Search NEL Online

Clinical Trial 2005; 26(5): 493-498 PubMed PMID: 16264413 Citation  Keywords:  Adult, Circadian Rhythm:physiology, Humans, Light, Lighting, Male, Melatonin:blood, Middle Aged, Photic Stimulation, Pupil:physiology, Retina:physiology, Signal Transduction:physiology,.   

OBJECTIVES: Published data, both on nocturnal melatonin suppression in humans and on widely accepted retinal structure and function, suggest that spectral opponency plays a role in human circadian phototransduction. We directly test subadditivity, implied by spectral opponency, in human circadian phototransduction in response to nearly monochromatic and to polychromatic light.

METHODS: Adult male human subjects were exposed for 60 minutes to two intensities each of two lighting conditions, during nighttime experimental sessions. One condition consisted of light from mercury vapor lamps (450 and 1050 lx), and one condition consisted of light from these lamps filtered such that only the spectral line from this lamp at 436 nm was presented to subjects (7.5 and 15 lx).

RESULTS: Melatonin suppression from the filtered illumination at 436 nm alone was greater than mercury lamp illumination (containing energy at 436 nm in addition to other wavelengths), even when the sources exposed subjects' retinae to equal amounts of irradiance at 436 nm.

CONCLUSION: This direct test of subadditivity, together with evidence from neuroanatomy, supports the inference that spectral opponency is a fundamental characteristic of human circadian phototransduction....

Read abstract  Full text PDF

Journal Article 2005; 26(5): 503-510 PubMed PMID: 16264410 Citation  Keywords:  Aging:physiology, Animals, Chickens:metabolism, Darkness, Female, Light, Male, Melatonin:metabolism, Organ Culture Techniques, Perfusion, Pineal Gland:metabolism, Temperature,.   

: The melatonin rhythm of cultured chicken pineal cells can be synchronized by cyclic environmental effects. Unlike the effects of light on the melatonin secretion, those of the temperature changes are much less known. Similarly, only a few data are available on the interactions between environmental illumination and periodic temperature changes and on the sensitivity of the pineal gland to temperature changes in different ages of animals. We monitored the effects of temperature on chicken pineals for several days in vitro, in a perifusion system under different illumination patterns. The effects of temperature on pineals from chicken of different age were also compared. The phase of the melatonin rhythm was controlled by periodic elevations of temperature under both constant darkness and continuous illumination. These results show that rhythmic changes of temperature prevent desynchronization induced by constant light. Following elevation of the temperature, the melatonin rhythm of pineals of young chickens (less, than 14 weeks old) was altered for 16 - 18 hours. Similar changes in melatonin rhythm were not found in older animals. It is concluded that the sensitivity for temperature changes of the pineal cells is varying with age....

Read abstract  Full text PDF

Journal Article 2005; 26(5): 526-532 PubMed PMID: 16264406 Citation  Keywords:  Animals, Astrocytes:drug effects, Blotting, Western, Cell Line, Estradiol:pharmacology, Estrogen Antagonists:pharmacology, Estrogen Receptor alpha:drug effects, Estrogen Receptor beta:drug effects, Gene Expression Regulation:drug effects, Ligands, Lucifer.   

OBJECTIVE: The mechanism through which estrogen exerts its neuroprotective and anti-neurodegenerative effects in the central nervous system is poorly understood. Human glial cells are implicated in the pathogenesis of Alzheimer's disease and have both alpha and beta estrogen receptors (ER). We developed a glial cell model for ER function using the N20.1 mouse oligodendroglial cell line to evaluate the response of ERalpha and ERbeta to estradiol (E2), a raloxifene analog LY117018 (LY) and 4-hydroxytamoxifen (4OHT).

DESIGN: We tested the ability of exogenous ER to activate transcription in response to ligands (100 nM) using the glial cell line N20.1 in a transient cotransfection assay with an ERalpha or ERbeta expression vector, an ERE-driven reporter and a Renilla luciferase transfection control.

RESULTS: Endogenous ER was not detected in the N20.1 cells by Western immunoblotting. E2 stimulated both ERalpha and ERbeta on both ERE- and AP-1 driven promoters. The transcription stimulation by E2 in the ERalpha and ERbeta through the AP-1driven promoter, though significant, was not of the same magnitude as the stimulation of the ERalpha through the ERE-driven promoter. 4OHT and LY did not show significant transcriptional activation of either the ERalpha or ERbeta, through either the ERE or AP-1 driven promoters. LY, at a 10-fold higher concentration than E2, showed a difference in its antagonist activity on the ERbeta through the AP-1 pathway when compared with the ERE- driven promoter, demonstrating not only promoter specificity, but also receptor specificity.

CONCLUSIONS: This is the first description of the activity of 4OHT and LY on estrogen receptors in glia....

Read abstract  Full text PDF

Journal Article 2005; 26(5): 541-547 PubMed PMID: 16264403 Citation  Keywords:  Aging:metabolism, Animals, Brain Chemistry:physiology, Digoxigenin, In Situ Hybridization, Liver:metabolism, Male, Mice, Mice, Inbred C57BL, RNA Probes, RNA, Complementary:biosynthesis, RNA, Messenger:analysis, Receptors, Cytoplasmic and Nuclear:biosynthe.   

OBJECTIVES: The distribution of Liver receptor homolog 1 (LRH-1) mRNA was studied in mice brain with the aim to establish whether this nuclear hormone receptor is expressed also in the brain in addition to liver and classical steroidogenic tissues.

METHODS: Expression of LRH-1 mRNA in juvenile (30 days old) and adult (60 days old) mouse brain was examined using non-radioactive in situ hybridization with digoxigenin labeled cRNA probes and with RT PCR using specific primers.

RESULTS: LRH-1 was strongly expressed throughout the brain. Semiquantitative RT PCR revealed very strong expression of LRH-1 mRNA in cerebrum in comparison to liver and testis, and in situ hybridization revealed that LRH-1 mRNA is uniformly expressed in most brain areas.

CONCLUSIONS: LRH-1 is strongly expressed throughout the mouse brain suggesting important roles for this transcription factor, although its precise roles in the CNS remain to be elucidated....

Read abstract  Full text PDF

Journal Article 2005; 26(5): 548-554 PubMed PMID: 16264402 Citation  Keywords:  Animals, Body Weight:drug effects, Follicle Stimulating Hormone:blood, Leptin:blood, Luteinizing Hormone:blood, Male, Orchiectomy, Rats, Rats, Sprague-Dawley, Testosterone:blood, Zinc:blood,.   

AIM: The aim of this study was to investigate how zinc-deficiency and testosterone supplementation, both in combination and individually, affect plasma LH, FSH and leptin levels in castrated rats.

DESIGN: Group 1, Control Group. Group 2, Castration Group. Group 3, Testosterone Group. Group 4, Zinc-deficient Group. Group 5, Testosterone, Zinc-deficient Group. Group 6, Zinc-deficient, Castration Group. Group 7, Testosterone, Castration Group. Group 8, Zinc-deficient, Testosterone, Castration Group.

MEASUREMENTS: Plasma zinc, leptin, LH, FSH, free and total testosterone levels were measured.

RESULTS: Group 2 had the highest levels of leptin and LH, besides having the highest FSH levels together with Group 6 (p<0.01). Groups 5 and 8 had the lowest leptin levels (p<0.01). Leptin levels in Groups 4 and 7 were higher than those in Groups 5 and 8, but lower than those in all other groups (p<0.01). LH levels in Group 4 were not different than those in Groups 3, 5 and 8, but significantly lower than those in all other groups (p<0.01). Free and total testosterone levels were higher in Group 4 than in castration groups that were not supplemented testosterone, but were lower in the former than in all others (p<0.01).

CONCLUSION: Plasma LH may be more effective than testosterone on plasma leptin and zinc can be an important mediator of the effect LH exercises on leptin....

Read abstract  Full text PDF

Journal Article 2005; 26(5): 561-566 PubMed PMID: 16264400 Citation  Keywords:  Actins:blood, Adult, Antigens, Neoplasm:blood, Blotting, Western, Cystinyl Aminopeptidase:blood, Female, Fetal Development:immunology, Humans, Immune Tolerance:physiology, Infant, Newborn, Infant, Premature, Placenta:metabolism, Pregnancy,.   

OBJECTIVES: Fetal maturity does not seem to be directly connected with the phenomenon of immune tolerance during pregnancy although the fetal maturation influences the process of initiation of the labor at term finishing the immune tolerance during pregnancy. CAP and RCAS1 are expressed by the trophoblast cells and afterwards by the placenta, these proteins are able to modulate the maternal immune response.

MATERIALS AND METHODS: 160 patients were randomly selected to our study. The patients were divided into two groups using K score according to the newborn's maturity: maturated and not fully maturated. Within the groups of matured and not fully matured newborns the subgroups were selected according to the type of the labor: spontaneous or induced. The oxytocinase plasma activity was established in plasma samples obtained from pregnant women a few days before delivery. The placental RCAS1 relative amount was assessed by Western blot analysis.

RESULTS: The differences in oxytocinase plasma level with respect to the fetal maturity were identified in our study however no RCAS1 expression changes were found regarding the fetal maturation. We determined the alterations in RCAS1 expression with respect to the occurrence of clinical symptoms of the spontaneous beginning of the labor in maturated and not-fully maturated groups of newborns.

CONCLUSIONS: Oxytocinase seems to be a useful marker of normal fetal development. The assessment of RCAS1 in placenta directly after delivery appears to indicate the level of maternal immune tolerance during the labor initiation. The level of the immune tolerance at the moment of the delivery drops independently of the fetal maturity....

Read abstract  Full text PDF

Journal Article 2005; 26(5): 603-608 PubMed PMID: 16264394 Citation  Keywords:  Adolescent, Adult, Birth Weight:physiology, Breech Presentation, Cesarean Section, Female, Humans, Infant, Newborn, Myasthenia Gravis:physiopathology, Pregnancy, Pregnancy Complications:physiopathology, Retrospective Studies, Thymectomy, Thyroiditis, Auto.   

OBJECTIVE: The aim of the study was to evaluate the effect of Myasthenia gravis (MG) on the course of pregnancy, labor and delivery, and the condition of neonate.

DESIGN AND SETTINGS: Retrospective chart review of pregnant patients with MG hospitalized in tertiary care center over 12 year period was performed. Course of MG before and during pregnancy, mode of delivery, and condition of the newborn were analyzed.

RESULTS: There was 42 913 deliveries in the Polish Mother's Research Institute in Lodz during analyzed period. Thirteen patients with MG were identified, giving the incidence of 3/10 000 live births. Mean age of the patients was 28 years, range 18 - 36 years. Average time since diagnosis was 9 years. Eleven women with MG delivered at term (one twin pregnancy), and two babies were born prematurely. In seven patients pregnancy was ended via normal spontaneous vaginal delivery (NSVD), one was forceps extraction, four patients had elective Cesarean Section (CS), and two had emergency CS. Indications for CS were purely obstetrical. Spontaneous vaginal deliveries were speedy. None of the patients had exacerbation of MG during current pregnancy. Mean birth weight of the newborns was 3014,3 g, range 1730 g to 3700 g. Mean Apgar score was 8,7 at 1 minute and 8,9 at 5 minutes. Only one neonate (second twin) developed Transient Neonatal Myasthenia Gravis (TNMG).

CONCLUSIONS: Myasthenia gravis did not have significant effect on the course of pregnancy or mode of delivery. In the twin pregnancies it is possible that only one twin will present with the symptoms of TNMG....

Read abstract  Full text PDF

Journal Article 2005; 26(5): 453-458 PubMed PMID: 16264391 Citation  Keywords:  Animals, Animals, Newborn:physiology, Arcuate Nucleus of Hypothalamus:cytology, Body Weight:physiology, Eating:physiology, Electrophysiology, Hypothalamic Hormones:pharmacology, Hypothalamus:cytology, In Vitro Techniques, Intracellular Signaling Peptides .   

OBJECTIVES: Hypothalamic neurons of rats overweight due to early postnatal overfeeding (SL) differ from those of control rats in their responses to feeding relevant hormones like leptin or insulin. The question arose whether prolactin and prolactin-releasing peptide (PrRP) express also differential action in SL rats. These peptides are described to have an effect on food intake and body weight regulation. Prolactin is co-synthesized in lateral hypothalamic neurons together with orexins that were also analyzed in this study.

METHODS: Single unit activity was extracellularly recorded in brain slices from adult control rats (CL) and from rats previously raised in small litters (SL). The action of the peptides on the firing rates was evaluated in the medial parvicellular part of the paraventricular nucleus (PaMP) and the medial arcuate nucleus (ArcM).

RESULTS: In control rats, PrRP significantly activated PaMP neurons, whereas prolactin and orexin-A induced also inhibition. In SL rats, there was a significantly different effect of orexin-B on PaMP neurons: the main effect changed from activation in controls to inhibition. ArcM neurons of both control and SL rats were mainly excited by prolactin and orexins.

CONCLUSION: Changes acquired during early development of neuronal responses to feeding relevant peptides are not a general non-specific mechanism of neurochemical plasticity, but concern specific hypothalamic nuclei and/ or hormones and neuropeptides. The increase in inhibition by orexin-B of hypothalamic paraventricular neurons could in vivo contribute to the neonatally acquired disposition towards persistingly increased food intake and reduced energy expenditure of overweight SL rats....

Read abstract  Full text PDF