1,721,028 research outputs found
Melatonin reduces ventricular arrhythmias and preserves capillary perfusion during ischemia-reperfusion events in cardiomyopathic hamsters
No full textmelatonin reduces microvascular damage and insulin resistance in hamsters due to chronic intermittent hypoxia
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H2O2-induced lipid peroxidation in rat brain homogenates is greatly reduced by melatonin.
No full textInfluence of melatonin on the testicular regression induced by subcutaneous testosterone pellets in male rats kept in long or short photoperiod.
No full textDaily afternoon injections of 25 micrograms melatonin for 12 weeks had no effect on testicular weights of male rats kept in long photoperiod (14L:10D); similarly, exposure of rats to short photoperiod (2L:22D) had no effect on gonadal weight. However, rats maintained in a long or short photoperiod and implanted every 2 weeks with a 15 mm Silastic pellet containing testosterone showed a significant reduction in testicular weight; this effect was more pronounced in rats exposed to a short photoperiod. Melatonin injections in testosterone-treated rats in a long photoperiod exacerbated the inhibitory effects of testosterone alone. Subcutaneous 2-weekly implants of a beeswax pellet containing 1 mg melatonin reversed the effects of the melatonin injections on relative testicular weights but not those due to short photoperiod exposure. Testosterone implants significantly reduced pituitary LH values in long and short photoperiod-exposed animals, more particularly in those exposed to short photoperiod. Melatonin injections alone or in combination with melatonin pellets did not further exaggerate the depression in pituitary LH due to testosterone alone in long photoperiod-exposed animals; similarly melatonin pellets did not reverse the depression in pituitary LH observed. No significant differences in plasma prolactin concentrations or in thyroxine concentrations or free thyroxine index were observed after any combination of treatments. We therefore suggest that the effects observed with short photoperiod may be due to melatonin
Melatonin reduces kainate-induced lipid peroxidation in homogenates of different brain regions.
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Depression in rat pineal N-acetyltransferase activity and melatonin content produced by a hind leg saline injection is time and darkness dependent.
No full textIt has recently been shown that a 1.5-ml subcutaneous saline injection into the dorsal aspect of the hind limb induces a dramatic and rapid fall in N-acetyltransferase activity and melatonin content of the rat pineal gland at night. Since many studies have shown the opposite response to stress during the day, the first experiment was undertaken to test whether the timing of the saline injection at night influences the response of the pineal gland. In the present studies, rats were kept under light:dark (LD) cycles of 14:10 with lights out daily at 2000 h. Groups of rats were then given a saline injection at one of the following times: 2315, 0015, 0115, 0215, or 0315. Early in the dark phase (2315 and 0015) the saline injection depressed both the N-acetyltransferase (NAT) activity and the melatonin content of the pineal. As the animals were treated later in the dark period, the response became more blunted and, finally, disappeared. In the second experiment, animals that were kept in light during the usual dark period showed no pineal response when subjected to a hind leg injection of saline at either 2315 or 0315. Additionally, no response was seen in the two pineal parameters when rats had darkness onset delayed by 4 h (to 2400) and were then treated with saline at 0410. The results of these studies indicate that the pineal response to saline injection is time dependent. Also, if the nighttime rise in melatonin is suppressed by light exposure, a saline injection has no further inhibitory effect on pineal NAT activity or melatonin levels
Melatonin reduces H2O2-induced lipid peroxidation in homogenates of different rat brain regions.
No full textTechnique for repeated collection of blood that has just perfused the pineal gland of sheep.
No full textA long catheter was inserted into the superior sagittal sinus of sheep and was maneuvered to the level of the rectus sinus. The catheter was then secured to the head, neck, and shoulder of the animal. The distal end of the catheter was connected to a 3-way valve through which blood samples were collected and heparin was injected. Blood loss during surgery was minimal; recovery was quick and complete. The simple surgical technique enabled the collection of blood that has just perfused the pineal gland
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