A melatonina é uma indolamina sintetizada principalmente pela glândula pineal, cuja função está associada à marcação do escuro. Além deste papel cronobiótico, a melatonina também tem papel na defesa e é sintetizada por outros sítios podendo exercer ação parácrina e autócrina, como em células imunocompetentes. Concentrações substancialmente elevadas de melatonina são encontradas no liquido cefalorraquidiano (LCR) que tem sido vinculada à síntese de melatonina por células do sistema nervoso central (SNC), como as microglias. Sabendo-se que estas células são os macrófagos residentes no SNC e que a síntese de melatonina por estes fagócitos já é comprovada, nosso trabalho teve por objetivo avaliar se microglias cerebelares sintetizam essa indolamina e se esta atua potencializando a fagocitose destas células. Nossos resultados mostram que o bloqueio dos receptores de melatonina com o antagonista luzindol, diminuiu tanto a fagocitose induzida por melatonina exógena, quanto à fagocitose basal, indicando que há síntese de melatonina por microglias cerebelares que, por sua vez, age na fagocitose. Esses resultados são relevantes e indicam que a melatonina sintetizada pela microglia, pode estar relacionada com a homeostase do ambiente neural. Sendo assim, nossos dados podem contribuir com estudos que estabeleçam novas estratégias terapêuticas para doenças neuroinflamatórias. / Melatonin is a indolamine synthesized primarily by the pineal gland, whose function is associated with the marking of the dark phase. Beyond this chronobiotic function, melatonin also plays a role in defense and is synthesized by other sites. It may exert paracrine and autocrine action, like in immunocompetent cells. High substantially concentrations of melatonin are found in the cerebrospinal fluid (CSF) that has been linked to the synthesis of melatonin by the central nervous system cells (CNS), such as microglia. Knowing that these cells are the resident macrophages in the CNS and that melatonin synthesis by these phagocytes is proven, our study aims to assess whether cerebellar microglia synthesize this indolamine and whther this acts enhancing phagocytosis of these cells. Our results show that blocking the melatonin receptors with the antagonist, luzindole, both the exogenous melatonin-induced phagocytosis and the basal phagocytosis decreased, indicating that there is melatonin synthesis by cerebellar microglia which acts on phagocytosis. These results are significant and indicate that melatonin synthesized by microglia may be related to the neural environment homeostasis. In this way, our data can contribute, for example, in studies to establish new therapeutic strategies for neuroinflammatory diseases.

Os linfócitos T sofrem rígida regulação homeostática desde seu desenvolvimento até sua maturação, expansão clonal e morte celular. Compostos endógenos ou exógenos que alterem as funções fisiológicas dos linfócitos T podem modular passos importantes da resposta imune. Triptofano tem um papel importante na manutenção da homeostasia dos linfócitos T e é o precursor da síntese de melatonina. Neste estudo, avaliamos os efeitos de triptofano, melatonina e seus produtos de oxidação sobre os principais processos de ativação e desativação dos linfócitos T. Inicialmente, investigamos os efeitos biológicos de L-quinurenina (KYN, composto formado na via de metabolização do triptofano), melatonina e seus produtos de oxidação N1-acetil-N2-formil-5-metoxiquinuramina (AFMK) e N1-acetil-5- metoxiquinuramina (AMK) sobre a proliferação dos linfócitos T humanos e na produção de interferon-gamma (IFN-γ) e das interleucinas IL-2, IL-10 e IL-12. Observamos que KYN, melatonina, AFMK e AMK inibem a linfoproliferação e a liberação de IL-2 e de IFN-γ . O efeito inibitório destes compostos na síntese de IFN-γ não está associado às variações na produção das duas citocinas mais importantes na regulação de IFN-γ , ou seja, IL-10 e IL-12. Na seqüência, descrevemos a ação da melatonina e seus produtos de oxidação, sobre a morte celular induzida por ativação (AICD) de hibridomas de linfócitos T e os possíveis mecanismos de ação. Os resultados deste estudo mostram que tanto melatonina quanto AFMK e AMK são potentes inibidores da apoptose dos linfócitos T. Estes compostos inibem a ativação do Fator de Transcrição Nuclear de Células T ativadas (NFAT) e suprimem a expressão da molécula Fas Ligante (FasL), que é o evento imprescindível para a indução da AICD. Como conclusões, verificamos que os produtos formados tanto a partir da oxidação de triptofano quanto de melatonina são potenciais reguladores da resposta imune e podem participar dos efeitos imunossupressores, nos quais a depleção de triptofano tem sido sugerida como principal mecanismo de regulação dos linfócitos T. Adicionalmente, nossos achados podem ter utilidade na avaliação de possíveis efeitos indesejáveis durante a utilização terapêutica de melatonina. / T Lymphocytes are exposed to severe homeostatic regulation from development stage up to their maturation, clonal expansion and cell death. Endogenous or exogenous compounds altering the physiological functions of T lymphocytes can modulate important steps of the immune response. Tryptophan plays an important role for maintaining the homeostasis of T lymphocytes and is the precursor of the melatonin synthesis. In this study we evaluated the effects of tryptophan, melatonin and their oxidation products concerning the main activation and deactivation processes of T lymphocytes. Firstly, we analyzed the biological effects of L-kynurenine (KYN, a compound formed at the tryptophan metabolization pathway), melatonin and its oxidation products, N-acetyl-N-formyl-5-methoxykynuramine (AFMK) and N-acetyl-5- methoxykynuramine (AMK), concerning the proliferation of human T lymphocytes and the production of interferon-gamma (IFN-γ) as well as of interleukins IL-2, IL-10 and IL-12. It was observed that KYN, melatonin, AFMK and AMK inhibit the lymphocytes proliferation and the release of IL-2 and IFN-γ. The inhibitory effect of these compounds in the IFN-γ synthesis is not related to the variations on the production of the two most important cytokines for the IFN-γ regulation, that is, IL-10 and IL-12. After that, we reported the melatonin action as well as of its oxidation products, in what concerns activation-induced cell death (AICD) of T lymphocytes hybridomas and probable activation mechanisms. The results of this study have shown that melatonin as well as AFMK and AMK are powerful inhibitors of the T lymphocytes apoptosis. These compounds inhibit the activation of the nuclear transcription factor of activated T cells (NFAT) and suppress the expression of the Fas-Ligand molecule (FasL), which is the essential event to the AICD induction. We concluded that products formed by the oxidation of either tryptophan or melatonin are potential regulators of the immune response and may participate on immunosuppression effects, in which the tryptophan depletion is believed to be the main mechanism for T lymphocytes regulation. Added to that, our results may be helpful for evaluating possible unwanted effects during the therapeutical use of melatonin.

Macrófagos são capazes de sintetizar melatonina quando ativados por agonistas de TLRs de forma dependente da ativação da via NF-κB. A melatonina produzida pelos macrófagos está relacionada com o favorecimento da fagocitose de partículas ricas em manose. Catecolaminas são capazes de ativar a via NF-κB em células imunocompetentes, e são produzidas por estas células quando ativadas. É conhecido que a descarga noturna de noradrenalina na glândula pineal é responsável pela produção de melatonina na fase de escuro. Hipotetizamos que catecolaminas, ao exemplo da glândula pineal, pudessem induzir a síntese de melatonina em macrófagos. Avaliamos se agonistas adrenérgicos poderiam regular a produção de melatonina nos macrófagos RAW 264.7. Analisamos também o efeito da melatonina em conjunto com agonistas adrenérgicos no modelo experimental de lesão pulmonar aguda. Ambas catecolaminas foram capazes de aumentar a expressão da enzima AA-NAT total ou fosforilada e induzir a síntese de melatonina, via ativação de β-adrenoceptores; sendo dependente de NF-κB, e não da sinalização mediada por AMPc. A instilação de LPS nos pulmões dos camundongos induz a expressão de Tnf e de Aa-nat, o que é inibido pelo agonista β2-adrenérgico. A melatonina exerce um efeito anti-inflamatório na produção de citocinas in vivo e in vitro, além de inibir a expressão de Nos2 em macrófagos MH-S, sem alterar arginase-1. Os dados aqui apresentados sugerem que a via de sinalização NF-κB faz a integração da sinalização adrenérgica com a produção de melatonina em macrófagos / TLRs-activated macrophages can synthesize melatonin in a NF-κB pathway-mediated manner. Macrophage-produced melatonin is related to the favoring of mannose-rich particles phagocytosis. Catecholamines can trigger NF-κB pathway in immunocompetent cells, and are produced after activation. It is well known that the nocturnal surge of noradrenaline in the pineal gland is responsible for the dark phase melatonin synthesis. We hypothesized that catecholamines, like in pineal gland, could induce melatonin synthesis by macrophages. We evaluated if adrenergic agonists could regulate melatonin production in RAW 264.7 macrophages. We also analyzed the effect of melatonin together with adrenergic agonist in the experimental model of acute lung injury. Both catecholamines were able to increase the expression of total or phosphorylated AA-NAT enzyme, and induce melatonin synthesis through β-adrenoceptor activation; in a NF-κB-dependent way, but not by the cAMP signaling. LPS instillation in the mice lungs induces Tnf and Aa-nat expression, which is inhibited by the β2-adrenergic agonist. Melatonin exerts an anti-inflammatory effect in cytokine production both in vivo and in vitro, besides the inhibition of Nos2 in MH-S macrophages, without changing arginase-1. The presented data suggests that the NF-κB signaling pathway fulfill the integration of adrenergic signaling with melatonin synthesis in macrophages

A síntese de melatonina por fagócitos mononucleares do colostro humano é iniciada após a indução com a partícula zimosan, com ou sem opsonização por IgA. Esta produção é dependente da ativação da via NFKB, o que foi observado após o bloqueio farmacológico da via com PDTC ou ALLN levando a diminuição da concentração de melatonina nas culturas. A localização do NFKB varia temporalmente após o estímulo inicial e as subunidades do NFKB são diferentes no núcleo de células ativadas. A subunidade p50 está presente em todas as condições experimentais (controle, zimosan e zimosan opsonizado), mas as subunidades Rel A e c-Rel apenas nas células tratadas. A melatonina apresenta atividade sobre células imunocompetentes em diversos modelos experimentais, mas o modelo de fagocitose ainda não havia sido relatado na literatura. Observamos que a melatonina é capaz de potenciar a fagocitose de zimosan não opsonizado. A capacidade de síntese de melatonina apresentada por células imunocompetentes é um fenômeno conhecido e agora pudemos demonstrar que a via NFKB é responsável também pela síntese de melatonina em fagócitos mononucleares do colostro. Ao contrário do que ocorre na glândula pineal onde a ativação da via do NFKB bloqueia a síntese de melatonina, nos leucócitos, a ativação desta via se faz necessária para o inicio da síntese. Uma possível justificativa para esta diferença é a presença da subunidade c-Rel apenas nos fagócitos, permitindo supor que esta subunidade seja responsável pela síntese de melatonina nestas células. Hipoteticamente, a síntese de melatonina dependente da ativação de um fator envolvido com a resposta inflamatória, abre a perspectiva de que a melatonina estaria participando deste processo. O aumento na taxa de fagocitose induzida pela melatonina mostra uma participação importante dessa indolamina durante uma infecção, diminuindo o tempo em que um possível patógeno se encontraria no meio extracelular auxiliando na sua rápida eliminação. Os dados apresentados no presente trabalho demonstram que as células imunocompetentes não apenas produzem esta indolamina, como também se utilizam dela para modular processos nos quais estas células participam. / The melatonin synthesis by human mononuclear phagocytes starts after the induction by IgA opsonized or not zymosan. This production is dependent on the activation of NFKB pathway since the pharmacological block of the pathway by PDTC or ALLN reduces the melatonin concentration in culture supernatants. The NFKB localization temporally varies after initial stimulus and the presence of specific subunits in the cell nucleus is different in activated cells when compared with control cells. We observed the presence of p50 subunit in all experimental conditions (control, zymosan, opsonized zymosan), but the Rel A and c-Rel subunits were only detected in treated cells. Melatonin shows activity over immune cells in many experimental models, but the phagocytosis model was not yet reported in literature. We observed that melatonin (1 nM) is able to potentiate the non opsonized zymosan phagocytosis. The capacity to synthesize melatonin presented by immune cells is a well known phenomenon and now we demonstrate that the NFKB pathway is also responsible for the melatonin synthesis in colostral mononuclear phagocytes. The activation of NFKB pathway inhibits the melatonin synthesis in pineal gland but, in leukocytes, the activation of this pathway is necessary to achieved melatonin synthesis. A possible explanation for this difference is the presence of c-Rel in the phagocytes, which presents transactivation domains, allowing the supposition that this subunit is the responsible for melatonin synthesis in these cells. Since, melatonin synthesis is dependent on the activation of a factor involved with an inflammatory response, this study opens the perspective that the melatonin could participate as a modulator of this process. The phagocytosis induced by melatonin discloses a significant role of this indolamine during an infection, promoting the fast elimination of pathogen in the extracellular medium. The data shows that immune cells not only produces this indolamine, but also use the melatonin to modulate the immune responses.

A malária é a doença parasitaria que mais mata no mundo. Metade da população mundial está sob risco de contrair a doença, que mata mais de 1 milhão de pessoas por ano, principalmente crianças com menos de 5 anos de idade. A periodicidade das febres é o sintoma característico da doença. A febre é resultado da lise dos eritrócitos mediada pela saída do parasita, para infectar novas células. Esse evento é sincronizado, com os parasitas rompendo as células ao mesmo tempo. Para que isso aconteça, os eventos celulares que são necessários para a maturação do parasita dentro do eritrócito tem que ser finamente regulada. O hormônio circadiano melatonina é o sinal que sincroniza o ciclo intraeritrocítico do Plasmodium. Neste trabalho, reportamos que a sincronia observada na maioria das espécies do parasita pode ser usada por ele como meio de evadir o sistema imune do hospedeiro e assegurar a continuidade da infecção. Quando dessincronizamos o desenvolvimento do parasita P. chabaudi utilizando luzindol, um antagonista da melatonina, foi observado que o uso de uma dose sub-otima do antimalárico cloroquina aumenta a sobrevida de camundongos infectados. Reportamos também que P. berghei, parasita de roedor que possui uma infecção não sincronizada, não percebe o hormônio. Diferentemente do que é observado com espécies que possuem sincronia, a melatonina falhou em induzir aumento de cálcio intracelular ou sincronizar o ciclo de vida do parasita in vitro. No trabalho também é relatado a construção de vetores para nocauteamento de genes em Plasmodium, afim de se conhecer a função das genes alvo por análise de fenótipo. / Malaria is the most killing parasitic disease in the world. Half of the world population is at risk of contracting the disease, which kills over 1 million people, being children under 5 the most affected. The fever periodicity is the characteristic symptom of the disease. The fever is a result of the burst of the erythrocyte when the parasite leaves the host cell to infect other ones. This event is highly synchronous, with the parasites going out of the cells at the same time. For this to happen, the cellular events that are necessary for parasite growth have to be very well regulated. The circadian hormone melatonin is the signal that synchronizes the intraerythrocytic cycle of Plasmodium. In this work, we report that this synchrony, observed in the majority of the parasites species, could be used as a way to evade the immune system, assuring the continuity of the infection. When we disrupt this synchrony with luzindole, a melatonin antagonist, we observe that a suboptimal dose of the antimalarial chloroquine increases the survival of the infected mice. We also report that P. berghei, rodent parasite that possess and unsynchronized infection, cant perceive the hormone. Unlike what is observed in species that have a synchronous infection, melatonin fail to induce intracellular calcium increase or promote cell cycle synchronization in vitro. Here we also report the construction of knockout vector for Plasmodium, to be used to investigate the functions of the target genes by phenotype analysis.

Orientador: Doris Hissako Sumida / Coorientadora: Sandra Helena Penha de Oliveira / Coorientador: Antonio Musarò / Banca: Carla Roberta de Oliveira Carvalho / Banca: Carlos Antonio de Miranda Bomfim / Banca: Solange Marta Franzói de Moraes / Banca: Fernando Yamamoto Chiba / Resumo: Produzida pela glândula pineal exclusivamente em período noturno e na escuridão, a melatonina apresenta papel fundamental na sincronização dos ritmos circadianos com o ciclo claro-escuro do meio ambiente. A exposição à luz suprime a síntese e secreção de melatonina pela glândula pineal, podendo prejudicar a ação insulínica em células do músculo esquelético. O transporte ineficiente de glicose no músculo esquelético pode promover atrofia, geralmente acompanhada por perda de massa óssea. Resistência à insulina, atrofia muscular esquelética e perda de massa óssea são efeitos patológicos que podem ser prevenidos ou atenuados pela prática regular de exercícios físicos. O objetivo do presente estudo foi avaliar o efeito do exercício resistido (ER) sobre a sensibilidade à insulina e manutenção da musculatura esquelética e tecido ósseo em ratos pinealectomizados. 40 ratos Wistar machos foram distribuídos, aleatória e igualmente, em 4 grupos: 1) controle (CNS); 2) exercitado (CNEX); 3) pinealectomizado (PNX) e 4) pinealectomizado exercitado (PNXEX). O ER foi realizado em escada, durante 8 semanas, 3 sessões semanais (em dias não consecutivos), 9 repetições por sessão e intervalo de tempo de 2 minutos entre as repetições. O teste de força máxima foi realizado a cada 2 semanas e a intensidade selecionada foi 60% de 1 repetição máxima (1RM). Após o período de treinamento, os animais foram submetidos ao teste de tolerância à insulina. Após o sacrifício, amostras de sangue foram coletadas ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Produced by the pineal gland exclusively at night time and in darkness, melatonin plays a key role in synchronizing circadian rhythms with the light dark cycle of the environment. Exposure to light suppresses the synthesis and secretion of melatonin by the pineal gland, and may impair insulin action in skeletal muscle cells. The inefficient transport of glucose in skeletal muscle can promote atrophy, usually accompanied by loss of bone mass. Insulin resistance, skeletal muscle atrophy and loss of bone mass are pathological effects that can be prevented or attenuated by regular physical exercise. The objective of the present study was to evaluate the effect of resistance exercise on insulin sensitivity and maintenance of skeletal muscle and bone tissue in pinealectomized rats. For this, 40 male Wistar rats were randomly and equally distributed in 4 groups: 1) control (CNS); 2) exercised (CNEX); 3) pinealectomized (PNX) and 4) pinealectomized exercised (PNXEX). Resistance training was performed on a ladder for 8 weeks, 3 weekly sessions (on non-consecutive days), 9 repetitions per session and 2 minutes interval between repetitions. The maximal strength test was performed every 2 weeks and the intensity selected was 60% of 1 maximal repetition (1RM). After the training period, the animals were submitted to the insulin tolerance test. After sacrifice, blood samples were collected for quantification of plasma glucose and insulin. From these values, insulin resistance was calculated by the HOMA-IR index. The calculation of the cross-sectional area of the extensor digitorum longus (EDL) was performed from the histological analysis using IMAGEJ software. Gene expression and phosphorylation of proteins present in skeletal muscle maintenance pathways were also evaluated: GLUT4, TNF-α, atrogin-1, MuRF1, IGF-1, Akt1, myostatin and SMAD2/3. The area... / Doutor

Vitamin A is an essential dietary component which primarily acts through its active metabolite, retinoic acid (RA), a potent transcriptional regulator that also has non-genomic activities. There is increasing evidence for a role for vitamin A in the regulation of circadian rhythms, and previous studies suggest that it serves important roles in the pineal gland, an integral component of the circadian system due to its function of melatonin production. However very little is currently known about how these effects are mediated, or about RA signalling in the pineal gland. This study aimed to establish whether RA is synthesised in the rat pineal gland and determine its role here. This included investigating whether RA is subject to diurnal changes in synthesis and signalling, and examining its involvement in the key rhythms in this gland: melatonin synthesis, kinase activation and clock gene expression. Organotypic culture of rat pineal glands, qPCR and western blotting were among the techniques employed to do this, as well as RA quantification using a reporter cell line. The rat pineal gland was found to produce RA and robust diurnal changes in synthesis were detected. Furthermore, diurnal changes in expression of RA signalling genes suggested there are corresponding changes in RA activity. RA was not found to rapidly regulate Aanat transcription, melatonin synthesis or clock gene expression in vitro, however it was found to rapidly down-regulate extracellular signal-regulated kinase (ERK) 1/2 phosphorylation. Furthermore, strong cytoplasmic expression of RA receptor α was detected in pinealocytes. These results suggest RA has a non-genomic role in the pineal gland and may be involved in driving the diurnal rhythm in kinase activation.

Pulmonary fibrosis (PF) is a serious lung disease, as its life expectancy is only 3-5 years upon occurrence and more than 50 % of the cases are idiopathic, i.e., unknown cause. Two drugs, pirfenidone (PIR) and nintedanib, have recently been approved; however, their efficacies are moderate without evidence of prolonged survival. While this is primarily due to our insufficient knowledge about key PF pathogenesis, inductions of oxidative stress and transforming growth factor-b1 (TGF-b1) have been suggested in PF lungs. Hence, anti-oxidative melatonin (MEL) and curcumin (CUR) have been studied yet their efficacies remain moderate without clear understanding about the mechanisms of action. Accordingly, this project hypothesized that a novel hybrid molecule of MEL and CUR, AM24, was a more potent inhibitor against oxidative stress and TGF-b1 induced PF pathobiologic events than MEL or CUR, so that its pulmonary delivery enabled therapeutic intervention in an animal model of PF. Free radical scavenging activity and various in vitro lung cell-based anti-fibrotic activities of AM24 were determined and compared with those of MEL and CUR as well as their admixture (MEL+CUR) and PIR. Pulmonary administration of AM24 was then examined for therapeutic intervention in a rat model of bleomycin (BLM)-induced experimental PF. AM24 was equipotent to MEL, but less potent than CUR in the hydrogen peroxide-induced free radical (ABTS) scavenging assay, ranked with the half-maximal inhibitory concentration (IC50) of 25.7, 32.0 and 11.4 uM, respectively. However, in the in vitro human lung fibroblast systems, AM24 was shown to be more potent than MEL or CUR and notably than MEL+CUR or PIR in the TGF-b1 induced 1) collagen synthesis by the picrosirius red assay, 2) proliferation by the MTT assay; and 3) differentiation to myofibroblast by western blot analysis of a myofibroblast marker, a-smooth muscle actin (a-SMA). In detail, at 10 uM, AM24 inhibited TGF-b1 induced 1) collagen synthesis by 90 %; 2) proliferation by ~72 %; and 3) differentiation to myofibroblast completely, while MEL, CUR, MEL+CUR and PIR resulted in 30-55 % or insignificant inhibition. In addition, in the in vitro human lung alveolar epithelial cell system, AM24 at 10 uM almost completely inhibited TGF-b1 induced epithelial-mesenchymal transition (EMT), as measured with western blot expressions of an epithelial marker, E-cadherin, and a mesenchymal marker, vimentin. Again, MEL, CUR, MEL+CUR and PIR exerted much less inhibitory activities. Hence, all these results consistently suggested that AM24 was a unique hybrid molecule of MEL and CUR and possessed highly potent anti-fibrotic activities in addition to the free radical scavenging activity. AM24 was then examined for therapeutic intervention in an in vivo rat model of BLM-induced PF. BLM was orotracheally spray-dosed to the lungs at 0.6 mg/kg on day 1 to develop experimental PF in 14 days. Lung administrations of AM24 at 0.1 mg/kg commenced at 6 hours of BLM induction on day 1 and continued thrice weekly over two weeks. Functional treadmill exercise endurance was measured on day 12 and 15; and lungs were harvested upon sacrifice on day 16. Overall, AM24 showed significant intervention activities as follows: 1) exercise endurance was reduced only ~20%, much lower than 78% of the untreated PF rats; 2) reduced fibrotic tissue area and alveolar structural destruction were seen by histological examinations; and 3) lung’s induced collagen deposition was inhibited by ~78 %. However, unlike the literature, the lung’s TGF-b1, PCNA (a cell proliferation marker), and a-SMA (a differentiation marker), were not largely induced in the BLM-induced PF model, so that the intervention activities of AM24 to these markers were not clearly shown. In contrast, induced EMT was seen in the BLM-induced model, represented by increased mesenchymal marker, vimentin, and by decreased epithelial marker, E-cadherin; and AM24 appeared to counter this induced EMT. Accordingly, while the BLM-induced PF model may need further optimizations for clearer pathogenic changes, AM24 exerted certain degree of in vivo efficacies with a lung dose of 0.1 mg/kg, which was much lower than the effective doses of MEL, CUR, PIR and nintedanib seen in the literature with BLM induced PF model. In conclusion, this thesis study has provided an early proof-of-concept for AM24, a novel MEL-CUR hybrid molecule, being potently anti-oxidative and anti-fibrotic in the in vitro lung cell-based assessments. As a result, AM24 enabled therapeutic intervention just with a lung dose of 0.1 mg/kg in the BLM-induced rat model of experimental PF.

Background: Anxiety is a barrier to dental care for many people. Preliminary studies suggest that melatonin may possess anxiolytic and sedative properties. Methods: Twelve subjects were selected for this study which compared melatonin, at a dose of 0.14 mg/kg, with placebo, as an oral premedication for anxious dental patients prior to receiving a general anesthetic. A visual analog scale (VAS) was used to measure anxiety. The Richmond Agitation Sedation Scale (RASS) was used to assess sedation, the Trieger Dot Test (TDT) for psychomotor impairment, and Digit Symbol Substitution Test (DSST) for cognitive impairment. A Quality of Recovery Questionnaire (QoR) was completed 24 hours after each appointment. Results: There were no significant differences in VAS scores for melatonin and placebo between baseline and at 30, 60, and 90 minutes. Similar results were found for RASS scores, TDT, DSST, and the QoR. Conclusion: At the doses used in this study, melatonin was not significantly different from placebo in anxiolysis, sedation, cognitive impairment, psychomotor impairment, and quality of recovery from anesthesia, for anxious dental patients.

Background: Anxiety is a barrier to dental care for many people. Preliminary studies suggest that melatonin may possess anxiolytic and sedative properties. Methods: Twelve subjects were selected for this study which compared melatonin, at a dose of 0.14 mg/kg, with placebo, as an oral premedication for anxious dental patients prior to receiving a general anesthetic. A visual analog scale (VAS) was used to measure anxiety. The Richmond Agitation Sedation Scale (RASS) was used to assess sedation, the Trieger Dot Test (TDT) for psychomotor impairment, and Digit Symbol Substitution Test (DSST) for cognitive impairment. A Quality of Recovery Questionnaire (QoR) was completed 24 hours after each appointment. Results: There were no significant differences in VAS scores for melatonin and placebo between baseline and at 30, 60, and 90 minutes. Similar results were found for RASS scores, TDT, DSST, and the QoR. Conclusion: At the doses used in this study, melatonin was not significantly different from placebo in anxiolysis, sedation, cognitive impairment, psychomotor impairment, and quality of recovery from anesthesia, for anxious dental patients.