Melatonina, lactancia materna y sueño: revisión del tema / Melatonin, breastfeeding and sleep: topic review

Se revisa en el binomio madre-recién nacidos o/y lactantes, los diferentes ritmos circadianos, especialmente del sueño, la secreción de melatonina y las características de la leche materna. Se aconseja manejo para evitar la cronodisrupción

It is reviewed in the binomial mother-newborns or/and infants, the different circadian rhythms, especially sleep, melatonin secretion and the characteristics of breast milk. Handling is advised to avoid chrono disruption

Research progress in control strategies of biological clock disorder / 生理学报

Circadian clock is an internal mechanism evolved to adapt to cyclic environmental changes, especially diurnal changes. Keeping the internal clock in synchronization with the external clock is essential for health. Mismatch of the clocks due to phase shift or disruption of molecular clocks may lead to circadian disorders, including abnormal sleep-wake cycles, as well as disrupted rhythms in hormone secretion, blood pressure, heart rate, body temperature, etc. Long-term circadian disorders are risk factors for various common critical diseases such as metabolic diseases, cardiovascular diseases, and tumor. To prevent or treat the circadian disorders, scientists have conducted extensive research on the function of circadian clocks and their roles in the development of diseases, and screened hundreds of thousands of compounds to find candidates to regulate circadian rhythms. In addition, melatonin, light therapy, exercise therapy, timing and composition of food also play a certain role in relieving associated symptoms. Here, we summarized the progress of both drug- and non-drug-based approaches to prevent and treat circadian clock disorders.

Melatonin and organ transplantation: what is the relationship?

SUMMARY Melatonin has anti-inflammatory and antioxidant properties that can influence tissue growth and apoptosis. This aspect may influence the success of organ transplantation. OBJECTIVE To evaluate the relationship between melatonin and organ transplantation. METHODS A systematic review was performed in PubMed databases using the search terms: "melatonin physiology" or "melatonin therapy" and "transplant pharmacology" or "transplant physiology" or "transplant therapy" or "Transplant therapy". Experiments on the organs of the reproductive system were not included. After analysis, five articles were selected after reading the title and abstract of 50 manuscripts. The works were divided into two aspects: a) analysis of the influence of the organ transplantation procedure on melatonin production; b) action of melatonin on organ transplantation. RESULTS The cardiac transplantation surgical procedure, immunosuppression, and graft did not influence melatonin secretion in rodents, but there was a significant reduction of melatonin in the renal transplantation procedure in patients with renal insufficiency. Melatonin administration in experimental models decreased rejection and improved transplant success. CONCLUSION Studies show that melatonin can reduce organ and species dependence, and the use of melatonin decreases graft rejection.

RESUMO A melatonina tem propriedades anti-inflamatórias e antioxidantes que podem influenciar o crescimento e a apoptose dos tecidos. Esse aspecto pode influenciar o sucesso do transplante de órgãos. OBJETIVO Avaliar a relação entre a melatonina e o transplante de órgãos. MÉTODO A revisão sistemática foi realizada nas bases de dados do PubMed, usando os termos de pesquisa: "fisiologia da melatonina" ou "terapêutica da melatonina" e "farmacologia do transplante" ou "fisiologia do transplante" ou "terapêutica do transplante" ou "terapia do transplante". Não foram incluídos os experimentos sobre os órgãos do sistema reprodutivo. Após análise, cinco artigos foram selecionados após a leitura do título e do resumo de 50 manuscritos. Os trabalhos foram divididos em duas vertentes: a) análise da influência do procedimento de transplante de órgão na produção de melatonina; b) ação da melatonina sobre o transplante de órgãos. RESULTADOS O procedimento cirúrgico do transplante cardíaco, a imunossupressão e o enxerto não influenciaram a secreção de melatonina em roedores, mas houve redução significante da melatonina nos casos do procedimento de transplante renal em pacientes com insuficiência renal. A ministração de melatonina em modelos experimentais diminuiu a rejeição e melhorou o sucesso de transplante. CONCLUSÃO Os estudos mostram que a melatonina pode reduzir a dependência da espécie e do órgão e que o emprego da melatonina diminui a rejeição do órgão.

A brief review about melatonin, a pineal hormone

ABSTRACT Melatonin is a ubiquitous molecule in nature, being locally synthesized in several cells and tissues, besides being a hormone that is centrally produced in the pineal gland of vertebrates, particularly in mammals. Its pineal synthesis is timed by the suprachiasmatic nucleus, that is synchronized to the light-dark cycle via the retinohypothalamic tract, placing melatonin synthesis at night, provided its dark. This unique trait turns melatonin into an internal synchronizer that adequately times the organism's physiology to the daily and seasonal demands. Besides being amphiphilic, melatonin presents specific mechanisms and ways of action devoted to its role as a time-giving agent, being widely spread in the organism. The present review aims to focus on melatonin as a pineal hormone with specific mechanisms and ways of action, besides presenting the clinical syndromes related to its synthesis and/or function disruptions.

The role of melatonin in diabetes: therapeutic implications

Melatonin referred as the hormone of darkness is mainly secreted by pineal gland, its levels being elevated during night and low during the day. The effects of melatonin on insulin secretion are mediated through the melatonin receptors (MT1 and MT2). It decreases insulin secretion by inhibiting cAMP and cGMP pathways but activates the phospholipaseC/IP3 pathway, which mobilizes Ca2+from organelles and, consequently increases insulin secretion. Both in vivo and in vitro, insulin secretion by the pancreatic islets in a circadian manner, is due to the melatonin action on the melatonin receptors inducing a phase shift in the cells. Melatonin may be involved in the genesis of diabetes as a reduction in melatonin levels and a functional interrelationship between melatonin and insulin was observed in diabetic patients. Evidences from experimental studies proved that melatonin induces production of insulin growth factor and promotes insulin receptor tyrosine phosphorylation. The disturbance of internal circadian system induces glucose intolerance and insulin resistance, which could be restored by melatonin supplementation. Therefore, the presence of melatonin receptors on human pancreatic islets may have an impact on pharmacotherapy of type 2 diabetes.

Pineal gland plays a role in gonadal development after eyelids separation in puppies / La glándula pineal juega un rol en el desarrollo gonadal luego de la separación de los párpados en cachorros

Several functional and morphological studies have been conducted on the pineal gland in many mammalian species; however, no published reports are available on the role of pineal gland on the gonadal development before and after eyelids separation in puppies. Therefore, this study aimed to trace the postnatal histo-morphological changes in the pineal gland and gonads of puppies before (2, 10 and 11 days old) and after (25, 35 and 40 days old) eyelids separation in an attempt to investigate the possible role of pineal gland on the gonadal development. In general, the differentiation of pineal cells, interstitial endocrine cells of testes and stromal ovarian cells coincides with the start of eyelids separation in puppies. Histological examination of stained pineal and gonadal slices of puppies after eyelids separation revealed a remarkable differentiation of pinealocytes and testicular interstitial endocrine cells, as well as presence of some evidence of folliculogenesis in ovary. Surprisingly, melatonin receptor (MT1) protein expression levels were significantly increased in the ovaries and testes of puppies after eyelids separation. Moreover, the mRNA and protein expression of AANAT, a rate-limiting enzyme in melatonin biosynthesis, was notably increased in the pineal gland of opened eyes puppies. Our results suggest an increase of melatonin production from the pineal gland of opened eyes puppies and this could play a vital role in the developmental changes observed in the gonads of these puppies.

Diversos estudios morfológicos y funcionales han sido realizados sobre la glándula pineal en distintas especies de mamíferos. Sin embargo, no hay informes publicados acerca del rol de la glándula pineal en el desarrollo gonadal antes y después de la separación de los párpados en cachorros. Este estudio tuvo como objetivo trazar los cambios histo-morfológicos postnatales en la glándula pineal y las gónadas de los cachorros antes (2, 10 y 11 días de edad) y después (25, 35 y 40 días de edad) de la separación de los párpados, en un intento por investigar el posible rol de la glándula pineal en el desarrollo gonadal. En general, la diferenciación de los pinealocitos, células intersticiales endocrinas de los testículos y las células estromales del ovario coincide con el inicio de la separación de los párpados en cachorros. El examen histológico de glándula pineal y los cortes gonadales de los cachorros, después de la separación de los párpados, reveló una notable diferenciación de los pinealocitos y las células intersticiales endocrinas testiculares, así como la posible evidencia de foliculogénesis en el ovario. Sorprendentemente, en el receptor de melatonina (MT1) los niveles de expresión de proteínas fueron significativamente superiores en los ovarios y los testículos de los cachorros después de la separación de los párpados. Además, el ARNm y la expresión de la proteína AANAT, una enzima limitante de la velocidad en la biosíntesis de la melatonina, aumentaron notablemente en la glándula pineal de los cachorros con los ojos abiertos. Nuestros resultados sugieren que existe un aumento de la producción de melatonina por parte de la glándula pineal en los cachorros con los ojos abiertos, lo que podría jugar un rol vital en los cambios evolutivos observados enlas gónadas de estos cachorros.

Cronobiología, sueño y depresión / Chronobiology, sleep and depression

Luego de una actualización sobre diversos aspectos del ciclo vigilia‑sueño, en el presente trabajo se analiza las consecuencias que tiene su alteración sobre el organismo. Además de las consecuencias neuroendócrinas y cardiovasculares, se hace especialmente hincapié en su efecto sobre el estado de ánimo, y la evidencia que surge sobre su vinculación con los episodios depresivos y trastornos bipolares. Finalmente,se establece, como elemento a tener en cuentapara la terapéutica de dicha patología, el uso de medicación que no solo actúe sobre los neurorreceptores, sino que también reestablezca un ordenado ciclo vigilia‑sueño, como forma de evitar la cronificación y agravamiento de los trastornos anímicos.

Repercussão do sono sobre o trabalho / Effect of sleep on the job

Trabalhadores, chefes, empresários, serviço de engenharia de segurança e medicina do trabalho devem ser alertados para os perigos e consequências das jornadas longas de trabalho ao volante, horas extras e mudanças de turno de trabalho.A alimentação, o repouso, as necessidades biológicas do indivíduo que opera uma máquina móvel extremamente perigosa para si, para o usuário, pedestre e a sociedade como um todo devem ser regulados. A equipe de segurança e medicina do tráfego precisa voltar-se para os sinais e sintomas muitas vezes subjetivos, mas importantes na prevenção de doenças ocupacionais e acidentes de trabalho.Quantos acidentes são causados todos os dias pelo sono e quanto tempo é necessário para o indivíduo se recuperar de uma jornada de trabalho?

Rat pinealectomy: a modified direct visual approach / Pinealectomia em ratos: técnica modificada com visualização direta

PURPOSE: To report a new, direct visual approach for rat pinealectomy. METHODS: Eighty adult female rats (Rattus norvegicus albinus EPM-1 strain) were weighted and anesthetized intraperitoneally with 15 mg/kg xylazine and 30 mg/kg ketamine. The animal was fastened to a dissection table, an incision was made in the skin and the subcutaneous tissue, bringing the lambda into view. The skullcap was opened with a dental drill, bringing the cerebral hemispheres and the superior sagittal sinus into view. The pineal gland, located under the venous sinus, was removed in a single piece using tweezers. Next, the bone fragment was returned to its place and the surgical layers were sutured. RESULTS: This new technique is easy to be done, avoids bleedings and removes only the pineal gland without damage to the remaining encephalon. In addition it makes possible the achievement of a sham surgery, allowing the pineal gland to remain intact. CONCLUSION: The proposed technique intends to facilitate studies aiming to better understanding the complexity and importance of the pineal gland on reproductive and other body systems.

OBJETIVO: Apresentar nova técnica para pinealectomia em ratos. MÉTODOS: 80 ratos adultos fêmeas (Rattus norvegicus albinus) foram pesados e em seguida anestesiados por via intraperitoneal com xilazina e cetamina. Em seguida os animais foram fixados em uma prancha de cortiça e feita uma incisão na pele e no tecido subcutâneo, na região superior da cabeça, evidenciando a junção dos ossos parietais e occipital. Na região do lambda, realizou-se uma perfuração circular, na calota craniana, com o auxilio de uma broca (4 mm) acoplada a um micromotor. Nesse orifício, após a dissecação da dura-mater visibiliza-se a confluência dos seios venosos longitudinal e transverso. Com o auxilio de uma pinça curva esses seios são deslocados, ligados e identificada a glândula pineal, que pode ser removida em peça única. Em seguida, o fragmento ósseo é devolvido ao seu lugar e as camadas cirúrgicas suturadas. RESULTADOS: Esta nova técnica é fácil de ser feita, evita hemorragias e só remove a glândula pineal, sem prejuízos para o restante do encéfalo. Além disso, possibilita a realização de uma cirurgia sham, visto que a glândula pineal permanece sem alterações. CONCLUSÃO: Espera-se que a técnica proposta facilite estudos visando a uma melhor compreensão da complexidade e importância da glândula pineal sobre a reprodução e outros sistemas do organismo.

Efeitos da melatonina no sistema genital feminino: breve revisão / Melatonin effects on the female genital system: a brief review

A melatonina é um hormônio produzido pela glândula pineal, cuja secreção está diretamente relacionada ao ciclo claro-escuro. É um poderoso antioxidante e tem papel fundamental na regulação do estado sono/vigília, do ritmo de vários processos fisiológicos, participando do controle do relógio biológico, inclusive nos seres humanos. Ressalta-se que há evidências da sua ação no sistema genital feminino, influenciando a função ovariana e a fertilidade. De fato, este hormônio interage com esteróides sexuais, como o estrogênio, modificando a sinalização celular e a resposta no tecido alvo. Estudos clínicos sugerem que o tratamento com a melatonina interviria com a evolução de neoplasia-dependente do estrogênio. O objetivo dessa revisão é analisar as principais ações da melatonina no sistema neuroendócrino, no ciclo sono-vigília, no sistema imunológico, no sistema cardiovascular, bem como no sistema reprodutor.

Melatonin is secreted by the pineal gland and this is linked to the day/night cycle. It is an antioxidant and plays a fundamental role in the regulation of the jet-lag stage, in several physiological reactions and in control of the biologic rhythm. Human melatonin has an important influence on the female genital system. In fact, melatonin may influence production and action of steroids, modifying cellular signalization on the target tissue. There are many evidences that the melatonin therapy may be interfering with neoplasia development, mainly of the estrogen-dependent tumor. This paper aims to analyze the actions of melatonin on the neuroendocrine, immunological and cardiovascular systems, as well as on the reproductive function.

Melatonin in pathogenesis and therapy of cancer.

Melatonin is a neuroendocrine hormone secreted by the pineal gland to transduce the body's circadian rhythms. An internal 24 hour time keeping system (biological clock) regulated by melatonin, controls the sleep-wake cycle. Melatonin production is a highly conserved evolutionary phenomenon. The indole hormone is synthesized in the pinealocytes derived from photoreceptors. Altered patterns and/or levels of melatonin secretion have been reported to coincide with sleep disorders, jetlag, depression, stress, reproductive activities, some forms of cancer and immunological disorders. Lately, the physiological and pathological role of melatonin has become a priority area of investigation, particularly in breast cancer, melanoma, colon cancer, lung cancer and leukemia. According to the 'melatonin hypothesis' of cancer, the exposure to light at night (LAN) and anthropogenic electric and magnetic fields (EMFs) is related to the increased incidence of breast cancer and childhood leukaemia via melatonin disruption. Melatonin's hypothermic, antioxidant and free radical scavenging properties, attribute it to an immunomodulator and an oncostatic agent as well. Many clinical studies have envisaged the potential therapeutic role of melatonin in various pathophysiological disorders, particularly cancer. A substantial reduction in risk of death and low adverse effects were reported from various randomized controlled trials of melatonin treatment in cancer patients. This review summarizes the physiological significance of melatonin and its potential role in cancer therapy. Furthermore, the article focuses on melatonin hypothesis to represent the cause-effect relationship of the three aspects: EMF, LAN and cancer.

Evaluation of the role of melatonin in formalin-induced pain response in mice.

BACKGROUND: Melatonin, the major secretory product of pineal gland has been suggested to play a regulatory role in the circadian rhythm of body activities including the pain sensitivity. Three subtypes of melatonin receptors, i.e. ML1, ML2 and ML3 have been identified. AIM: To investigate the antinociceptive activity of melatonin and to unravel the underlying receptor mechanisms involved in this action. MATERIAL AND METHODS: Effect of melatonin (25-100 mg/kg, ip) and its interaction with putative melatonin receptor antagonists and opioidergic and serotoninergic agents have been studied in formalin test, a model of tonic continuous pain. Formalin (0.1 ml of 1% solution) was injected under the plantar surface of right hind paw of mice and the time an animal spent in licking the injected paw was measured. STATISTICAL ANALYSIS: The data were analysed by one-way ANOVA followed by Tukey's test for multiple comparisons. RESULTS: Injection of formalin produced two phases of intense licking, an early phase (0-5 min) and a late phase (20-25 min). Melatonin dose-dependently decreased the licking response in both the phases, effect being more marked in the late phase. Luzindole, a ML1 receptor antagonist did not block but rather enhanced the antinociceptive activity of melatonin. However, prazosin, a ML2 receptor antagonist in the low dose (0.5 mg/kg) significantly attenuated but in higher dose (1 mg/kg) enhanced the analgesic effect of melatonin. Naloxone, an opioid receptor antagonist did not reverse but morphine, an opioid agonist enhanced the antinociceptive activity of melatonin. Both mianserin and ondansetron the 5HT2 and 5HT3 receptor antagonists, respectively increased the analgesic effect of melatonin. CONCLUSION: The present results suggest the involvement of ML2 receptors in mediating the antinociceptive activity of melatonin in formalin-induced pain response. Further an interplay between melatonin, alpha-1 adrenergic and 5HT2 and 5HT3 serotoninergic receptors may also be participating in this action.

Neuroprotective role of melatonin in oxidative stress vulnerable brain.

The brain is deficient in oxidative defense mechanisms and hence is at greater risk of damage mediated by reactive oxygen species (ROS) resulting in molecular and cellular dysfunction. Emerging evidence suggesting the activation of glutamate gated cation channels, may be another source of oxidative stress, leading to neuronal degeneration. Oxidative stress has been implicated in the development of neurodegenerative diseases like Parkinsonism, Alzheimer's disease, Huntington's disease, amyotrophic lateral sclerosis, epileptic seizures, and stroke. Melatonin, the pineal hormone, acts as a direct free radical scavenger and indirect antioxidant. It is suggested that the increase in neurodegenerative diseases is attributable to a decrease in the levels of melatonin with age. Melatonin has been shown to either stimulate gene expression for the antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase) or to increase their activity. Additionally, it neutralizes hydoxyl radical, superoxide radical, peroxyl radical, peroxynitrite anion, singlet oxygen, hydrogen peroxide, nitric oxide, and hypochlorous acid. Unlike other antioxidants, melatonin can easily cross all morphophysiological barriers, e.g., the blood brain barrier, and enters cells and subcellular compartments. Though evidence are accumulating to suggest the potential of melatonin in neurodegenerative conditions, much information needs to be generated before the drug can find place in neurology clinics.

A glândula pineal e o metabolismo de carboidratos / The pineal gland and the carbohydrate metabolism

A influência da glândula pineal sobre o metabolismo de carboidratos vem sendo investigada há décadas. Entretanto, resultados contraditórios não esclarecem, até o momento, o verdadeiro papel da melatonina sobre a homeostasia dos carboidratos. Através de estudos recentes, contribuímos de maneira ineqüívoca para a caracterização do papel da glândula pineal como moduladora do metabolismo de carboidratos. Além disso, à luz dos conhecimentos atuais, demonstramos quais passos do mecanismo de ação da insulina estão envolvidos nessa modulação. Nossos estudos revelaram que a pinealectomia promove um quadro de resistência à insulina, sem obesidade. A captação máxima de 2-deoxi-glicose, estimulada por insulina, em adipócitos isolados está diminuída, sem entretanto modificar a capacidade da insulina ligar-se ao seu receptor e estimular a fosforilação dos substratos intracelulares representados pela pp 185. Por outro lado, em vários tecidos sensíveis à insulina, observou-se uma diminuição no conteúdo da proteína transportadora de glicose GLUT4, mas diminuição no mRNA do GLUT4 apenas em alguns desses tecidos, sugerindo uma regulação tecido-específica. Adicionalmente, foi demonstrado que a regulação da glândula pineal sobre o metabolismo de carboidratos é mediado pela melatonina: o hormônio aumentou a sensibilidade à insulina de adipócitos isolados e o tratamento de reposição com melatonina restaurou o conteúdo de GLUT4 no tecido adiposo branco. Em síntese, os estudos aqui relatados evidenciam um importante papel da glândula pineal na modulação da homeostasia de carboidratos. Essa regulação é dependente da melatonina e pode ser resumida, até o presente momento, como um aumento da sensibilidade tecidual à insulina, que envolve alterações na expressão gênica do GLUT4.

Neurobiología y farmacología clínica de la melatonina / Neurobiology and pharmacology of melatonin

La melatonina es una hormona sintetizada y liberada por la glándula pineal. La secreción comienza a aumentar alrededor de las 21.00-23.00 horas, observándose los niveles plasmáticos máximos entre las 2.00 y las 4.00 de la madrugada. Los fármacos bloqueadores de los adrenoceptores beta, los antiinflamatorio no esteroideos y los derivados benzodiacepínicos suprimen la liberación de melatonina. En cambio la zopiclona y el zopiclona y el zolpidem no interfieren en la liberación de la hormona. La melatonina es efectiva en los trastornos del sueño vinculados a una alteración del ritmo circadiano, incluyendo el jet lag, el cambio frecuente en el turno de trabajo y el trastorno de retardo de fase. También se ha mostrado eficaz en los trastornos del sueño de personas ciegas, donde la liberación de melatonina sigue un curso libre. Estudios recientes tienden a indicar que la melatonina es también efectiva en pacientes de la tercera edad con insomnio primario crónico acompañado de un descenso de los niveles endógenos de la hormona

Evolution of circadian organization in vertebrates

Circadian organization means the way in which the entire circadian system above the cellular level is put together physically and the principles and rules that determine the interactions among its component parts which produce overt rhythms of physiology and behavior. Understanding this organization and its evolution is of practical importance as well as of basic interest. The first major problem that we face is the difficulty of making sense of the apparently great diversity that we observe in circadian organization of diverse vertebrates. Some of this diversity falls neatly into place along phylogenetic lines leading to firm generalizations: i) in all vertebrates there is a "circadian axis" consisting of the retinas, the pineal gland and the suprachiasmatic nucleus (SCN), ii) in many non-mammalian vertebrates of all classes (but not in any mammals) the pineal gland is both a photoreceptor and a circadian oscillator, and iii) in all non-mammalian vertebrates (but not in any mammals) there are extraretinal (and extrapineal) circadian photoreceptors. An interesting explanation of some of these facts, especially the differences between mammals and other vertebrates, can be constructed on the assumption that early in their evolution mammals passed through a "nocturnal bottleneck". On the other hand, a good deal of the diversity among the circadian systems of vertebrates does not fall neatly into place along phylogenetic lines. In the present review we will consider how we might better understand such "phylogenetically incoherent" diversity and what sorts of new information may help to further our understanding of the evolution of circadian organization in vertebrates.

Some aspects of the pineal gland function

Rhythmic production of melatonin by the mammalian pineal gland occurs in response to noradrenergic stimulation which produces a cascade of biochemical events within the pinealocyte. Melatonin is involved in a wide range of physiological processes, including seasonal reproduction and diurnal activity rhythms. It was recently discovered that melatonin is a very potent hydroxyl radical scavenger, reinforcing its relationship with the aging process and the immune system.

Mecanismo de acción intracelular del neuromodulador melatonina: estado actual y perspectivas / Intracellular action mechanisms of the melatonin neuromodulator. Actual state and perspectives

La melatonina es una hormona que es secretada por la glándula pineal durante el periodo de oscuridad. A pesar de que se conocen sus efectos farmacológicos y fisiológicos, su mecanismo de acción no se conoce con exactitud. En este artículo se revisó la evidencia que apoya que la melatonina interacciona con la calmodulina. La unión de la melatonina a la calmodulina sugiere que la hormona modula la actividad celular por medio de su unión intracelular a esta proteína. El antagonismo de la melatonina por la calmodulina podría modular rítmicamente muchas funciones celulares. Los efectos de la melatonina sobre el citoesqueleto microtubular sugieren que a bajas concentraciones (10-9 M), los efectos de la hormona sobre el citoesqueleto son mediados por un antagonismo de Ca++- calmodulina. A concentraciones farmacológicas (10-5 M) ocurre una unión inespecífica a la tubulina que prevalece sobre el antagonismo a la calmodulina. Dado que la melatonina y la calmodulina son estructuras filogenéticamente bien conservadas, la interacción melatonina-calmodulina probablemente represente un mecanismo primario para la regulación y la sincronización de la fisiología celular