iMS-Bmal1-/- mice show evident signs of sarcopenia that are counteracted by exercise and melatonin therapies.

Sarcopenia is an age-related disease characterized by a reduction in muscle mass, strength, and function and, therefore, a deterioration in skeletal muscle health and frailty. Although the cause of sarcopenia is still unknown and, thus, there is no treatment, increasing evidence suggests that chronodisruption, particularly alterations in Bmal1 clock gene, can lead to those deficits culminating in sarcopenia. To gain insight into the cause and mechanism of sarcopenia and the protective effect of a therapeutic intervention with exercise and/or melatonin, the gastrocnemius muscles of male and female skeletal muscle-specific and inducible Bmal1 knockout mice (iMS-Bmal1-/- ) were examined by phenotypic tests and light and electron microscopy. Our results revealed a disruption of the normal activity/rest rhythm, a drop in skeletal muscle function and mass, and increased frailty in male and female iMS-Bmal1-/- animals compared to controls. A reduction in muscle fiber size and increased collagenous tissue were also detected, accompanied by reduced mitochondrial oxidative capacity and a compensatory shift towards a more oxidative fiber type. Electron microscopy further supports mitochondrial impairment in mutant mice. Melatonin and exercise ameliorated the damage caused by loss of Bmal1 in mutant mice, except for mitochondrial damage, which was worsened by the latter. Thus, iMS-Bmal1-/- mice let us to identify Bmal1 deficiency as the responsible for the appearance of sarcopenia in the gastrocnemius muscle. Moreover, the results support the exercise and melatonin as therapeutic tools to counteract sarcopenia, by a mechanism that does not require the presence of Bmal1.

From Chronodisruption to Sarcopenia: The Therapeutic Potential of Melatonin.

Sarcopenia is an age-related condition that involves a progressive decline in muscle mass and function, leading to increased risk of falls, frailty, and mortality. Although the exact mechanisms are not fully understood, aging-related processes like inflammation, oxidative stress, reduced mitochondrial capacity, and cell apoptosis contribute to this decline. Disruption of the circadian system with age may initiate these pathways in skeletal muscle, preceding the onset of sarcopenia. At present, there is no pharmacological treatment for sarcopenia, only resistance exercise and proper nutrition may delay its onset. Melatonin, derived from tryptophan, emerges as an exceptional candidate for treating sarcopenia due to its chronobiotic, antioxidant, and anti-inflammatory properties. Its impact on mitochondria and organelle, where it is synthesized and crucial in aging skeletal muscle, further highlights its potential. In this review, we discuss the influence of clock genes in muscular aging, with special reference to peripheral clock genes in the skeletal muscle, as well as their relationship with melatonin, which is proposed as a potential therapy against sarcopenia.

The Relationship between Clock Genes, Sirtuin 1, and Mitochondrial Activity in Head and Neck Squamous Cell Cancer: Effects of Melatonin Treatment.

The circadian clock is a regulatory system, with a periodicity of approximately 24 h, which generates rhythmic changes in many physiological processes, including mitochondrial activity. Increasing evidence links chronodisruption with aberrant functionality in clock gene expression, resulting in multiple diseases such as cancer. Melatonin, whose production and secretion oscillates according to the light-dark cycle, is the principal regulator of clock gene expression. In addition, the oncostatic effects of melatonin correlate with an increase in mitochondrial activity. However, the direct links between circadian clock gene expression, mitochondrial activity, and the antiproliferative effects of melatonin in cancers, including head and neck squamous cell carcinoma (HNSCC), remain largely unknown. In this study, we analyzed the effects of melatonin on HNSCC cell lines (Cal-27 and SCC9), which were treated with 500 and 1000 µM melatonin. We found that the antiproliferative effect of melatonin is not mediated by the Bmal1 clock gene. Additionally, high doses of melatonin were observed to result in resynchronization of oscillatory circadian rhythm genes (Per2 and Sirt1). Surprisingly, the resynchronizing effect of melatonin on Per2 and Sirt1 did not produce alterations in the oscillation of mitochondrial respiratory activity. These results increase our understanding of the possible antiproliferative mechanisms in melatonin in the treatment of head and neck squamous cell carcinoma and suggest that its antiproliferative effects are independent of clock genes but are directly related to mitochondrial activity.

Chronodisruption and Loss of Melatonin Rhythm, Associated with Alterations in Daily Motor Activity and Mitochondrial Dynamics in Parkinsonian Zebrafish, Are Corrected by Melatonin Treatment.

Beyond sleep/wake, clock genes regulate the daily rhythms of melatonin production, motor activity, innate immunity, and mitochondrial dynamics, among others. All these rhythms are affected in Parkinson's disease (PD), suggesting that chronodisruption may be an early stage of the disease. The aim of this study was to evaluate the connection between clock genes and these rhythms in PD, and whether melatonin administration reestablished the normal clock function. Parkinsonism was induced with 600 µM MPTP (N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) in 24-120 h post fertilization (hpf) zebrafish embryos and melatonin was administered at a dose of 1 µM. Day-night melatonin rhythm disappeared in MPTP-treated embryos, which showed an advance in the activity phase in parallel with changes in the rhythm of clock genes. An alteration in the fission-to-fusion mitochondrial dynamics was also detected in parkinsonian embryos, increasing the former and leading to apoptosis. Melatonin administration to MPTP-treated embryos fully restored the circadian system, including the rhythms of clock genes, motor activity, melatonin rhythm, and mitochondrial dynamics, and decreasing apoptosis. Because clock-controlled rhythms such as sleep/wake alterations are early events in PD, the data here reported may point to chronodisruption as one initial pathophysiological event of the disease.

The Zebrafish, an Outstanding Model for Biomedical Research in the Field of Melatonin and Human Diseases.

The zebrafish has become an excellent model for the study of human diseases because it offers many advantages over other vertebrate animal models. The pineal gland, as well as the biological clock and circadian rhythms, are highly conserved in zebrafish, and melatonin is produced in the pineal gland and in most organs and tissues of the body. Zebrafish have several copies of the clock genes and of aanat and asmt genes, the latter involved in melatonin synthesis. As in mammals, melatonin can act through its membrane receptors, as with zebrafish, and through mechanisms that are independent of receptors. Pineal melatonin regulates peripheral clocks and the circadian rhythms of the body, such as the sleep/wake rhythm, among others. Extrapineal melatonin functions include antioxidant activity, inducing the endogenous antioxidants enzymes, scavenging activity, removing free radicals, anti-inflammatory activity through the regulation of the NF-κB/NLRP3 inflammasome pathway, and a homeostatic role in mitochondria. In this review, we introduce the utility of zebrafish to analyze the mechanisms of action of melatonin. The data here presented showed that the zebrafish is a useful model to study human diseases and that melatonin exerts beneficial effects on many pathophysiological processes involved in these diseases.

Age and Chronodisruption in Mouse Heart: Effect of the NLRP3 Inflammasome and Melatonin Therapy.

Age and age-dependent inflammation are two main risk factors for cardiovascular diseases. Aging can also affect clock gene-related impairments such as chronodisruption and has been linked to a decline in melatonin synthesis and aggravation of the NF-κB/NLRP3 innate immune response known as inflammaging. The molecular drivers of these mechanisms remain unknown. This study investigated the impact of aging and NLRP3 expression on the cardiac circadian system, and the actions of melatonin as a potential therapy to restore daily rhythms by mitigating inflammaging. We analyzed the circadian expression and rhythmicity of clock genes in heart tissue of wild-type and NLRP3-knockout mice at 3, 12, and 24 months of age, with and without melatonin treatment. Our results support that aging, NLRP3 inflammasome, and melatonin affected the cardiac clock genes expression, except for Rev-erbα, which was not influenced by genotype. Aging caused small phase changes in Clock, loss of rhythmicity in Per2 and Rorα, and mesor dampening of Clock, Bmal1, and Per2. NLRP3 inflammasome influenced the acrophase of Clock, Per2, and Rorα. Melatonin restored the acrophase and the rhythm of clock genes affected by age or NLRP3 activation. The administration of melatonin re-established murine cardiac homeostasis by reversing age-associated chronodisruption. Altogether, these results highlight new findings about the effects aging and NLRP3 inflammasome have on clock genes in cardiac tissue, pointing to continuous melatonin as a promising therapy to placate inflammaging and restore circadian rhythm in heart muscle. Additionally, light microscopy analysis showed age-related morphological impairments in cardiomyocytes, which were less severe in mice lacking NLRP3. Melatonin supplementation preserved the structure of cardiac muscle fibers in all experimental groups.

El extracto acuoso de orégano (Lippia graveolens HBK) del norte de México tiene actividad antioxidante sin mostrar un efecto tóxico in vitro e in vivo / The aqueous extract from oregano (Lippia graveolens HBK) from the north of Mexico has antioxidant activity without showing a toxic effect in vitro and in vivo

Desde tiempos antiguos la medicina tradicional ha usado extensamente las especies del género Lippia como analgésicos, antiinflamatorios, antipiréticos, antifúngicos, etc. Numerosos estudios describen diversos compuestos presentes en extractos acuosos, metanólicos, o aceites esenciales de estas plantas, siendo los flavonoides los compuestos más abundantes. Sin embargo, la composición y cantidad de los metabolitos secundarios dependen de la zona geográfica, factores climáticos, altitud, época de cosecha y estado de crecimiento de estas plantas. El objetivo de este estudio fue evaluar la actividad antioxidante del extracto acuoso de orégano (Lippia graveolens HBK) del Norte de México y su efecto tóxico in vitro e in vivo. La capacidad antioxidante del extracto acuoso se midió por el método de DPPH en seis diluciones del extracto (5-160 mg/mL) y se utilizó Trolox como referencia; para el efecto tóxico in vitro se usó el ensayo de citotoxicidad con larvas de Artemia salina. Para el efecto in vivo se emplearon 24 ratones árabes machos divididos en 6 grupos de animales (n=4): 4 grupos experimentales con 10, 100, 1000 y 5000 mg del extracto/ kg de peso administrados vía oral respectivamente, además de un grupo control positivo (5 mg de colchicina/kg de peso vía i.p) y un grupo control negativo (solo agua destilada). Después del tratamiento los ratones se sacrificaron y se colectaron muestras de hígado y riñón que se sometieron a estudios histológicos e histoquímicos, además se realizó un análisis cuantitativo. La actividad antioxidante del extracto acuoso de orégano se presentó a 160 mg/mL. La CL50 fue mayor a 1,000 ug/mL por lo que el extracto se considera no tóxico. En el análisis morfológico in vivo con distintas dosis del extracto acuoso de orégano no se observó un efecto tóxico. Los resultados obtenidos validan el uso del orégano en la medicina tradicional...

Since ancient times, traditional medicine has widely used species of the genus Lippia as analgesics, anti-inflammatory, antipyretic, antifungal, etc. Numerous studies describe several compounds present in aqueous extracts, methanol, or essential oils of these plants, being flavonoids the most abundant compounds. However, the composition and quantity of secondary metabolites depend on the geographical area, climatic factors, altitude, time of harvest and growth status of these plants. The objective of this study was to evaluate the antioxidant activity of aqueous extract of oregano (Lippia graveolens HBK) from the North of Mexico and its toxic effect in vitro and in vivo. The antioxidant activity of the aqueous extract was measured by DPPH method in six dilutions of the extract (5-160 mg / mL), Trolox was used as a reference. For the in vitro toxic effect, cytotoxicity assay with larvae of Artemia salina was used. For the in vivo effect, 24 males mice were used and divided into 6 groups (n = 4): 4 experimental groups with 10, 100, 1000 and 5000 mg extract / kg body weight administered orally respectively, also we used a group positive control (5 mg of colchicine / kg body weight administered via ip) and a negative control group (distilled water only). After treatment all mice were sacrificed, and samples from liver and kidney were collected and analyzed by histological and histochemical studies. Also a quantitative analysis was done. The antioxidant activity of aqueous extract of oregano was presented at 160 mg/mL. The LC50 was greater than 1.000 mg/mL, so the extract is considered nontoxic. In the morphological analysis in vivo with different doses of aqueous extract of oregano, no toxic effect was observed. The results validate the use of oregano in traditional medicine...