کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
2808639 1157801 2007 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Rat brain opioid peptides-circadian rhythm is under control of melatonin
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی علوم غدد
پیش نمایش صفحه اول مقاله
Rat brain opioid peptides-circadian rhythm is under control of melatonin
چکیده انگلیسی

Several experiments have revealed an Endogenous Opioid System (EOS)-circadian rhythm. The brain-borne hormone, melatonin (MEL) has been shown to regulate the organism photoperiodic activity and may be implicated in the EOS-circadian rhythm. To explore this hypothesis, we studied the effect of functional pinealectomy on the EOS-circadian rhythm by measuring the immunoreactive content of Met-Enkephalin, Leu-Enkephalin and Synenkephalin in both hypothalamus and hippocampus of the rat brain, using standard radioimmunoassay procedures. Experimental animals exposed to white fluorescent light (WFL) for 15 days (<50 lux), displayed a disruption of the EOS-circadian rhythm, showing that absence of MEL induced a significant decrease of tissue content of enkephalin peptides at 01:00 h during the dark-phase of the 24-h circadian rhythm, when compared to control rats. Functional pinealectomized rats exposed to 4 or 6 h period of darkness (used to revert the effects induced by the absence of melatonin) significantly increased the tissue content of ME-IR and LE-IR, when compared to both controls and non-exposed WFL-treated rats. In addition, subcutaneous administration of exogenous melatonin (10, 100, 150, 300, 600 μg/kg), in WFL-treated animals produced significant dose-dependent increases of ME-IR in both brain regions tested. Finally, luzindole (melatonin receptor antagonist) administration, was not able to prevent the enkephalin tissue increase, induced with the MEL administration (150 μg/kg). This data suggest that MEL not only regulates the EOS-circadian rhythm, but also appears to modulate their synthesis in the rat brain from their respective neurons.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Neuropeptides - Volume 41, Issue 6, December 2007, Pages 389–397
نویسندگان
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