respectively. The ALP and PICP values remained at a similar level until the end of observation, whereas ICTP, HYP and Ca gradually decreased. MEL levels were decreased during the 2nd week following surgery and slightly increased 2 weeks later. The serum MEL levels in the ovariectomized group were significantly and negatively correlated with serum ICTP and both urinary HYP and Ca levels.r />r /> CONCLUSION: Our findings in rats seem to corroborate the concept of secondary changes in MEL levels co-participating in the development of bone mass changes characteristic for postmenopausal osteoporosis....

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Journal Article 2001; 22(2): 121-127 PubMed PMID: 11335888 Citation  Keywords:  Body Constitution, Body Mass Index, Bone and Bones:metabolism, Circadian Rhythm, Collagen:analysis, Collagen Type I, Female, Humans, Melatonin:analysis, Middle Aged, Obesity:metabolism, Osteoporosis, Postmenopausal:prevention & control, Peptide Fragments:.   

BACKGROUND: Few experimental and clinical studies show that melatonin (MEL) can play a significant part to modulate circadian bone metabolism. On this basis it was suggested that MEL secretion which altered during 24-h in obese women could be of importance to regulate bony mass defect after menopause.r />r /> OBJECTIVE: The aim of the study was to prove if there were any connection between changes in 24-h profile of serum MEL levels and circadian metabolism of type I collagen in postmenopausal women with visceral obesity.r />r /> METHODS: The relationship of 24-h profile of salivary MEL and circadian metabolism of type I collagen (as assessed by measuring saliva concentrations of carboxyterminal propeptide of type I procollagen--PICP and cross-linked carboxyterminal telopeptide of type I collagen--ICTP) was investigated in 26 women with visceral obesity (33.5 < BMI < 42.1 kg/m(2)) and 18 healthy volunteers with correct body mass (21 < BMI < 24.5 kg/m(2); 0.73 < WHR < 0.76). The specimens were collected at subjects' home at 3 h intervals during a 24 h span. The age range of all subjects was 52-60 years.r />r /> RESULTS: In all the obese women studied a tendency to suppress circadian levels of tested biochemical markers of bone metabolism was observed (especially regarding ICTP); those alterations were accompanied by substantial increment in MEL concentrations during the day. Significant and negative correlation was found between values of acrophase MEL and PICP rhythms and both amplitude and acrophase of MEL and ICTP rhythms.r />r /> CONCLUSION: Our results confirm hypothesis that alterations in MEL concentrations might have a protective effect against postmenopausal loss of bone mass....

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Journal Article 2001; 22(2): 109-117 PubMed PMID: 11335887 Citation  Keywords:  Adult, Circadian Rhythm, Duodenal Ulcer:metabolism, Humans, Male, Melatonin:biosynthesis, Middle Aged, Remission Induction,.   

UNLABELLED: OBJECTIVES. This work was designed to study melatonin (M) production levels in duodenal ulcer (DU) patients in the exacerbation and remission stages and in DU patients with a different course of DU in the exacerbation and remission stages.r />r /> METHODS: DU patients (15 men aged 20 to 45, mean age 34,2 +/- 1,1 years) were studied. The control group included 11 healthy volunteers (men aged 20-45, mean age 32,5 +/- 1,4 years). M was measured by RIA-method using H(3)-labeled M in daily urine collected at 3-hour intervals (8 portions per day). Mathematical processing was carried out using ANOVA, Student's t-test, and cosinor analysis. Differences at p< or = 0,05 were considered to be significant.r />r /> RESULTS: A strong disturbance of M secretion in DU patients both in the exacerbation and remission stages and a direct correlation between the degree of M production disturbance and severity of clinical course of DU were revealed.r />r /> CONCLUSION: The obtained results suggest that circadian rhythms of M production are altered in DU patients. M was supposed to be involved in the pathogenesis of DU....

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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.r />r /> 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.r />r /> 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.r />r /> 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): 93-99 PubMed PMID: 11335885 Citation  Keywords:  Alcoholism:complications, Animals, Autoradiography, Cell Division:drug effects, Ethanol:administration & dosage, Leydig Cells:drug effects, Male, Rats, Rats, Sprague-Dawley, Seminiferous Tubules:drug effects, Spermatogonia:drug effects, Testicular Disease.   

OBJECTIVES: Considering the possibility that alcoholism induces gonadal dysfunction, the present work was designed to investigate the morphophysiology of rat testes submitted to experimental alcoholism.r />r /> METHODS: Male Sprague-Dawley rats weighing 150+/-5 gm were chronically given 40% ethanol solution at a dose of 3 g/kg body weight for 30 days. (3)H-thymidine autoradiographic investigations and histological studies were carried out to determine the proliferative activity and/or different stages of spermatogenesis in the seminiferous tubule cycle and Leydig cells.r />r /> RESULTS: The 3H-thymidine autoradigraphic investigation revealed that there was a significant inhibition in the proliferative activity of the spermatogonia in all stages of the seminiferous tubule cycle in the alcohol-treated rats versus controls as indicated by the values of (3)H-labelling indices. The histological and numerical investigations indicated that the alcohol-treated rats presented testicular lesions including a significant decrease in the diameter of the seminiferous tubules, the number of different germ cells in all stages of the seminiferous tubule cycle and the presence of degenerative germ cells. In addition, there was a significant decrease in the number of Leydig cells.r />r /> CONCLUSION: The present work suggests the deleterious effects of alcohol on the testes. These effects may be due to the effect of alcohol on the gonadotrophic cells of the pituitary gland and/or directly on the seminiferous tubules and Leydig cells....

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Journal Article 2001; 22(2): 87-92 PubMed PMID: 11335884 Citation  Keywords:  Animals, Brain Ischemia:chemically induced, Capillaries:ultrastructure, Cell Communication, Cell Movement, Cerebral Cortex:blood supply, Endothelium, Vascular:ultrastructure, Extracellular Matrix:ultrastructure, Intercellular Junctions:ultrastructure, Mal.   

OBJECTIVES: Focal ischemia in the cerebral cortex has an effect on neurohypophysis. The morphological changes of microvessels of neurohypophysis were evaluated in a model of the cerebral infarction initiated by a photochemical reaction in the cerebral cortex. After photochemically induced platelet aggregation, we observed the morphological features of angiogenesis.r />r /> METHOD: The model of photochemically-induced cerebral ischemia was used. Seven days after intravenous injection of rose bengal and irradiation from a halogen lamp source through an intact cranium, the sampled material from neurohypophysis is processed for transmission electron microscopy using standard procedures.r />r /> RESULTS: We observed morphological features of the new vessel formation: the alterations in the endothelium and extracellular matrix during separation of the endothelial cell from each other in a "mother" vessel, the migration of the endothelial cells in the extracellular matrix, the communication of the lumen of the new and the "mother" vessels.r />r /> CONCLUSION: We observed development of the angiogenic phenotype in the neurohypophysis after focal ischemia in the cerebral cortex. The endothelium, basement membrane and extracellular matrix undergo morphological alterations which lead to new blood vessel formation....

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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.r />r /> 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.r />r /> 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.r />r /> 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): 53-73 PubMed PMID: 11393163 Citation  Keywords:  Adrenal Glands:physiology, Animals, Biological Clocks, Blood Pressure:physiology, Chronobiology Disorders:physiopathology, Chronobiology Phenomena, Chronotherapy, Circadian Rhythm:physiology, Drug Administration Schedule, Genomics, Homeostasis, Humans, Pi.   

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