Melatonin and its brain metabolite N1‐acetyl‐5‐methoxykynuramine prevent mitochondrial nitric oxide synthase induction in parkinsonian mice

Producción CientíficaMelatonin prevents mitochondrial failure in models of sepsis through its ability to inhibit the expression and activity of both cytosolic (iNOS) and mitochondrial (i-mtNOS) inducible nitric oxide synthases. Because Parkinson's disease (PD), like sepsis, is associated with iNOS induction, we assessed the existence of changes in iNOS/i-mtNOS and their relation with mitochondrial dysfunction in the MPTP model of PD, which also displays increased iNOS expression. We also evaluated the role of melatonin (aMT) and its brain metabolite, N(1)-acetyl-5-methoxykynuramine (AMK), in preventing i-mtNOS induction and mitochondrial failure in this model of PD. Mitochondria from substantia nigra (SN) and, to a lesser extent, from striatum (ST) showed a significant increase in i-mtNOS activity, nitrite levels, oxidative stress, and complex I inhibition after MPTP treatment. MPTP-induced i-mtNOS was probably related to mitochondrial failure, because its prevention by aMT and AMK reduced oxidative/nitrosative stress and restored complex I activity. These findings represent the first experimental evidence of a potential role for i-mtNOS in the mitochondrial failure of PD and support a novel mechanism in the neuroprotective effects of aMT and AMK

Melatonin protects rats from radiotherapy-induced small intestine toxicity

Radiotherapy-induced gut toxicity is among the most prevalent dose-limiting toxicities following radiotherapy. Prevention of radiation enteropathy requires protection of the small intestine. However, despite the prevalence and burden of this pathology, there are currently no effective treatments for radiotherapy-induced gut toxicity, and this pathology remains unclear. The present study aimed to investigate the changes induced in the rat small intestine after external irradiation of the tongue, and to explore the potential radio-protective effects of melatonin gel. Male Wistar rats were subjected to irradiation of their tongues with an X-Ray YXLON Y.Tu 320-D03 irradiator, receiving a dose of 7.5 Gy/day for 5 days. For 21 days post-irradiation, rats were treated with 45 mg/day melatonin gel or vehicle, by local application into their mouths. Our results showed that mitochondrial oxidative stress, bioenergetic impairment, and subsequent NLRP3 inflammasome activation were involved in the development of radiotherapy-induced gut toxicity. Oral treatment with melatonin gel had a protective effect in the small intestine, which was associated with mitochondrial protection and, consequently, with a reduced inflammatory response, blunting the NF-κB/NLRP3 inflammasome signaling activation. Thus, rats treated with melatonin gel showed reduced intestinal apoptosis, relieving mucosal dysfunction and facilitating intestinal mucosa recovery. Our findings suggest that oral treatment with melatonin gel may be a potential preventive therapy for radiotherapy-induced gut toxicity in cancer patients.This study was partially supported by grant no. SAF2009-14037 from the Spanish Ministry of Economy and Competitivity (MINECO), GREIB.PT_2010_04 from the CEIBiotic Program of the University of Granada, Spain, and CTS-101 from the Consejería de Innovación, Ciencia y Empresa, Junta de Andalucía, Spain

Timing of host feeding drives rhythms in parasite replication

Circadian rhythms enable organisms to synchronise the processes underpinning survival and reproduction to anticipate daily changes in the external environment. Recent work shows that daily (circadian) rhythms also enable parasites to maximise fitness in the context of ecological interactions with their hosts. Because parasite rhythms matter for their fitness, understanding how they are regulated could lead to innovative ways to reduce the severity and spread of diseases. Here, we examine how host circadian rhythms influence rhythms in the asexual replication of malaria parasites. Asexual replication is responsible for the severity of malaria and fuels transmission of the disease, yet, how parasite rhythms are driven remains a mystery. We perturbed feeding rhythms of hosts by 12 hours (i.e. diurnal feeding in nocturnal mice) to desynchronise the hosts' peripheral oscillators from the central, light-entrained oscillator in the brain and their rhythmic outputs. We demonstrate that the rhythms of rodent malaria parasites in day-fed hosts become inverted relative to the rhythms of parasites in night-fed hosts. Our results reveal that the hosts' peripheral rhythms (associated with the timing of feeding and metabolism), but not rhythms driven by the central, light-entrained circadian oscillator in the brain, determine the timing (phase) of parasite rhythms. Further investigation reveals that parasite rhythms correlate closely with blood glucose rhythms. In addition, we show that parasite rhythms resynchronise to the altered host feeding rhythms when food availability is shifted, which is not mediated through rhythms in the host immune system. Our observations suggest that parasites actively control their developmental rhythms. Finally, counter to expectation, the severity of disease symptoms expressed by hosts was not affected by desynchronisation of their central and peripheral rhythms. Our study at the intersection of disease ecology and chronobiology opens up a new arena for studying host-parasite-vector coevolution and has broad implications for applied bioscience

Melatonin in antinociception: Its therapeutic applications

10.2174/157015912800604489Current Neuropharmacology102167-178CNUE

Learning, Cognitive And Ca1-Prefrontal Synaptic Impairments In A Mice Model Of Accelerated Senescence

Trabajo presentado en el 8th Fens Forum of Neuroscience, celebrado en Barcelona, Española, del 14-18 de julio de 2012Peer Reviewe