The extent of involvement of ouabain, hippocampal expression of Na+/K+-ATPase, and corticosterone/melatonin receptors ratio in modifying stress-induced behavior differs according to the stressor in context

The aim of this study was to assess the effect of two types of stressors, regarding the extent of involvement of ouabain (OUA), hippocampal sodium/potassium ATPase (NKA) expression, and the hippocampal corticosterone receptors (CR)/melatonin receptors (MR) expression ratio, on the behavioral and cardiovascular responses and on the hippocampal cornu ammonis zone 3 (CA3) and dentate gyrus (DG). Thirty adult male Wistar albino rats aged 7-8 months were exposed to either chronic immobilization or a disturbed dark/light cycle and treated with either ouabain or vehicle. In the immobilized group, in the absence of hippocampal corticosterone (CORT) changes, rats were non-responsive to stress, despite experiencing increased pulse rate, downregulated hippocampal sodium/potassium pump, and enhanced hippocampal CR/MR expression ratio. Prolonged darkness precipitated a reduced upright attack posture, with elevated CORT against hippocampal MR downregulation. Both immobilization and, to a lesser extent, prolonged darkness stress resulted in histopathological and ultrastructural neurodegenerative changes in the hippocampus. OUA administration did not change the behavioral resilience in restrained rats, despite persistence of the underlying biochemical derangements, added to decreased CORT. On the contrary, with exposure to short photoperiods, OUA reverted the behavior towards a combative reduction of inactivity, with unvaried CR/MR and CORT, while ameliorating hippocampal neuro-regeneration, with co-existing NKA and MR repressions. Therefore, the extent of OUA, hippocampal NKA expression, and CR/MR expression, and subsequent behavioral and cardiac responses and hippocampal histopathology, differ according to the type of stressor, whether immobilization or prolonged darkness.

Manual Acupuncture Stimulation of Paired Acupoints Can Relieve Sleep Disorder Possibly by Upregulating Pineal Melatonin Protein and Its Receptor mRNA Levels in the Suprachiasmatic Nucleus in Insomnia Rats / 针刺研究

OBJECTIVE: To observe the effect of manual acupuncture stimulation of paired "Baihui" (GV 20)+ "Shenmen" (HT 7), GV 20+ "Sanyinjiao" (SP 6), and GV 20+ non-acupoint on expression of melatonine (MT) and suprachiasmatic melatonin receptor 1 (MT1) and melatonin receptor 2 (MT2) mRNAs in insomnia rats, so as to explore their action difference and the underlying mechanism in improving insomnia. METHODS: Male SD rats were randomly divided into normal control (n=12), mo-del (n=8), GV 20+HT 7(n=12), GV 20+SP 6(n=11), and GV 20+ non-acupoint (n=10) groups. The insomnia model was established by intraperitoneal injection of Para-chlorophenylalanine suspension (50 mg/mL, 50 mg/100 g), once daily for 2 days. The abovementioned acupoints GV 20, bilateral HT 7, SP 6 and non-acupoints (the midpoint between the elbow-tip and armpit on the medial side of the upper-arm) were punctured with filiform needles and manipulated by rotating the needle for about 1 min which was repeated once again every 10 min during 30 minutes' needle-retaining. The treatment was conducted once daily for 7 days. The expression levels of MT immunoactivity in the conarium tissue, and MT1 and MT2 mRNAs of the suprachiasmatic nucleus (SCN) region were detected using immunohistochemistry and fluorescence quantitative real time-PCR, respectively. RESULTS: After modeling, the expression levels of pineal MT (an increase of gray value means a decrease of immunoactivity), SCN MT1 and MT2 mRNAs were notably down-regulated in the model group relevant to the normal control group (P0.05). CONCLUSION: Manual acupuncture stimulation of GV 20+ HT 7 and GV 20+ SP 6 can improve the sleep disorder in insomnia rats, which may be related to its effects in increasing the levels of pineal MT protein, and MT1 and MT2 mRNAs in hypothalamic SCN.

Melatonin and thermal stress regulate differential expression of heat shock proteins and melatonin receptors in spleen of mice.

Cellular defence by expression of heat shock proteins (Hsps) against stress stimulation is the most universal phenomenon in stress physiology. Melatonin is well known as an anti-stress molecule possessing hypothermic effects. It protects cells and tissues in stressed conditions. Individually, Hsp70 and melatonin shows its functional ability in stressed organisms as well as in immune functions. The aim of the present study was to determine the interaction of melatonin receptors (MT1/MT2) in exogenous melatonin modulated expression of heat shock proteins (Hsp70/Hsc70) in spleen of thermally stressed male mice. Results of the study showed thermal stress significantly increased the Hsp70/Hsc70 and melatonin receptor MT2 expression in spleen of mice. The administration of melatonin significantly increased Hsp70 expression, but decreased Hsc70 expression. Both MT1/MT2 receptor expressions increased after melatonin treatment, whereas thermal stress to melatonin treated mice showed decrease in MT1/MT2 receptor expression than the only melatonin treated mice. MT2 receptor is responding in all experimental conditions corresponding to changes in Hsp70 protein expression. Therefore, the present study might suggest that MT2 receptor is interacting in coordination of melatonin mediated heat shock proteins expression in mice spleen after thermally stressed conditions.

Changes of melatonin and melatonin receptors on 6-OHDA induced Parkinson's disease in rat / 中华行为医学与脑科学杂志

Objective To observe the changes of dopamine and its metabolites,melatonin,as well as melatonin receptors in the substantia nigras (SN) in 6-OHDA induced hemiparkinsonian rats.Methods PD rat was established by a unilateral injection of 6-OHDA into the right substantia nigra pars compacta and medial forebrain bundle.Rats were divided into PD groups and vehicle groups,and sacrificed at 10:00 and 22:00 respectively,at 3 and 6 weeks post-lesion.The contents of dopamine and its metabolites as well as melatonin were measured by HPLC.The expressions of MT1 and MT2 mRNA and protein were detected by RT-PCR and Western-Blot respectively.Results Dopamine levels declined by 83％ and 88％ respectively at 3 and 6 weeks post-lesion in the injected side of PD rats,compared with the contralateral side.Melatonin levels in the injected side increased by 22％ and 29％ respectively.However,melatonin increased by 46％ and 31％ respectively at 10:00 and 22:00,at 6 weeks post-lesion in the contralateral side,compared with the same side of the vehicle.The expressions of MT1 and MT2 receptors mRNA were significantly decreased by 91.04％ and 90.24％ respectively in comparison with the vehicle,while the protein expression of MT1 and MT2 receptors significantly declined by 58％ and 70％ respectively.Conclusion Increased melatonin and down-regulated MT1 and MT2 receptors in the lesioned SN in 6-OHDA-induced rats may be associated with the progression of PD.

Melatonin in Chagas´ disease: Possible therapeutic value / La melatonina en la enfermedad de Chagas: Su posible valor terapéutico

Chagas' disease is a severe health problem in Latin America, causing approximately 50 000 deaths a year, with approximately 18 million infected people. About 25-30% of the patients infected with Trypanosoma cruzi develop the chronic form of the disease. The protective response against T. cruzi depends on both innate and acquired immunity involving macrophages, natural killer cells, T and B lymphocytes, and the production of proinflammatory Th-1 cytokines. In addition, an increased nitric oxide (NO) production in macrophages leading to effective microbicidal action is needed to control parasitemia. Melatonin is detectable in T. cruzi and may play a role in promoting infection whereas, when administered in high doses during the acute phase of T. cruzi infection, it can decrease parasitemia while reducing NO production. During chronic disease progression, the sustained oxidative stress concomitant to myocardial damage could be reduced by administering melatonin. It is hypothesized that the coordinated administration of a melatonin agonist like the MT1/MT2 agonist ramelteon, that lacks antioxidant activity and may not affect NO production during the acute phase, and of melatonin in doses high enough to decrease oxidative damage, to preserve mitochondrial and to prevent cardiomyopathy during the chronic phase, could be a novel add-on treatment of Chagas´ disease.

La enfermedad de Chagas es un problema grave de salud en América Latina, causando cerca de 50 000 muertes al año y unos 18 millones de infectados. Alrededor del 25-30% de los pacientes infectados con Trypanosoma cruzi desarrollan la forma crónica de la enfermedad. La respuesta de defensa ante el T. cruzi depende de la inmunidad innata y adquirida con la participación de macrófagos, células “natural killer”, linfocitos T y B, y la producción de citoquinas proinflamatorias de tipo Th-1. Además, el aumento en la producción de óxido nítrico (NO) en los macrófagos lleva a una acción microbicida eficaz necesaria para controlar la parasitemia. La melatonina es detectable en T. cruzi y podría desempeñar un papel en la promoción de la infección como lo hace en el paludismo, mientras que, cuando se administra en dosis farmacológicas altas durante la fase aguda de la infección por T. cruzi, disminuye la parasitemia, aun en presencia de una reducción de la producción de NO. Durante la progresión de la enfermedad de Chagas a la cronicidad, el estrés oxidativo aumentado con el concomitante daño miocárdico podría reducirse por la administración de melatonina, de reconocida acción antioxidante. Se propone como un nuevo enfoque complementario en el tratamiento de la enfermedad de Chagas la administración durante la fase aguda de un agonista MT1/MT2 de la melatonina como el ramelteon, que carece de actividad antioxidante y podría no afectar a la producción de NO, y de melatonina durante la fase crónica de en dosis suficientemente altas como para disminuir el daño oxidativo y prevenir la miocardiopatía.

Effects of light on the expression patterns of circadian clock-related genes in the peripheral lymphocytes / 中华物理医学与康复杂志

Objective To explore the effects of light on the expression patterns of clock and clock-related genes in peripheral lymphocytes.To develop basic knowledge needed for clinical application of the circadian clock.Methods One hundred Sprague-Dawley rats were housed under constant dark(DD)or normal light-dark(LD 12:12)conditions for six weeks.Peripheral iymphoeytes were collected at different time points.The expression level of the clock gene and melatonin receptor genes mt1 and mt2 were detected using semi-quantitative RT-PCR.The data were analyzed with cosine software.Results Circadian expression of the genes was observed in both groups,but the peak phase,amplitude and strength of expression of each gene differed with the light conditions.Conclusion Light influences the expression of clock and clock-related genes in rats' peripheral lymphocytes.The clock gene might play an important role in regulating the expression of mt1 and mt2.

MOLECULAR CLONING AND MAKING OF THE cRNA PROBES OF MELATONIN RECEPTOR1a AND RETINOID-RELATED ORPHAN RECEPTORβ / 神经解剖学杂志

In order to study the expression of melatonin receptors Mel1a and RORβ in the human brain,and to furthe investigate the melatonin's function in Alzheimer's disease,two melatonin receptor cDNAs were cloned and introduced into pBluescript Ⅱ (KS+)vector.The recombinant plasmids were identified by using restriction enzymes and then sequenced.The results indicated that the cloned DNA sequences and the Genbandk Sequences were inentical.The cRNA probes made from them can be used in the in situ hybridization immunohistochemistry to detect the mRNA expression level in the future study.