摘要:

Abstract:We describe a newly developed enzyme immunoassay (EIA) for the determination of 6‐sulphatoxy‐melatonin (aMT6s) in human urine, using a aMT6s‐bovine serum albumin‐horseradish peroxidase (aMT6s‐BSA‐HRP) conjugate as the enzyme label. The assay incorporates a highly specific antibody raised in rabbits. The EIA has a sensitivity of 2 pg/well (40 pg/ml) with intraassay coefficients of variation of 2.3–6.1% in the range of the assay. The material with the highest level of cross‐reactivity was N‐acetyl serotonin sulphate, with a relative potency of 0.000078%. One hundred thirty‐four urine samples from children and adults at different time points were assayed and the results compared with those from an established radioimmunoassay (RIA) and with a newly developed RIA using the same antibody as the EIA. The correlation coefficient,r, comparing the two RIA's was 0.9869, and the regression equation was log (kit) = 0.9340 log (new) + 0.1213. The correlation coefficient,r, comparing the EIA with the newly developed RIA, was 0.9686, and regression equation log (new) = 0.9674 log (EIA) + 0.0600. The EIA for the measurement of aMT6s in urine represents a new approach in the investigation

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1996.tb00239.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract:Reverse transcription‐polymerase chain reaction (RT‐PCR) analysis performed on total RNA from different tissues ofXenopus laevisshowed that the melatonin receptor gene cloned from dermal melanophores is expressed in the whole brain, skin, and retina, and that apart from the ovary, there is no expression in tissues having origin outside the central nervous system. Comparative studies using in vitro autoradiography and in situ hybridization demonstrated that the melatonin receptor is expressed with discrete allocation inXenopusbrain. Though the distribution pattern of the specific messenger RNA conforms well with that of the corresponding receptor protein, it is not always coincid

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1996.tb00240.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract:Recent reports indicate that benzodiazepines can suppress melatonin levels and that melatonin can increase brain benzodiazepine binding. We have studied the possibility of reciprocal effects of chronic diazepam and melatonin on brain melatonin and benzodiazepine binding sites. Daily injections (3 weeks) of diazepam markedly reduced125I‐melatonin binding site density in the medulla‐pons but not cortex of male rats, whereas benzodiazepine binding was not significantly affected. Melatonin, administered via the drinking water, significantly enhanced benzodiazepine (3H‐RO 15‐1788) binding in the medulla‐pons and slightly reduced it in the cortex, but did not affect125I‐melatonin binding. Diazepam and melatonin combination reversed the suppression by diazepam of125I‐melatonin binding in the medulla‐pons and the suppression by melatonin of benzodiazepine (3H‐RO 15‐1788 and3H‐flunitrazepam) binding in the cerebral cortex. These results indicate benzodiazepine‐mediated suppression of brain melatonin binding sites that can be abrogated by m

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1996.tb00241.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract:To examine the role of melatonin in pathological hyperprolactinemia we compared untreated young females (N = 5) with hyperprolactinemic amenorrhea owing to pituitary microadenoma to healthy female controls (N = 6). Serum samples for melatonin, prolactin, and luteinizing hormone (LH) concentrations were obtained every 15 min from 1900 hr to 0700 hr in a controlled light‐dark environment with simultaneous sleep recordings. The mean (±SD) light‐time period, dark‐time period, and the integrated nocturnal melatonin secretion values (area under the curve, or AUC) in patients (51 ± 11 pmol/L, 157 ± 33 pmol/L, and 102 ± 19 pmol/min‐L × 103, respectively) were similar to the values obtained in controls (79 ± 39, 165 ± 44, 111 ± 31, respectively). The onset of the nocturnal melatonin rise, peak level, and peak time were similar in the two groups. A significant nocturnal prolactin rise was observed in patients (112 ± 9 vs. 65 ± 11 μg/L,P<0.006) and controls (19 ± 2 vs. 10 ± 3 μg/L,P<0.006). The time of prolactin peak was similar in patients and controls (0424 ± 3: 36 vs. 0350 ± 2: 21) and paralleled that of melatonin (0354 ± 1: 46 vs. 0337 ± 1: 30). The mean ± SD light‐time period, dark‐time period, and the AUC values of LH were similar in patients and controls. The number of LH pulses in patients (7.2 ±1.9 per 12 hr) were not different from those in controls (7.7 ±2.1). The LH pulse interval was 100 ± 22 min in patients compared with 94 ± 23 min in controls. The mean (±SD) nocturnal estradiol (E2) levels were significantly lower in patients (84 ±15 pmol/L) than in controls (224 ± 77)(P<0.005). Analysis of LH and melatonin secretory profiles revealed significant pulses for both hormones. No significant relationship was observed between the LH and melatonin pulses. However, a negative correlation between LH pulse amplitude and the number of melatonin pulses(P<0.04) and a positive correlation between LH amplitude and duration of melatonin pulses(P<0.04) were observed. Taken together, these data suggest that the suppression of normal ovarian cycles in women with hyperprolactinemic amenorrhea owing to pituitary microadenoma may be mediated by blocking of gonadotropin action by prolactin at the ovarian level; yet it remains possible that chronically elevated prolactin might prevent the LH surge and thus lead to amenorrhea. Pulsatile melatonin secretion is unaltered in these patients, and the frequent occurrence of amenorrhea in this po

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1996.tb00242.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract:Melatonin, a hormone produced in the pineal gland and released into the general circulation on a diurnal basis, has been implicated in many behavioral processes, where it has been shown to have anxiolytic, sedative, and anticonvulsant effects. Male gerbils (Meriones unguiculatus) injected daily with melatonin (25 μg, s.c.) exhibited a reduced seizure response to pentylenetetrazol (PTZ, 60 mg/kg, s.c). The present studies determined 1) whether melatonin's effect was related to the time of day that it was administered and 2) whether a single acute injection of melatonin at various doses could produce anticonvulsant activity. Gerbils provided with 13 weeks of daily melatonin injections (25 μg, s.c.) exhibited fewer convulsions after PTZ treatment irrespective of the time of day melatonin was injected. In addition, the melatonin‐treated gerbils had lower mortality rates (1/12) than the untreated or vehicle‐injected gerbils (5/12). On the other hand, single acute injections of melatonin (0.1–10 mg/kg, i.p.) produced no anticonvulsant activity. It appears that the anticonvulsant effects of melatonin occur only after the animals are chronically exposed to the indole. In addition, melatonin's anticonvulsant ability may utilize a different mechanism than those involved in its endocrine effects, since no diurnal difference in melatonin's anticonvulsant activity was o

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1996.tb00243.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract:We demonstrated that the pineal neurohormone melatonin exerts immunoregulatory effects via T‐helper 2 (Th2) cell products. Th2 products may modulate the secretion and/or action of inflammatory cytokines, which play an important role in the development of septic shock associated with endotoxemia. Here we report that a single melatonin injection protects mice treated with a lethal dose of lipolysaccharide (LPS) especially when melatonin was injected 3 to 6 hr after LPS. This effect did not apparently involve Th cells or inhibition of inflammatory cytokines or macrophage nitric oxide (NO) generation. Nevertheless, plasma nitrate concentration, which reflects the rate of NO synthesis, showed a significant reduction at 18 and 24 hr after LPS administration. Melatonin is being studied in humans for cancer immunotherapy. The data presented here identify melatonin as potential therapy for septic shoc

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1996.tb00244.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract:It has been hypothesized that pineal structure and function might differ between temperate zone and tropical species of mammals because of lower amplitudes of seasonal change in photoperiod and, in some areas, less seasonal climatic variation.Anoura geoffroyiproduce a single offspring in November or December of each year on the Caribbean island of Trinidad, at 10°N latitude in the deep tropics. Previous work has shown that this population lacks reproductive responses to photoperiod, and must be enforcing seasonal breeding using a non‐photoperiodic cue.Anoura geoffroyihave a minute, thin, and rod‐like pineal gland. Throughout much of its length, the pineal courses irregularly within the ventrolateral wall of the great cerebral vein. This intimate relationship may have functional implications. Despite having a very small pineal gland, this species produced a nocturnal rise in serum melatonin. Serum melatonin levels in most individuals were below or near undetectable levels during the light period and rose to a peak averaging 100 pg/ml in the last third of the dark period. Our results indicate that, although the pineal gland of A.geoffroyiis extremely small, serum melatonin levels are comparable to those of other mam

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1996.tb00245.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract:We have purified the major metabolite of melatonin, 6‐sulphatoxymelatonin, from urine and compared it to its synthetic counterpart. For preparation of the biological material, oral melatonin was administered to human volunteers and their urine extracted onto Amberlite XAD‐2 resin to remove urea; the glucuronide metabolites of melatonin were removed by silica chromatography; and 6‐sulphatoxymelatonin was separated from N‐acetyl serotonin sulphate, the other sulphate metabolite of melatonin, by preparative thin‐layer chromatography. Synthetic 6‐sulphatoxymelatonin was produced by reacting 6‐hydroxymelatonin with chlorosulphonic acid in dimethylformamide; the reaction mixture was purified on Florisil and preparative thin‐layer chromatography was used to remove indolic by‐products of the reaction. Elemental and X‐ray microanalysis of the biological and synthetic products showed that classical methods used for their purification introduced inorganic impurities, such as silicon‐ and chlorine‐ containing compounds, which were not detectable by thin‐layer chromatography, infrared spectroscopy, nuclear magnetic resonance spectroscopy, or gas chromatography‐mass spectrometry. We introduced further purification steps to remove these inorganic impurities, monitoring the process using elemental and X‐ray microanalysis. Extensive characterization of the resulting purified products showed that the biological and synth

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1996.tb00246.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY