Journal of Pineal Research最新文献

Melatonin (N-acetyl-5-methoxytryptamine), a well-known mammalian hormone, has been having a great relevance in the Plant World in recent years. Many of its physiological actions in plants are leading to possible features of agronomic interest, especially those related to improvements in tolerance to stressors and in the postharvest life of fruits and vegetables. Thus, through the exogenous application of melatonin or by modifying the endogenous biosynthesis of phytomelatonin, some change can be made in the functional levels of melatonin in tissues and their responses. Also, acting in the respective phytomelatonin biosynthesis enzymes, regulating the expression of tryptophan decarboxylase (TDC), tryptamine 5-hydroxylase (T5H), serotonin N-acetyltransferase (SNAT), N-acetylserotonin O-methyltransferase (ASMT), and caffeic acid O-methyltransferase (COMT), and recently the possible action of deacetylases on some intermediates offers promising opportunities for improving fruits and vegetables in postharvest and its marketability. Other regulators/effectors such as different transcription factors, protein kinases, phosphatases, miRNAs, protein–protein interactions, and some gasotransmitters such as nitric oxide or hydrogen sulfide were also considered in an exhaustive vision. Other interesting aspects such as the role of phytomelatonin in autophagic responses, the posttranslational reprogramming by protein-phosphorylation, ubiquitylation, SUMOylation, PARylation, persulfidation, and nitrosylation described in the phytomelatonin-mediated responses were also discussed, including the relationship of phytomelatonin and several plant hormones, for chilling injury and fungal decay alleviating. The current data about the phytomelatonin receptor in plants (CAND2/PMTR1), the effect of UV-B light and cold storage on the postharvest damage are presented and discussed. All this on the focus of a possible new action in the preservation of the quality of fruits and vegetables.

This contribution reviews the role of inbred and transgenic mouse strains for deciphering the mammalian melatoninergic and circadian system. It focusses on the pineal organ as melatonin factory and two major targets of the melatoninergic system, the suprachiasmatic nuclei (SCN) and the hypophysial pars tuberalis (PT). Mammalian pinealocytes sharing molecular characteristics with true pineal and retinal photoreceptors synthesize and secrete melatonin into the blood and cerebrospinal fluid night by night. Notably, neuron-like connections exist between the deep pinealocytes and the habenular/pretectal region suggesting direct pineal-brain communication. Control of melatonin biosynthesis in rodents involves transcriptional regulation including phosphorylation of CREB and upregulation of mPer1. In the SCN, melatonin acts upon MT1 and MT2 receptors. Melatonin is not necessary to maintain the rhythm of the SCN molecular clockwork, but it has distinct effects on the synchronization of the circadian rhythm by light, facilitates re-entrainment of the circadian system to phase advances in the level of the SCN molecular clockwork by acting upon MT2 receptors and plays a stabilizing role in the circadian system as evidenced from locomotor activity recordings. While the effects in the SCN are subtle, melatonin is essential for PT functions. Via the MT1 receptor it drives the PT-intrinsic molecular clockwork and the retrograde and anterograde output pathways controlling seasonal rhythmicity. Although inbred and transgenic mice do not show seasonal reproduction, the pathways from the PT are fully intact if the animals are melatonin proficient. Thus, only melatonin-proficient strains are suited to investigate the circadian and melatoninergic systems.

RETRACTION: Carbajo-Pescador S, Martín-Renedo J, García-Palomo A, Tuñón MJ, Mauriz JL, González-Gallego J. Changes in the expression of melatonin receptors induced by melatonin treatment in hepatocarcinoma HepG2 cells. Journal of Pineal Research, 2009;47: 330-338. https://doi.org/10.1111/j.1600-079X.2009.00719.x

The above article, published online on 14 October 2009 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal Editor-in-Chief, Gianluca Tosini, and John Wiley and Sons Ltd. Following publication, concerns were raised by third parties regarding Figure 5. The authors could not provide the original data for this figure, and were unable to provide a satisfactory explanation to resolve the concerns. The retraction has been agreed because of concerns that portions of the figure were duplicated, affecting the interpretation of the data and results presented. The authors disagree with this decision.

Previous studies have reported inconsistent results about exogenous melatonin's sleep-promoting effects. A possible explanation relies on the heterogeneity in administration schedule and dose, which might be accountable for differences in treatment efficacy. In this paper, we undertook a systematic review and meta-analysis of double-blind, randomized controlled trials performed on patients with insomnia and healthy volunteers, evaluating the effect of melatonin administration on sleep-related parameters. The standardized mean difference between treatment and placebo groups in terms of sleep onset latency and total sleep time were used as outcomes. Dose−response and meta-regression models were estimated to explore how time of administration, dose, and other treatment-related parameters might affect exogenous melatonin's efficacy. We included 26 randomized controlled trials published between 1987 and 2020, for a total of 1689 observations. Dose−response meta-analysis showed that melatonin gradually reduces sleep onset latency and increases total sleep time, peaking at 4 mg/day. Meta-regression models showed that insomnia status (β = 0.50, p < 0.001) and time between treatment administration and the sleep episode (β = −0.16, p = 0.023) were significant predictors of sleep onset latency, while the time of day (β = −0.086, p < 0.01) was the only significant predictor of total sleep time. Our results suggest that advancing the timing of administration (3 h before the desired bedtime) and increasing the administered dose (4 mg/day), as compared to the exogenous melatonin schedule most used in clinical practice (2 mg 30 min before the desired bedtime), might optimize the efficacy of exogenous melatonin in promoting sleep.

RETRACTION: Tuñón MJ, Miguel BS, Crespo I, Jorquera F, Santamaría E, Alvarez M, Prieto J, González-Gallego J. Melatonin attenuates apoptotic liver damage in fulminant hepatic failure induced by the rabbit hemorrhagic disease virus. J Pineal Res 2011;50:38-45. https://doi.org/10.1111/j.1600-079X.2010.00807.x

The above article, published online on 22 October 2010 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal Editor-in-Chief, Gianluca Tosini, and John Wiley and Sons Ltd. Following publication, concerns were raised by third parties that portions of Figure 4 are duplicated in Figures 4, 2A, and 1B, respectively, of three other articles by the same author group.^1-3 The authors provided some of the original data, but these were not sufficient to resolve the concerns, and the authors were unable to provide a satisfactory explanation for the concerns. The retraction has been agreed because of concerns that portions of the figure overlap with the authors' previous articles, affecting the interpretation of the data and results presented. The authors disagree with this decision.

1. Kretzmann NA, Fillmann H, Mauriz JL, Marroni, CA, Marroni N, González-Gallego J, Tuñón MJ. Effects of glutamine on pro-inflammatory gene expression and activation of nuclear factor kappa B and signal transducers and activators of transcription in TNBS-induced colitis. Inflamm Bowel Dis 2008;14:1504-1513. doi:10.1002/ibd.20543

2. Crespo I, García-Mediavilla MV, Gutiérrez B, Sánchez-Campos S, Tuñón MJ, González-Gallego J. A comparison of the effects of kaempferol and quercetin on cytokine-induced pro-inflammatory status of cultured human endothelial cells. Br J Nutr 2008;100(5):968-976. doi:10.1017/S0007114508966083

3. Laliena A, Miguel BS, Crespo I, Alvarez M, González-Gallego J, Tuñón MJ. Melatonin attenuates inflammation and promotes regeneration in rabbits with fulminant hepatitis of viral origin. J Pineal Res 2012;53:270-278. doi:10.1111/j.1600-079X.2012.00995.x

RETRACTION: Martín-Renedo J, Mauriz JL, Jorquera F, Ruiz-Andrés O, González P, González-Gallego J. Melatonin induces cell cycle arrest and apoptosis in hepatocarcinoma HepG2 cell line. J Pineal Res 2008;45:532-540. https://doi.org/10.1111/j.1600-079X.2008.00641.x

The above article, published online on 9 October 2008 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal Editor-in-Chief, Gianluca Tosini, and John Wiley and Sons Ltd. Following publication, concerns were raised by third parties regarding Figure 5B. The authors could not provide the original data for this figure, and were unable to provide a satisfactory explanation to resolve the concerns. The retraction has been agreed because of concerns that portions of the figure were duplicated, affecting the interpretation of the data and results presented. The authors disagree with this decision.